Value of monoenergetic low-kV dual energy CT datasets for improved image quality of CT pulmonary angiography

Purpose

High vessel attenuation and high contrast-to-noise ratio (CNR) are prerequisites for high diagnostic confidence in CT pulmonary angiography (CTPA). This study evaluated the impact of calculated monoenergetic dual-energy (DE) CTPA datasets on vessel attenuation and CNR.

Materials and methods

50 Patients (24 men, mean age 68 ± 14 years) who underwent DE-CTPA were retrospectively included in this study. The 80 and 140-kV DE polyenergetic image data were used to calculate virtual monoenergetic image datasets in 10 kiloelectron volt (keV) increments from 40 to 120 keV. Vessel and soft tissue attenuation and image noise were measured in various regions of interest and the CNR was subsequently calculated. Differences in vessel attenuation and CNR were compared between the different monoenergetic datasets. The best monoenergetic dataset was then compared to the standard 120-kV polyenergetic dataset.

Results

Vessel attenuation and CNR of 70-keV CTPA datasets were superior to all other monoenergetic image datasets (all p < 0.05). 70-keV monoenergetic datasets provided a statistically significant 12% increase in mean vessel attenuation compared to standard 120-kV polyenergetic datasets (384 ± 117 HU vs. 342 ± 106 HU, respectively; p < 0.0001) and a statistically significant 18% increase in mean CNR (29 ± 13 vs. 24± 11 respectively; p < 0.0001).

Conclusion

Virtual 70-keV monoenergetic CTPA image datasets significantly increase vessel attenuation and CNR of DE-CTPA studies, suggesting that clinical application of low-keV monoenergetic reconstructions may allow a decrease in the amount of iodinated contrast required for adequate image quality in DE-CTPA examinations.     

Image quality on dual-source computed-tomographic coronary angiography

Multi-detector CT reliably permits visualization of coronary arteries, but due to the occurrence of motion artefacts at heart rates >65 bpm caused by a temporal resolution of 165 ms, its utilisation has so far been limited to patients with a preferably low heart rate. We investigated the assessment of image quality on computed tomography of coronary arteries in a large series of patients without additional heart rate control using dual-source computed tomography (DSCT). DSCT (Siemens Somatom Definition, 83-ms temporal resolution) was performed in 165 consecutive patients (mean age 64 +/- 11.4 years) after injection of 60-80 ml of contrast. Data sets were reconstructed in 5% intervals of the cardiac cycle and evaluated by two readers in consensus concerning evaluability of the coronary arteries and presence of motion and beam-hardening artefacts using the AHA 16-segment coronary model. Mean heart rate during CT was 65 +/- 10.5 bpm; visualisation without artefacts was possible in 98.7% of 2,541 coronary segments. Only two segments were considered unevaluable due to cardiac motion; 30 segments were unassessable due to poor signal-to-noise ratio or coronary calcifications (both n = 15). Data reconstruction at 65-70% of the cardiac cycle provided for the best image quality. For heart rates >85 bpm, a systolic reconstruction at 45% revealed satisfactory results. Compared with earlier CT generations, DSCT provides for non-invasive coronary angiography with diagnostic image quality even at heart rates >65 bpm and thus may broaden the spectrum of patients that can be investigated non-invasively.     

双能量CT碘值定量法早期评价兔肝纤维化的实验研究

目的探讨双能量CT碘定量法对兔肝纤维化评价的应用价值。方法对55例新西兰兔先行造模、CT扫描、病检分期。图像后处理避开血管与胆道,分别选取感兴趣区,测量肝实质平扫、门脉期、实质期的碘值,定量分析肝纤维化的严重程度。各肝纤维化级别组碘值结果比较采用方差分析,碘值与肝纤维化严重程度的相关性采用Spearman法。结果随着肝纤维化程度的加重,三期时相的碘值呈现出下降的趋势,且门脉期S3、S4期分别与S0、S1、S2期的差异有统计学意义。门脉期碘值与肝纤维化严重程度的相关性较高(r=-0.815,P0.05)。结论双能量CT碘定量法能定量分析肝纤维化病程中的改变,尤其是门脉期的碘值与肝纤维化严重程度的相关性较高,对临床诊断及治疗后的随访具有较高的应用价值。     

护理干预在双源CT冠状动脉成像的价值

目的：探讨护理干预在双源CT冠状动脉成像中的应用价值。方法：收集我院2009年6月~11月双源CT冠状动脉成像病例共1000例（男563例,女437例）,年龄27~83岁,平均62.4岁。所有患者扫描前、中、后进行细致的护理干预,均未使用药物控制心率。结果：双源CT冠状动脉成像病例成功率为95.6%。影响成功率的因素主要为呼吸运动及吞咽运动（23例）和心律失常（11例）,全部病例检查无并发症发生。结论：对患者在检查双源CT前、中、后进行细致科学的护理干预,可消除患者的恐惧心理,保证呼吸和吞咽的配合,保持患者心率平稳,从而提高检查成功率,并有助于避免并发症发生。     

Low dose dual-source CT angiography in infants with complex congenital heart disease: a randomized study

Objectives

To investigate the radiation dose and image quality of prospective ECG-triggering dual-source CT angiography in infants with complex congenital heart disease (CHD) in comparison with retrospective ECG-gated scanning.

Methods

Ninety-six infants less than 1 year old (60/36 male/female, age: 4.8 ± 2.7 months, weight: 5.8 ± 1.8 kg) with complex CHD were enrolled. Three image acquisition protocols were set: group 1: 80 kV, 100 mA, retrospective ECG-gated protocol; group 2: 80 kV, 100 mA, prospective ECG-triggering protocol with acquisition window of 380 ms; group 3: 80 kV, 100 mA, prospective ECG-triggering protocol with acquisition window of 200 ms. Patients were selected to any one of the protocols randomly. The signal-to-noise ratios (SNR) were calculated in the ascending aorta and the pulmonary artery trunk. Image quality was assessed by a five-point score. A score of <3 represents non-diagnostic. Effective radiation dose (ED) was calculated.

Results

Image quality score of groups 1, 2 and 3 were 4.1 ± 0.4, 4.0 ± 0.6 and 4.2 ± 0.6 (p = 0.224). SNR of ascending aorta and pulmonary artery trunk among them had no statistical difference (all p > 0.05). The average ED (median) of groups 1, 2 and 3 were 1.17 ± 0.07 mSv (1.25 mSv), 0.72 ± 0.24 mSv (0.78 mSv) and 0.48 ± 0.41 mSv (0.39 mSv). Any two of the three groups had significant differences (all p < 0.001).

Conclusion

Prospective ECG-triggering DSCT angiography associated with a significantly lower ED than retrospective protocol, while maintaining image quality for diagnosis. Prospective ECG-triggering DSCT angiography could be used as a very important second-line diagnostic tool in infants with complex CHD.     

Reduced iodine load with CT coronary angiography using dual-energy imaging: A prospective randomized trial compared with standard coronary CT angiography

BackgroundThere is concern regarding the administration of iodinated contrast to patients with impaired renal function because of the increased risk of contrast-induced nephropathy.ObjectiveEvaluate image quality and feasibility of a protocol with a reduced volume of iodinated contrast and utilization of dual-energy coronary CT angiography (DECT) vs a standard iodinated contrast volume coronary CT angiography protocol (SCCTA).MethodsA total of 102 consecutive patients were randomized to SCCTA (n = 53) or DECT with rapid kVp switching (n = 49). Eighty milliliters and 35 mL of iodinated contrast were administered in the SCCTA and DECT cohorts, respectively. Two readers measured signal and noise in the coronary arteries; signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) were calculated. A 5-point signal/noise Likert scale was used to evaluate image quality; scores of <3 were nondiagnostic. Agreement was assessed through kappa analyses.ResultsDemographics and radiation dose were not significantly different; there was no difference in CNR between both cohorts (P = .95). A significant difference in SNR between the groups (P = .02) lost significance (P = .13) when adjusted for body mass index. The median Likert score was inferior for DECT for reader 1 (3.6 ± 0.6 vs 4.3 ± 0.6; P < .001) but not reader 2 (4.1 ± 0.6 vs 4.3 ± 0.5; P = .06). Agreement in diagnostic interpretability in the DECT and SCCTA groups was 91% (95% confidence interval, 86%–100%) and 96% (95% confidence interval, 90%–100%), respectively.ConclusionDECT resulted in inferior image quality scores but demonstrated comparable SNR, CNR, and rate of diagnostic interpretability without a radiation dose penalty while allowing for >50% reduction in contrast volume compared with SCCTA.     

双源双能量CT肺动脉成像辐射剂量与图像质量的比较研究

_目的：比较第一代双源双能量 CT（DECT）与第二代双源双能量 CT 肺动脉成像（CTPA）的辐射剂量和图像质量。方法：120例疑似肺栓塞患者行 DE-CTPA 检查,其中40例患者行第二代双源 DECT 80/Sn140 kV 检查（第一组）,40例患者行第二代双源 DECT 100/Sn140 kV 检查（第二组）,40例患者行第一代双源 DECT 140/80 kV 检查（第三组）。测量每例患者肺动脉主干、肺动脉段、空气及背部脂肪的 CT 值及标准差,对肺动脉图像进行主观评分,计算图像信噪比（SNR）、对比噪声比（CNR）及每例患者的有效剂量（ED）。结果：第一组肺动脉平均 CT 值[（354．1±73．4）HU]明显高于第二组[（290．1±73．1）HU,P＜0．001]和第三组[（303．9±73．3）HU,P＜0．001],但第二组与第三组差异无统计学意义（P＝0．399）;第三组平均 SNR（24．8±8．4）低于第一组（40．4±12．9,P＜0．001）和第二组（44．6±12．9,P＜0．001）,但第一组与第二组差异无统计学意义（P＝0．115）。第一组平均 CNR（435．3±77．7）明显高于第二组（355．8±77．8,P＜0．001）和第三组（384．8±79．0,P＝0．005）,但第二组与第三组差异无统计学意义（P＝0．100）。三组图像主观质量评分差异无统计学意义（P＞0．05）。第一组的 ED[（1．2±0．3）mSv]明显低于第二组[（2．4±0．7）mSv]和第三组[（3．0±0．7）mSv],差异均有统计学意义（P＜0．05）。结论：第二代双源 DECT 80/Sn140 kV 扫描方案可在大幅度降低辐射剂量的同时获得满足诊断需求的图像。     

Systolic reconstruction in patients with low heart rate using coronary dual-source CT angiography

Objectives

The purpose of our study was to determine the relationship between the predictive factors and systolic reconstruction (SR) as an optimal reconstruction window in patients with low heart rate (LHR; less than 65 bpm).

Methods

391 patients (262 male and 129 female, mean age; 67.1 ± 10.1 years of age) underwent coronary CTA without the additional administration of a beta-blocker. Affecting factors for SR were analyzed in age, gender, body weight (BW), diabetes mellitus (DM), coronary arterial disease (CAD), ejection fraction (EF), systolic and diastolic body pressure (BP) and heart rate variability (HRV) during coronary CTA.

Results

In 29 (7.4%) of the 391 patients, SR was needed, but there was no apparent characteristic difference between the systolic and diastolic reconstruction groups in terms of gender, age, BW, DM, CAD and EF. In a multivariate analysis, the co-existence of DM [P < 0.05; OR, 0.27; 95% CI, 0.092-0.80], diastolic BP [P < 0.01; OR, 0.95; 95% CI, 0.92-0.98] and HRV [P < 0.01; OR, 0.98; 95% CI, 0.96-0.99] were found to be the factors for SR. In gender-related analysis, HRV was an important factor regardless of sex, but co-existence of DM affected especially for female and BP for male.

Conclusion

Especially in the patients with LHR who had a medication of DM, high HRV or high BP, SR, in addition to DR, was needed to obtain high-quality coronary CTA images.     

Image quality and artifacts in coronary CT angiography with dual-source CT: Initial clinical experience

Introduction

We aimed to characterize artifacts observed in a routine clinical coronary CT angiography (CCTA) performed by a dual-source CT (DSCT) scanner (Definition; Siemens Medical Solutions).

Methods

Studies of 167 consecutive patients referred for CCTA, performed after β-blockade (if not contraindicated), were prospectively analyzed for artifacts with a predefined visual approach. American Heart Association coronary segments (n = 2589) were assessed in 40%-80% R-R interval phases by 2 experts for stenosis, plaque presence or composition, and presence or type of artifacts. Each segment was considered evaluable when image quality was diagnostic in at least one cardiac phase. Artifacts included motion (cardiac, respiratory, patient), phase misregistration because of varying heart beats, calcified plaque blooming or beam hardening, metal beam hardening, large patient size, and contrast timing error.

Results

Maximum HR (HR) during CCTA ranged from 45 to 120 beats/min (66.4 ± 14.8 beats/min). Artifacts of some type were observed in 69 (41.3%) of 167 studies. Calcified plaque was the most common source of artifacts (14.4%), followed by misregistration (13.8%). Only 25 (1%) of 2589 coronary segments, in 6 (4%) of 167 patients were unevaluable, primarily because of calcified plaque blooming (coronary calcium score [CCS], 1112 ± 1255]. Artifacts were associated with CCS (P = 0.002), change in HR (P = 0.01), age (P = 0.03), and body mass index (P = 0.048). The optimal phase for evaluation of all coronary arteries was 70% (mid-diastole), with a shift toward the systolic phases for HR > 70 beats/min.

Conclusion

CCTA artifacts with DSCT were related primarily to calcified plaque and cardiac phase misregistration. When correctly recognized, the artifacts did not have a serious effect on the final interpretation.     

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.     

双能量CT虚拟单能量重建技术显示肝癌TACE术后碘油沉积的价值

目的：探讨双能量CT虚拟单能量重建技术对肝癌经导管动脉化疗栓塞（TACE）术后碘油沉积的临床诊断价值。方法：对11例肝癌TACE术后患者进行双能量腹部CT平扫。在100 kVp、140 kVp、线性融合图像（M＝0．5）和以9组虚拟单能量（40、60、80、100、120、140、160、180和190 keV）图像上,在碘油沉积最显著的层面,测量伪影区及正常肝实质区的CT值,计算图像噪声（SD）和伪影指数（AI）。对伪影大小、图像噪声、碘油形态及综合图像质量分别进行主观评分。结果：客观评估：80 keV 图像的AI 值最小;线性融合图像、80 keV 图像的噪声最小。主观评估：在140 kVp、100～190 keV图像上伪影较少;线性融合图像和80 keV 图像的噪声评分最小;碘油形态以140 kVp、线性融合图像、80及100 keV图像上显示较为清晰。整体综合评分以线性融合图像和80 keV图像最高。结论：双能量CT 虚拟单能量重建技术在肝癌TACE术后碘油沉积的显示中,可以改善图像质量,以80 keV的虚拟单能量重建图像为最佳。     

Prospectively ECG-triggered high-pitch coronary angiography with third-generation dual-source CT at 70 kVp tube voltage: Feasibility,image quality,radiation dose,and effect of iterative reconstruction

BackgroundLow tube voltage reduces radiation exposure in coronary CT angiography (CTA). Using 70 kVp tube potential has so far not been possible because CT systems were unable to provide sufficiently high tube current with low voltage.ObjectiveWe evaluated feasibility, image quality (IQ), and radiation dose of coronary CTA using a third-generation dual-source CT system capable of producing 450 mAs tube current at 70 kVp tube voltage.MethodsCoronary CTA was performed in 26 consecutive patients with suspected coronary artery disease, selected for body weight <100 kg and heart rate <60 beats/min. High-pitch spiral acquisition was used. Filtered back projection (FBP) and iterative reconstruction (IR) algorithms were applied. IQ was assessed using a 4-point rating scale (1 = excellent, 4 = nondiagnostic) and objective parameters.ResultsMean age was 62 ± 9 years (46% males; mean body mass index, 27.7 ± 3.8 kg/m²; mean heart rate, 54 ± 5 beats/min). Mean dose-length product was 20.6 ± 1.9 mGy × cm; mean estimated effective radiation dose was 0.3 ± 0.03 mSv. Diagnostic IQ was found in 365 of 367 (FBP) and 366 of 367 (IR) segments (P nonsignificant). IQ was rated “excellent” in 53% (FBP) and 86% (IR) segments (P = .001) and “nondiagnostic” in 2 (FBP) and 1 segment (IR) (P nonsignificant). Mean IQ score was lesser in FBP vs IR (1.5 ± 0.4 vs 1.1 ± 0.2; P < .001). Image noise was lower in IR vs FBP (60 ± 10 HU vs 74 ± 8 HU; P < .001).ConclusionIn patients <100 kg and with a regular heart rate <60 beats/min, third-generation dual-source CT using high-pitch spiral acquisition and 70 kVp tube voltage is feasible and provides both robust IQ and very low radiation exposure.     

基于双源CT增强扫描的动脉导管未闭的介入治疗

目的评价术前双源心脏CT(DSCT)检查在动脉导管未闭(PDA)介入治疗中的临床应用价值,探讨脱离术中造影进行PDA介入治疗的方法。方法 38例经超声诊断为PDA的患者,其中21例术前行心脏DSCT检查,重建获得PDA影像,并与术中造影所显示PDA形态对比;在此基础上,后17例经超声诊断为PDA的患者,尝试根据术前CT检查结果指导选择合适的封堵器,术中不穿刺股动脉、不进行降主动脉造影,经静脉途径直接完成介入治疗,术中、术后以心脏超声随诊评价疗效。结果术中造影组21例PDA患者CT重建图像与术中造影影像形态高度一致,CT重建图像、术中造影PDA最窄径分别为(5.2±1.9)mm vs(4.7±1.7)mm(相关系数0.88);释放后封堵器腰部直径为(7.0±2.0)mm(与CT重建PDA最窄径相关系数为0.92,与术中造影PDA最窄径相关系数为0.90);术前接受CT检查、术中未进行造影,尝试直接封堵的17例患者皆成功完成介入治疗,CT重建PDA最窄径以及释放后封堵器腰部直径分别为(5.0±1.9)mm vs(6.7±2.2)mm,术后随访未见左肺动脉、降主动脉医源性狭窄。结论术前心脏DSCT检查可以获得准确的PDA解剖影像资料,初步临床资料显示,它可以替代术中造影,为PDA的介入治疗提供充足的支持;同时术前CT检查有助于发现合并的心脏大血管畸形,对于指导临床实践具有重要意义,但DSCT检查的辐射剂量问题以及如何减少辐射计量仍是一个需要考虑的问题。     

双源CT自适应前瞻性心电门控冠状动脉成像技术的初步应用

目的：初步探讨双源CT前瞻性心电门控冠状动脉成像的图像质量和辐射剂量。方法：对50例临床怀疑冠心病的受检者进行双源CT自适应前瞻性门控冠状动脉成像,检查前均未服用琥珀酸美托洛尔。图像质量分4级,依照美国心脏病协会（AHA）冠状动脉分段标准分别评价各个冠状动脉节段的图像质量,分别计算每例的有效辐射剂量（ED）。结果：50例受检者平均体重指数（BM I）为（25.00±2.58）kg/m2,扫描时平均心率（71.13±9.63）次/min,平均有效辐射剂量（3.31±1.08）mSv,显示了94.76%能满足诊断要求的冠状动脉节段,图像质量优秀占79.49%。结论：双源CT自适应前瞻性心电门控冠状动脉成像对于无严重心律失常的受检者都可得到满足诊断要求的图像,辐射剂量低,具有广阔的应用前景。     

Flash双源CT脑血管成像双能量减影去骨比率值的优化研究

目的 探讨双能量减影去骨比率值的调节在脑血管成像中的临床应用价值.方法 回顾分析45例双源CT二期双能量脑血管检查患者资料.双能量法按不同去骨比率(Ratio)值分别分成A组(Ratio=1.6),B组(Ratio=1.7),C组(Ratio=1.8),D组(Ratio=1.9,默认值);100 kV Neuro-DSA减影法定为E组.采用双盲法按去骨程度及血管完整程度对图像质量评分(1~5分,1分为差,5分为优,3~5分为满意).通过自身对比分析不同双能量去骨Ratio值对减影图像质量的影响,并以Neuro-DSA减影为对照,比较各组图像信噪比(SNR)、对比噪声比(CNR)及图像质量评分的统计学差异.结果 双能量减影不同去骨Ratio值组的颅底动脉图像评分总体满意率分别为:A组73.33%,B组91.11%,C组78.52%,D组70.37%.Ratio值取1.7时,虹吸段及岩骨段动脉的评分达满意显示率最高,差异有统计学意义(P<0.05).B组、D组、E组3组间SNR与CNR的差异不显著(P>0.05).结论 双源CT单次增强双能量减影去骨Ratio值的调节优化后的图像质量与100 kV Neuro-DSA减影一致性较好,可弥补双能量减影颅底脑血管缺损的不足,推荐在临床急诊脑血管检查中应用.     

Low-dose adaptive sequential scan for dual-source CT coronary angiography in patients with high heart rate: Comparison with retrospective ECG gating

Purpose

To explore feasibility of dual-source CT (DS-CT) prospective ECG-gated coronary angiography in patients with heart rate (HR) higher than 70 beat per minute (bpm), and evaluate image quality and radiation dose with comparison to retrospective ECG-gated spiral scan.

Materials and methods

One hundred patients who underwent DS-CT coronary angiography (DS-CTCA) with mean HR higher than 70 bpm but below 110 bpm were enrolled in the study, 50 were scanned by adaptive sequential scan and another 50 were analyzed by retrospectively gated CT scan. The imaging quality of coronary artery segments in the two groups was evaluated using a four-point grading scale by two independent reviewers. Patient radiation dose was calculated by multiplying dose length product by conversion coefficient of 0.017.

Results

There was no significant difference between the two groups for mean HR (p = 0.305), HR variability (p = 0.103), body mass index (p = 0.472), and scan length (p = 0.208). There was good agreement for image quality scoring between the two reviewers (Kappa = 0.72). Coronary evaluability of adaptive sequential scan was 99.7% (608 of 610 segments), while that of retrospective gated scan was 98.7% (614 of 622 segments), showing similar coronary evaluability (p = 0.061). Effective doses of adaptive sequential scan and retrospective gated scan were 5.1 ± 1.6 and 11.8 ± 4.5 mSv, respectively (p < 0.001), showing that adaptive sequential scan reduced radiation dose by 57% compared with that of retrospective gated scan.

Conclusions

In patients with 70-110 bpm HR, DS-CTCA adaptive sequential scan shows similar image quality as retrospective ECG-gated spiral scan with 57% reduction of radiation dose.     

CT angiography of lower extremity vascular bypass grafts

Over the past several years computed tomography (CT) technology has advanced to such a degree that CT angiography (CTA) has become the study of choice at our institution for imaging lower extremity vascular bypass grafts. CTA quickly provides anatomic information about the state of the graft and identifies virtually all forms of bypass graft failure and related complications. Furthermore, detailed vascular anatomy is seen beyond the graft and affords sufficient anatomic detail for surgical revision without the need for other angiographic studies. Although catheter angiography, duplex-ultrasound, magnetic resonance angiography, and nuclear medicine studies all continue to play some role in the evaluation of vascular grafts, they are more often used as problem solving modalities when CTA findings are equivocal. Whereas it was once essential to catheterize directly through a failing bypass graft or pass catheters into the graft from a distant arterial puncture to obtain an angiogram of a failing bypass graft, CTA produces arteriograms with only intravenous contrast administration, a brief visit to the CT scanner, and return to daily activities without catheterization, discomfort, or risk to the bypass conduit.     

Advances of dual source, dual-energy imaging in postmortem CT

This paper focuses on the use of multi-detector row dual-energy computed tomography (DECT) in the evaluation of postmortal examinations. The use of dual energy moves postmortem CT to an entirely new dimension of diagnostic sensitivity where contrast in the image is not merely limited to X-ray attenuation differences, but may include elements of functional and tissue characterization. This additional information may be used to improve the benefit postmortem imaging can provide to supplement and simplify the conventional autopsy.