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Purpose: Vessel-encoded arterial spin labeling (VE-ASL) is able to provide noninvasive information about the contribution of individual arteries to the cerebral perfusion. The aim of this study was to compare VE-ASL to the diagnostic standard digital subtraction angiography (DSA) with respect to its ability to visualize vascular territories., Methods: In total, 20 VE-ASL and DSA data sets of 17 patients with Moyamoya angiopathy with and without revascularization surgery were retrospectively analyzed. Two neuroradiologists independently assessed the agreement between VE-ASL and DSA using a 4-point Likert scale (no- very high agreement). Additionally, grading of the vascular supply of subterritories (A1-A2, M1-M6) on the VE-ASL images and angiograms was performed. The intermodal agreement was calculated for all subterritories in total and for the subdivision into without and after revascularization (direct or indirect bypass)., Results: There was a very high agreement between the VE-ASL and the DSA data sets (median = 1, modus = 1) with a substantial inter-rater agreement (k w = 0.762 (95% CI 0.561-0.963)). The inter-modality agreement between VE-ASL and DSA in vascular subterritories was almost perfect for all subterritories (k = 0.899 (0.865-0.945)), in the subgroup of direct revascularized subterritories (k = 0.827 (0.738-0.915)), in the subgroup of indirect revascularized subterritories (k = 0.843 (0.683-1.003)), and in the subgroup of never revascularized subterritories (k = 0.958 (0.899-1.017))., Conclusion: Vessel-encoded ASL seems to be a promising non-invasive method to depict the contributions of individual arteries to the cerebral perfusion before and after revascularization surgery., (© 2024. The Author(s).)

Background: The aim of this study was to evaluate long-term outcomes in patients who underwent carotid artery stenting (CAS) for symptomatic or asymptomatic high-grade stenosis., Methods: A total of 1158 patients (asymptomatic, n = 636; symptomatic, n = 522) underwent CAS at our center between 2009 and 2020. A total of 560 patients or contacts (asymptomatic, n = 316; symptomatic, n = 244) were interviewed by telephone to evaluate long-term outcomes with a mean follow-up of 5 years. Mortality from all causes, myocardial infarction, and stroke, as well as comorbidities influencing their occurrence, including overall survival and stroke-free survival, were examined., Results: The overall survival rate for all-cause mortality was 91.6% at 1 year, 77.1% at 5 years, and 55.7% at 10 years. A total of 39 (6.9%) patients had an ischemic stroke during long-term follow-up. The stroke-free survival rates at 1 year, 5 years, and 10 years were 97.9%, 92.7%, and 86.6%, respectively. Stroke-free survival and overall survival did not differ significantly between the symptomatic and asymptomatic groups (overall survival, p = 0.304; stroke-free survival, p = 0.336). Regular physical activity reduced the risk of stroke and death and was associated with better long-term clinical outcomes. Age at treatment and diabetes mellitus were statistically significantly associated with death during follow-up., Conclusion: Long-term follow-up data confirmed the effectiveness and durability of CAS as a therapy option for both symptomatic and asymptomatic patients. In patient selection for CAS, special consideration should be paid to patient age, ability to engage in physical activity, and diabetes mellitus., (© 2023. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Purpose: Patients with Moyamoya Angiopathy (MMA) require hemodynamic assessment to evaluate the risk of stroke. Hemodynamic evaluation by use of breath-hold-triggered fMRI (bh-fMRI) was proposed as a readily available alternative to the diagnostic standard [ 15 O]water PET. Recent studies suggest voxel-wise hemodynamic delay correction in hypercapnia-triggered fMRI. The aim of this study was to evaluate the effect of delay correction of bh-fMRI in patients with MMA and to compare the results with [ 15 O]water PET., Methods: bh-fMRI data sets of 22 patients with MMA were evaluated without and with voxel-wise delay correction within different shift ranges and compared to the corresponding [ 15 O]water PET data sets. The effects were evaluated combined and in subgroups of data sets with most severely impaired CVR (apparent steal phenomenon), data sets with territorial time delay, and data sets with neither steal phenomenon nor delay between vascular territories., Results: The study revealed a high mean cross-correlation (r = 0.79, p < 0.001) between bh-fMRI and [ 15 O]water PET. The correlation was strongly dependent on the choice of the shift range. Overall, no shift range revealed a significantly improved correlation between bh-fMRI and [ 15 O]water PET compared to the correlation without delay correction. Delay correction within shift ranges with positive high high cutoff revealed a lower agreement between bh-fMRI and PET overall and in all subgroups., Conclusion: Voxel-wise delay correction, in particular with shift ranges with high cutoff, should be used critically as it can lead to false-negative results in regions with impaired CVR and a lower correlation to the diagnostic standard [ 15 O]water PET., (© 2022. The Author(s).)

Purpose: Patients with Moyamoya Angiopathy (MMA) require hemodynamic evaluation to assess the risk of stroke. Assessment of cerebral blood flow with [ 15 O]water PET and acetazolamide challenge is the diagnostic standard for the evaluation of the cerebral perfusion reserve (CPR). Estimation of the cerebrovascular reactivity (CVR) by use of breath-hold-triggered fMRI (bh-fMRI) as an index of CPR has been proposed as a reliable and more readily available approach. Recent findings suggest the use of resting-state fMRI (rs-fMRI) which requires minimum patient compliance. The aim of this study was to compare rs-fMRI to bh-fMRI and [ 15 O]water PET in patients with MMA., Methods: Patients with MMA underwent rs-fMRI and bh-fMRI in the same MRI session. Maps of the CVR gained by both modalities were compared retrospectively by calculating the correlation between the mean CVR of 12 volumes of interest. Additionally, the rs-maps of a subgroup of patients were compared to CPR-maps gained by [ 15 O]water PET., Results: The comparison of the rs-maps and the bh-maps of 24 patients revealed a good correlation (Pearson's r = 0.71 ± 0.13; preoperative patients: Pearson's r = 0.71 ± 0.17; postoperative patients: Pearson's r = 0.71 ± 0.11). The comparison of 7 rs-fMRI data sets to the corresponding [ 15 O]water PET data sets also revealed a high level of agreement (Pearson's r = 0.80 ± 0.19)., Conclusion: The present analysis indicates that rs-fMRI might be a promising non-invasive method with almost no patient cooperation needed to evaluate the CVR. Further prospective studies are required., (© 2021. The Author(s).)

Purpose: To assess the prevalence of false-positive meningeal contrast enhancement in patients with solid tumors who were undergoing chemotherapy., Methods: A total of 2572 magnetic resonance imaging (MRI) examinations of the brain were retrospectively evaluated by two readers for the presence of pathological meningeal contrast enhancement conspicuous for neoplastic meningitis. These patients either had malignant melanoma, breast or lung cancer, or lymphoma. The reference standards were cerebrospinal fluid cytology results and follow-up MRI. In cases with pathological contrast enhancement that decreased upon follow-up and non-malignant cytology, the enhancement pattern was further described as pial or dural, local or diffuse, or supra- or infra-tentorial. Moreover, the underlying therapy regimes were assessed., Results: The final study cohort included 78 patients (51 females, median age 57 years), of which 11 patients (14.1%) had a repeated non-malignant cytology ('pseudomeningeosis'). In one case, this finding, a granular pleocytosis, was attributed to previous radiotherapy. Of the remaining patients, seven were receiving multimodal, immunotherapy-based therapy regimens. Patients with unsuspicious cytology had a predominantly supratentorial distribution pattern in comparison to patients with neoplastic meningitis., Conclusions: The overall prevalence of the presence of false-positive meningeal contrast enhancement is low (< 1%) and not associated with specific imaging patterns. We hypothesize that there is a possible relationship between immunotherapy and 'pseudomeningeosis'. Therefore, in all cases with suspected neoplastic meningitis, the cerebrospinal fluid should be analyzed to confirm the diagnosis, especially in patients undergoing immunotherapy.

Purpose: The use of dynamic susceptibility contrast (DSC) perfusion and 11 C-methionine positron emission tomography (MET-PET) for glioma grading is currently not standardized. The purpose of this study was to identify regions of interest (ROIs) that enable the best performance and clinical applicability in both methods, as well as to evaluate the complementarity of DSC perfusion and MET-PET in spatial hotspot definition., Methods: In 41 patient PET/MRI datasets, different ROIs were drawn: in T2-hyperintense tumour, in T2-hyperintense tumour and adjacent oedema and in tumour areas with contrast enhancement, altered perfusion or pathological radiotracer uptake. The performance of DSC perfusion and MET-PET using the different ROIs to distinguish high- and low-grade gliomas was assessed. The spatial overlap of hotspots identified by DSC perfusion and MET-PET was assessed visually., Results: ROIs in T2 fluid attenuated inversion recovery (FLAIR) sequence-hyperintense tumour revealed the most significant differences between high- and low-grade gliomas and reached the highest diagnostic performance in both DSC perfusion (p = 0.046; area under the curve = 0.74) and MET-PET (p = 0.007; area under the curve = 0.80). The combination of methods yielded an area under the curve of 0.80. Hotspots were completely overlapped in one half of the patients, partially overlapped in one third of the patients and present in only one method in approximately 20% of the patients., Conclusions: For multi-parametric examinations with DSC perfusion and MET-PET, we recommend an ROI definition based on T2-hyperintense tumour. DSC perfusion and MET-PET contain complementary information concerning the spatial hotspot definition.

Purpose: This paper aims to evaluate a new iterative metal artifact reduction algorithm for post-interventional evaluation of brain tissue and intracranial arteries., Methods: The data of 20 patients that underwent follow-up cranial CT and cranial CT angiography after clipping or coiling of an intracranial aneurysm was retrospectively analyzed. After the images were processed using a novel iterative metal artifact reduction algorithm, images with and without metal artifact reduction were qualitatively evaluated by two readers, using a five-point Likert scale. Moreover, artifact strength was quantitatively assessed in terms of CT attenuation and standard deviation alterations., Results: The qualitative analysis yielded a significant increase in image quality (p = 0.0057) in iteratively processed images with substantial inter-observer agreement (ĸ = 0.72), while the CTA image quality did not differ (p = 0.864) and even showed vessel contrast reduction in six cases (30%). The mean relative attenuation difference was 27% without metal artifact reduction vs. 11% for iterative metal artifact reduction images (p = 0.0003)., Conclusions: The new iterative metal artifact reduction algorithm enhances non-enhanced CT image quality after clipping or coiling, but in CT-angiography images, the contrast of adjacent vessels can be compromised.

Introduction: The aim if this study is to find out if contrast between gray (GM) and white matter (WM) on non-enhanced brain CT (NECT) can be enhanced by using a frequency selective non-linear blending., Methods: Thirty consecutive patients (40 % female; mean age 67.73 ± 12.71 years), who underwent NECT of the brain, were retrospectively included in this study. Brain scan readings were performed by two radiologists independently, for NECT and subsequently the images were read using a new frequency selective non-linear blending algorithm (best contrast, BC). Optimal settings of BC for enhanced delineation of anatomical structures were set at an averaged center of 30 HU, averaged delta of 5 HU, and a slope of 5. For contrast-to-noise ratio calculation (CNR), gray and white matter attenuation values were measured for both NECT and BC in different anatomical structures., Results: CNR increase in the gray matter was 5.91 ± 2.45 for the cortical gray matter and 4.41 ± 1.82 for the basal ganglia. The contrast ratio between cortical gray and white matter was 1.87 and 1.7 (basal ganglia/WM) for BC quantification vs. 1.43 (cortex/WM) and 1.33 (basal ganglia/WM) for standard NECT (both p < 0.0001). Improved CNR did not depend on the anatomical structures measured., Conclusion: Frequency selective non-linear blending allows better discrimination between WM and GM and therefore may enhance diagnostic accuracy of NECT.

Introduction: The purpose of this study was to evaluate the feasibility of intravoxel incoherent motion (IVIM) imaging and its value in differentiating the histologic grade among human gliomas., Methods: The IVIM model generated parametric images for apparent diffusion coefficient ADC, slow diffusion coefficient D (or D slow), fast diffusion coefficient D* (or D fast), and fractional perfusion-related volume f in 22 patients with gliomas (WHO grade II-IV) using monopolar Stejskal-Tanner diffusion-weighted imaging (DWI) scheme and 14 b values ranging from 0 s/mm2 to a maximum of 1,300 s/mm2. A region-of-interest analysis on the tumor as well as in the white matter was conducted. The parameter values were tested for significant differences. The repeatability of the measurements was tested by coefficient of variation and Bland-Altman plots., Results: D, D*, and f in the high-grade gliomas demonstrated significant differences compared to the healthy white matter. D* and f showed a significant difference between low- and high-grade gliomas. D tended to be slightly lower in the WHO grade II compared to WHO grade III-IV tumors. f and D* demonstrated higher coefficients of variation than the ADC and D in tumor. The Bland-Altman plots demonstrated satisfactory results without any outliers outside the mean ± 1.96 standard deviation., Conclusion: The IVIM-fitted post-processing of DWI-signal decay in human gliomas could show significantly different values of fractional perfusion-related volume and fast diffusion coefficient between low- and high-grade tumors, which might enable a noninvasive WHO grading in vivo.

Treatment of a symptomatic stenosis is known to be most beneficial within 14 days after the presenting event but this can frequently not be achieved in daily practice. The aim of this study was the assessment of factors responsible for this time delay to treatment. A retrospective analysis of a prospective two-center CAS database was carried out to investigate the potential factors that influence a delayed CAS treatment. Of 374 patients with a symptomatic carotid stenosis, 59.1% were treated beyond ≥14 days. A retinal TIA event (OR = 3.59, 95% CI 1.47-8.74, p < 0.01) was found to be a predictor for a delayed treatment, whereas the year of the intervention (OR = 0.32, 95% CI 0.20-0.50, p < 0.01) and a contralateral carotid occlusion (OR = 0.42, 95% CI 0.21-0.86, p = 0.02) were predictive of an early treatment. Similarly, within the subgroup of patients with transient symptoms, the year of the intervention (OR = 0.28, 95% CI 0.14-0.59, p < 0.01) was associated with an early treatment, whereas a retinal TIA as the qualifying event (OR = 6.96, 95% CI 2.37-20.47, p < 0.01) was associated with a delayed treatment. Treatment delay was most pronounced in patients with an amaurosis fugax, whereas a contralateral carotid occlusion led to an early intervention. Although CAS is increasingly performed faster in the last years, there is still scope for an even more accelerated treatment strategy, which might prevent future recurrent strokes prior to treatment.

Introduction: When scanning the size of the substantia nigra (SN), for example in Parkinson's disease, it is important to precisely locate its true anatomic location. The hypointense areas on T2-weighted magnetic resonance images (T2w) at the level of the upper midbrain are usually labeled as the SN. Recent studies showed that the line of demarcation between the SN and the crus cerebri (CC) in T2w images seems not to be clear. The purpose of our study was to evaluate the depiction of the SN and the CC on calculated R2 maps by analyzing the regional distribution of T2 values in both regions., Methods: In 36 healthy subjects, triple echo turbo spin echo were obtained at 1.5 T and R2 maps calculated. Proton density-weighted turbo spin echo images (PDw) were used as reference. The CC and SN were manually traced on PDw sections (CCP and SNP) and also the hyperintense areas on the R2 maps, suggestive of the SN (DT2). The obtained volumes were evaluated in terms of total size, intersections size, and residual areas, as well as the corresponding T2 values., Results: DT2 corresponded to anterolateral parts of the SNP and showed an extension to anteromedial part of the CC. The intersections between DT2 and CCP and DT2 and SNP presented both decreased but different T2 values (102 +/- 5 and 95 +/- 4 ms)., Conclusion: An exact differentiation of the SN from the CC is not possible on the basis of T2w images but rather on the basis of the underlying calculated T2 values from the triple echo sequence.

Case Report: We report on the case of a 31-year old female presenting a massive bleeding during extraction of left lower wisdom tooth, which could be managed by local compression. In the following transfemoral angiography an extensive arteriovenous malformation (avm) in the pterygomandibular space with osseous infiltration was diagnosed and embolised during the same session. After the acute stage the malformation could be controlled by repeated embolisation, the wound being closed by use of a transposition flap., Conclusions: Although arteriovenous malformations of the head and neck are rare, they can manifest with dramatic bleeding complications during surgical interventions. A thrill on palpation and auscultation may also refer to the existence of such a vascular lesion. An av-malformation may be stimulated by hormonal changes during puberty or pregnancy as well as by local trauma. Colour coded duplex sonography, magnetic resonance imaging and transfemoral angiography are suitable diagnostic tools. The treatment of choice is superselective embolisation followed by surgical resection of the vascular nidus, which should be performed by under an interdisciplinary approach.

Purpose: The purpose of this study was to report the case of a patient with a saccular, intraorbital aneurysm of the ophthalmic artery and to analyze the correlation between clinical symptoms and aneurysm localization with regard to the literature., Method: We correlated the patient's clinical findings with anatomical substrates on magnetic resonance imaging and angiographic studies., Results: A 64-year-old woman presented with a rapidly progressive loss of visual acuity in her right eye, temporo-basal visual field defects, a temporal pallor of the optic disc and third and sixth nerve palsies. This apex orbitae compression syndrome was due to an aneurysm of the proximal intraorbital segment of the ophthalmic artery at a position inferolateral to the optic nerve, inferior to the third and medial to the sixth cranial nerve., Conclusion: The symptoms caused by an aneurysm of the ophthalmic artery depend on its localization and spatial relationship to neural structures. While aneurysms of the intracranial and distal intraorbital segments may remain asymptomatic, those arising from the intracanalicular segment become clinically apparent with optic nerve conduction disorders. Aneurysms in the proximal intraorbital segment additionally provoke oculomotor disturbances due to compression of the third and sixth cranial nerves.

Paragangliomas of the glomus caroticum are relatively rare, but highly vascularized neoplasmas, which develop from chemoreceptors. They can be develop at any age, but most often in the third or fourth decade of life. Paragangliomas grow very slowly and are most always of benign origin. There is a familial predisposition, and an autosomal-dominant transmission is presumed. They are commonly located in the jugular region; in rare cases a polytopic manifestation is found. We describe the case of a 47-year-old male patient who was referred to our department because of a progressive swelling of the neck on both sides. Contrast-enhanced computed tomography had displayed soft tissue tumors in the jugular regions. We performed an operative exploration, which showed a highly vascularized tumor. Histopathologic analysis revealed the diagnosis of a paraganglioma. An angiography of the neck and thoracic region, furthermore, revealed an additional paraganglioma in the anterior mediastinum. Using a surgical approach via lateral cervicotomies and thoracotomy the paragangliomas were extirpated. Our case report demonstrates the rare polytopic manifestation of paragangliomas. This perivascular neoplasms have to be removed before haemodynamic complications develop. The extent of this tumors is clearly illustrated by use of an angiography. Because of the familial predisposition, clinical and radiological examinations of relatives are mandatory.