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BackgroundScientific data on the safety and efficacy of flow diverter stents (FDS) for the treatment of unruptured internal carotid artery (ICA) aneurysms with compressive neuro-ophthalmological symptoms are scarce. We studied this subject in a retrospective international multicenter series, pooling data of 9 tertiary care neurointerventional departments.ObjectiveTo investigate, in a retrospective, multicentric cohort of patients presenting with visual or oculomotor symptoms attributed to a compressive carotid artery in an unruptured intracranial aneurysm, the safety and efficacy profiles of FDS, by analyzing neuro-opthalmologic symptom evolution following FDS placement, complications, and aneurysm obliteration rates.MethodsAll patients treated since 2015 with a FDS for an unruptured aneurysm of the ICA with signs of compressive cranial nerve symptoms (CN II, III, IV, VI) were included.ResultsWe treated 55 patients with 55 aneurysms; 21 (38.2%) patients had oculomotor and 15 (27.3%) visual symptoms only; 19 (34.5%) presented with a combination of both. Treatment-related morbidity/mortality occurred in 7.2% and 3.6%, respectively. At last imaging follow-up (13.1±10.5 months) rates of complete aneurysm occlusion, neck remnant, and aneurysm remnant were 72%, 14%, and 14%, respectively. At last clinical follow-up after 13±10.5 months, 19/51 (37.3%) patients had recovered completely and 18/51 (35.3%) had recovered at least partially from their neuro-ophthalmological symptoms. In multivariable models, a longer delay between symptom onset and treatment was associated with higher odds for incomplete recovery and lower odds for any improvement (aOR 1.03 (95% CI 1.01 to 1.07), p=0.047 and 0.04 (0–0.81), p=0.020). Incomplete recovery was independently associated with older age and fusiform aneurysms.ConclusionFDS are effective to treat patients with compressive aneurysms of the ICA causing neuro-ophthalmological symptoms, especially when treatment is initiated early after symptom onset, and aneurysm occlusion is adequate. However, serious complications are not rare.

Background Cardiovascular comorbidity anticipates poor prognosis of SARS-CoV-2 disease (COVID-19) and correlates with the systemic atherosclerotic transformation of the arterial vessels. The amount of aortic wall calcification (AWC) can be estimated on low-dose chest CT. We suggest quantification of AWC on the low-dose chest CT, which is initially performed for the diagnosis of COVID-19, to screen for patients at risk of severe COVID-19. Methods Seventy consecutive patients (46 in center 1, 24 in center 2) with parallel low-dose chest CT and positive RT-PCR for SARS-CoV-2 were included in our multi-center, multi-vendor study. The outcome was rated moderate (no hospitalization, hospitalization) and severe (ICU, tracheal intubation, death), the latter implying a requirement for intensive care treatment. The amount of AWC was quantified with the CT vendor's software. Results Of 70 included patients, 38 developed a moderate, and 32 a severe COVID-19. The average volume of AWC was significantly higher throughout the subgroup with severe COVID-19, when compared to moderate cases (771.7 mm3 (Q1 = 49.8 mm3, Q3 = 3065.5 mm3) vs. 0 mm3 (Q1 = 0 mm3, Q3 = 57.3 mm3)). Within multivariate regression analysis, including AWC, patient age and sex, as well as a cardiovascular comorbidity score, the volume of AWC was the only significant regressor for severe COVID-19 (p = 0.004). For AWC > 3000 mm3, the logistic regression predicts risk for a severe progression of 0.78. If there are no visually detectable AWC risk for severe progression is 0.13, only. Conclusion AWC seems to be an independent biomarker for the prediction of severe progression and intensive care treatment of COVID-19 already at the time of patient admission to the hospital; verification in a larger multi-center, multi-vendor study is desired.

Objective The NeVa M1 thrombectomy device is a novel hybrid-cell stent retriever with multifunctional zones for optimized retrieval of resistant clots located in the M1 segment of the middle cerebral artery. The objective was to evaluate the safety and efficacy of the NeVa in a “real-life” setting. Methods Twenty-nine consecutive patients (median age: 77 years) treated with the NeVa M1 for acute ischemic stroke of the M1 segement were retrospectively reviewed. First-pass and final modified thrombolysis in cerebral infarction (mTICI) scores, device-related complications, symptomatic intracranial hemorrhage, and 90-day modified Rankin scale (mRS) scores are reported. Primary outcome parameters were first-pass mTICI 2b-3 reperfusion and mRS 0–2 at 90 days. Results Median National Institutes of Health Stroke Scale scores decreased from 16 to 12 after treatment. mTICI 2b-3 reperfusion rates were 55% after the first pass, 79% after 1–2 passes, and 100% after the final pass. mTICI 2c-3 was obtained in 48% after the first pass, 62% after 1–2 passes, and 72% after the final pass. Rescue treatment was performed in 4 patients (14%). Device-related complications included 1 asymptomatic caroticocavernous fistula, 1 asymptomatic M2 dissection, and 1 symptomatic intracranial hemorrhage. The procedure-related vasospasm rate was 48%. A 90-day mRS of 0–2 was achieved by 31%. Conclusions The NeVa M1 provides a high first-pass complete reperfusion rate with an adequate safety profile. To retrieve resistant clots, the stent design exerts high mechanical traction forces, which may trigger vasospasm and vessel wall damage. Large, comparative studies are warranted to draw a definite conclusion on this device.

European radiology 31(6), 4148-4155 (2021). doi:10.1007/s00330-020-07615-w, Published by Springer, Berlin

Purpose: Little is known about catheter-based endovascular treatment of vertebrobasilar artery branch occlusion (VEBABO) in acute ischemic stroke (AIS). Nonetheless, the experience of mechanical thrombectomy (MT) in distal small sized arteries of the anterior circulation seems promising in AIS. In this multicenter study, we report the feasibility, efficacy and safety of MT in VEBABO. Methods: Retrospective analysis of consecutive AIS patients treated with MT due to VEBABO including posterior and anterior inferior cerebellar artery (PICA, AICA) and superior cerebellar artery (SCA) occlusions at seven tertiary care centers between January 2013 and May 2020. Baseline demographics and angiographic outcomes including recanalization success of the affected cerebellar arteries and procedural complications were recorded. Clinical outcomes were evaluated by the modified Rankin scale (mRS) at discharge and 90 days. Results: Out of 668 endovascularly treated posterior circulation strokes we identified 16 (0.02%) cases with MT for VEBABO. Most frequently, MT of the SCA was done (13/16, 81%). Most VEBABOs occurred after MT of initial basilar/posterior cerebral artery occlusion (9/16, 56%). In 10/16 (63%) procedures, the affected VEBABO was successfully recanalized. Out of four patients three (75%) with isolated VEBABO had benefited from endovascular therapy. Subarachnoid hemorrhage was observed in 3/16 (19%) procedures. The rate of favorable outcome (mRS ≤2) was 40% at discharge and 47% at 90-day follow-up. Mortality was 13% (2/15). Conclusion: The use of MT for VEBABO is rare but appears to be feasible and effective; however, the comparatively high rate of procedure-related hemorrhage highlights that the indications for MT in these occlusion sites should be carefully weighed up.

To evaluate artifact reduction by virtual monoenergetic images (VMI) and metal artifact reduction algorithms (MAR) as well as the combination of both approaches (VMIMAR) compared to conventional CT images (CI) as standard of reference. In this retrospective study, 35 patients were included who underwent spectral-detector CT (SDCT) with additional MAR-reconstructions due to artifacts from coils or clips. CI, VMI, MAR and VMIMAR (range: 100–200 keV, 10 keV-increment) were reconstructed. Region-of-interest based objective analysis was performed by assessing mean and standard deviation of attenuation (HU) in hypo- and hyperdense artifacts from coils and clips. Visually, extent of artifact reduction and diagnostic assessment were rated. Compared to CI, VMI ≥ 100 keV, MAR and VMIMAR between 100–200 keV increased attenuation in hypoattenuating artifacts (CI/VMI200keV/MAR/VMIMAR200keV, HU: −77.6 ± 81.1/−65.1 ± 103.2/−36.9 ± 27.7/−21.1 ± 26.7) and decreased attenuation in hyperattenuating artifacts (HU: 47.4 ± 32.3/42.1 ± 50.2/29.5 ± 18.9/20.8 ± 25.8). However, differences were only significant for MAR in hypodense and VMIMAR in hypo- and hyperdense artifacts (p ≥140/100keV, MAR and VMIMAR≥100keV. Diagnostic assessment of surrounding brain tissue was significantly improved in VMI≥100keV, MAR and VMIMAR≥100keV. The combination of VMI and MAR facilitates a significant reduction of artifacts adjacent to intracranial coils and clips. Hence, if available, these techniques should be combined for optimal reduction of artifacts following intracranial aneurysm treatment.

The management of residual or persistent intracranial aneurysms after flow-diversion therapy is not well defined in the literature. In this multicentric study, we report clinical and angiographic outcomes of 11 patients that underwent retreatment for 12 aneurysms initially treated with flow-diverter stents. The median patient age was 53 years. Aneurysms (median size, 7.3 mm) were located at the internal carotid artery in 9 cases, and at the posterior circulation in 3. Treatment strategies, complications, and angiographic outcome were retrospectively assessed. Retreatment was feasible in all cases and performed by overlapping flow-diverter implantation. Overall, 12 side vessels were covered during retreatment, whereof 10 (83.3%) remained patent until mid-term follow-up. There were no further technical or symptomatic complications and no treatment-related morbidity. Angiographic follow-up (median, 17 months) showed improved aneurysm occlusion in all patients. Complete or near-complete aneurysm occlusion was achieved in 11 aneurysms (91.7%). Required retreatment after failed flow-diversion therapy can be performed with adequate safety and efficacy by placement of additional flow-diverter stents.

Background: Stent retriever technology has evolved, and significantly longer devices have become available for mechanical thrombectomy (MT) of large cerebral vessel occlusions in ischemic stroke. We hypothesized that increased stent retriever length may improve the rate of complete angiographic reperfusion and decrease the respective number of attempts, resulting in a better clinical outcome. Methods: Retrospective analysis of patients with large vessel occlusion in the anterior and posterior circulation treated with stent retriever MT. The study group was dichotomized into short (20 mm) and long (>20 mm) retrievers using propensity matching. In the anterior circulation, the clot burden score was evaluated. Primary end points were first-pass modified thrombolysis in cerebral infarction (mTICI) 3 reperfusion and first-pass mTICI ≥ 2b reperfusion, and the secondary end point was functional independence (defined as modified Rankin Scale score 0–2) at discharge and 90 days. Results: Overall, 394 patients were included in the analysis. In the anterior circulation, short stent retrievers had a significantly higher rate of first-pass reperfusion in cases with low clot burden (mTICI 3: 27% vs. 17%; p = 0.009; mTICI ≥ 2b: 42 vs. 30%; p = 0.005) and in middle cerebral artery occlusions (mTICI ≥ 2b: 51 vs. 41%; p = 0.024). Higher rates of favorable outcome at discharge and 90 days were observed for the short stent retriever group (p < 0.001). Conclusion: Stent retriever length should be adjusted to clot burden score and vessel occlusion site.

BackgroundMechanical thrombectomy (MT) is a safe and effective therapy for ischemic stroke. Nevertheless, very elderly patients aged ≥90 years were either excluded or under-represented in previous trials. It remains uncertain whether MT is warranted for this population or whether there should be an upper age limit.MethodsWe retrospectively reviewed 79 patients with stroke aged ≥90 years from three neurointerventional centers who underwent MT between 2013 and 2017. Good functional outcome was defined as modified Rankin scale (mRS) ≤2 and assessed at 90-day follow-up. Successful recanalization was graded by Thrombolysis in Cerebral Infarction Scale (TICI) ≥2 b. Feasibility and safety assessments included unsuccessful recanalization attempts (TICI 0), time from groin puncture to recanalization, symptomatic intracranial hemorrhage (sICH), mortality, and intervention-related serious adverse events.ResultsOnly occlusions within the anterior circulation were included. Median time from groin puncture to recanalization was 39 min (IQR 25–57 min). The rate of successful recanalization (TICI ≥2 b) was 69.6% (55/79). Good functional outcome (mRS ≤2) at 90 days was observed in 16% (12/75) of patients. In-hospital mortality was 29.1% (23/79) and increased significantly at 90 days (46.7%, 35/75; pConclusionMT in nonagenarians leads to high mortality rates and less frequently good functional outcome compared with younger patient cohorts in previous large randomized trials. However, MT appears to be safe and beneficial for a certain number of very elderly patients and therefore should generally not be withheld from nonagenarians.

Purpose To evaluate the reduction of artifacts caused by total hip replacements (THR) in dual-layer DECT (DLCT) provided by the combination of virtual monoenergetic images (VMI) and orthopedic metal artifact reduction (MAR). Materials and Methods A total of 24 consecutive patients carrying THR, who received DLCT, were included. Four different images were reconstructed from the same CT dataset: a) conventional images (CI), b) conventional images with orthopedic metal artifact reduction (CIMAR) c) VMI and d) VMI combined with orthopedic metal artifact reduction (VMIMAR). VMI and VMIMAR were reconstructed at 140 keV, 160 keV, 180 keV and 200 keV. Attenuation (HU) and noise (SD) were measured in order to evaluate reduction of hypodense and hyperdense artifacts, evaluate reduction of image noise as well as to calculate contrast-to-noise ratios (CNR). Image quality was additionally rated with regard to: a) extent of artifact reduction and assessment of b) pelvic organs, c) bone and d) muscle adjacent to the metal implants. Statistical analysis was performed using Wilcoxon test. Results VMIMAR at high keV, 140, 160, 180 and 200 keV, led to the greatest reduction of hypodense artifacts in comparison to plain VMI or CIMAR (p Conclusion The combination of VMI and MAR yields strongest reduction of hypo- and hyperdense artifacts caused by total hip replacements in staging DLCT in comparison to each technique by itself.

Background Data on outcome of endovascular treatment in patients with acute ischaemic stroke due to large vessel occlusion suffering from intravenous thrombolysis-associated intracranial haemorrhage prior to mechanical thrombectomy remain scarce. Addressing this subject, we report our multicentre experience. Methods A retrospective analysis of consecutive acute ischaemic stroke patients treated with mechanical thrombectomy due to large vessel occlusion despite the pre-interventional occurrence of intravenous thrombolysis-associated intracranial haemorrhage was performed at five tertiary care centres between January 2010–September 2020. Baseline demographics, aetiology of stroke and intracranial haemorrhage, angiographic outcome assessed by the Thrombolysis in Cerebral Infarction score and clinical outcome evaluated by the modified Rankin Scale at 90 days were recorded. Results In total, six patients were included in the study. Five individuals demonstrated cerebral intraparenchymal haemorrhage on pre-interventional imaging; in one patient additional subdural haematoma was observed and one patient suffered from isolated subarachnoid haemorrhage. All patients except one were treated by the ‘drip-and-ship’ paradigm. Successful reperfusion was achieved in 4/6 (67%) individuals. In 5/6 (83%) patients, the pre-interventional intracranial haemorrhage had aggravated in post-interventional computed tomography with space-occupying effect. Overall, five patients had died during the hospital stay. The clinical outcome of the survivor was modified Rankin Scale=4 at 90 days follow-up. Conclusion Mechanical thrombectomy in patients with intravenous thrombolysis-associated intracranial haemorrhage is technically feasible. The clinical outcome of this subgroup of stroke patients, however, appears to be devastating with high mortality and only carefully selected patients might benefit from endovascular treatment.

Endovascular thrombectomy (EVT) is the standard of care for anterior circulation acute ischemic stroke (AIS) with large vessel occlusion (LVO). Young patients with AIS-LVO have distinctly different underlying stroke mechanisms and etiologies. Much is unknown about the safety and efficacy of EVT in this population of young AIS-LVO patients. All consecutive AIS-LVO patients aged 50 years and below were included in this multicenter cohort study. The primary outcome measured was functional recovery at 90 days, with modified Rankin Scale of 0-2 deemed as good functional outcome. A total of 275 AIS-LVO patients that underwent EVT from 10 tertiary centers in Germany, Sweden, Singapore, and Taiwan were included. Successful reperfusion was achieved in 85.1% (234/275). Good functional outcomes were achieved in 66.0% (182/275). Arterial dissection was the most prevalent stroke etiology (42/195, 21.5%). National Institutes of Health Stroke Scale (NIHSS) score at presentation was inversely related to good functional outcomes (aOR: 0.92, 95% CI: 0.88-0.96 per point increase, p

To identify factors associated with early angiographic reperfusion improvement (EARI) following intra-arterial fibrinolytics (IAF) after failed or incomplete mechanical thrombectomy (MT). A subset of patients treated with MT and IAF rescue after incomplete reperfusion included in the INFINITY (INtra-arterial FIbriNolytics In ThrombectomY) multicenter observational registry was analyzed. Multivariable logistic regression was used to identify factors associated with EARI. Heterogeneity of the clinical effect of EARI on functional independence (defined as modified Rankin Score &le, 2) was tested with interaction terms. A total of 228 patients (median age: 72 years, 44.1% female) received IAF as rescue for failed or incomplete MT and had a post-fibrinolytic angiographic control run available (50.9% EARI). A cardioembolic stroke origin (adjusted odds ratio (aOR) 3.72, 95% confidence interval (CI) 1.39&ndash, 10.0) and shorter groin puncture to IAF intervals (aOR 0.82, 95% CI 0.71&ndash, 0.95 per 15-min delay) were associated with EARI, while pre-interventional thrombolysis showed no association (aOR 1.15, 95% CI 0.59&ndash, 2.26). The clinical benefit of EARI after IAF seemed more pronounced in patients without or only minor early ischemic changes (Alberta Stroke Program Early Computed Tomography Score (ASPECTS) &ge, 9, aOR 4.00, 95% CI 1.37&ndash, 11.61) and was absent in patients with moderate to severe ischemic changes (ASPECTS &le, 8, aOR 0.94, 95% CI 0.27&ndash, 3.27, p for interaction: 0.095). Early rescue and a cardioembolic stroke origin were associated with more frequent EARI after IAF. The clinical effect of EARI seemed reduced in patients with already established infarcts. If confirmed, these findings can help to inform patient selection and inclusion criteria for randomized-controlled trials evaluating IAF as rescue after MT.

Background and Purpose Data on safety and efficacy of intra-arterial (IA) fibrinolytics as adjunct to mechanical thrombectomy (MT) are sparse.Methods INtra-arterial FIbriNolytics In ThrombectomY (INFINITY) is a retrospective multi-center observational registry of consecutive patients with anterior circulation large-vessel occlusion ischemic stroke treated with MT and adjunctive administration of IA fibrinolytics (alteplase [tissue plasminogen activator, tPA] or urokinase [UK]) at 10 European centers. Primary outcome was the occurrence of symptomatic intracranial hemorrhage (sICH) according to the European Cooperative Acute Stroke Study II definition. Secondary outcomes were mortality and modified Rankin Scale (mRS) scores at 3 months.Results Of 5,612 patients screened, 311 (median age, 74 years; 44.1% female) received additional IA after or during MT (194 MT+IA tPA, 117 MT+IA UK). IA fibrinolytics were mostly administered for rescue of thrombolysis in cerebral infarction (TICI) 0-2b after MT (80.4%, 250/311). sICH occurred in 27 of 308 patients (8.8%), with an increased risk in patients with initial TICI0/1 (adjusted odds ratio [aOR], 2.3; 95% confidence interval [CI], 1.1 to 5.0 per TICI grade decrease) or in those with intracranial internal carotid artery occlusions (aOR, 3.7; 95% CI, 1.2 to 12.5). In patients with attempted rescue of TICI0-2b and available angiographic follow-up, 116 of 228 patients (50.9%) showed any angiographic reperfusion improvement after IA fibrinolytics, which was associated with mRS ≤2 (aOR, 3.1; 95% CI, 1.4 to 6.9).Conclusions Administration of IA fibrinolytics as adjunct to MT is performed rarely, but can improve reperfusion, which is associated with better outcomes. Despite a selection bias, an increased risk of sICH seems possible, which underlines the importance of careful patient selection.

BackgroundWhether to approach distal occlusions endovascularly or not in medium-sized vessels secondary to proximal large vessel occlusion stroke remains unanswered.ObjectiveTo investigates the technical feasibility and safety of thrombectomy for secondary posterior circulation distal, medium vessel occlusions (DMVO).MethodsTOPMOST (Treatment fOr Primary Medium vessel Occlusion STroke) is an international, retrospective, multicenter, observational registry of patients treated for distal cerebral artery occlusions. This study subanalysis endovascularly treated occlusions of the posterior cerebral artery in the P2 and P3 segment secondary preprocedural or periprocedural thrombus migration between January 2014 and June 2020. Technical feasibility was evaluated with the modified Thrombolysis in Cerebral Infarction (mTICI) scale. Procedural safety was assessed by the occurrence of symptomatic intracranial hemorrhage (sICH) and intervention-related serious adverse events.ResultsAmong 71 patients with secondary posterior circulation DMVO who met the inclusion criteria, occlusions were present in 80.3% (57/71) located in the P2 segment and in 19.7% (14/71) in the P3 segment. Periprocedural migration occurred in 54.9% (39/71) and preprocedural migration in 45.1% (32/71) of cases. The first reperfusion attempt led in 38% (27/71) of all cases to mTICI 3. On multivariable logistic regression analysis, increased numbers of reperfusion attempts (adjusted odds ratio (aOR)=0.39, 95% CI 0.29 to 0.88, p=0.009) and preprocedural migration (aOR=4.70, 95% CI,1.35 to 16.35, p=0.015) were significantly associated with mTICI 3. sICH occurred in 2.8% (2/71).ConclusionThrombectomy for secondary posterior circulation DMVO seems to be safe and technically feasible. Even though thrombi that have migrated preprocedurally may be easier to retract, successful reperfusion can be achieved in the majority of patients with secondary DMVO of the P2 and P3 segment.

Complete reperfusion (mTICI 3) in anterior circulation ischemic stroke patients after a single mechanical thrombectomy (MT) pass has been identified as a predictor of favorable outcome (modified Rankin Score 0-2) and defined as true first-pass effect recently. This effect has not yet been demonstrated in posterior circulation ischemic stroke. We hypothesized a true first-pass effect for the subgroup of acute basilar artery occlusions (BAO).Consecutive patients with acute thromboembolic occlusions in the posterior circulation, treated between 2010 and 2017, were screened and all BAO patients with complete angiographic reperfusion and known symptom onset included for unmatched and matched analysis after adjustment for multiple confounding factors (demographics, time intervals, stroke severity, posterior circulation Alberta Stroke Program early computed tomography Score and comorbidity. The primary objective was outcome at 90 days between matched cohorts of single pass vs. multi pass complete reperfusion patients.90 MTs in BAO were analyzed, yielding 56 patients with known symptom onset, in whom we achieved complete reperfusion (mTICI 3), depending on whether complete reperfusion was achieved after a single pass (n = 28) or multiple passes (n = 28). Multivariable analysis of 56 non-matched patients revealed a significant association between first-pass complete reperfusion and favorable outcome (p 0.01). In matched cohorts (n = 7 vs. n = 7), favorable outcome was only seen if complete reperfusion was achieved after a single pass (86% vs. 0%).Single pass complete reperfusion in acute basilar artery occlusion is an independent predictor of favorable outcome. Achieving complete reperfusion after multiple passes might impair favorable patient recovery.

BACKGROUND AND PURPOSE: CTA provides a noninvasive alternative technique to DSA in the follow-up after endovascular aneurysm treatment to evaluate aneurysm occlusion and exclude intraluminal narrowing after stent or flow-diverter implantation; however, assessability may be impeded by stent material artifacts. The objective of this in vitro study was to compare the visual assessability of different conventional stents and flow diverters as well as different reconstructions of dual-layer CT images. MATERIALS AND METHODS: Four conventional intracranial stents and 4 flow diverters were implanted in identical aneurysm phantoms. Conventional and monoenergetic images (40, 50, 60, 90, 120, 180 keV) were acquired to evaluate attenuation alteration, visible lumen diameter, and SNR. Image quality was rated subjectively by 2 independent radiologists using a 4-point Likert scale. RESULTS: Low kiloelectron volt (40–60 keV) monoenergetic reconstructions showed an improved SNR and an improved lumen density ratio compared with high kiloelectron volt reconstructions (90–180 keV) and conventional reconstructions, however without reaching significance compared with the latter. Assessment of the adjacent aneurysm and subjective evaluation was not affected by the imaging technique and stent type. Artifact susceptibility varied with the device used and increased among flow diverters. CONCLUSIONS: Low kiloelectron volt reconstructions improved the assessment of the stent lumen in comparison with high kiloelectron volt reconstructions. No significant improvement in image quality could be shown compared with conventional images. For some devices, iodine-specific reconstructions led to severe artifacts and are therefore not recommended. There was no relevant improvement in the assessability of the adjacent aneurysm.

BackgroundEndovascular thrombectomy (ET) has transformed acute ischemic stroke (AIS) therapy in patients with large vessel occlusion (LVO). Left ventricular systolic dysfunction (LVSD) decreases global cerebral blood flow and predisposes to hypoperfusion. We evaluated the relationship between LVSD, as measured by LV ejection fraction (LVEF), and clinical outcomes in patients with anterior cerebral circulation LVO who underwent ET.MethodsThis multicenter retrospective cohort study examined anterior circulation LVO AIS patients from six international stroke centers. LVSD was measured by assessment of the echocardiographic LVEF using Simpson’s biplane method of discs according to international guidelines. LVSD was defined as LVEF ResultsWe included 440 AIS patients with LVO who underwent ET. On multivariate analyses, pre-existing diabetes mellitus (OR 2.05, 95% CI 1.24 to 3.39;p=0.005), unsuccessful reperfusion (Treatment in Cerebral Infarction (TICI) grade 0-2a) status (OR 4.21, 95% CI 2.04 to 8.66; pConclusionAnterior circulation LVO AIS patients with LVSD have poorer outcomes after ET, suggesting the need to consider cardiac factors for ET, the degree of monitoring and prognostication post-procedure.

Background Patients aged ≥90 were excluded or under‐represented in past thrombectomy trials; thus, uncertainty remains whether treatment benefits can be expected regardless of age. This study investigates outcome and safety of thrombectomy in nonagenarians to improve decision making in a real‐world setting. Methods and Results All currently available data of patients aged ≥90 enrolled in the GSR‐ET (German Stroke Registry–Endovascular Treatment) were combined with a smaller cohort from 3 tertiary stroke centers. Baseline characteristics, procedural (Thrombolysis in Cerebral Infarction scale) and functional outcomes (modified Rankin Scale; mRS ), as well as complications (symptomatic intracranial hemorrhage, serious adverse events; SAEs) were analyzed. Good functional outcome was defined as mRS ≤3 at 90‐days. 203 patients with anterior circulation stroke and prestroke mRS ≤3 were included. The rate of successful recanalization (Thrombolysis in Cerebral Infarction scale ≥2b) was 75.9% (154/203). Good functional outcome ( mRS ≤3) was observed in 21.6% (41 of 193) at 90‐days. In‐hospital mortality was 27.1% (55 of 203) and increased significantly at 90 days to 48.9% (93 of 190; P CI , 1.01–3.70; P =0.046) and initial National Institute of Health Stroke Scale (adjusted odds ratio, 0.85; 95% CI , 0.76–0.97; P =0.014) as independent predictors for good outcome. Patients with successful recanalization had a significant ( P =0.001) shift of mRS distribution with higher rates of good functional outcomes (23.8% [34 of 143] versus 14.9% [7 of 47]) and lower mortality at 90‐days (46.8% [67 of 143] versus 55.3% [26 of 47]). Conclusions Despite high mortality and less frequent favorable outcome, our data suggest that thrombectomy is still effective and safe for nonagenarians. Decision making for thrombectomy in patients aged ≥90 should be based on a case‐by‐case basis with regard to initial National Institute of Health Stroke Scale and Alberta Stroke Program Early CT Score.

Purpose To evaluate the correlation between left atrial diverticula (LAD) and left-sided septal pouches (LSSP) with ischemic brain alterations in MRI. Methods A retrospective analysis of 174 patients who received both, a dedicated cardiac CT angiography (CCTA) and a brain MRI examination was performed. Two radiologists independently reviewed all examinations for the presence of LAD and LSSP as well as ischemic alterations of the brain. Subsequently, the correlation between these cardiac and cerebral findings as well as to other potentially related risk factors was assessed. Results 71 LAD (total prevalence 41%) and 65 LSSP (total prevalence 37%) were identified in 174 patients. Combined prevalence was 10%. Ischemic brain alterations were found in patients with a LAD in 42.3% (30/71) and with a LSSP in 64.6% (42/65). Patients without any anatomical variant in the left atrium showed ischemic brain alterations in 39.4% (26/66). The presence of a LSSP was associated with an increased risk for ischemic brain alterations in multivariate logistic regression analysis after adjusting for other risk factors (OR = 3.57, 95% CI = 0.51–2.09, p Conclusion In our study cohort LAD and LSSP are highly prevalent anatomical structures within the left atrium. Patients with LSSP showed an approximated 3.5-fold higher probability for ischemic brain alterations. Therefore, LSSP should be considered as a potential risk factor for cardioembolic strokes and its presence should be stated in cardiac CT reports.

To evaluate quantitative iodine density mapping (IDM) with spectral detector computed tomography (SDCT) as a quantitative biomarker for separation of vertebral trabecular bone metastases (BM) from healthy-appearing trabecular bone (HTB). IRB-approved retrospective single-center-study of portal venous SDCT datasets acquired between June 2016 and March 2017. Inclusion of 43 consecutive cancer patients with BM and 40 without. Target lesions and non-affected control vertebrae were defined using follow-up imaging, MRI, and/or bone scintigraphy. ID and standard deviation were determined with ROI measures by two readers in (a) bone metastases, (b) HTB of BM patients and controls, and (c) ID of various vessels. Volumetric bone mineral density (vBMD) of the lumbar spine and age were recorded. Multivariate ROC analyses und Wilcoxon test were used to determine thresholds for separation of BM and HTB. p

Among patients with acute ischemic stroke treated with mechanical thrombectomy (MT), patients with diabetes (DP) show a poorer outcome compared with patients without diabetes (NDP). This study aims to provide a comprehensive analysis of factors associated with unfavorable outcome in DP receiving MT for stroke of the anterior circulation.This study included 317 of 498 consecutive patients who received interventional treatment for acute ischemic stroke in the terminal internal carotid artery and/or middle cerebral artery, including 46 DP. The study data included pre- and posttreatment stroke computed tomography, including perfusion data, collateral status, treatment data including treatment times, pre-existing cardiovascular risk factors, cerebrovascular events, comorbidities, laboratory parameters, and medication. Neurologic status was assessed at baseline (National Institute of Health Stroke Scale [NIHSS]/modified Rankin Scale [mRS]) and after 90 days (mRS 90).Compared with NDP, DP showed a significantly poorer outcome (mRS902) (P0.05). Collateralization and infarct core size did not differ between groups, whereas the penumbra was significantly smaller in DP than in NDP (P0.05). The poorer mRS90 outcome (mRS902) in DP was associated with poor collaterals (P = 0.01) and hyperglycemia on admission (P0.05). Shorter time to reperfusion was associated with favorable mRS90 in the NDP (P0.001) but not the DP (P = 0.49) group. In univariate logistic regression, the following parameters were significantly associated with mRS90: diabetes, hyperglycemia at admission, time to reperfusion, and the NIHSS score (P0.05 each). In multivariate analyses and partition regression models of all variables, DP with admission hyperglycemia (≥132 mg/dL) and older age (≥66 years) showed a particularly poor outcome.The main factors for an unfavorable outcome of DP after MT are admission hyperglycemia, age, and NIHSS score.

To evaluate calcium suppressed images (CaSupp) in dual-layer detector computed tomography (DLCT) for the detection of bone marrow edema (BME) in vertebral fractures.The retrospective study was approved by the institutional review board. 34 patients with synchronous DLCT and MRI, who were diagnosed with one or more acute vertebral fractures, were included. MRI were systematically analyzed as reference standard. Two blinded and independent readers evaluated CaSupp for vertebral BME. Additionally, both readers determined the optimal calcium suppression indices (CaSupp-I) for visualization of BME in consensus and correlated the CaSupp-I with parallel measurement of trabecular density as surrogate parameter for bone mineral density. ROI-based measurements of the contrast-to-noise ratios (CNR) were also conducted. Interrater agreement was determined by kappa-statistics. CNR were analyzed using Wilcoxon signed rank test.Fifty-seven acute fractured vertebrae out of 383 vertebrae (14.9%) were found. CaSupp yielded an average sensitivity of 87% and specificity of 99%, a positive predictive value of 95%, a negative predictive value of 98% and an accuracy of 97% for the detection of fracture-associated edema. Interrater agreement was excellent (kappa 0.91). Increase in CNR of BME correlated with increasing CaSupp-I. Edema adjacent to the cortical endplates was better visualized using CaSupp-I of 70 and 80, while extensive edema was better visualized using a CaSupp-I of 90 and 100 (chi2 0.0001). No correlation between optimal CaSupp-I and trabecular density was found (p 0.2).CaSupp reconstructed from DLCT enable visualization and detection of BME in traumatic fractured vertebrae with high diagnostic accuracy using CaSupp-I of 70-100.

The stent retriever assisted vacuum-locked extraction (SAVE) technique was introduced as an effective thrombectomy method in stroke patients suffering from intracranial large vessel occlusion (LVO). This article presents our multicenter, large-scale experience with SAVE. The study involved a retrospective core team analysis of 200 patients undergoing mechanical thrombectomy using the SAVE technique due to intracranial LVO at 4 German centers. Primary endpoints were first-pass and overall complete/near complete reperfusion, defined as a modified thrombolysis in cerebral infarction (mTICI) score of 2c and 3. Secondary endpoints were the number of passes, time from groin puncture to reperfusion, embolization to new territories (ENT), postinterventional symptomatic intracranial hemorrhage (sICH), and favorable outcome at discharge, defined as a modified Rankin Scale (mRS) score ≤ 2. The median age was 78 years (interquartile range IQR 68–85). Median National Institutes of Health stroke scale (NIHSS) at admission was 16 (IQR 12–20). Occlusions sites were: internal carotid artery (ICA-T) in 39/200 (19.5%), M1 in 126/200 (63%), M2 in 30/200 (15%), and others in 5/200 (2.5%) cases. The primary endpoints were documented in 114/200 (57% first pass mTICI 2c or 3) and 154/200 (77% overall mTICI 2c or 3) patients, respectively. The overall median time from groin puncture to reperfusion was 34 min (IQR 25–52) with a median of 1 (IQR 1–2) attempts. An ENT was observed in 3 patients (1.5%) and the rate of sICH was 2.6%. The rate of successful reperfusion (mTICI ≥ 2b) on final angiograms was 95%. At discharge, 73/200 (36.5%) patients revealed a favorable outcome. Mechanical thrombectomy using the SAVE technique seems to be effective, fast and safe. First-line use of SAVE leads to high rates of complete and near complete reperfusion.

We aimed to test the potential of phantomless volumetric bone mineral density (PLvBMD) measurements for the determination of volumetric bone mineral density (vBMD) in routine contrast-enhanced computed tomography (CECT). We evaluated 56 tri-phasic abdominal computed tomography scans, including an unenhanced scan as well as defined CECT scans in the arterial and portalvenous phase. PLvBMD analysis was performed by 4 radiologists using an FDA-approved tool for phantomless evaluation of bone density (IntelliSpace, Philips, The Netherlands). Mean vBMD of the first 3 lumbar vertebrae in each contrast phase was determined and interobserver variance of vBMD independent of contrast phase was analyzed using intraclass correlation, Bland-Altman plots, and Student's t test. CECT scans were associated with a significantly higher PLvBMD compared with unenhanced scans (unenhanced computed tomography: 97.8 mg/cc; arterial CECT: 106.3 mg/cc, portalvenous CECT: 106.3 mg/cc). Overall, there was no significant difference of PLvBMD between data acquisition in arterial and portalvenous phases (increase of 8.6% each, standard deviation ratio 37.7%–38.3%). In Bland-Altman analysis, there was no evidence of a relevant reader-related bias or an increase in standard deviation of PLvBMD measurements in contrast-enhanced scans compared with unenhanced scans. The following conversion formulas for unenhanced PLvBMD were determined: unenhanced PLvBMD = 0.89 × arterial PLvBMD + 3 , 74 m g / c c (r 2 = 0.94) and unenhanced PLvBMD = 0.88 × venous PLvBMD + 4 , 56 m g / c c (r 2 = 0.93) . Compared with the results of phantom-based quantitative computed tomography measurements reported in the literature, the PLvBMD changes associated with contrast enhancement were relatively moderate with an increase of 8.6% in average. The time-point of the contrast-enhanced PLvBMD measurements after injection of contrast media did not appear to affect the results. With the adjustment formulas provided in this study, the method can improve osteoporosis screening through detection of reduced bone mass of the vertebrae in routinely conducted CECT.

Objectives Image quality in head and neck imaging is often severely hampered by artifacts arising from dental implants. This study evaluates metal artifact (MA) reduction using virtual monoenergetic images (VMI) compared to conventional CT images (CI) from spectral-detector computed tomography (SDCT). Methods 38 consecutive patients with dental implants were included in this retrospective study. All examinations were performed using a SDCT (IQon, Philips, Best, The Netherlands). Images were reconstructed as conventional images (CI) and as VMI in a range of 40–200 keV (10 keV increment). Quantitative image analysis was performed ROI-based by measurement of attenuation (HU) and standard deviation in most pronounced hypo- and hyperdense artifact, fat and soft tissue with presence of artifacts. Qualitatively, extent of artifact reduction, assessment of soft palate and cheeks were rated on 5-point Likert-scales by two radiologists. Statistical data evaluation included ANOVA and Wilcoxon-test with correction for multiple comparisons; interrater-agreement was determined by intraclass-correlation coefficient (ICC). Results The hypo- and hyperattenuating artifacts showed an increase and decrease of HU-values in VMIhigh (CI/VMI200 keV: −218.7/−174.4 HU, p = 0.1; and 309.8/119.2, p ≤ 0.05, respectively). Artifacts in the fat, as depicted by image noise did also decrease in VMIhigh (CI/VMI200 keV: 23.9/16.4, p ≤ 0.05). Qualitatively, hyperdense artifacts were decreased significantly in VMI ≥100 keV (e.g. CI/VMI200 keV: 2(1–3)/3(1–5), p ≤ 0.05). Artifact reduction resulted in improved assessment of the soft palate and cheeks (e.g. CI/VMI200 keV: 2(1–4)/3(1–5) and 2(1–5)/3(1–5), p ≤ 0.05). Overall interrater agreement was good (ICC = 0.77). Conclusions Virtual monoenergetic images from SDCT reduce metal artifacts from dental implants and improve diagnostic assessment of surrounding soft tissue.

This study compares metal artifact (MA) reduction in imaging of total hip replacements (THR) using virtual monoenergetic images (VMI), for MA-reduction-specialized reconstructions (MAR) and conventional CT images (CI) from detector-based dual-energy computed tomography (SDCT).Twenty-seven SDCT-datasets of patients carrying THR were included. CI, MAR and VMI with different energy-levels (60-200 keV) were reconstructed from the same scans. MA width was measured. Attenuation (HU), noise (SD) and contrast-to-noise ratio (CNR) were determined in: extinction artifact, adjacent bone, muscle and bladder. Two radiologists assessed MA-reduction and image quality visually.In comparison to CI, VMI (200 keV) and MAR showed a strong artifact reduction (MA width: CI 29.9±6.8 mm, VMI 17.6±13.6 mm, p0.001; MAR 16.5±14.9 mm, p0.001; MA density: CI -412.1±204.5 HU, VMI -279.7±283.7 HU; p0.01; MAR -116.74±105.6 HU, p0.001). In strong artifacts reduction was superior by MAR. In moderate artifacts VMI was more effective. MAR showed best noise reduction and CNR in bladder and muscle (p0.05), whereas VMI were superior for depiction of bone (p0.05). Visual assessment confirmed that VMI and MAR improve artifact reduction and image quality (p0.001).MAR and VMI (200 keV) yielded significant MA reduction. Each showed distinct advantages both regarding effectiveness of artifact reduction, MAR regarding assessment of soft tissue and VMI regarding assessment of bone.• Spectral-detector computed tomography improves assessment of total hip replacements and surrounding tissue. • Virtual monoenergetic images and MAR reduce metal artifacts and enhance image quality. • Evaluation of bone, muscle and pelvic organs can be improved by SDCT.

The aims of this study were to compare virtual monoenergetic images and polyenergetic images reconstructed from unenhanced dual-layer detector computed tomography (DLCT) of the head and to determine kiloelectron volt levels that optimize image quality, particularly the gray-white matter contrast, and reduce beam hardening artifacts caused by the skull.Institutional review board approval was obtained. Forty patients that received DLCT were included in this retrospective study; of these patients, 22 were women and 18 were men. The average age was 61.5 ± 14.3 years. Virtual monoenergetic images were reconstructed from spectral base images at 40 keV to 120 keV. To calculate signal-to-noise ratio and contrast-to-noise ratio, attenuation and standard deviation of supratentorial gray and white matter were measured in virtual monoenergetic and polyenergetic images. Beam hardening artifacts were detected close to the calvarium and in the posterior fossa. Two radiologists rated the assessment of gray-white matter differentiation and of the subcalvarial space, as well as the artifacts caused by the skull and image noise. Student t test and Wilcoxon test were used to determine significance.Compared with polyenergetic images, superior signal-to-noise ratio and superior contrast-to-noise ratio of gray and white matter were observed in virtual monoenergetic images at low kiloelectron volt levels (P0.0001). Subcalvarial artifacts were significantly lower at 120 keV (P0.02). Artifacts measured in the posterior fossa were generally lower at high kiloelectron volt levels; however, no statistical significance was detected. Virtual monoenergetic images were rated superior to polyenergetic images in regard to all 4 criteria (P0.0001). The observers reported an optimal radiological assessment of gray-white matter differentiation at 65 keV and optimal assessment of subcalvarial space at 120 keV.In comparison to polyenergetic images, virtual monoenergetic images reconstructed from unenhanced DLCT of the head at 65 keV and 120 keV allow to optimize gray-white matter contrast and reduce beam hardening artifacts caused by the skull, respectively.

In unenhanced computed tomography (CT) of acute ischemic stroke, the density of occluding clots is associated with the content of red blood cells and successful recanalization with stent thrombectomy. However, no CT marker for fibrin content is established. In order to improve clot diagnostics, we conducted an in vitro study to investigate thrombus composition of histologically defined ovine blood clots with unenhanced and contrast-enhanced CT using spectral detector CT (SDCT). Ovine blood clot types containing defined amounts of red blood cells (RBC; pure fibrin clots: RBC 0% ± 0, fibrin 100% ± 0), mixed clots (RBC 35.1% ± 4.11, fibrin 79.2% ± 5.6) and red clots (RBC 99.05% ± 1.14, fibrin 0.95% ± 1.14) were scanned in a SDCT (IQon®, Philips, Amsterdam, The Netherlands) (a) in a tube containing saline, (b) 5 min and (c) 3 days after exposure to a 1:50 dilution of iohexol (Accupaque-350®, GE-Healthcare, Boston, MA, USA). The attenuation of the clots was measured in Hounsfield units (HU) in conventional CT datasets as well as virtual noncontrast reconstructions (VNC) of nonenhanced and contrast-enhanced SDCT in a blinded and randomized fashion. Statistical analysis was conducted with ANOVA, Spearman’s correlation, linear and multivariable regression models. In unenhanced scans, clots differed in density with linear interrelation (fibrin 23.6 ± 1.1, mixed 34.9 ± 1.6, red 46.7 ± 1.6, mean HU ± SD). The blood clots did not show any overlap of density in the native scans and VNC at different time points (p < 0.0001 for each setting and clot type). However, they could not be differentiated after initial contrast exposure (fibrin 108.5 ± 7.8, mixed 105.3 ± 3.5, red 104.8 ± 3.8, mean HU ± SD). After prolonged exposure, the fibrin rich clots showed a significant increase of density due to further uptake of contrast medium (fibrin 163.6 ± 3.6, mixed 138.3 ± 4.1, red 109.6 ± 5.4, mean HU ± SD). In multivariable models, native CT density and contrast enhancement were independent variables associated with thrombus type (p < 0.01 each). The fibrin content in blood clots is strongly associated with contrast uptake. As previously shown, the density of the clot formations in native CT scans is dependent on the RBC. Our data show that CT density and relative enhancement of clots are independent determinants of clot composition. Using both variables in the CT workup of acute ischemic stroke has the potential to have a decisive impact on patient stratification for treatment.

BackgroundData on the frequency and outcome of repeated mechanical thrombectomy (MT) in patients with short-term re-occlusion of intracranial vessels is limited. Addressing this subject, we report our multicenter experience with a systematic review of the literature.MethodsA retrospective analysis was conducted of consecutive acute stroke patients treated with MT repeatedly within 30 days at 10 tertiary care centers between January 2007 and January 2020. Baseline demographics, etiology of stroke, angiographic outcome and clinical outcome evaluated by the modified Rankin Scale (mRS) at 90 days were noted. Additionally, a systematic review of reports with repeated MT due to large vessel occlusion (LVO) recurrence was performed.ResultsWe identified 30 out of 7844 (0.4%) patients who received two thrombectomy procedures within 30 days due to recurrent LVO. Through systematic review, three publications of 28 participants met the criteria for inclusion. Combined, a total of 58 participants were analyzed: cardioembolic events were the most common etiology for the first (65.5%) and second LVO (60.3%), respectively. Median baseline NIHSS (National Institutes of Health Stroke Scale) was 13 (IQR 8–16) before the first MT and 15 (IQR 11–19) before the second MT (p=0.031). Successful reperfusion was achieved in 91.4% after the first MT and in 86.2% patients after the second MT (p=0.377). The rate of functional independence (mRS 0–2) was 46% at 90 days after the second procedure.ConclusionRepeated MT in short-term recurrent LVO is a rarity but appears to be safe and effective. The second thrombectomy should be pursued with the same extensive effort as the first procedure as these patients may achieve similar good outcomes.

Peritoneal carcinomatosis (PC) is a prognostically relevant metastatic disease which may be difficult to depict in postoperative patients, particularly in early stages. This study aimed to determine whether PC could be diagnosed more accurately when using a combination of spectral detector CT (SDCT)-derived conventional images (CI) and iodine overlay images (IO) compared with CI only. Thirty patients with PC and 30 patients with benign peritoneal alterations (BPA) who underwent portal-venous abdominal SDCT were included. Four radiologists determined the presence/absence of PC for each patient and assessed lesion conspicuity, diagnostic certainty, and image quality using 5-point Likert scales. Subjective assessment was conducted in two sessions comprising solely CI and CI/IO between which a latency of 6 weeks was set. Iodine uptake and HU attenuation were determined ROI-based to analyze quantitative differentiation of PC/BPA. Specificity for PC was significantly higher when using CI/IO compared with using CI only (0.86 vs. 0.78, p ≤ 0.05), while sensitivity was comparable (0.79 vs. 0.81, p = 1). In postoperative patients, the increase in specificity was the highest (0.93 vs. 0.80, p ≤ 0.05). Lesion conspicuity was rated higher in CI/IO (4 (3–5)) compared with that in CI only (3 (3–4); p ≤ 0.05). Diagnostic certainty was comparable (both 4 (3–5); p = 0.5). CI/IO received the highest rating for overall image quality and assessability (CI/IO 5 (4–5) vs. CI 4 (4–4) vs. IO 4 (3–4); p ≤ 0.05). Area under the receiver operating characteristics curve (AUC) for quantitative differentiation between PC and BPA was higher for iodine (AUCIodine = 0.95, AUCHU = 0.90). Compared with CI, combination of CI/IO improves specificity in the assessment of peritoneal carcinomatosis at comparable sensitivity, particularly in postoperative patients. • Combination of iodine overlays and conventional images improves specificity when assessing patients with peritoneal carcinomatosis at comparable sensitivity. • Particularly in postsurgical patients, iodine overlays could help to avoid false-positive diagnosis of peritoneal disease. • Iodine overlays alone provided inferior image quality and assessability than conventional images, while the combination of both received the highest ratings. Iodine overlays should therefore be used in addition to and not as a substitute for conventional images.

Stent protected Angioplasty of extracranial carotid artery stenosis using the dual-layered CGUARD stent is a novel treatment option. In this study we evaluate the feasibility and the safety of the CGUARD in symptomatic and asymptomatic patients in comparison to Casper-RX and Wallstent. This is a multi-center study of consecutive patients treated with the CGUARD, Casper-RX and Wallstent at two German high volume neurovascular centers between April 2017 and May 2018. Patient characteristics, neuroimaging data and angiographic outcome were retrospectively analyzed. The primary end points of the study were acute occlusion of the carotid stent and symptomatic intracerebral hemorrhage (sICH). Carotid artery stenting was performed in 76 patients; of those 26 (34%) were treated with the CGUARD, 25 (33%) with Casper-RX, and 25 (33%) with Wallstent. In 58/76 (76%) cases carotid artery stenosis was symptomatic with a median baseline National Institutes of Health Stroke Scale of 4. Angioplasty and stenting as part of a mechanical thrombectomy for acute ischemic stroke was performed in 25/76 (33%) patients. Baseline patient characteristics were similar between the treatment groups, except for a higher portion of scheduled cases in the Casper-RX group. There were no significant differences in the rate of acute in stent occlusions (CGUARD, 2/26 (8%); Casper-RX, 1/25(4%); Wallstent, 1/25 (4%)) and postinterventional sICH (1/26 (4%), 0/25(0%), 0/25 (0%)). Clinical outcome at discharge did not differ between groups. Treatment of carotid artery stenosis using CGUARD is feasible with a good safety profile comparable to that of Casper-RX and Wallstent.

Background To investigate if iodine density overlay maps (IDO) and virtual monoenergetic images at 40 keV (VMI40keV) acquired from spectral detector computed tomography (SDCT) can improve detection of incidental skeletal muscle metastases in whole-body CT staging examinations compared to conventional images. Methods In total, 40 consecutive cancer patients who underwent clinically-indicated, contrast-enhanced, oncologic staging SDCT were included at this retrospective study: 16 patients with n = 108 skeletal muscle metastases confirmed by prior or follow-up CT, 18F-FDG-PET, MRI or histopathology, and a control group of 24 patients without metastases. Four independent readers performed blinded, randomized visual detection of skeletal muscle metastases in conventional images, IDO and VMI40keV, indicating diagnostic certainty for each lesion on a 5-point Likert scale. Quantitatively, ROI-based measurements of attenuation (HU) in conventional images and VMI40keV and iodine concentration in IDO were conducted. CNR was calculated and receiver operating characteristics (ROC) analysis of quantitative parameters was performed. Results Regarding subjective assessment, IDO (63.2 (58.5–67.8) %) and VMI40keV (54.4 (49.6–59.2) %) showed an increased sensitivity for skeletal muscle metastases compared to conventional images (39.8 (35.2–44.6) %). Specificity was comparable in VMI40keV (69.8 (63.2–75.8) %) and conventional images (69.2 (60.6–76.9) %), while in IDO, it was moderately increased to 74.2 (65.3–78.4) %. Quantitative image analysis revealed that CNR of skeletal muscle metastases to circumjacent muscle was more than doubled in VMI40keV (25.8 ± 11.1) compared to conventional images (10.0 ± 5.3, p ≤ 0.001). Iodine concentration obtained from IDO and HU acquired from VMI40kev (AUC = 0.98 each) were superior to HU attenuation in conventional images (AUC = 0.94) regarding differentiation between healthy and metastatic muscular tissue (p ≤ 0.05). Conclusions IDO and VMI40keV provided by SDCT improve diagnostic accuracy in the assessment of incidental skeletal muscle metastases compared to conventional CT.

To comprehensively assess precision, reproducibility, and repeatability of iodine maps from spectral detector CT (SDCT) in a phantom and in patients with repetitive examination of the abdomen. Seventy-seven patients who underwent examination two (n = 52) or three (n = 25) times according to clinical indications were included in this IRB-approved, retrospective study. The anthropomorphic liver phantom and all patients were scanned with a standardized protocol (SSDE in patients 15.8 mGy). In patients, i.v. contrast was administered and portal venous images were acquired using bolus-tracking technique. The phantom was scanned three times at three time points; in one acquisition, image reconstruction was repeated three times. Region of interest (ROI) were placed automatically (phantom) or manually (patients) in the liver parenchyma (mimic) and the portal vein; attenuation in conventional images (CI [HU]) and iodine map concentrations (IM [mg/ml]) were recorded. The coefficient of variation (CV [%]) was used to compare between repetitive acquisitions. If present, additional ROI were placed in cysts (n = 29) and hemangioma (n = 29). Differences throughout all phantom examinations were

The objective of this study was to evaluate the intra-individual, longitudinal consistency of iodine measurements regarding the vascular and renal blood pool in patients that underwent repetitive spectral detector computed tomography (SDCT) examinations to evaluate their utility for oncologic imaging. Seventy-nine patients with two (n = 53) or three (n = 26) clinically indicated biphasic SDCT scans of the abdomen were retrospectively included. ROI-based measurements of Hounsfield unit (HU) attenuation in conventional images and iodine concentration were performed by an experienced radiologist in the following regions (two ROIs each): abdominal aorta, vena cava inferior, portal vein, and renal cortices. Modified variation coefficients (MVCs) were computed to assess intra-individual longitudinal between the different time points. Variation of HU attenuation and iodine concentration measurements was significantly lower in the venous than in the arterial phase images (attenuation/iodine concentration: arterial − 4.2/− 3.9, venous 0.4/1.0; p ≤ 0.05). Regarding attenuation in conventional images of the arterial phase, the median MVC was − 1.8 (− 20.5–21.3) % within the aorta and − 6.5 (− 44.0–25.0) % within the renal cortex while in the portal venous phase, it was 0.62 (− 11.1–11.7) % and − 1.6 (− 16.2–10.6) %, respectively. Regarding iodine concentration, MVC for arterial phase was − 2.5 (− 22.9–28.4) % within the aorta and − 5.8 (− 55.9–29.6) % within the renal cortex. The referring MVCs of the portal venous phase were − 0.7 (− 17.9–16.9) % and − 2.6 (− 17.6–12.5) %. Intra-individual iodine quantification of the vascular and cortical renal blood pool at different time points works most accurately in venous phase images whereas measurements conducted in arterial phase images underlay greater variability. • There is an intra-individual, physiological variation in iodine map measurements from dual-energy computed tomography. • This variation is smaller in venous phase examinations compared with arterial phase and therefore venous phase images should be preferred to minimize this intra-individual variation. • Care has to be taken, when considering iodine measurements for clinical decision-making, particularly in the context of oncologic initial or follow-up imaging.

Importance Clinical evidence of the potential treatment benefit of mechanical thrombectomy for posterior circulation distal, medium vessel occlusion (DMVO) is sparse. Objective To investigate the frequency as well as the clinical and safety outcomes of mechanical thrombectomy for isolated posterior circulation DMVO stroke and to compare them with the outcomes of standard medical treatment with or without intravenous thrombolysis (IVT) in daily clinical practice. Design, Setting, and Participants This multicenter case-control study analyzed patients who were treated for primary distal occlusion of the posterior cerebral artery (PCA) of the P2 or P3 segment. These patients received mechanical thrombectomy or standard medical treatment (with or without IVT) at 1 of 23 comprehensive stroke centers in Europe, the United States, and Asia between January 1, 2010, and June 30, 2020. All patients who met the inclusion criteria were matched using 1:1 propensity score matching. Interventions Mechanical thrombectomy or standard medical treatment with or without IVT. Main Outcomes and Measures Clinical end point was the improvement of National Institutes of Health Stroke Scale (NIHSS) scores at discharge from baseline. Safety end point was the occurrence of symptomatic intracranial hemorrhage and hemorrhagic complications were classified based on the Second European-Australasian Acute Stroke Study (ECASSII). Functional outcome was evaluated with the modified Rankin Scale (mRS) score at 90-day follow-up. Results Of 243 patients from all participating centers who met the inclusion criteria, 184 patients were matched. Among these patients, the median (interquartile range [IQR]) age was 74 (62-81) years and 95 (51.6%) were female individuals. Posterior circulation DMVOs were located in the P2 segment of the PCA in 149 patients (81.0%) and in the P3 segment in 35 patients (19.0%). At discharge, the mean NIHSS score decrease was -2.4 points (95% CI, -3.2 to -1.6) in the standard medical treatment cohort and -3.9 points (95% CI, -5.4 to -2.5) in the mechanical thrombectomy cohort, with a mean difference of -1.5 points (95% CI, 3.2 to -0.8; P = .06). Significant treatment effects of mechanical thrombectomy were observed in the subgroup of patients who had higher NIHSS scores on admission of 10 points or higher (mean difference, -5.6; 95% CI, -10.9 to -0.2; P = .04) and in the subgroup of patients without IVT (mean difference, -3.0; 95% CI, -5.0 to -0.9; P = .005). Symptomatic intracranial hemorrhage occurred in 4 of 92 patients (4.3%) in each treatment cohort. Conclusions and Relevance This study suggested that, although rarely performed at comprehensive stroke centers, mechanical thrombectomy for posterior circulation DMVO is a safe, and technically feasible treatment option for occlusions of the P2 or P3 segment of the PCA compared with standard medical treatment with or without IVT.

Background Besides throat-nose swab polymerase chain reaction (PCR), unenhanced chest computed tomography (CT) is a recommended diagnostic tool for early detection and quantification of pulmonary changes in COVID-19 pneumonia caused by the novel corona virus. Demographic factors, especially age and comorbidities, are major determinants of the outcome in COVID-19 infection. This study examines the extra pulmonary parameter of bone mineral density (BMD) from an initial chest computed tomography as an associated variable of pre-existing comorbidities like chronic lung disease or demographic factors to determine the later patient's outcome, in particular whether treatment on an intensive care unit (ICU) was necessary in infected patients. Methods We analyzed 58 PCR-confirmed COVID-19 infections that received an unenhanced CT at admission at one of the included centers. In addition to the extent of pulmonary involvement, we performed a phantomless assessment of bone mineral density of thoracic vertebra 9–12. Results In a univariate regression analysis BMD was found to be a significant predictor of the necessity for intensive care unit treatment of COVID-19 patients. In the subgroup requiring intensive care treatment within the follow-up period a significantly lower BMD was found. In a multivariate logistic regression model considering gender, age and CT measurements of bone mineral density, BMD was eliminated from the regression analysis as a significant predictor. Conclusion Phantomless assessed BMD provides prognostic information on the necessity for ICU treatment in course of COVID-19 pneumonia. We recommend using the measurement of BMD in an initial CT image to facilitate a potentially better prediction of severe patient outcomes within the 22 days after an initial CT scan. Consequently, in the present sample, additional bone density analysis did not result in a prognostic advantage over simply considering age. Significantly larger patient cohorts with a more homogenous patient age should be performed in the future to illustrate potential effects. Clinical relevance While clinical capacities such as ICU beds and ventilators are more crucial than ever to help manage the current global corona pandemic, this work introduces an approach that can be used in a cost-effective way to help determine the amount of these rare clinical resources required in the near future., Highlights • COVID-19 • Computed tomography • Bone mineral density • Prognosis of intensive care treatment

In the present study, we investigated the potential for routine staging computed tomography (CT) to assess fracture risk in breast cancer patients.A total of 184 randomized CT data sets of women with breast cancer were studied. Intellispace Density software (Philips, Amsterdam, Netherlands) was used to determine the mean volumetric bone mineral density (vBMD) of 3 nonfractured vertebral bodies (T12-L4) and predictors according to the quantitative and qualitative tumor morphology. Two radiologists detected prevalent vertebral fractures and classified them (osteoporotic vs. metastatic). For the determination of an association between bone mineral density, metastatic vertebral bone involvement, and the prevalence of vertebral fractures, a statistical analysis was conducted using multivariable logistic regression and receiver operating characteristic analyses.Of 184 women, 50 (27%) were diagnosed with prevalent vertebral metastases, of whom, 42 had vertebral fractures (23%). Of these fractures, 20 were found to be osteoporotic (11%), and 22 were associated with metastatic bone disease (12%). The vBMD T score showed the strongest association with osteoporotic fractures (odds ratio, 2.9; 95% confidence interval, 1.4-6.0; area under the curve [AUC], 0.89; P .01). Metastatic vertebral fractures showed a strong association with the simple prevalence of metastases, regardless of tumor size (odds ratio, 9.8; 95% confidence interval, 4.3-22.3; AUC, 0.90; P .01). Compared with the prevalence of metastases in the multivariate receiver operating characteristic statistic, the further detection of tumor size T0 and cortical bone infiltration showed a nonsignificant greater association with prevalent vertebral fractures (AUC, 0.92, P = .3; and AUC, 0.93, P = .07).vBMD measurements and the detection of metastases and their morphology from routine staging CT allow the discrimination of breast cancer with and without vertebral fractures. The simple prevalence of vertebral metastases is strongly associated with prevalent metastatic fractures.

Highlights • Obesity and body composition determined in initial LDCT is a risk factor for SARS‐CoV‐2 infected patients. • An initial LDCT can be used to screen opportunistically for obese COVID-19 patients. • Unfavorable body composition is associated with increased risk for the need of intensive care treatment., Purpose Low-dose computed tomography (LDCT) of the chest is a recommended diagnostic tool in early stage of COVID-19 pneumonia. High age, several comorbidities as well as poor physical fitness can negatively influence the outcome within COVID-19 infection. We investigated whether the ratio of fat to muscle area, measured in initial LDCT, can predict severe progression of COVID-19 in the follow-up period. Method We analyzed 58 individuals with confirmed COVID-19 infection that underwent an initial LDCT in one of two included centers due to COVID-19 infection. Using the ratio of waist circumference per paravertebral muscle circumference (FMR), the body composition was estimated. Patient outcomes were rated on an ordinal scale with higher numbers representing more severe progression or disease associated complications (hospitalization/ intensive care unit (ICU)/ tracheal intubation/ death) within a follow-up period of 22 days after initial LDCT. Results In the initial LDCT a significantly higher FMR was found in patients requiring intensive care treatment within the follow-up period. In multivariate logistic regression analysis, FMR (p

Purpose To evaluate the use of spectral CT for differentiation between noncalcified benign pleural lesions and pleural carcinomatosis. Materials and Methods In this retrospective study, patients who underwent contrast agent-enhanced late venous phase spectral CT of the chest between June 1, 2016, and July 1, 2018 with histopathologic and/or imaging confirmation of noncalcified pleural lesions were evaluated. Conventional images, iodine overlay (IO) images, and virtual monoenergetic images at 40 keV (hereafter, VMI40keV) were reconstructed from contrast-enhanced spectral chest CT. Four blinded radiologists determined lesion presence and indicated lesion conspicuity and diagnostic certainty. Hounsfield unit attenuation from conventional images and iodine concentration (IC) (in milligrams per milliliter) from IO images were determined. Area under the receiver operating characteristics curve determined thresholds for quantitative lesion differentiation and cutoff values were validated in an independent data set. Results Eighty-four patients were included (mean age, 66.2 years; 54 men and 30 women; 44 patients with cancer with confirmed pleural carcinomatosis and 40 patients with benign pleural lesions). The area under the receiver operating characteristics curve for IC was greater than that of conventional Hounsfield units (0.96 vs 0.91; P ≤ .05, respectively). The optimal IC threshold was 1.3 mg/mL, with comparable sensitivity and specificity when applied to the test data set. The sensitivities to depict pleural carcinomatosis with spectral reconstructions versus conventional CT were 96% (199 of 208) and 83% (172 of 208), respectively, with specificities of 84% (161 of 192) and 63% (120 of 192), respectively (P ≤ .001 each). Conclusion Compared with conventional images, spectral CT with iodine maps improved both quantitative and qualitative determination of pleural carcinomatosis versus noncalcified benign pleural lesions. © RSNA, 2019 See also the editorial by K. S. Lee and H. Y. Lee .

To evaluate feasibility and diagnostic performance of multi-level calcium suppression in spectral detector computed tomography (SDCT) for assessment of bone metastasis. Retrospective IRB-approved study on 21 patients who underwent SDCT (120 kV, reference mAs 116) and MRI. Thoracic and lumbar vertebrae (n = 357) were included and categorized as normal (n = 133) or metastatic (n = 203) based on MRI (STIR, T1w, ±contrast). The multi-level virtual non-calcium (VNCa) algorithm computes dynamic soft tissue/calcium pairs allowing for computation of different suppression index levels to address inter-individual variance of prevalent calcium composition weights. We computed images with low, medium, and high calcium suppression indices and compared them with conventional images (VNCa_low/med/high and conventional images (CI)). For quantitative image analysis, regions of interest were placed in normal and metastatic bone. Two readers reviewed the datasets independently in multiple sessions. They determined the presence of vertebral metastases on a per vertebra basis using a binary scale. Statistic assessment was performed using ANOVA with Tukey HSD, Student’s T test, and ROC analysis. Attenuation of both normal and metastatic bone was lower in VNCa images than that in conventional images (e.g., CI/VNCa_low, − 46.3 to 238.8 HU/343.3–60.2 HU; p ≤ 0.05). VNCa_low+med improved separation of normal and metastatic bone in ROC analysis (AUC, CI/VNCa_low/VNCa_med = 0.74/0.95/0.98; p ≤ 0.05). In subjective analysis, both sensitivity and specificity were clearly improved in VNCa_low as compared with CI (0.85/0.84 versus 0.78/0.82). Readers showed a good inter-rater reliability (kappa = 0.65). Multi-level VNCa reconstructed from SDCT improve quantitative separation of normal and metastatic bone and subjective determination of bone metastases when using low to intermediate calcium suppression indices. • Spectral detector CT allows for multi-level calcium suppression in CT images and low and medium calcium suppression indices improved separation of normal and metastatic bone. • Thus, multi-level calcium suppression allows to optimize image contrast in regard to dedicated pathologies. • Low-level virtual non-calcium images (index 25–50) improved diagnostic performance regarding detection of metastasis.

Background: One endovascular treatment option of acute ischemic stroke due to tandem occlusion (TO) comprises intracranial thrombectomy and acute extracranial carotid artery stenting (CAS). In this setting, the order of treatment may impact the clinical outcome in this stroke subtype. Methods: Retrospective analysis was performed on data prospectively collected in 4 international stroke centers between 2013 and 2017. One hundred sixty-five patients with anterior TO were treated by endovascular therapy. Clinical and procedural data were evaluated. Favorable clinical outcome was defined as modified Rankin Scale (mRS) ≤2 at 90 days. Propensity score matching was performed for different treatment strategies. Results: Patients’ mean age was 65 ± 11 years and 118 were male (69%). The median admission National Institutes of Health Stroke Scale was 15 (interquartile range 8). In 59% of the patients (n = 101), the antegrade strategy (first stenting, then thrombectomy) was ­performed, in 41% (n = 70) retrograde treatment (first thrombectomy, then stenting). Successful reperfusion (mTICI ≥2b) was achieved in 128 patients (75%). Fifty-nine patients (39%) showed a favorable clinical outcome after 90 days. After propensity score matching, data of 100 patients could be analyzed. Analysis revealed that the retrograde strategy yielded a significantly higher rate of successful reperfusion compared to the antegrade strategy (92 vs. 56%; p < 0.001). The rate of favorable clinical outcome after 90 days (mRS ≤2) was consistently higher (44 vs. 30%; p < 0.05) in the retrograde strategy group. Conclusion: Mechanical thrombectomy prior to acute CAS in TO is a predictive factor for favorable clinical outcome at 90 days.

Background The Stent Retriever Assisted Vacuum-locked Extraction (SAVE) technique has been introduced as an effective embolectomy method in stroke patients suffering from intracranial large vessel occlusion (LVO). We present our multicenter, long-term experience with SAVE. Methods Retrospective, core-team analysis of 200 patients undergoing embolectomy using the SAVE technique due to intracranial LVO at 4 German centers. Primary endpoints were first-pass and overall complete/near-complete reperfusion, defined as a modified Thrombolysis in Cerebral Infarction (mTICI) score of 2 c and 3. Secondary endpoints were number of passes, time from groin puncture to reperfusion, embolization to new territories (ENT), and post-interventional symptomatic intracranial hemorrhage (sICH). Results Median age was 78 years (IQR 68–85). Median NIHSS at admission was 16 (IQR 12–20). Occlusions sites were: ICA-T in 39/200 (19.5%), M1 in 126/200 (63%), M2 in 30/200 (15%), and others in 5/200 (2.5%) cases. The primary endpoints were documented in 114/200 (57% first-pass mTICI2c or 3) and 154/200 (77% overall mTICI2c or 3) patients, respectively. The overall median time from groin puncture to reperfusion was 34 min (IQR 25–52) with a median of 1 (IQR 1–2) attempts. ENTs were observed in 3 patients (1.5%) and the rate of sICH was 2.6%. The rate of successful reperfusion (mTICI ≥2 b) on final angiograms was 95%. Conclusion SAVE is an effective, fast and secure embolectomy method. First-line use of SAVE leads to high-rates of complete/near-complete reperfusion. Disclosures M. Psychogios: 3; C; Stryker, Phenox, Acandis, Penumbra, Siemens. S. Henkel: None. A. Riabikin: None. C. Riedel: None. D. Behme: 3; C; Stryker, Phenox, Penumbra. I. Tsogkas: None. A. Hesse: None. N. Abdullayev: None. O. Jansen: None. M. Wiesmann: 1; C; Abbott. 3; C; Stryker, Bracco, Medtronic, Siemens. A. Mpotsaris: 2; C; Neuravi, Penumbra, Sequent Medical. V. Maus: None.

Objective Acute dissecting aneurysms of the posterior circulation are a rare cause of subarachnoid hemorrhage. Established endovascular treatment options include parent artery occlusion and stent-assisted coiling, but appear to be associated with an increased risk of ischemic stroke. Vessel reconstruction with flow diverters is an alternative treatment option; however, its safety and efficacy in the acute stage remains unclear. Methods This is a multicentric retrospective analysis of 15 consecutive acutely ruptured dissecting posterior circulation aneurysms treated with flow diverters. The primary end point was favorable aneurysm occlusion, defined as OKM C1-3 and D (O'Kelly Marotta scale). Secondary end points were procedure-related complications and clinical outcome. Results Nine of 15 aneurysms (60%) arose from the intradural portion of the vertebral artery, 3 were located on the posterior inferior cerebellar artery and 1 each on the anterior inferior cerebellar artery, posterior cerebral artery, and basilar artery. Flow diverter placement was technically successful in 14 of 15 cases (93%). After endovascular treatment, none of the ruptured aneurysms rebled. Median clinical follow-up was 217 days and median angiographic follow-up was 203 days. Favorable occlusion was observed in 7 of 14 aneurysms (50%) directly after flow diverter placement; of those, 5 were completely occluded (36%). Seven patients (47%) with poor-grade subarachnoid hemorrhage died in the acute phase. Favorable clinical outcome (modified Rankin scale ≤2) was observed in 4 of 15 patients (27%) and a moderate outcome (modified Rankin scale 3/4) was observed in 5 of 15 patients (33%). All aneurysms showed complete occlusion at follow-up. Conclusions Flow diverters might be a feasible, alternative treatment option for acutely ruptured dissecting posterior circulation aneurysms and may effectively prevent rebleeding. Larger cohort studies are required to validate these results.

Aim of this study was to assess the artifact reduction in patients with orthopedic hardware in the spine as provided by (1) metal-artifact-reduction algorithms (O-MAR) and (2) virtual monoenergetic images (MonoE) as provided by spectral detector CT (SDCT) compared to conventional iterative reconstruction (CI). In all, 28 consecutive patients with orthopedic hardware in the spine who underwent SDCT-examinations were included. CI, O-MAR and MonoE (40–200 keV) images were reconstructed. Attenuation (HU) and noise (SD) were measured in order to calculate signal-to-noise ratio (SNR) of paravertebral muscle and spinal canal. Subjective image quality was assessed by two radiologists in terms of image quality and extent of artifact reduction. O-MAR and high-keV MonoE showed significant decrease of hypodense artifacts in terms of higher attenuation as compared to CI (CI vs O-MAR, 200 keV MonoE: −396.5HU vs. –115.2HU, −48.1HU; both p ≤ 0.001). Further, artifacts as depicted by noise were reduced in O-MAR and high-keV MonoE as compared to CI in (1) paravertebral muscle and (2) spinal canal—CI vs. O-MAR/200 keV: (1) 34.7 ± 19.0 HU vs. 26.4 ± 14.4 HU, p ≤ 0.05/27.4 ± 16.1, n.s.; (2) 103.4 ± 61.3 HU vs. 72.6 ± 62.6 HU/60.9 ± 40.1 HU, both p ≤ 0.001. Subjectively both O-MAR and high-keV images yielded an artifact reduction in up to 24/28 patients. Both, O-MAR and high-keV MonoE reconstructions as provided by SDCT lead to objective and subjective artifact reduction, thus the combination of O-MAR and MonoE seems promising for further reduction.

To compare the image quality of virtual monoenergetic images and polyenergetic images reconstructed from dual-layer detector CT angiography (DLCTA). Thirty patients who underwent DLCTA of the head and neck were retrospectively identified and polyenergetic as well as virtual monoenergetic images (40 to 120 keV) were reconstructed. Signals (± SD) of the cervical and cerebral vessels as well as lateral pterygoid muscle and the air surrounding the head were measured to calculate the CNR and SNR. In addition, subjective image quality was assessed using a 5-point Likert scale. Student's t-test and Wilcoxon test were used to determine statistical significance. Compared to polyenergetic images, although noise increased with lower keV, CNR (p 0.05) of the cervical, petrous and intracranial vessels were improved in virtual monoenergetic images at 40 keV and virtual monoenergetic images at 45 keV were also rated superior regarding vascular contrast, assessment of arteries close to the skull base and small arterial branches (p < 0.0001 each). Compared to polyenergetic images, virtual monoenergetic images reconstructed from DLCTA at low keV ranging from 40 to 45 keV improve the objective and subjective image quality of extra- and intracranial vessels and facilitate assessment of vessels close to the skull base and of small arterial branches. • Virtual monoenergetic images greatly improve attenuation, while noise only slightly increases. • Virtual monoenergetic images show superior contrast-to-noise ratios compared to polyenergetic images. • Virtual monoenergetic images significantly improve image quality at low keV.

Objective The aim of the study was to investigate the performance and diagnostic value of metal artifact reduction in virtual monoenergetic images generated from dual-layer computed tomography (DLCT). Methods 35 patients that received a DLCT at the University Hospital Cologne and had an orthopedic implant in the examined region were included in this study. For each DLCT virtual monoenergetic images of different energy levels (64 keV, 70 keV, 105 keV, 140 keV, 200 keV and an optimized photon energy) were reconstructed and analyzed by three blinded observers. Images were analyzed with regard to subjective criteria (extent of artifacts, diagnostic image quality) and objective criteria (width and density of artifacts). Results 21 patients had implants in the spine, 8 in the pelvis and 6 patients in the extremities. Diagnostic image quality improved significantly at high photon energies from a Likert-score of 4.3 (±0.83) to 2.3 (±1.02) and artifacts decreased significantly from a score of 4.3 (±0.66) to 2.6 (±2.57). The average optimized photon energy was 149.2 ± 39.4 keV. The density as well as the width of the most pronounced artifacts decreased from−374.6 ± 251.89 HU to −12.5 ± 205.84 HU and from 14.5 ± 8.74 mm to 6.4 ± 10.76 mm, respectively. Conclusion Using virtual monoenergetic images valuable improvements of diagnostic image quality can be achieved by reduction of artifacts associated with metal implants. As preset for virtual monoenergetic images, 140 keV appear to provide optimal artifact reduction. In 20% of the patients, individually optimized keV can lead to a further improvement of image quality compared to 140 keV.