Endoleaks after endovascular aortic aneurysm repair: Improved detection with noise-optimized virtual monoenergetic dual-energy CT

PurposeTo assess image quality and diagnostic performance of a noise-optimized algorithm to reconstruct virtual monoenergetic images (VMI+) for the detection of endoleaks after endovascular abdominal aortic aneurysm repair (EVAR) using dual-energy CT angiography (DE-CTA).Materials and methodsSeventy-five patients (42 men; 66.2 ± 11.7 years) underwent DE-CTA following EVAR. Arterial phase images were acquired in dual-energy mode for the reconstruction of standard linearly-blended M_0.5, VMI+ and traditional monoenergetic images (VMI) at 40–100 keV in 10-keV intervals. Contrast-to-noise ratios (CNR) were calculated for the area of leakage in patients with endoleaks. Diagnostic accuracy for endoleak detection was evaluated by three blinded radiologists using the objectively best series for each reconstruction technique.ResultsThirty-four out of 75 patients showed endoleaks. Quantitative image parameters were highest at 40-keV VMI+ (CNR, 21.3 ± 11.1), compared to M_0.5 (CNR, 10.9 ± 5.5) and all VMI series that showed highest values at 70 keV (CNR, 13.5 ± 6.6; all P < 0.001). ROC analysis for endoleak detection revealed an area under the curve (AUC) of 0.992 for 40-keV VMI+ series, which was significantly higher (P ≤ 0.039) compared to 70-keV VMI (0.914) and M_0.5 series (0.916).ConclusionsNoise-optimized VMI+ series at 40 keV improve diagnostic accuracy for the detection and rule-out of endoleaks after EVAR.     

Comparison of 16-row multislice CT angiography with conventional angiography for detection and evaluation of intracranial aneurysms

Purpose

The aim of this study is to compare the diagnostic performance of 16-row computed tomographic angiography (MDCTA) with digital subtraction angiography (DSA) for the detection and characterization of intracranial aneurysms in patients with nontraumatic subarachnoid hemorrhages (SAH).

Materials and methods

One-hundred and twelve consecutive patients with suspected intracranial aneurysm underwent both 16-row MDCTA and DSA. The MDCT angiograms were interpreted in a blinded fashion by using combination with VRI, MIP and MPR techniques. Sensitivity specificity and accuracy were calculated for the CTA and DSA. The results were compared with each other. The DSA reader's interpretation was accepted as the reference standard.

Results

A total of 164 aneurysms were detected at DSA in 112 patients, no aneurysms were detected by DSA and MDCTA in 16 patients. Eight aneurysms were missed by MDCTA. The overall sensitivity, specificity, and accuracy of MDCTA on a per-aneurysm basis were 95.1%, 94.1%, and 95%, respectively. According to the size of the aneurysm less than 3 mm; sensitivity, specificity and diagnostic accuracy of MDCTA were 86.1%, 94.1%, 88.6%, respectively.

Conclusion

This study suggests that MDCTA is equally as sensitive as DSA in the detection of intracranial aneurysms of greater than 3 mm, and it also reveals 100% detection rate for ruptured aneurysms.     

Analysis of left atrial appendix by dual-source CT coronary angiography: morphologic classification and imaging by volume rendered CT images

Aim

We investigated the evaluability of left atrial appendix by dual source coronary CT angiography and analyzed morphologic features.

Materials and methods

We included 106 consecutive patients who underwent coronary CT angiography for various indications. Technical parameters were slice thickness 0.6 mm, reconstruction interval 0.3 mm, gantry rotation time 165 ms. Images were reconstructed from 10% to 100% R-R intervals at 10% intervals to evaluate the left atrial appendix and 4-D inspace software was used for analysis. We recorded the R-R intervals when the left atrial appendix was at maximum and minimum volume. We also evaluated visibility of appendix at R-R intervals. Maximum appendix volume was calculated. Atrial appendices were classified morphologically based on number of chambers (types 1–3) seen on volume rendered images.

Results

There were 60 male and 46 female patients in the study group and, mean age was 55 ± 13. Mean heart rate was 72 (ranges 47–110). Left atrial was evaluable at maximum and minimum volume by coronary CT angiography in all patients. We noted types 1–3 appendix in 29 (27%), 73 (69%), and 4 (4%) patients, respectively. Mean R-R intervals at maximum and minimum volume were 40% ± 6 (95% CI; 28–52%) and 95% ± 5 (95% CI; 85–5%), respectively. Mean appendix maximum volume was 7 ± 4 cm³. Appendix contours were mildly, moderately and severely irregular in 10 (9%), 58 (55%), 38 (36%) patients, respectively.

Conclusion

Left atrial appendix was visualized in all patients independent of heart rate at maximum and minimum volumes. Volume rendered CT images can allow excellent depiction of left atrial appendix morphology and classification. Presence of moderate and severe irregularity of appendix contour in most of the patients may be the cause of slow flow. This morphologic appearance may be the underlying reason for the propensity to atrial appendix thrombus formation.     

Carotid stenosis: a comparison between MR and spiral CT angiography

We performed a preliminary study comparing three-dimensional time-of-flight (3 D TOF) magnetic resonance angiography (MRA) and spiral CT angiography (SCTA) in the detection and assessment of internal carotid artery stenosis. Digital subtraction angiography (DSA) was the reference examination. We examined 20 patients with signs of cerebrovascular insufficiency, who underwent MRA, SCTA and DSA within a 3 day period. Both internal carotid arteries were assessed by three blinded readers for degree of stenosis at two different levels (bulb and remaining section) giving a total of 80 assessments. Interobserver variability, sensitivity, specificity, diagnostic accuracy, concordance, overestimation and underestimation were assessed. Interobserver variability was not statistically significant. MRA showed higher sensitivity, specificity, diagnostic accuracy and concordance than SCTA (92.0 % vs 80.8 %, 98.2 % vs 96.4 %, 96.3 % vs 91.3 % and 96.0 % vs 88.0 %, respectively). MRA gave rise to a 5.0 % overestimation rate, whereas SCTA occasioned a 7.5 % underestimation rate. These differences are not statistically significant. These results suggest that MRA is a more useful, noninvasive modality for assessment of the internal carotid artery with a more than 70 % stenosis. Received: 8 August 1997 Accepted: 10 October 1997     

脑CT灌注成像和血管成像术在海岛医院中的应用价值

目的探讨海岛医院应用CT灌注成像（CT perfusion imaging，CTPI）和CT血管成像（CT angiography，CTA）对超早期脑梗死诊断的应用价值。方法采用四排螺旋CT对24例突发偏瘫或失语、发病时间少于6h、CT检查阴性的患者，即行CTPI和CTA检查，定量分析病灶侧灰质区及皮层区的脑血流量（cerbral blood flow，CBF）、脑血容量（cerebral blood volume，CBV）、达峰时间（time to peak，TTP），并与对侧相应部位进行比较。在第2天及第7天行CT及MRI复查，对照观察CTPI和CTA的诊断价值。结果24例入选病例中4例CTA检查诊断为短暂性脑缺血发作（transient ischemic attack，TIA），其余20例中右侧颈内动脉段梗塞3例，右侧大脑中动脉主干支梗塞4例，右侧大脑中动脉分支梗塞8例，左侧大脑中动脉主干支梗塞3例，左侧大脑中动脉分支梗塞1例，左大脑后动脉主干支梗塞1例。上述病例在第2天、第7天在CT或MRI检查中均被证实，诊断符合率100％。脑梗死（cerebral infarction，CI）患侧的灰质CBF、灰质与白质CBV明显低于对侧（均P〈0．05）。CI组患侧脑白质区及灰质区的CBV明显低于TIA组（均P〈0．05）。结论联合进行头颅CT平扫、CTPI和CTA检查，有助于临床超早期识别CI、TIA；患侧脑白质区及灰质区的CBV状态是识别CI较为敏感的指标；CTA图像能敏感反映是否存在血管阻塞，是区分TIA与CI的可靠指标。     

Dose performance and image quality: dual source CT versus single source CT in cardiac CT angiography

Objective

To evaluate dose performance and image quality of 64-slice dual source CT (DSCT) in comparison to 64-slice single source CT (SSCT) in cardiac CT angiography (CTA).

Methods

100 patients examined by DSCT and 60 patients scanned by SSCT were included in this study. Objective indices such as image noise, contrast-to-noise ratio and signal-to-noise ratio were analyzed. Subjective image quality was assessed by two cardiovascular radiologists in consensus using a four-point scale (1 = excellent to 4 = not acceptable). Estimation of effective dose was performed on the basis of dose length product (DLP).

Results

At low heart rates (<70 bpm), image quality of SSCT was equivalent to that of DSCT (P > 0.05), but, at high heart rates (>70 bpm), DSCT provided robust image quality (P < 0.05). The average effective dose of SSCT was 9.3 ± 0.9 mSv at low heart rates (<70 bpm) while, the average estimated effective doses of DSCT were 9.1 ± 1.3 mSv, 8.3 ± 1.1 mSv, 7.9 ± 1.1 mSv, 6.9 ± 0.7 mSv, and 5.9 ± 1.3 mSv, corresponding to heart rates of 50-59 bpm, 60-69 bpm, 70-79 bpm, 80-89 bpm, and 90-100 bpm.

Conclusion

For cardiac CTA, both DSCT and SSCT can get good image quality at low heart rates (<70 bpm) with a similar radiation dose, but, at high heart rates (>70 bpm), DSCT is able to provide robust diagnostic image quality at doses far below that of SSCT.     

Techniques in interventional radiology: renal CT angiography

Multidetector row CT angiography has become an important tool in the evaluation of patients with suspected renovascular hypertension. The following article presents a review of the published data on accuracy of this method of evaluation as well as a comparison to other diagnostic strategies, in particular, renal MR angiography.     

Carotid artery stenosis: reproducibility of automated 3D CT angiography analysis method

The aim of this study was to assess the reproducibility and anatomical accuracy of automated 3D CT angiography analysis software in the evaluation of carotid artery stenosis with reference to rotational DSA (rDSA). Seventy-two vessels in 36 patients with symptomatic carotid stenosis were evaluated by 3D CT angiography and conventional DSA (cDSA). Thirty-one patients also underwent rotational 3D DSA (rDSA). Multislice CT was performed with bolus tracking and slice thickness of 1.5 mm (1-mm collimation, table feed 5 mm/s) and reconstruction interval of 1.0 mm. Two observers independently performed the stenosis measurements on 3D CTA and on MPR rDSA according to the NASCET criteria. The first measurements on CTA utilized an analysis program with automatic stenosis recognition and quantitation. In the subsequent measurements, manual corrections were applied when necessary. Interfering factors for stenosis quantitation, such as calcifications, ulcerations, and adjacent vessels, were registered. Intraobserver and interobserver correlation for CTA were 0.89 and 0.90, respectively. (p<0.001). The interobserver correlation between two observers for MPR rDSA was 0.90 (p<0.001). The intertechnique correlation between CTA and rDSA was 0.69 (p<0.001) using automated measurements but increased to 0.81 (p<0.001) with the manually corrected measurements. Automated stenosis recognition achieved a markedly poorer correlation with MPR rDSA in carotids with interfering factors than those in cases where there were no such factors. Automated 3D CT angiography analysis methods are highly reproducible. Manually corrected measurements facilitated avoidance of the interfering factors, such as ulcerations, calcifications, and adjacent vessels, and thus increased anatomical accuracy of arterial delineation by automated CT angiography with reference to MPR rDSA.     

Comparison of doses for pulmonary embolism detection with helical CT and pulmonary angiography

The objective of this study was to compare the radiation exposure delivered by helical CT and pulmonary angiography (PA) for the detection of pulmonary embolism (PE), with an anthropomorphic phantom. A preliminary survey defined a representative standard procedure for helical CT and PA (n=148) by choosing the exposure settings most frequently used. Then, radiation doses were measured with thermoluminescent dosimeters TLD 100 (Lif) introduced into the depth of an anthropomorphic phantom. Average doses were approximately five times smaller with helical CT than with PA (6.4±1.5 and 28±7.6 mGy, respectively). The most important doses were abreast the pulmonary apex for CT, and abreast the pulmonary arteries for PA. Compared with PA, helical CT dose distribution was relatively uniform (10–13 mGy). Finally, concerning abdomen and pelvis, doses were more important for PA than for CT scan (0.06–2.86 and 0.2–11.5 mGy, respectively). For the diagnostics of PE, radiation exposure is five times smaller with helical CT than with pulmonary angiography.     

Multi-detector CT angiography of the intra-cranial circulation: normal anatomy and pathology with angiographic correlation

Multidetector computed tomography angiography (MD-CTA) of the intra-cranial circulation shows great potential in the evaluation of intra-cranial vascular disease. Interpreting these studies requires a detailed knowledge of the technique, its advantages and disadvantages, as well as a strong understanding of normal intra-cranial vascular anatomy. The purpose of this review is to describe the technique for MD-CTA, demonstrate normal anatomy, anatomic variants and vascular pathology with an emphasis on aneurysms.     

Bilateral internal carotid agenesis: value of CT angiography and correlation to embryogenesis

Bilateral internal carotid artery agenesis is an uncommon disease, difficult to differentiate from bilateral carotid artery thrombosis. A few case reports have described the contribution of conventional angiogram to make the diagnosis and recognize the anatomic details of this rare malformation. Advantages of CT angiography as a non-invasive radiologic tool are discussed in this case report. Received: 2 May 2000 Revised: 16 August 2000 Accepted: 21 August 2000     

CT和MR血管成像诊断急性肺栓塞的Meta分析

目的：应用 Meta 分析法,以 DSA 为金标准,探讨 CT 肺动脉成像（CTPA）和磁共振肺血管成像（MRPA）对肺动脉栓塞（PE）的诊断价值。方法：检索 Cochrane 图书馆、Medline 数据库、Springerlink 数据库及 Ovid 循证医学数据库中1994～2013年发表的英文文献以及知网数据库和万方医学数据库中1994～2013年发表的中文文献,按照 Cochrane 协作网推荐的诊断性实验的纳入标准,严格筛选与“CTPA 和／或 MRPA 诊断急性 PE”相关的文献。在符合条件的文献中提取诊断信息（包括真阳性值、假阳性值、真阴性值、假阴性值）和其它相关数据。采用 Stata 12软件和 Meta-disc 1．4软件对纳入文献行统计学处理,包括异质性检验,计算敏感度和特异度及其95％可信区间,选择相应的效应模型予以加权定量合并,绘制汇总的工作特征曲线（SROC）,最后进行敏感性分析。结果：按照纳入标准共获取有效文献17篇,其中与 CTPA相关的文献10篇,与 MRPA 相关的文献7篇。17篇文献均满足诊断性研究质量评价工具（QUADAS）中提出的14项标准中的10项以上。CTPA 及 MRPA 两组中的相关研究均有异质性,按照随机效应模型对纳入文献进行汇总分析。结果显示,CTPA 诊断肺栓塞的敏感度、特异度及各自的95％可信区间分别为0．78（0．74～0．82）和0．90（0．87～0．92）,MR-PA 为0．86（0．79～0．92）和0．97（0．94～0．99）,SROC 下面积分别为94％和98％。结论：CTPA 和 MRPA 对急性肺栓塞的诊断均具有很高的价值,两种方法的诊断特异度均很高,作为诊断肺栓塞的无创性检查方法可基本替代 DSA 检查。     

Update on multidetector coronary CT angiography of coronary stents: in vitro evaluation of 29 different stent types with dual-source CT

The aim of this study was to test a large sample of the latest coronary artery stents using four image reconstruction approaches with respect to lumen visualization, lumen attenuation, and image noise in dual-source multidetector row CT (DSCT) in vitro and to provide a CT catalogue of currently used coronary artery stents. Twenty-nine different coronary artery stents (19 steel, 6 cobalt-chromium, 2 tantalum, 1 iron, 1 magnesium) were examined in a coronary artery phantom (vessel diameter 3 mm, intravascular attenuation 250 HU, extravascular density −70 HU). Stents were imaged in axial orientation with standard parameters: 32 × 0.6 collimation, pitch 0.24, 400 mAs, 120 kV, rotation time 0.33 s. Image reconstructions were obtained with four different convolution kernels (soft, medium-soft, standard high-resolution, stent-dedicated). To evaluate visualization characteristics of the stent, the lumen diameter, intraluminal density, and noise were measured. The stent-dedicated kernel offered best average lumen visualization (54 ± 8.3%) and most realistic lumen attenuation (222  ± 44 HU) at the expense of increased noise (23.9 ± 1.9 HU) compared with standard CTA protocols (p < 0.001 for all). The magnesium stent showed the least artifacts with a lumen visibility of 90%. The majority of stents (79%) exhibited a lumen visibility of 50–59%. Less than half of the stent lumen was visible in only six stents. Stent lumen visibility largely varies depending on the stent type. Magnesium is by far more favorable a stent material with regard to CT imaging when compared with the more common materials steel, cobalt-chromium, or tantalum. The magnesium stent exhibits a lumen visibility of 90%, whereas the majority of the other stents exhibit a lumen visibility of 50–59%. David Maintz and Matthias Burg contributed equally to this publication.     

64-slice multidetector coronary CT angiography: in vitro evaluation of 68 different stents

The purpose of this study was to test a large sample of different coronary artery stents using four image reconstruction approaches with respect to lumen visualization, lumen attenuation, and image noise in 64-slice multidetector-row computed tomography (MDCT) in vitro and to provide a catalogue of currently used coronary artery stents when imaged with state-of the-art MDCT. We examined 68 different coronary artery stents (57 stainless steel, four cobalt-chromium, one cobalt-alloy, two nitinol, four tantalum) in a coronary artery phantom (vessel diameter 3 mm, intravascular attenuation 250 HU, extravascular density −70). Stents were imaged in axial orientation with standard parameters: 32x0.6 collimation, pitch 0.24, 680 mAs, 120 kV, rotation time 0.37 s. Four different image reconstructions were obtained with varying convolution kernels and section thicknesses: (1) soft, 0.6 mm, (2) soft, 0.75, (3) medium soft, 0.6, and (4) stent-optimized sharp, 0.6. To evaluate visualization characteristics of of the stent, the lumen diameter, intraluminal density and noise were measured. The high-resolution kernel offered significantly better average lumen visualization (57% ±10%) and more realistic lumen attenuation (222 HU ±66 HU) at the expense of increased noise (15.3 HU ±3.7 HU) compared with the soft and medium-soft CT angiography (CTA) protocol (p<0.001 for all). Stents with a lumen visibility of more than 66% were: Arthos pico, Driver, Flex, Nexus2, S7, Tenax complete, Vision (all 67%), Symbiot, Teneo (70%), and Radius (73%). Only ten stents showed a lumen visibility of less than 50%. Stent lumen visibility largely varies depending on the stent type. Even with the improved spatial resolution of 64-slice CT, a stent-optimized kernel remains beneficial for stent visualization when compared with the standard medium-soft CTA protocol. Using 64-slice CT and high-resolution kernel, the majority of stent products show a lumen visibility of more than 50% of the stent diameter.     

Screening and detection of blunt vertebral artery injury in patients with upper cervical fractures: The role of cervical CT and CT angiography

Objective

To evaluate the clinical utility of nonenhanced CT (NECT)-based screening criteria and CTA in detection of blunt vertebral artery injury (BVAI) in trauma patients with C1 and/or C2 fractures.

Methods

We retrospectively reviewed the clinical records of all blunt trauma patients with C1 and/or C2 fractures between 8/2006 and 9/2011. Cervical CTA was prompted by cervical fractures involving/adjacent to a transverse foramen, and/or subluxation on NECT. Two neuroradiologists independently reviewed the CTA studies, and graded the BVAI.

Results

210 patients were included; of these, 124 underwent CTA (21/124 with digital subtraction angiography, DSA), and 2 underwent DSA only. Overall, 30/126 suffered BVAI. Among 21 patients who underwent both CTA and DSA, there was 1 false negative and 1 false positive (both grade 1). There was strong interobserver agreement regarding CTA-based BVAI detection (kappa = 0.93, p < 0.001) and grading (kappa = 0.90, p < 0001). Only 3/30 BVAI patients suffered a posterior circulation stroke; none of the patients who had a negative CTA or were not selected for CTA, based on NECT screening criteria, suffered symptomatic stroke. While C1/C2 comminuted fracture was more common in patients with high grade BVAI (p = 0.039), simultaneous C3–C7 comminuted fracture increased the overall BVAI risk (p = 0.011).

Conclusion

CTA reliably detects symptomatic BVAI in patients with upper cervical fractures. Utilization of NECT-based screening criteria such as transverse foraminal involvement or subluxation may be adequate in deciding whether to perform CTA, as no patients who were not selected for CTA suffered a symptomatic stroke. However, CTA may miss lower grade, asymptomatic BVAI.     

Technical challenges of coronary CT angiography: Today and tomorrow

Rapid advancements in multidetector row computed tomography (MDCT) are beginning to revolutionise cardiac imaging applications. As a consequence, coronary CT angiography (CTA) is fast emerging as a highly effective, noninvasive imaging technique for the assessment of coronary artery disease (CAD). Technology is improving at a robust pace, which brings with it the benefits of superior spatial and temporal resolution as well as fast volume coverage, achieved through the development of systems with an increased number of detectors and shorter gantry rotation time, as well as the advent of systems equipped with dual-source X-ray tubes. The main power of CTA was thought to lie in its high negative predictive value in excluding coronary disease with a high degree of accuracy in patients with low probability for CAD. However, this rapid progress has meant that we are also adding to the growing list of additional potential applications of CTA that are possible with the technology. The aim of this review is to present an overview of the technical capabilities of cardiac MDCT relating to coronary CTA and other applications, the limitations of current technologies, as well as discuss political perspectives and how to address these in medical practice.     

脑血管成像中减影CTA与常规CTA去骨技术的对照

目的探讨减影CTA去骨技术和常规CTA去骨技术在脑血管成像中重建时间及图像质量的差异。方法回顾性分析30例行脑血管减影CTA和常规CTA检查的患者的资料,后处理重建均用最大密度投影技术(MIP)和容积再现技术(VR),以评价减影CTA和常规CTA图像质量及重建时间。结果减影CTA图像质量优于常规CTA图像质量,且重建时间短于常规CTA。显示血管狭窄及颅底动脉瘤优于常规CTA。结论减影CTA去骨技术用于脑血管成像质量优良,重建血管迅速,显示血管狭窄及颅底动脉瘤优于常规CTA。减影CTA结合曲面重建(CPR)既能显示管腔又能有效的显示动脉管壁情况,弥补了DSA的不足。     

Evaluation of peripheral artery stent with 64-slice multi-detector row CT angiography: Prospective comparison with digital subtraction angiography

Purpose

To assess the accuracy of 64-slice multi-detector row computed tomography (MDCT) angiography in the evaluation of peripheral artery in-stent or peristent restenosis, with conventional digital subtraction angiography (DSA) as the reference standard.

Materials and methods

Forty-one patients (30 men, 11 women; mean age, 69.8 ± 9.2 years) with symptomatic peripheral arterial occlusive disease after peripheral artery stenting (81 stented lesions) underwent both conventional DSA and 64-slice MDCT angiography. Each stent was classified as evaluable or unevaluable, and every stent was divided into three segments (proximal stent, stent body, and distal stent), resulting in 243 segments. For evaluation, stenosis was graded as follows: 1, none or slight stenosis (<25%); 2, mild stenosis (25-49%); 3, moderate stenosis (50-74%); 4, severe stenosis or total occlusion (≥75%). Two readers evaluated all CT angiograms with regard to narrowing of in-stent or peristent restenosis by consensus. Results were compared with findings of the DSA.

Results

Of 81 stents, 62 (76.5%) were determined to be assessable. The metal artifact of the gold marker and motion artifact increased uninterpretability of the images of stents. Overall, 24 of 28 in-stent restenosis and 38 of 53 persistent restenosis were correctly detected by MDCT (85.7% and 71.7% sensitivity). In evaluable stents, 21 of 22 in-stent restenoses and 27 of 28 persistent restenosis were correctly detected (95.4% and 96.4% sensitivity). Additionally, as the grade of stenosis increases, the mean level of CT values in the stent lumina decreases linearly accordingly.

Conclusion

64-Slice MDCT has a high accuracy for the detection of significant in-stent or peristent restenosis of assessable stents in patients with peripheral artery stent implantation and therefore can be considered as a valuable noninvasive technique for stent surveillance.     

CT angiography for planning transcatheter aortic valve replacement using automated tube voltage selection: Image quality and radiation exposure

PurposeTo assess image quality and accuracy of CT angiography (CTA) for transcatheter aortic valve replacement (TAVR) planning performed with 3rd generation dual-source CT (DSCT).Material and methodsWe evaluated 125 patients who underwent TAVR-planning CTA on 3rd generation DSCT. A two-part protocol was performed including retrospectively ECG-gated coronary CTA (CCTA) and prospectively ECG-triggered aortoiliac CTA using 60 mL of contrast medium. Automated tube voltage selection and advanced iterative reconstruction were applied. Effective dose (ED), signal-to-noise (SNR) and contrast-to-noise ratios (CNR) were calculated. Five-point scales were used for subjective image quality analysis. In patients who underwent TAVR, sizing parameters were obtained.ResultsImage quality was rated good to excellent in 97.6% of CCTA and 100% of aortoiliac CTAs. CTA studies at >100 kV showed decreased objective image quality compared to 70–100 kV (SNR, all p ≤ 0.0459; CNR, all p ≤ 0.0462). Mean ED increased continuously from 70 to >100 kV (CCTA: 4.5 ± 1.7 mSv–13.6 ± 2.9 mSv, all p ≤ 0.0233; aortoiliac CTA: 2.4 ± 0.9 mSv–6.8 ± 2.7 mSv, all p ≤ 0.0414). In 39 patients TAVR was performed and annulus diameter was within the recommended range in all patients. No severe cardiac or vascular complications were noted.Conclusion3rd generation DSCT provides diagnostic image quality in TAVR-planning CTA and facilitates reliable assessment of TAVR device and delivery option while reducing radiation dose.     

Thoracic aortic stent graft: comparison of contrast-enhanced MR angiography and CT angiography in the follow-up: initial results

The objective of this study was to compare contrast-enhanced magnetic resonance angiography (CE MRA) and multislice computed tomographic angiography (MS CTA) in the follow-up of thoracic stent-graft placement. The CE MRA and MS CTA were performed following nitinol stent-graft treatment due to thoracic aneurysm (n=4), intramural bleeding (n=2) and type-B aortic dissection (n=5). Corresponding evaluation of arterial-phase imaging characteristics focused on the stent-graft morphology and leakage assessment. Stent-graft and aneurysm extensions were comparable between both techniques. Complete exclusion (aneurysm, n=4; dissection, n=2) was assessed with high confidence with CE MRA and MS CTA. Incomplete exclusion (intramural bleeding, n=2; dissection, n=3) was assigned to lower confidence scores on CE MRA compared with MS CTA. On CE MRA the stent-graft lumen demonstrated an inhomogeneous signal, the stent struts could not be assessed. The CE MRA can be used as alternative non-invasive imaging for follow-up of nitinol stent grafts. Arterial-phase leak assessment can be less evident in CE MRA compared with MS CTA studies; therefore, the use of late-phase imaging seems to be necessary. The diagnostic gap of stent-graft fracture evaluation using MRA may be filled with plain radiographs.