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Abstract: Background: Despite continuous improvements in CT technology, accurate stent lumen delineation remains challenging. Purpose: The aim was to evaluate the quality of coronary stent lumen delineation with CT using a detector with integrated electronics. Methods: Twelve coronary stents placed in plastic tubes and filled with contrast agent (CT number 250 HU) were imaged with either a 128-section dual-source CT machine equipped with conventional detector or with integrated electronics. On both scanners, images were reconstructed with filtered back projection (slice thickness 0.6 mm; increment 0.4 mm) and sinogram-affirmed iterative reconstruction (slice thickness 0.6 mm; increment 0.4 mm), and with iterative reconstruction (slice thickness 0.5 mm; increment 0.3 mm) on the integrated scanner. Two blinded, independent readers assessed image quality, noise, in-stent diameter, in-stent attenuation, and image sharpness by using signal intensity profiles across stents. Results: Interreader agreement for image quality assessment was substantial (κ = 0.798). Both readers rated best image quality in data sets from integrated detector at highest spatial resolution (86 or 72% of stents rated best quality). Image noise was significantly lower in data sets scanned with integrated detector, being lowest at 0.6 mm slice thickness (14.3 vs 21.0 HU; P < .001). Differences between measured and true in-stent diameters and differences in attenuation across stents were smallest, and average/maximum image sharpness was highest in data sets from the integrated detector using iterative reconstructions. Conclusion: CT coronary stent imaging is significantly improved by using a detector with integrated electronics combined with iterative reconstructions. [Copyright &y& Elsevier]

Objectives: This study sought to determine whether the classification of human coronary atherosclerotic plaques with T1, T2, and ultrashort echo time (UTE) cardiac magnetic resonance (CMR) would correlate well with atherosclerotic plaque classification by histology. Background: CMR has been extensively used to classify carotid plaque, but its ability to characterize coronary plaque remains unknown. In addition, the detection of plaque calcification by CMR remains challenging. Here, we used T1, T2, and UTE CMR to evaluate atherosclerotic plaques in fixed post-mortem human coronary arteries. We hypothesized that the combination of T1, T2, and UTE CMR would allow both calcified and lipid-rich coronary plaques to be accurately detected. Methods: Twenty-eight plaques from human donor hearts with proven coronary artery disease were imaged at 9.4-T with a T1-weighted 3-dimensional fast low-angle shot (FLASH) sequence (250-μm resolution), a T2-weighted rapid acquisition with refocused echoes (RARE) sequence (in-plane resolution 0.156 mm), and an UTE sequence (300-μm resolution). Plaques showing selective hypointensity on T2-weighted CMR were classified as lipid-rich. Areas of hypointensity on the T1-weighted images, but not the UTE images, were classified as calcified. Hyperintensity on the T1-weighted and UTE images was classified as hemorrhage. Following CMR, histological characterization of the plaques was performed with a pentachrome stain and established American Heart Association criteria. Results: CMR showed high sensitivity and specificity for the detection of calcification (100% and 90%, respectively) and lipid-rich necrotic cores (90% and 75%, respectively). Only 2 lipid-rich foci were missed by CMR, both of which were extremely small. Overall, CMR-based classification of plaque was in complete agreement with the histological classification in 22 of 28 cases (weighted κ = 0.6945, p < 0.0001). Conclusions: The utilization of UTE CMR allows plaque calcification in the coronary arteries to be robustly detected. High-resolution CMR with T1, T2, and UTE contrast enables accurate classification of human coronary atherosclerotic plaque. [Copyright &y& Elsevier]

Objectives: This study sought to determine the accuracy of plaque pattern assessment by coronary computed tomography angiography (CCTA) to differentiate between early and advanced atherosclerotic lesions as defined by histology. Background: A ringlike attenuation pattern of coronary atherosclerotic plaques termed as napkin-ring sign (NRS) was described in CCTA of patients who had acute coronary syndrome. Methods: All procedures were performed in accordance with local and federal regulations and the Declaration of Helsinki. Approval of the local ethics committees was obtained. We investigated 21 coronary arteries of 7 donor hearts. Overall, 611 histological sections were obtained and coregistered with CCTA images. The CCTA cross sections were read in random order for conventional plaque categories (noncalcified [NCP], mixed [MP], calcified [CP]) and plaque patterns (homogenous, heterogeneous with no napkin-ring sign [non-NRS], and heterogeneous with NRS). Results: No plaque was detected in 134 (21.9%), NCP in 254 (41.6%), MP in 191 (31.3%), and CP in 32 (5.2%) CCTA cross sections. The NCP and MP were further classified into homogenous plaques (n = 207, 46.5%), non-NRS plaques (n = 200, 44.9%), and NRS plaques (n = 38, 8.6%). The specificities of NCP and MP to identify advanced lesions were moderate (57.9%, 95% confidence interval [CI]: 50.1% to 65.6%, and 72.1%, 95% CI: 64.7% to 79.4%, respectively), which were similar to the homogenous and heterogeneous plaques (62.6%, 95% CI: 54.8% to 70.3%, and 67.3%, 95% CI: 58.6% to 76.1%, respectively). In contrast, the specificity of the NRS to identify advanced lesions was excellent (98.9%, 95% CI: 97.6% to 100%). The diagnostic performance of the pattern-based scheme to identify advanced lesions was significantly better than that of the conventional plaque scheme (area under the curve: 0.761 vs. 0.678, respectively; p = 0.001). Conclusions: The assessment of the plaque pattern improves diagnostic accuracy of CCTA to identify advanced atherosclerotic lesions. The CCTA finding of NRS has a high specificity and high positive predictive value for the presence of advanced lesions. [Copyright &y& Elsevier]

Abstract: Objective: To assess prospectively the intra- and interobserver variability, accuracy, and prognostic value of right and left ventricular short-axis diameter (RVd and LVd) measurements for risk stratification in patients with pulmonary embolism (PE) using ECG-gated compared to non-gated CT. Materials and methods: Sixty consecutive patients (33 women; mean age 58.7±10.3 years) with suspicion of PE underwent both non-gated and ECG-gated chest CT. RVd and LVd on four-chamber views and intra- and interobserver agreements were calculated for both protocols. RVd/LVd ratios were calculated and were related to 30-days adverse clinical events using receiver operating characteristics with area-under-the-curve (AUC) analyses. Results: Both inter- and intraobserver variability showed narrower limits of agreement for all measurements with ECG-gated as compared to non-gated CT. Diameter measurements were significantly lower using non-ECG-gated CT as compared to ECG-gated CT for RVd and LVd (both p <.05). The AUC for the RVd/LVd ratio from ECG-gated CT was significantly larger than that from non-gated CT (0.956, 95% CI: 0.768–0.999 versus 0.675, 95% CI: 0.439–0.860; p =.048). Conclusion: RVd and LVd measurements from ECG-gated chest CT show less intra- and interobserver variability and more accurately reflect ventricular function. In our patient cohort ECG-gated chest CT allows better prediction of short-term outcome of patients with acute PE that needs to be validated in a larger outcome study. [Copyright &y& Elsevier]

Abstract: Purpose: To prospectively determine the best cut-off value of stenosis degree for low-dose computed tomography coronary angiography (CTCA) to predict the hemodynamic significance of coronary artery stenoses compared to catheter angiography (CA) using a cardiac magnetic resonance based approach as standard of reference. Materials and methods: Fifty-two patients (mean age, 64±10 years) scheduled for CA underwent cardiac magnetic resonance (CMR) at 1.5-T and dual-source CTCA using prospective ECG-triggering the same day. Diagnostic performance of CTCA and CA to detect myocardial ischemia was evaluated with CMR as the standard of reference. The diagnostic performance and best cut-off values to predict the hemodynamic significance of coronary were determined from receiver operating characteristics analysis (ROC). Results: CA revealed >50% stenoses in 131/832 segments (15.7%) in 78/156 (50.0%) coronary arteries in 32/52 (62%) patients. CTCA revealed >50% stenoses in 148/807 (18.3%) segments, corresponding to 83/156 (53.2%) coronary arteries in 34/52 (65.4%) patients. CMR revealed ischemia in 118/832 (14.2%) myocardial segments corresponding to the territories of 60/156 (38.5%) coronary arteries in 29/52 (56%) patients. ROC analysis showed equal diagnostic performance for low-dose CTCA and CA with areas under the curve (AUC) of 0.82 and 0.83 (P =0.64). The optimal cut-off value was determined at stenosis of >60% for the prediction of hemodynamically significant coronary stenosis by CTCA. Using this cut-off value, sensitivity, specificity, NPV and PPV to predict hemodynamic significance by CTCA were 100%, 83%, 100%, and 88% on a per-patient basis and 88%, 73%, 83% and 81% on a per-artery analysis, respectively. Conclusion: By considering coronary stenosis >60%, diagnostic performance for predicting the hemodynamic significance of coronary stenosis by CTCA is optimal and equals that of CA. [Copyright &y& Elsevier]

Purpose: To prospectively investigate the technical feasibility and performance of image fusion for whole-body diffusion-weighted imaging (wbDWI) and computed tomography (CT) to detect metastases using hybrid positron emission tomography/computed tomography (PET/CT) as reference standard. Material and Methods: Fifty-two patients (60 ± 14 years; 18 women) with different malignant tumor disease examined by PET/CT for clinical reasons consented to undergo additional wbDWI at 1.5 Tesla. WbDWI was performed using a diffusion-weighted single-shot echo-planar imaging during free breathing. Images at b = 0 s/mm2 and b = 700 s/mm2 were acquired and apparent diffusion coefficient (ADC) maps were generated. Image fusion of wbDWI and CT (from PET/CT scan) was performed yielding for wbDWI/CT fused image data. One radiologist rated the success of image fusion and diagnostic image quality. The presence or absence of metastases on wbDWI/CT fused images was evaluated together with the separate wbDWI and CT images by two different, independent radiologists blinded to results from PET/CT. Detection rate and positive predictive values for diagnosing metastases was calculated. PET/CT examinations were used as reference standard. Results: PET/CT identified 305 malignant lesions in 39 of 52 (75%) patients. WbDWI/CT image fusion was technically successful and yielded diagnostic image quality in 73% and 92% of patients, respectively. Interobserver agreement for the evaluation of wbDWI/CT images was κ = 0.78. WbDWI/CT identified 270 metastases in 43 of 52 (83%) patients. Overall detection rate and positive predictive value of wbDWI/CT was 89% (95% CI, 0.85–0.92) and 94% (95% CI, 0.92–0.97), respectively. Conclusion: WbDWI/CT image fusion is technically feasible in a clinical setting and allows the diagnostic assessment of metastatic tumor disease detecting nine of 10 lesions as compared with PET/CT. [ABSTRACT FROM AUTHOR]

Abstract: Objective: To compare, in patients with suspicion of coronary artery disease (CAD) and low heart rates, image quality, diagnostic performance, and radiation dose values of prospectively and retrospectively electrocardiography (ECG)-gated dual-source computed tomography coronary angiography (CTCA) for the diagnosis of significant coronary stenoses. Materials and methods: Two-hundred consecutive patients with heart rates ≤70bpm were retrospectively enrolled; 100 patients undergoing prospectively ECG-gated CTCA (group 1) and 100 patients undergoing retrospectively-gated CTCA (group 2). Coronary artery segments were assessed for image quality and significant luminal diameter narrowing. Sensitivity, specificity, positive predictive values (PPV), negative predictive values (NPV), and accuracy of both CTCA groups were determined using conventional catheter angiography (CCA) as reference standard. Radiation dose values were calculated. Results: Both groups were comparable regarding gender, body weight, cardiovascular risk profile, severity of CAD, mean heart rate, heart rate variability, and Agatston score (all p >0.05). There was no significant difference in the rate of non-assessable coronary segments between group 1 (1.6%, 24/1404) and group 2 (1.4%, 19/1385; p =0.77); non-diagnostic image quality was significantly (p <0.001) more often attributed to stair step artifacts in group 1. Segment-based sensitivity, specificity, PPV, NPV, and accuracy were 98%, 98%, 88%, 100%, and 100% among group 1; 96%, 99%, 90%, 100%, and 98% among group 2, respectively. Parameters of diagnostic performance were similar (all p >0.05). Mean effective radiation dose of prospectively ECG-gated CTCA (2.2±0.4mSv) was significantly (p <0.0001) smaller than that of retrospectively ECG-gated CTCA (8.1±0.6mSv). Conclusion: Prospectively ECG-gated CTCA yields similar image quality, performs as accurately as retrospectively ECG-gated CTCA in patients having heart rates ≤70bpm while being associated with a lower mean effective radiation dose. [Copyright &y& Elsevier]

Rationale and Objectives: To evaluate the quality of stent lumen delineation using dual-source computed tomography (DSCT) in the standard-pitch mode (SP) as compared to the high-pitch mode (HP) in a phantom study. Materials and Methods: Forty different coronary stents placed in plastic tubes filled with contrast agent were imaged with a second generation DSCT system in a SP (pitch 0.23) and HP (pitch 3.4) mode in orientations of 0°, 45°, and 90° relative to the z-axis. Two observers independently measured the in-stent lumen and the attenuation values in the center of the stents. The artificial lumen narrowing (ALN) was calculated using the measured in-stent lumen and the nominal diameter of the plastic tube. Results: Interobserver correlation was excellent for in-stent lumen (0.86) and attenuation measurements (0.91). There was no significant difference neither for ALN (SP: 54.7–62.8%; HP: 55.8–64.0%) nor attenuation (SP: 356–395 Hounsfield units [HU]; HP: 352–384 HU) between SP and HP mode. For both modes, the orientation of the stent relative to the z-axis significantly affected ALN and attenuation (each P < .001). CT volume dose index was significantly lower using HP mode as compared to SP mode (P < .001). Conclusion: The HP mode in DSCT provides visualization of the coronary in-stent lumen comparable to that measured in SP mode while reducing applied radiation dose in a stationary phantom model. [ABSTRACT FROM AUTHOR]

Background: Identification and differentiation of coronary atherosclerotic plaques may improve risk stratification for incident coronary events. Objective: We investigated the ability of dual-source computed tomography (CT) to depict and characterize atherosclerotic coronary plaques. Methods: Contrast-enhanced CT was performed in 25 human heart specimens with a total of 322 histologically determined plaques. Coronary plaques were classified on CT as (1) noncalcified, mixed, or calcified and (2) by CT attenuation values. Atherosclerotic plaques were histopathologically characterized according to the Stary classification. Results: CT detected 79% (245/322) of all plaques. Lesions missed by CT were generally early lesions, type I (n = 31), type II (n = 38), or type III (n = 8), according to Stary. CT detected 29% of early (Stary I–III) and 100% of advanced (Stary IV–VIII) plaques. Plaque classification as noncalcified was sensitive (100%) and specific (72%) for early, whereas classification as mixed/calcified was sensitive (92%, 89%) and specific (100%) for advanced plaques. Calcified plaques on CT were detected with high sensitivity (80%) and specificity (95%). Other subtypes were not distinguishable with CT according to the presence or absence of calcification. CT density was significantly higher for advanced (306 ± 470 HU) than for early (42 ± 14 HU; P < 0.01) plaques. The mean CT density value of type VII plaques (512 ± 349 HU) was significantly higher than those of other plaques (34–101 HU; P < 0.001). Conclusions: CT reliably depicts advanced coronary plaques and allows for the differentiation between early and advanced plaques. [ABSTRACT FROM AUTHOR]

Rationale and Objectives: To assess the performance of dual-energy computed tomography (DECT) equipped with the new tin filter technology to classify phantom renal lesions as cysts or enhancing masses. Materials and Methods: Forty spherical lesion proxies ranging in diameter from 6 to 27 mm were filled with either distilled water (n = 10) representing cysts or titrated iodinated contrast solutions with a concentration of 0.45 (n = 10), 0.9 (n = 10), and 1.8 mg/mL (n = 10) representing enhancing masses. The lesion proxies were placed in a 12-cm diameter renal phantom containing minced beef and submerged in a 28-cm water bath. DECT was performed using the new dual-source CT system (Definition Flash, Siemens Healthcare, Forchheim, Germany) allowing for an improved energy separation by using a tin filter. DECT was performed at tube voltages of 140/80 kV without the tin filter (protocol A) and with tin filter (protocol B). The tube current time product was selected in each protocol to achieve a constant CTDI (computed tomography dose index) with both protocols of 19 mGy (full dose), 9.5 mGy (half dose), and 4.8 mGy (quarter dose). Two blinded readers classified each lesion as a cyst or enhancing mass by using iodine overlay (IO) images. One reader measured the CT numbers of each lesion at 120 kV, in the IO, linear blending (LB), and virtual noncontrast (VNC) images. Results: The CT numbers of the lesions at 120 kV were 0.1 ± 0.7 HU (0 mg iodine/mL), 9.1 ± 0.7 HU (0.45 mg/mL), 18.1 ± 1.4 HU (0.9 mg/mL), and 37.6 ± 1.6 HU (1.8 mg/mL). Mean diameter of the lesion proxies filled with water or different iodine concentrations was similar (P = 0.38). Image noise was not significantly different in protocols A and B at the corresponding dose levels. At full dose, protocol A had a sensitivity of 93% and a specificity of 60% for discriminating renal lesions. Sensitivity and specificity declined to 84% and 38% at quarter dose. In protocol B, sensitivity was 100% and specificity was 90% at full dose and 93% and 70% at quarter dose. All misclassifications occurred in cyst or low iodine concentration (0.45 mg/mL) lesion proxies. The differences between CT numbers at 120 kV and in the IO, VNC, and AW (average weighted) images were significantly lower in protocol B compared to protocol A (each P < .05). Conclusions: DECT using the tin filter results in an improved sensitivity and specificity for discriminating renal cysts from enhancing masses in a kidney phantom model and demonstrates higher dose efficiency as compared to former dual energy technology without tin filters. [Copyright &y& Elsevier]

Rationale and Objectives: The aim of this study was to prospectively investigate the diagnostic value of triple rule-out computed tomography (CT) in patients suspected of having acute pulmonary embolism (PE). Materials and Methods: A total of 125 patients with suspicion of PE, of whom 14 patients had the additional clinical suspicion of acute aortic syndrome, underwent electrocardiogram-gated triple rule-out dual-source CT. The contrast media application protocol was adjusted to obtain a homogenous attenuation of the pulmonary arteries, thoracic aorta, and coronary arteries. The diagnostic performance of triple rule-out CT was assessed by using adjudicated discharge diagnoses as reference standards. Results: A total of 161 adjudicated cardiovascular discharge diagnoses were made in the 125 patients (including all true-positive and true-negative findings): acute PE was found in 26 (21%) and was excluded by CT in 99 (79%), coronary artery disease was found in 3 (3%) and was excluded by catheter angiography in 9 (6%), left ventricular systolic dysfunction was found in 2 (2%) and was excluded by echocardiography in 8 (6%), and acute aortic syndrome was found in 5 (4%) and was excluded by CT in 9 (7%) patients. Nonvascular chest disease was found in 34 (27%) and included pneumonia (n = 17), neoplasms (n = 5), fractures/osteolysis (n = 3), pericarditis (n = 2), and post-pneumonectomy syndrome (n = 1). Triple rule-out CT was normal in 53 (42%) patients. Overall sensitivity, specificity, and positive and negative predictive value of triple rule-out CT for cardiovascular disease were 100% (95% confidence interval [CI] 90-100%), 98% (95%CI 94-100%), 95% (95%CI 82-99%), and 100% (95%CI 97-100%, respectively). Conclusions: Triple rule-out CT is feasible in patients with suspicion of PE, reveals a wide range of vascular and non-vascular chest disease, and offers an excellent overall diagnostic performance. [ABSTRACT FROM AUTHOR]

Rationale and Objectives: The aim of this study was to prospectively investigate the diagnostic value of triple rule-out computed tomography (CT) in patients suspected of having acute pulmonary embolism (PE). Materials and Methods: A total of 125 patients with suspicion of PE, of whom 14 patients had the additional clinical suspicion of acute aortic syndrome, underwent electrocardiogram-gated triple rule-out dual-source CT. The contrast media application protocol was adjusted to obtain a homogenous attenuation of the pulmonary arteries, thoracic aorta, and coronary arteries. The diagnostic performance of triple rule-out CT was assessed by using adjudicated discharge diagnoses as reference standards. Results: A total of 161 adjudicated cardiovascular discharge diagnoses were made in the 125 patients (including all true-positive and true-negative findings): acute PE was found in 26 (21%) and was excluded by CT in 99 (79%), coronary artery disease was found in 3 (3%) and was excluded by catheter angiography in 9 (6%), left ventricular systolic dysfunction was found in 2 (2%) and was excluded by echocardiography in 8 (6%), and acute aortic syndrome was found in 5 (4%) and was excluded by CT in 9 (7%) patients. Nonvascular chest disease was found in 34 (27%) and included pneumonia (n = 17), neoplasms (n = 5), fractures/osteolysis (n = 3), pericarditis (n = 2), and post-pneumonectomy syndrome (n = 1). Triple rule-out CT was normal in 53 (42%) patients. Overall sensitivity, specificity, and positive and negative predictive value of triple rule-out CT for cardiovascular disease were 100% (95% confidence interval [CI] 90–100%), 98% (95%CI 94–100%), 95% (95%CI 82–99%), and 100% (95%CI 97–100%, respectively). Conclusions: Triple rule-out CT is feasible in patients with suspicion of PE, reveals a wide range of vascular and non-vascular chest disease, and offers an excellent overall diagnostic performance. [Copyright &y& Elsevier]

Objectives: The aim of this study was to assess the value of multislice computed tomography (CT) for the assessment of valvular abnormalities in patients with infective endocarditis (IE) in comparison with transesophageal echocardiography (TEE) and intraoperative findings. Background: Multislice CT has recently shown promising data regarding valvular imaging in a 4-dimensional fashion. Methods: Thirty-seven consecutive patients with clinically suspected IE were examined with TEE and 64-slice CT or dual-source CT. Twenty-nine patients had definite IE and underwent surgery. Results: The diagnostic performance of CT for the detection of evident valvular abnormalities for IE compared with TEE was: sensitivity 97%, specificity 88%, positive predictive value (PPV) 97%, and negative predictive value (NPV) 88% on a per-patient basis (n = 37; excellent intermodality agreement κ = 0.84). CT correctly identified 26 of 27 (96%) patients with valvular vegetations and 9 of 9 (100%) patients with abscesses/pseudoaneurysms compared with the intraoperative specimen. On a per-valve–based analysis, diagnostic accuracy for the detection of vegetations and abscesses/pseudoaneurysms compared with surgery was: sensitivity 96%, specificity 97%, PPV 96%, NPV 97%, and sensitivity 100%, specificity 100%, PPV 100%, NPV 100%, respectively, without significant differences as compared with TEE. Vegetation size measurements by CT correlated (r = 0.95; p <0.001) with TEE (mean 7.6 ± 5.6 mm). The mobility of vegetations was accurately diagnosed in 21 of 22 (96%) patients with CT, but all of 4 leaflet perforations (≤2 mm) were missed. CT provided more accurate anatomic information regarding perivalvular extent of abscess/pseudoaneurysms than TEE. Conclusions: Multislice CT shows good results in detecting valvular abnormalities in IE and could be applied in pre-operative planning and exclusion of coronary artery disease before surgery. [Copyright &y& Elsevier]

Abstract: Objective: To determine the radiation doses and image quality of different dual-source computed tomography coronary angiography (CTCA) protocols tailored to the heart rate (HR) and body mass index (BMI) of the patients. Materials and methods: Two hundred consecutive patients (68 women; mean age 61±9 years) underwent either helical CTCA with retrospective ECG-gating or sequential CT with prospective ECG-triggering: 50 patients (any BMI, any HR) were examined with a standard, non-tailored protocol (helical CTCA, 120kV, 330mAs), whereas the other 150 patients were examined with a tailored protocol: 40 patients (group A, BMI≤25kg/sqm, HR≤70bpm) with sequential CTCA (100kV, 190mAsref), 43 patients (group B, BMI≤25kg/sqm, HR>70bpm) with helical CTCA (100kV, 220mAs), 28 patients (group C, BMI>25kg/sqm, HR≤70bpm) with sequential CTCA (120kV, 330mAsref), and 39 patients (group D, BMI>25kg/sqm, HR>70bpm) with helical CTCA (120kV, 330mAs). The effective radiation dose estimates were calculated from the dose-length-product for each patient. Image quality was classified as being diagnostic or non-diagnostic in each coronary segment. Results: Image quality was diagnostic in 2403/2460 (98%) and non-diagnostic in 57/2460 (2%) of all coronary segments. No significant differences in image quality were found among all five CTCA protocols (p =0.78). The non-tailored helical CTCA protocol was associated with a radiation dose of 9.0±1.0mSv, being significantly higher compared to that using sequential CTCA (group A: 1.3±0.3mSv, p <0.001; group C: 2.9±0.6mSv, p <0.001), and helical CTCA at reduced tube voltage and tube current (group B: 4.2±0.6mSv, p <0.01). No significant differences were found compared to the non-tailored CTCA protocol in patients with HR>70bpm (group D: 8.5±0.9mSv, p =0.51). Conclusions: Dual-source CTCA is associated with radiation doses ranging between 1.3 and 9.0mSv, depending on the protocol used. Tailoring of the CTCA protocol to the HR and BMI of the individual patient results in dose reductions of up to 86%, while maintaining a diagnostic image quality of the examination. [Copyright &y& Elsevier]

Rationale and Objectives: The aim of this study was to compare the diagnostic accuracy of 64-slice computed tomographic coronary angiography (CTCA) in groups of patients with low, intermediate, and high risk for coronary artery disease (CAD) events. Materials and Methods: The institutional review board approved this study; written informed consent was obtained from all patients. Eighty-eight consecutive patients with suspected CAD (40 women; mean age, 64.3 ± 9.4 years; range, 39–82) underwent CTCA, calcium scoring, and invasive coronary angiography and were grouped according to their Framingham 10-year risk for hard coronary events into low (<10%), intermediate (10%–20%), and high (>20%) risk categories. Significant stenoses (luminal diameter narrowing ≥50%) were assessed on an intention-to-diagnose-basis; no coronary segment was excluded and nonevaluative segments were rated false positive. To determine differences between groups, Kruskal-Wallis tests were performed for individually determined values of diagnostic performance. Results: Per-patient sensitivity, specificity, negative predictive, and positive predictive values were 90.0%, 79.2%, 95.0%, and 64.3%, respectively, with low (n = 34), 87.5%, 92.3%, 85.7%, and 93.3%, respecitively, with intermediate (n = 29), and 100%, 75.0%, 100%, and 89.5%, respectively, with high risk (n = 25), with a trend toward higher positive predictive value (P = .07). Per-segment negative predictive value was lower with high pretest probability (P < .01). Mean calcium-score units were 90, 220, and 312 (P = .23), and the prevalence of CAD was 29.4%, 55.2%, and 68.0% (P < .01) with low, intermediate, and high risk. Conclusion: Sensitivity and specificity of CTCA are not influenced by the prevalence of CAD, whereas the negative predictive value is lower and the positive predictive value tends to be higher in patients with a high prevalence of CAD. [Copyright &y& Elsevier]

An abstract of the paper "Comparison of 3D and 2D Acquisition of Late Gadolinium Enhancement in Patients With Acute, Subacute and Chronic Myocardial Infarction," by Robert Goetti and colleagues is presented.

Abstract: Objectives: To compare image quality of coronary artery plaque visualization at CT angiography with images reconstructed with filtered back projection (FBP), adaptive statistical iterative reconstruction (ASIR), and model based iterative reconstruction (MBIR) techniques. Methods: The coronary arteries of three ex vivo human hearts were imaged by CT and reconstructed with FBP, ASIR and MBIR. Coronary cross-sectional images were co-registered between the different reconstruction techniques and assessed for qualitative and quantitative image quality parameters. Readers were blinded to the reconstruction algorithm. Results: A total of 375 triplets of coronary cross-sectional images were co-registered. Using MBIR, 26% of the images were rated as having excellent overall image quality, which was significantly better as compared to ASIR and FBP (4% and 13%, respectively, all p <0.001). Qualitative assessment of image noise demonstrated a noise reduction by using ASIR as compared to FBP (p <0.01) and further noise reduction by using MBIR (p <0.001). The contrast-to-noise-ratio (CNR) using MBIR was better as compared to ASIR and FBP (44±19, 29±15, 26±9, respectively; all p <0.001). Conclusions: Using MBIR improved image quality, reduced image noise and increased CNR as compared to the other available reconstruction techniques. This may further improve the visualization of coronary artery plaque and allow radiation reduction. [Copyright &y& Elsevier]

Abstract: Purpose: To investigate the ex vivo performance of high-resolution computed tomography (CT) for quantitative assessment of percentage diameter stenosis in coronary arteries compared to histopathology. Materials and methods: High-resolution CT was performed in 26 human heart specimens after the injection of iodinated contrast media into the coronary arteries. Coronary artery plaques were visually identified on CT images and the grade of stenosis for each plaque was measured with electronic calipers. All coronary plaques were characterized by histopathology according to the Stary classification, and the percentage of stenosis was measured. Results: CT depicted 84% (274/326) of all coronary plaques identified by histology. Missed plaques by CT were of Stary type I (n =31), type II (n =16), and type III (n =5). The stenosis degree significantly correlated between CT and histology (r =0.81, p <0.001). CT systematically overestimated the stenosis of calcified plaques (mean difference - 11.0±9.5%, p <0.01) and systematically underestimated the stenosis of non-calcified plaques (mean difference −6.8±10.4%, p <0.05), while there was no significant difference for mixed-type plaques (mean difference −0.4±11.7%, p =0.85). There was a significant underestimation of stenosis degree as measured by CT for Stary II plaques (mean difference −14±9%, p <0.01) and a significant overestimation for Stary VII plaques (mean difference 9±10%, p <0.05), but there was no significant difference in stenosis degree between both modalities for other plaque types. Conclusions: High-resolution CT reliably depicts advanced stage coronary plaques with an overall good correlation of stenosis degree compared to histology, however, the degree of stenosis is systematically overestimated in calcified and underestimated in non-calcified plaques. [Copyright &y& Elsevier]

Abstract Purpose To investigate 18F-fluoro-ethyl-tyrosine positron emission tomography (FET-PET) imaging characteristics of adult brainstem glioma (BSG). Materials and methods FET-PET imaging and progression-free survival (PFS) of 16 adult patients with BSG was analyzed (9 high-grade gliomas, 7 low-grade gliomas). SUV max , TBR, and time activity curves of FET-PET were calculated. Results Progressive gliomas had higher SUV max (3.57 ± 1.47 vs. 1.60 ± 0.51; p = 0.003) and TBR max (3.00 ± 1.12 vs. 1.36 ± 0.33; p = 0.001) than stable gliomas. Kaplan-Meier analysis showed longer PFS of tumors with TBR max < 2.0 compared to tumors with TBR max > 2.0 (665 ± 32 days versus 220 ± 39 days; p < 0.001). Conclusion FET-PET uptake might be associated with disease progression in adult BSG. Highlights • Progressive gliomas have higher SUV max (3.57 vs. 1.60; p = 0.003) and TBR max (3.00 vs. 1.36; p = 0.001) than stable gliomas. • Patients with tumors TBR max < 2.0 have longer progression-free survival compared to patients with tumor TBR max > 2.0. • FET-PET might eventually be able to prognosticate progression of adult BSG. Tumors with a TBR max > 2.0 might progress more rapidly. [ABSTRACT FROM AUTHOR]

Purpose: To prospectively evaluate the detection and conspicuity of pulmonary nodules in an oncological population, using a tri-modality PET/CT-MR protocol including a respiration-gated T2-PROPELLER sequence for possible integration into a simultaneous PET/MR protocol.Methods: 149 patients referred for staging of malignancy were prospectively enrolled in this single-center study. Imaging was performed on a tri-modality PET/CT-MR setup and was comprised of PET/CT and 3T-MR imaging with 3D dual-echo GRE pulse sequence (Dixon) and an axial respiration-gated T2-weighted PROPELLER (T2-P) sequence. Images were assessed for presence, conspicuity, size and interpretation of the pulmonary parenchymal nodules. McNemar's test was used to evaluate paired differences in nodule detection rates between MR and CT from PET/CT. The correlation of pulmonary nodule size in CT and MR imaging was assessed using Pearson correlation coefficient.Results: 299 pulmonary nodules were detected on PET/CT. The detectability was significantly higher on T2-P (60%, p<0.01) compared to T1-weighted Dixon-type sequences (16.1-37.8%). T2-P had a significantly higher detection rate among FDG-positive (92.4%) and among confirmed malignant nodules (75.9%) compared to T1-Dixon. Nodules <10mm were detected less often by MR sequences than by CT (p < 0.01). However, nodules >10mm were detected equally well with T2-P (92.2%) and CT (p >0.05). In a per-patient analysis, there was no significant change in the clinical interpretation of the nodules detected with T2-P and CT.Conclusion: Despite the overall lower detection rate compared with CT, the free-breathing respiratory gating T2-w sequence showed higher detectability in all evaluated categories compared to breath-hold T1-weighted MR sequences. Specifically, the T2-P was found to be not statistically different from CT in FDG-positive nodules, in detection of nodules >10mm and concerning conspicuity of pulmonary nodules. Overall, the additional time investment into T2-P seems to be justified since clinical relevant assessment of pulmonary lung nodules can mostly be done by T2-P in a whole body PET/MR staging of oncologic patients. [ABSTRACT FROM AUTHOR]

Purpose To compare the diagnostic accuracy of PET+MR with PET/CT in the initial staging of head and neck cancer. Materials and methods Contrast-enhanced PET/CT+MR was performed in 27 patients with newly diagnosed head and neck cancer. PET/CT and PET+MR were evaluated separately, and the TNM stage and factors influencing treatment were assessed. Results The TNM staging by PET+MR was comparable to PET/CT (T: p = 0.331, N: p = 0.453, M: p = 0.034). The sensitivity/specificity/accuracy of treatment-influencing factors by PET/CT and PET+MR were 0.68/0.99/0.97, and 1.00/1.00/0.99, respectively. Conclusions Whole-body staging with PET+MR yields at least equal diagnostic accuracy as PET/CT in head and neck cancer. [ABSTRACT FROM AUTHOR]

Abstract: Stem cells have been repeatedly suggested for cardiac regeneration after myocardial infarction (MI). However, the low retention rate of single cell suspensions limits the efficacy of current therapy concepts so far. Taking advantage of three dimensional (3D) cellular self-assembly prior to transplantation may be beneficial to overcome these limitations. In this pilot study we investigate the principal feasibility of intramyocardial delivery of in-vitro generated stem cell-based 3D microtissues (3D-MTs) in a porcine model. 3D-MTs were generated from iron-oxide (MPIO) labeled human adipose-tissue derived mesenchymal stem cells (ATMSCs) using a modified hanging-drop method. Nine pigs (33 ± 2 kg) comprising seven healthy ones and two with chronic MI in the left ventricle (LV) anterior wall were included. The pigs underwent intramyocardial transplantation of 16 × 103 3D-MTs (1250 cells/MT; accounting for 2 × 10 7 single ATMSCs) into the anterior wall of the healthy pigs (n = 7)/the MI border zone of the infarcted (n = 2) of the LV using a 3D NOGA electromechanical mapping guided, transcatheter based approach. Clinical follow-up (FU) was performed for up to five weeks and in-vivo cell-tracking was performed using serial magnet resonance imaging (MRI). Thereafter, the hearts were harvested and assessed by PCR and immunohistochemistry. Intramyocardial transplantation of human ATMSC based 3D-MTs was successful in eight animals (88.8%) while one pig (without MI) died during the electromechanical mapping due to sudden cardiac-arrest. During FU, no arrhythmogenic, embolic or neurological events occurred in the treated pigs. Serial MRI confirmed the intramyocardial presence of the 3D-MTs by detection of the intracellular iron-oxide MPIOs during FU. Intramyocardial retention of 3D-MTs was confirmed by PCR analysis and was further verified on histology and immunohistochemical analysis. The 3D-MTs appeared to be viable, integrated and showed an intact micro architecture. We demonstrate the principal feasibility and safety of intramyocardial transplantation of in-vitro generated stem cell-based 3D-MTs. Multimodal cell-tracking strategies comprising advanced imaging and in-vitro tools allow for in-vivo monitoring and post-mortem analysis of transplanted 3D-MTs. The concept of 3D cellular self-assembly represents a promising application format as a next generation technology for cell-based myocardial regeneration. [Copyright &y& Elsevier]

Abstract: Objective: To compare radiation doses delivered at prospectively ECG-triggered sequential- (SEQ), retrospectively ECG-gated spiral- (RETRO) and prospectively ECG-triggered high-pitch spiral- (HP) computed tomography coronary angiography (CTCA) protocols, as well as catheter coronary angiography (CCA) using an anthropomorphic phantom. Materials and methods: An anthropomorphic Alderson phantom equipped with 50 thermoluminescent dosimeters (TLDs) was scanned using different CTCA protocols and an uncomplicated diagnostic CCA examination was simulated. Absorbed doses were experimentally determined and effective doses calculated using the dose-length product (DLP) for CTCA and the dose-area product (DAP) for CCA, as well as according to International Commission on Radiation Protection (ICRP) publications 60 and 103. Results: Effective organ doses were significantly lower for HP protocols (100kV: 0.17±0.26mSv; 120kV: 0.26±0.39mSv) compared to SEQ protocols (100kV: 0.50±0.79mSv; 120kV: 0.90±1.41mSv; each p <0.05) and compared to RETRO protocols (100kV: 1.59±2.12mSv; 120kV: 2.75±3.50mSv; each p <0.05). Effective organ doses at HP-CTCA tended to be lower than at CCA (0.37±0.40mSv), however this was not statistically significant (p =0.13). Effective doses calculated according to ICRP guidelines could be estimated using the DLP and a conversion coefficient of k =0.034mSv/[mGycm] (ICRP103) or k =0.028mSv/[mGycm] (ICRP60), respectively. HP-CTCA led to a dose reduction of 89% compared to RETRO-CTCA, regardless of the calculation method used. Conclusions: Radiation doses as determined by phantom measurements are significantly lower at HP-CTCA compared to SEQ-CTCA and RETRO-CTCA and comparable to uncomplicated diagnostic CCA. [Copyright &y& Elsevier]

Objectives: This study was designed to determine whether multislice computed tomography (MSCT) coronary angiography has incremental prognostic value over single-photon emission computed tomography myocardial perfusion imaging (MPI) in patients with suspected coronary artery disease (CAD). Background: Although MSCT is used for the detection of CAD in addition to MPI, its incremental prognostic value is unclear. Methods: In 541 patients (59% male, age 59 ± 11 years) referred for further cardiac evaluation, both MSCT and MPI were performed. The following events were recorded: all-cause death, nonfatal infarction, and unstable angina requiring revascularization. Results: In the 517 (96%) patients with an interpretable MSCT, significant CAD (MSCT ≥50% stenosis) was detected in 158 (31%) patients, and abnormal perfusion (summed stress score [SSS]: ≥4) was observed in 168 (33%) patients. During follow-up (median 672 days; 25th, 75th percentile: 420, 896), an event occurred in 23 (5.2%) patients. After correction for baseline characteristics in a multivariate model, MSCT emerged as an independent predictor of events with an incremental prognostic value to MPI. The annualized hard event rate (all-cause mortality and nonfatal infarction) in patients with none or mild CAD (MSCT <50% stenosis) was 1.8% versus 4.8% in patients with significant CAD (MSCT ≥50% stenosis). A normal MPI (SSS <4) and abnormal MPI (SSS ≥4) were associated with an annualized hard event rate of 1.1% and 3.8%, respectively. Both MSCT and MPI were synergistic, and combined use resulted in significantly improved prediction (log-rank test p value <0.005). Conclusions: MSCT is an independent predictor of events and provides incremental prognostic value to MPI. Combined anatomical and functional assessment may allow improved risk stratification. [Copyright &y& Elsevier]