[18F]-Fluorodeoxyglucose Positron Emission Tomography/CT to Assess the Early Metabolic Response in Patients with Hormone Receptor-Positive HER2-Negative Metastasized Breast Cancer Treated with Cyclin-Dependent 4/6 Kinase Inhibitors.

INTRODUCTION: Addition of cyclin-dependent 4/6 kinase (CDK4/6) inhibitors to endocrine therapy is standard of care in the treatment of women with advanced hormone receptor-positive HER2-negative breast cancer. However, the predictive factors for the treatment response to CDK4/6 inhibitor therapy are poorly elucidated. Early changes in the by [18F]-fluorodeoxyglucose positron emission tomography (FDG-PET) uptake of tumors receiving different kinds of therapy have proven to reliably predict treatment outcomes in a variety of malignancies. Therefore, the feasibility of early metabolic response assessment to predict the long-term treatment response to CDK4/6 inhibitor therapy was evaluated in the present study. METHODS: Eight patients underwent FDG-PET/CT before and after the initiation of CDK4/6 inhibitor therapy (ribociclib, palbociclib or abemcaciclib). CDK4/6 inhibitor therapy was combined with either aromatase inhibition or fulvestrant. The median interval between the treatment start (including baseline PET) and the follow-up PET examination was 14 days. Conventional radiographic staging was performed 3 months after the start of CDK4/6 inhibitor therapy. The percentual changes in molecular tumor volume, SUVpeak, the summed SUVpeak of up to 5 metastases (PERCIST-5), and total lesion glycolysis (TLG) were calculated for each patient. RESULTS: Three patients showed progressive disease after 3 months of CDK4/6 inhibitor therapy, whereas 5 patients showed disease control (3 stable disease and 2 partial remission). Disease control was maintained in these patients (follow-up range 7-22 months). Patients with disease control had a significantly greater decline in TLG (-55.3 vs. 16.7%; p < 0.05). The same was true for the PERCIST-5 (-21.9 vs. 11.3%, p < 0.05). All patients with progressive TLG showed treatment failure and/or a poor outcome. CONCLUSION: Elevated TLG on early FDG-PET seems to be associated with long-term treatment failure and a poor outcome in patients undergoing CDK4/6 inhibitor therapy for metastatic breast cancer. Early findings indicate a potential prognostic value of early FDG-PET in this setting and warrant a prospective evaluation.

Tin-filter enhanced dual-energy-CT: image quality and accuracy of CT numbers in virtual noncontrast imaging.

OBJECTIVES: To measure and compare the objective image quality of true noncontrast (TNC) images with virtual noncontrast (VNC) images acquired by tin-filter-enhanced, dual-source, dual-energy computed tomography (DECT) of upper abdomen. MATERIALS AND METHODS: Sixty-three patients received unenhanced abdominal CT and enhanced abdominal DECT (100/140 kV with tin filter) in portal-venous phase. VNC images were calculated from the DECT datasets using commercially available software. The mean attenuation of relevant tissues and image quality were compared between the TNC and VNC images. Image quality was rated objectively by measuring image noise and the sharpness of object edges using custom-designed software. Measurements were compared using Student two-tailed t-test. Correlation coefficients for tissue attenuation measurements between TNC and VNC were calculated and the relative deviations were illustrated using Bland-Altman plots. RESULTS: Mean attenuation differences between TNC and VNC (HUTNC - HUVNC) image sets were as follows: right liver lobe -4.94 Hounsfield units (HU), left liver lobe -3.29 HU, vena cava -2.19 HU, spleen -7.46 HU, pancreas 1.29 HU, fat -11.14 HU, aorta 1.29 HU, bone marrow 36.83 HU (all P < .05); right kidney 0.46 HU, left kidney 0.56 HU, vena portae -0.48 HU and muscle -0.62 HU (nonsignificant). Good correlations between VNC and TNC series were observed for liver, vena portae, kidneys, pancreas, muscle and bone marrow (Pearson's correlation coefficient ≥0.75). Mean image noise was significantly higher in TNC images (P < .0001). Measurements of edge sharpness revealed no significant differences between VNC and TNC images (P = .19). CONCLUSION: The Hounsfield units in VNC images closely resemble TNC images in the majority of the organs of the upper abdomen (kidneys, liver, pancreas). In spleen and fat, Hounsfield numbers in VNC images are tend to be higher than in TNC images. VNC images show a low image noise and satisfactory edge sharpness. Other criteria of image quality and the depiction of certain lesions need to be evaluated additionally.

Safety and Efficacy of the Prostar XL Vascular Closing Device for Percutaneous Closure of Large Arterial Access Sites.

Purpose. The purpose of this study is to retrospectively evaluate the efficacy and safety of the Prostar XL device for percutaneous large access site closure in an unselected patient and operator collective. Materials and Methods. All patients (n = 50) who had received percutaneous vascular closing with the Prostar XL device in our institution with follow-up data of at least 6 months were retrospectively included. Primary (freedom from surgical conversion) and continued (freedom from groin surgery in further course) technical success and major (deviations from expected outcome requiring surgery) and minor (other deviations from expected outcome) complications were assessed. Success and complications rates were correlated with delivery system size (Mann-Whitney Rank Sum Tests) and operator experience (paired samples t-test). Results. Rates of primary and continued technical success as well as major and minor complications were 93.6%, 89.7%, 10.3%, and 10.3% (groin based) and 90.0%, 84.0%, 16.0%, and 16.0% (patient based), respectively. No correlation of success and complications rate was found with delivery system sizes and operator experience. Conclusions. Application of the Prostar XL device for percutaneous closure of large arterial access sites is safe with a relatively high rate of technical success and low rate of major complications. Sizes of the delivery systems and the experience of the operator did not influence the results.

Clinical evaluation and potential radiation dose reduction of the novel sinogram-affirmed iterative reconstruction technique (SAFIRE) in abdominal computed tomography angiography.

RATIONALE AND OBJECTIVES: Computed tomographic angiography is the standard in routine follow-up after endovascular aneurysm repair, causing radiation exposure; thus, dose-saving strategies should be applied. The aim of this study was to evaluate the novel sinogram-affirmed iterative reconstruction (SAFIRE) algorithm in terms of clinical usability and potential reduction of radiation exposure. MATERIALS AND METHODS: Forty-six patients underwent computed tomographic angiographic follow-up after endovascular aneurysm repair. Data were acquired using a dual-source computed tomographic scanner running both x-ray tubes at the same voltage (120 kV). Raw data were reconstructed using projections of both tubes with filtered back projection (FBP) and of only one tube with FBP and SAFIRE, corresponding to synthetic acquisition with half the radiation dose of the clinical routine radiation dose. Image sets were objectively compared regarding signal-to-noise ratio and edge sharpness. Two radiologists independently assessed a set of subjective criteria, including diagnostic usability, depiction of contrasted vessels, and image noise. RESULTS: Half-dose (HD) SAFIRE images showed significantly higher signal-to-noise ratios compared to full-dose FBP images (P < .001), while having equal edge sharpness (P = .56). Most of the subjectively assessed parameters, such as diagnostic usability and depiction of contrasted vessels, were rated similar for HD SAFIRE and full-dose FBP images. Full-dose FBP images depicted fine anatomic structures more clearly (P < .05), while HD SAFIRE data sets showed less noise (P < .01). HD FBP images performed worse on all criteria (P < .001). Interrater agreement was good (κ = 0.74-0.80). CONCLUSIONS: Using the SAFIRE algorithm, the radiation dose of high-contrast abdominal computed tomographic angiography is reducible from routine clinical levels by up to 50% while maintaining good image quality and diagnostic accuracy.

Hepatocellular carcinoma: initial tumour response after short-term and long-interval chemoembolization with drug-eluting beads using modified RECIST.

OBJECTIVE: The aim of this study was to evaluate the initial tumour response after one, respectively, two transarterial chemoembolizations (TACE) with drug-eluting (DC) beads in patients with hepatocellular carcinoma (HCC). METHODS: A total of 26 patients with clinically approved HCC underwent one or two TACE with DC Beads within 6 weeks and were evaluated after 12 weeks by MRI or computed tomography on the basis of the modified Response Evaluation Criteria in the Solid Tumours guidelines for HCC. For improved comparability of both groups, 16 patients were matched in terms of Child-Pugh classification, Barcelona classification of liver cancer, age and sex. RESULTS: The overall tumour response showed progressive disease in 11% and an objective response in 89% for the double TACE group compared with progressive disease in 29.5%, objective response in 34.5% and stable disease in 35% for the single TACE group. In the matched population, absolute tumour shrinkage was 61.1 ± 28.3% for the double TACE group and 14.1 ± 38.5% for the single TACE group (P<0.05). CONCLUSION: This retrospective study shows significantly higher tumour shrinkage in patients who underwent two TACE within 6 weeks compared with patients who underwent a single intervention in terms of the initial response rate after 12 weeks. It emphasizes the use of matched populations for the evaluation of tumour response in HCC after TACE.

High-pitch computed tomography coronary angiography-a new dose-saving algorithm: estimation of radiation exposure.

Purpose. To estimate effective dose and organ equivalent doses of prospective ECG-triggered high-pitch CTCA. Materials and Methods. For dose measurements, an Alderson-Rando phantom equipped with thermoluminescent dosimeters was used. The effective dose was calculated according to ICRP 103. Exposure was performed on a second-generation dual-source scanner (SOMATOM Definition Flash, Siemens Medical Solutions, Germany). The following scan parameters were used: 320 mAs per rotation, 100 and 120 kV, pitch 3.4 for prospectively ECG-triggered high-pitch CTCA, scan range of 13.5 cm, collimation 64 × 2 × 0.6 mm with z-flying focal spot, gantry rotation time 280 ms, and simulated heart rate of 60 beats per minute. Results. Depending on the applied tube potential, the effective whole-body dose of the cardiac scan ranged from 1.1 mSv to 1.6 mSv and from 1.2 to 1.8 mSv for males and females, respectively. The radiosensitive breast tissue in the range of the primary beam caused an increased female-specific effective dose of 8.6%±0.3% compared to males. Decreasing the tube potential, a significant reduction of the effective dose of 35.8% and 36.0% can be achieved for males and females, respectively (P < 0.001). Conclusion. The radiologist and the CT technician should be aware of this new dose-saving strategy to keep the radiation exposure as low as reasonablly achievable.

Virtual nonenhanced dual-energy CT urography with tin-filter technology: determinants of detection of urinary calculi in the renal collecting system.

PURPOSE: To retrospectively determine which features of urinary calculi are associated with their detection after virtual elimination of contrast medium at dual-energy computed tomographic (CT) urography by using a novel tin filter. MATERIALS AND METHODS: The institutional ethics committee approved this retrospective study, with waiver of informed consent. A total of 152 patients were examined with single-energy nonenhanced CT and dual-energy CT urography in the excretory phase (either 140 and 80 kV [n=44] or 140 and 100 kV [n=108], with tin filtration at 140 kV). The contrast medium in the renal pelvis and ureters was virtually removed from excretory phase images by using postprocessing software, resulting in virtual nonenhanced (VNE) images. The sensitivity regarding the detection of calculi on VNE images compared with true nonenhanced (TNE) images was determined, and interrater agreement was evaluated by using the Cohen k test. By using logistic regression, the influences of image noise, attenuation, and stone size, as well as attenuation of the contrast medium, on the stone detection rate were assessed. Threshold values with maximal sensitivity and specificity were calculated by means of receiver operating characteristic analyses. RESULTS: Eighty-seven stones were detected on TNE images; 46 calculi were identified on VNE images (sensitivity, 52.9%). Interrater agreement revealed a κ value of 0.95 with TNE images and 0.91 with VNE data. Size (long-axis diameter, P=.005; short-axis diameter, P=.041) and attenuation (P=.0005) of the calculi and image noise (P=.0031) were significantly associated with the detection rate on VNE images. As threshold values, size larger than 2.9 mm, maximum attenuation of the calculi greater than 387 HU, and image noise less than 20 HU were found. CONCLUSION: After virtual elimination of contrast medium, large (>2.9 mm) and high-attenuation (>387 HU) calculi can be detected with good reliability; smaller and lower attenuation calculi might be erased from images, especially with increased image noise.

Endovascular aneurysm management of a gastroduodenal artery aneurysm in a multipara pregnant woman.

The authors describe a case of an intrapancreatic gastroduodenal artery aneurysm in a pregnant woman. Successful endovascular therapy was performed for the first time in a visceral artery aneurysm during pregnancy as a bailout solution. The attributive risk to the fetus from scattered radiation during endovascular treatment did not exceed a critical level.

Accuracy of automated attenuation-based 3-dimensional segmentation: in the analysis of left ventricular function compared with magnetic resonance imaging.

We evaluated attenuation-based 3-dimensional segmentation for the analysis of left ventricular function, using as our standard of reference magnetic resonance imaging and dual-source computed tomography with traditional short-axis planimetry.Twenty patients with known or suspected coronary artery disease were examined prospectively. In all magnetic resonance and computed tomographic datasets, global functional values were determined by 2-dimensional planimetry. Computed tomographic scans were further evaluated by automated 3-dimensional segmentation, and the results were compared by Pearson correlation and Bland-Altman analysis.Agreement between magnetic resonance imaging and dual-source computed tomographic 2-dimensional planimetry was good for all values (end-diastolic volume, bias= -4.2, r=0.99; end-systolic volume, bias= -1.7, r=0.99, stroke-volume, bias= -2.4, r=0.98; ejection fraction, bias=0.26, r=0.94; and myocardial mass, bias= 2.5, r=0.90). By contrast, dual-source computed tomographic 3-dimensional segmentation overestimated end-diastolic volume (bias= -19.1, P <0.001), stroke-volume (bias= -16.9, P <0.001), and myocardial mass (bias= -34.4, P <0.001). Moreover, correlation with magnetic resonance imaging proved disappointing for ejection fraction (r=0.72). Results were similar in a direct comparison between dual-source computed tomographic 2-dimensional planimetry and 3-dimensional segmentation (end-diastolic volume, bias= -14.9, r=0.94; end-systolic volume, bias= -0.5, r=0.90; stroke volume, bias= -14.5, r=0.83; ejection fraction, bias= -2.8, r=0.74; and myocardial mass, bias= -36.8, r=0.79).Due to significant overestimation of volumes and poor correlation of ejection fraction with cine magnetic resonance imaging results, attenuation-based 3-dimensional segmentation compares unfavorably with traditional planimetry. Hence this method should be used with caution, and its time benefits should be weighed against its imprecision of functional analysis.

Asymptomatic melanoma of the superior cavo-atrial junction: The challenge of imaging.

METASTATIC LESIONS IN THE SUPERIOR VENA CAVA AND THE RIGHT ATRIUM ARE DIFFICULT TO DIAGNOSE: in computed tomography (CT), they are easily misinterpreted as artifacts, and the same region may be difficult to access using echocardiography. We present a case of asymptomatic metastasis of a malignant melanoma which was overlooked initially due to deficiencies in imaging. Using 18F-fluorodeoxyglucose positron emission tomography-CT, the metastasis was clearly identified and finally treated successfully. We discuss the diagnostic value of the various imaging modalities for intracardiac masses.

CT angiography of various superficial femoral artery stents: an in vitro phantom study.

PURPOSE: To evaluate CT reconstruction parameters to improve stent lumen visualization in vitro. MATERIAL AND METHODS: 12 latest superficial femoral artery (SFA) stents were placed in a vessel phantom (diameter 4.7 mm, intravascular attenuation 250 HU, extravascular density 50 HU). Stents were imaged with a 128-slice scanner (SOMATOM Definition Flash, Siemens, Germany) with standard parameters: 120 kV, 200 mAs, collimation 128mm × 0.6mm. Different reconstruction parameters were evaluated: B26f, B30f, B45f, B46f and B60f kernel; slice thickness of 0.6, 2.0 and 5.0mm. To measure visualization characteristics, stent lumen diameter and intraluminal attenuation were assessed. RESULTS: Best stent lumen visualization could be obtained using the B46f kernel (p<0.001). The visible stent lumen ranged from 66.4% to 83.3% with a mean diameter of 77.7 ± 4.6%. Nitinol stents showed a significant improved lumen visibility compared to the cobalt-chromium stent (p = 0.02). The most realistic lumen attenuation was achieved using the B46f kernel with a mean attenuation of 259.3 ± 8.9 HU. The visible lumen diameter in protocols with 5mm slice thickness was significantly lower (70.0 ± 4.9%) compared to thinner slices (p<0.001). CONCLUSION: CTA of SFA stents should be reconstructed with a slice thickness of 2.0mm and a B46f kernel to achieve best image quality and to become more sensitive to exclude instent restenosis.

Estimation of radiation exposure of different dose saving techniques in 128-slice computed tomography coronary angiography.

PURPOSE: To estimate the effective dose of cardiac CT with different dose saving strategies dependent on varying heart rates. MATERIALS AND METHODS: For dose measurements, an Alderson-Rando-phantom equipped with thermoluminescent dosimeters was used. The effective dose was calculated according to ICRP 103. Exposure was performed on a 128-slice single source scanner providing a rotation time of 0.30s and standard protocols with 120 kV and 160 mAs/rot. Protocols were evaluated without ECG-pulsing, with two different ECG-pulsing techniques, and automated exposure control with a simulated heart rate of 60 and 100 beats per minute. RESULTS: Depending on different dose saving techniques and heart rate, the effective whole-body dose of a cardiac scan ranged from 2.8 to 9.5 mSv and from 4.3 to 16.0 mSv for males and females, respectively. The radiation-sensitive breast tissue in the primary scan range results in an increased female dose of 66.7 ± 6.0%. Prospective triggering has the greatest potential to reduce the effective dose to 27.8%, compared to a comparable scan protocol with retrospective ECG-triggering with no ECG-pulsing. Furthermore, the heart rate influences the radiation exposure by increasing significantly at lower heart rates. CONCLUSION: Due to this broad variability in radiation exposure of a cardiac CT, the radiologist and the CT technician should be aware of the different dose reduction strategies.

Evaluation of computer-assisted quantification of carotid artery stenosis.

The purpose of this study was to evaluate the influence of advanced software assistance on the assessment of carotid artery stenosis; particularly, the inter-observer variability of readers with different level of experience is to be investigated. Forty patients with suspected carotid artery stenosis received head and neck dual-energy CT angiography as part of their pre-interventional workup. Four blinded readers with different levels of experience performed standard imaging interpretation. At least 1 day later, they performed quantification using an advanced vessel analysis software including automatic dual-energy bone and hard plaque removal, automatic and semiautomatic vessel segmentation, as well as creation of curved planar reformation. Results were evaluated for the reproducibility of stenosis quantification of different readers by calculating the kappa and correlation values. Consensus reading of the two most experienced readers was used as the standard of reference. For standard imaging interpretation, experienced readers reached very good (k = 0.85) and good (k = 0.78) inter-observer variability. Inexperienced readers achieved moderate (k = 0.6) and fair (k = 0.24) results. Sensitivity values 80%, 91%, 83%, 77% and specificity values 100%, 84%, 82%, 53% were achieved for significant area stenosis >70%. For grading using advanced vessel analysis software, all readers achieved good inter-observer variability (k = 0.77, 0.72, 0.71, and 0.77). Specificity values of 97%, 95%, 95%, 93% and sensitivity values of 84%, 78%, 86%, 92% were achieved. In conclusion, when supported by advanced vessel analysis software, experienced readers are able to achieve good reproducibility. Even inexperienced readers are able to achieve good results in the assessment of carotid artery stenosis when using advanced vessel analysis software.

Automated computed tomography dose-saving algorithm to protect radiosensitive tissues: estimation of radiation exposure and image quality considerations.

PURPOSE: To evaluate radiation exposure and image quality in thoracic computed tomography (CT) using a new dose-saving algorithm to protect radiosensitive organs. MATERIALS AND METHODS: For dose measurements, an Alderson RANDO phantom equipped with thermoluminescent dosimeters was used. The effective dose was calculated according to the International Commission on Radiologic Protection 103. Exposure was performed on a second-generation dual-source CT. The following parameters for thoracic CT were used: 160 effective mAs, 120 kV, scan range of 30 cm, collimation of 128 × 0.6 mm. For the acquisition, the tube current modulation type XCare was used, which reduces the tube current for anterior tube position to minimize direct exposure to anterior located organs. To compare differences, scans with and without XCare were performed. Objective signal-to-noise measurements were evaluated, and the subjective noise perception was rated in a 3-point scale (1: excellent, 3: affecting diagnostic accuracy) in 30 patients with a standard thoracic examination and a follow-up using XCare. RESULTS: A substantial dose reduction in radiosensitive tissues was evident using the dose-saving algorithm XCare. Specifically, reductions of 35.2% for the female breast and 20.1% for the thyroid gland were measured, resulting in a decreasing effective whole-body dose of 8.0% and 14.3% for males and females, respectively. The objective and subjective evaluation of image quality showed no significant differences between both scan protocols (P > 0.05). Mean signal-to-noise ratio was 1.3 ± 0.2 and 1.2 ± 0.2 in scan protocols without and with XCare, respectively. The subjective scores at the level of the pulmonary trunk were 1.2 ± 0.4 and 1.4 ± 0.5 in standard chest scan and scans with the dose-saving algorithm XCare, respectively. CONCLUSIONS: The XCare technique protects radiosensitive organs like the female breast and the thyroid gland without affecting image quality. Therefore, this dose-saving algorithm may be used in thoracic CT examinations in male and female patients.

Carotid artery stenosis: performance of advanced vessel analysis software in evaluating CTA.

OBJECTIVES: The aim of this study was to evaluate time efficiency and diagnostic reproducibility of an advanced vessel analysis software for diagnosis of carotid artery stenosis. MATERIAL AND METHODS: 40 patients with suspected carotid artery stenosis received head and neck DE-CTA as part of their pre-interventional workup. Acquired data were evaluated by 2 independent radiologists. Stenosis grading was performed by MPR eyeballing with freely adjustable MPRs and with a preliminary prototype of the meanwhile available client-server and advanced visualization software syngo.via CT Vascular (Siemens Healthcare, Erlangen, Germany). Stenoses were graded according to the following 5 categories: I: 0%, II: 1-50%, III: 51-69%, IV: 70-99% and V: total occlusion. Furthermore, time to diagnosis for each carotid artery was recorded. RESULTS: Both readers achieved very good specificity values and good respectively very good sensitivity values without significant differences between both reading methods. Furthermore, there was a very good correlation between both readers for both reading methods without significant differences (kappa value: standard image interpretation k=0.809; advanced vessel analysis software k=0.863). Using advanced vessel analysis software resulted in a significant time saving (p<0.0001) for both readers. Time to diagnosis could be decreased by approximately 55%. CONCLUSIONS: Advanced vessel analysis application CT Vascular of the new imaging software syngo.via (Siemens Healthcare, Forchheim, Germany) provides a high rate of reproducibility in assessment of carotid artery stenosis. Furthermore a significant time saving in comparison to standard image interpretation is achievable.

Endovascular repair of acute symptomatic pararenal aortic aneurysm with three chimney and one periscope graft for complete visceral artery revascularization.

PURPOSE: To describe a modified endovascular technique for complete revascularization of visceral and renal arteries in symptomatic pararenal aortic aneurysm (PRAA). TECHNIQUE: Arterial access was surgically established in both common femoral arteries (CFAs) and the left subclavian artery (LSA). Revascularization of the left renal artery, the celiac trunk, and the superior mesenteric artery was performed through one single sheath via the LSA. Suitable covered stents were put in the aortic branches but not deployed. The right renal artery was accessed over the left CFA. Due to the longitudinal extension of the presented aneurysm two stent-grafts were introduced via the right CFA. After deploying the aortic stent-grafts, all covered stents in the side branches were deployed consecutively with a minimum overlap of 5 mm over the cranial and caudal stent-graft edges. Simultaneous ballooning was performed to fully expand all stent-grafts and warranty patency. CONCLUSION: This is the first report in the literature of chimney grafting in PRAA for complete revascularization of visceral and renal branches by using more than two covered stents introduced from one side through one single sheath. However this technique is modified, it should be used only in bailout situations when branched stent-grafts are not available and/or surgery is not suitable.

Estimation of radiation exposure of retrospective gated and prospective triggered 128-slice triple-rule-out CT angiography.

BACKGROUND: CT has become an important role in the differential diagnosis of acute chest pain to exclude an aortic dissection, pulmonary embolism and acute coronary artery syndrome. However, the additional radiation exposure is a cause of concern and dose saving strategies should be applied, if possible. PURPOSE: To estimate effective dose of retrospective gated and prospective ECG-triggered triple-rule-out computed tomography angiography (TRO-CTA). MATERIAL AND METHODS: An Alderson-Rando-phantom equipped with thermoluminescent dosimeters was used for dose measurements. Exposure was performed on a 128-slice single source scanner. The following scan parameters were used (retrospective ECG-gated): 120 kV, 190 mAs/rot., collimation 128x0.6 mm, rotation time 0.3 s. Protocols with a simulated heart rate (HR) of 60 and 100 bpm were performed using the standard ECG-pulsing as well as MinDose. Additionally, a prospective triggered TRO-CTA was acquired (HR 60 bpm). RESULTS: The estimated effective dose of retrospective ECG-gated TRO-CTA ranged from 7.4-13.4 mSv and from 10.1-17.5 mSv for men and women, respectively. Due to radiosensitive breast tissue, women received a significant increased effective dose of up to 64.7% ± 0.03% (p = 0.028) compared to men. MinDose reduces radiation exposure of up to 33.0% ± 6.5% in comparison to standard ECG-pulsing (p < 0.001). The effective dose increased significantly with lower heart rates (p < 0.001). Prospective ECG-triggered TRO-CTA showed an effective dose of 5.9 mSv and 8.2 mSv for men and women, respectively. Compared to retrospective ECG-gated TRO-CTA a significant dose reduction was observed (p < 0.001). CONCLUSION: Due to the significant different dose exposure, scan protocols should be specifically adapted in a patient- and problem-oriented manner.

Endovascular aneurysm repair using a reverse chimney technique in a patient with Marfan syndrome and contained ruptured chronic type B dissection.

We report endovascular thoracic and abdominal aneurysm repair (EVAR) with reverse chimney technique in a patient with contained ruptured type B dissection. EVAR seems feasible as a bailout option in Marfan patients with acute life-threatening disease.

Plaque distribution in clopidogrel responders and low responders as determined by multislice computed tomography.

Via multidetector computed tomography (MDCT) with retrospective electrographic gating, we sought to evaluate whether plaque distribution differs between responders and low responders to clopidogrel treatment. Low response was defined as a post-treatment aggregation of 35% to 70%. In this observational study, we enrolled 62 patients (mean age, 64.8 ± 8.9 yr; 51 men). In addition to determining coronary calcium scores, we performed noninvasive coronary angiography with MDCT before stent implantation. Plaques were visually classified as calcified, mixed, or completely noncalcified. Mean density was measured. Residual platelet aggregation (RPA) was evaluated by aggregometry 6 hr after administration of a 600-mg loading dose of clopidogrel. Patients with an RPA of less than 35% were defined as responders.The median calcium score was 736 Agatston score equivalent (ASE) (range, 0-5,772) and mean platelet inhibition was 35% ± 19% (range, 0-70%). A total of 494 coronary plaques were detected (responders: calcified, 197; mixed, 47, noncalcified, 5; and low responders: calcified, 177; mixed, 65; noncalcified, 3). Responders (n = 35) had significantly lower ASEs and fewer mixed but more calcified plaques than did low responders. In mean plaque density (measured within the noncalcified part of the plaques), no statistically significant difference existed between the 2 patient groups. By use of MDCT, we showed that ASE and plaque distribution were associated with RPA after clopidogrel treatment. Patients with a low coronary plaque burden and a small proportion of mixed plaques were more likely to have low RPA after administration of clopidogrel.