High-resolution flat panel CT versus 3-T MR arthrography of the wrist: initial results in vivo.

OBJECTIVES: The objective of this study was to compare the diagnostic performance of direct C-arm flat panel computed tomography arthrography (FPCT-A) with direct magnetic resonance arthrography (MR-A) of the wrist in patients with clinically suspected pathologies. METHODS: Forty-nine patients underwent tri-compartmental wrist arthrography. FPCT-A was acquired using a high-resolution acquisition mode, followed by a 3-T MR exam using a dedicated wrist coil. Image quality and artifacts of FPCT-A and MR-A were evaluated with regard to the depictability of anatomical structures. The time stamps for the different image acquisitions were recorded for workflow assessment. RESULTS: Image quality was rated significantly superior for all structures for FPCT-A (p < 0.001) as compared to MR-A including intrinsic ligaments, TFCC, cartilage, subchondral bone, and trabeculae. The differences in image quality were highest for cartilage (2.0) and lowest for TFCC (0.9). The artifacts were rated lower in MR-A than in FPCT-A (p < 0.001). The procedure was more time-efficient in FPCT-A than in MR-A. CONCLUSIONS: FPCT-A of the wrist provides superior image quality and optimized workflow as compared to MR-A. Therefore, FPCT-A should be considered in patients scheduled for dedicated imaging of the intrinsic structures of the wrist. KEY POINTS: • FPCT arthrography allows high-resolution imaging of the intrinsic wrist structures. • The image quality is superior as compared to MR arthrography. • The procedure is more time-efficient than MR arthrography.

Evaluation of a newly developed 2D parametric parenchymal blood flow technique with an automated vessel suppression algorithm in patients with chronic thromboembolic pulmonary hypertension undergoing balloon pulmonary angioplasty.

AIM: To evaluate the feasibility of two-dimensional parametric parenchymal blood flow (2D-PPBF) to quantify perfusion changes in the lung parenchyma following balloon pulmonary angioplasty (BPA) for treatment of chronic thromboembolic pulmonary hypertension. MATERIALS AND METHODS: Overall, 35 consecutive interventions in 18 patients with 98 treated pulmonary arteries were included. To quantify changes in pulmonary blood flow using 2D-PPBF, the acquired digital subtraction angiography (DSA) series were post-processed using dedicated software. A reference region of interest (ROI; arterial inflow) in the treated pulmonary artery and a distal target ROI, including the whole lung parenchyma distal to the targeted stenosis, were placed in corresponding areas on DSA pre- and post-BPA. Half-peak density (HPD), wash-in rate (WIR), arrival to peak (AP), area under the curve (AUC), and mean transit time (MTT) were assessed. The ratios of the reference ROI to the target ROI (HPDparenchyma/HPDinflow, WIRparenchyma/WIRinflow; APparenchyma/APinflow, AUCparenchyma/AUCinflow, MTTparenchyma/MTTinflow) were calculated. The relative differences of the 2D-PPBF parameters were correlated to changes in the pulmonary flow grade score. RESULTS: The pulmonary flow grade score improved significantly after BPA (1 versus 3; p<0.0001). Likewise, the mean HPDparenchyma/HPDinflow (-10.2%; p<0.0001), APparenchyma/APinflow (-24.4%; p=0.0007), and MTTparenchyma/MTTinflow (-3.5%; p=0.0449) decreased significantly, whereas WIRparenchyma/WIRinflow (+82.4%) and AUCparenchyma/AUCinflow (+58.6%) showed a significant increase (p<0.0001). Furthermore, a significant correlation between changes of the pulmonary flow grade score and changes of HPDparenchyma/HPDinflow (ρ=-0.21, p=0.04), WIRparenchyma/WIRinflow (ρ=0.43, p<0.0001), APparenchyma/APinflow (ρ=-0.22, p=0.03), AUCparenchyma/AUCinflow (ρ=0.48, p<0.0001), and MTTparenchyma/MTTinflow (ρ=-0.39, p<0.0001) could be observed. CONCLUSION: The 2D-PPBF technique is feasible for the quantification of perfusion changes following BPA and has the potential to improve monitoring of BPA.

Extravascular incidental findings in run-off CT angiography in patients with acute limb ischaemia: incidence and clinical relevance.

AIM: To evaluate the incidence and clinical relevance of extravascular incidental findings (EVIFs) in CT angiography of the abdominal aorta and lower extremities (run-off CTA) in patients presenting with acute limb ischaemia (ALI). MATERIALS AND METHODS: In this institutional review board-approved, retrospective study, 141 run-off CTA examinations conducted between 2005 and 2013 of patients (67 women, mean age 80 years; 74 men, mean age 69 years) presenting with clinical symptoms of ALI were re-evaluated by two radiologists (2 and 7 years of experience in interpreting run-off CTA). Imaging was conducted using 16- and 64-section CT systems. Image acquisition ranged from the costodiaphragmatic recess to the forefoot. The medical history form of each patient served as the standard of reference for assessment of incidence of EVIFs. CT morphology was assessed to assign EVIFs to one of three categories of clinical relevance: (I) immediate, (II) potential, and (III) no clinical relevance. RESULTS: Thirty-eight patients had category I findings, including four patients (2.8%) with previously unknown malignancy and 67 patients with category II EVIFs. In total 473 extravascular EVIFs were found in 141 patients: 52 category I, 163 category II and 258 category III. CONCLUSION: EVIFs with immediate clinical relevance are very common in run-off CTA in patients presenting with acute peripheral artery disease. Therefore, it is important to evaluate all body regions included in a CT examination carefully, even if the clinical focus is on vascular evaluation. The adequate classification of these EVIFs is required to avoid possible unnecessary diagnostic work-up with associated risks and costs.

Photon-counting detector CT (PCD-CT) generated iodine maps to characterize parenchymal lung disease: A feasibility study.

BACKGROUND: With photon-counting CT, spectral imaging is always available, and iodine maps with high spatial and spectral resolution can be generated. OBJECTIVES: The aim of this study was to investigate whether iodine uptake in different parenchymal patterns can be used to characterise parenchymal disease with increased lung attenuation. METHODS: 325 patients were scanned with a photon-counting CT using four scan protocols, all with lung parenchymal contrast. Lesions were classified into three basic patterns: consolidation, ground-glass opacities (GGO), and reticular pattern. Lesion classification was performed by 2 of 3 radiologists who were blinded to the diagnosis. Classification was performed twice using a 5-point Likert scale (with and without iodine maps). In case of disagreement, a third reader was consulted, and the decision was made by consensus. RESULTS: 206 lesions were found with a confirmed diagnosis (83 consolidations, 72 GGO, and 51 reticular). Diagnostic confidence improved when iodine maps were included in the evaluation. The mean Likert score increased significantly for all three basic patterns (consolidations: 3.3 vs. 3.9, GGO: 3.4 vs. 4.1, and reticular: 3.6 vs. 4.4, p < 0.001). However, the score for GGO and reticular pattern was downgraded in three and one cases, respectively. The downgrading occurred for morphologically uncertain GGO findings (3) and atelectasis (1) with inhomogeneous iodine uptake. In 29 lesions, the classification was changed when the iodine maps were included in the evaluation. CONCLUSION: Including iodine maps adds contrast uptake information and improves the diagnostic confidence of radiologists in the characterization of parenchymal pathologies. CLINICAL IMPACT: Iodine maps have the potential to provide complementary information for the interpretation of lung opacities with overlapping morphology.

Optimal table feed in run-off CT angiography in patients with abdominal aortic aneurysms.

OBJECTIVES: To assess the influence of different table feeds (TFs) on vascular enhancement and image quality in patients with an abdominal aortic aneurysm (AAA) undergoing computed tomography (CT) angiography of the lower extremities (run-off CTA). METHODS: Seventy-nine patients (71 ± 8 years) with an AAA (>30 mm) who underwent run-off CTA between January 2004 and August 2011 were included in this retrospective institutional review board-approved study. Run-off CTA was conducted using 16- and 64-row CT. The range of TFs was 30-86 mm/s and was categorised in quartiles TF1 (32.6 ± 1.9 mm/s), TF2 (38.9 ± 0.9 mm/s), TF3 (43.9 ± 3.1 mm/s) and TF4 (57.4 ± 10.5 mm/s). Image quality was rated independently by two radiologists and vessel enhancement was assessed. RESULTS: Image quality was diagnostic at all aortic, pelvic and almost all thigh levels. Below the knee, the number of diagnostic levels was highest for TF1 and decreased to TF4. Arterial enhancement between the aorta and fibular trunk was not different in all TF groups, P > 0.05. At the calf and foot strongest arterial enhancement was noted for TF1 and TF2 and decreased to TF4, P < 0.01. CONCLUSION: Results indicate that the highest image quality of run-off CTA in patients with an AAA may be obtained using table feeds measuring 30-35 mm/s. KEY POINTS: • CTA has become a key investigation for peripheral vascular disease. • Run-off CTA is more complex in patients with an abdominal aortic aneurysm. • Run-off CTA is feasible with a short bolus of intravenous contrast medium. • A constant 30-35 mm/s table feed provides the highest likelihood of diagnostic images.

Adrenal venous sampling in primary hyperaldosteronism: correlation of hormone indices and collimated C-arm CT findings.

PURPOSE: To evaluate the feasibility and effect of an approach to adrenal venous sampling (AVS) analysis by combining established selective cortisol and aldosterone indices with the acquisition of a collimated C-arm CT(CACTColl). METHODS: Overall, 107 consecutive patients (45f,62 m; 54 ± 10 years) undergoing 111 AVS procedures without hormonal stimulation from 7/13 to 2/20 in a single institution were retrospectively analysed. Hormone levels were measured in sequential samples of the suspected adrenal veins and right iliac vein, and selectivity indices (SI) computed. Stand-alone SICortisol and/or SIAldosterone ≥ 2.0 as well as SICortisol and/or SIAldosterone ≥ 1.1 combined with positive right-sided CACTColl of the adrenals (n = 80; opacified right adrenal vein) were defined as a successful AVS procedure. Radiation exposure of CACT was measured via dose area product (DAP) and weighed against an age-/weight-matched cohort (n = 66). RESULTS: Preliminary success rates (SICortisol and/or SIAldosterone ≥ 2.0) were 99.1% (left) and 72.1% (right). These could be significantly increased to a 90.1% success rate on the right, by combining an adjusted SI of 1.1 with a positive CACTColl proving the correct sampling position. Sensitivity for stand-alone collimated CACT (CACTColl) was 0.93, with 74/80 acquired CACTColl confirming selective cannulation by adrenal vein enhancement. Mean DAPColl_CACT measured 2414 ± 958 µGyxm2, while mean DAPFull-FOV_CACT in the matched cohort measured 8766 ± 1956 µGyxm2 (p < 0.001). CONCLUSION: Collimated CACT in AVS procedures is feasible and leads to a significant increase in success rates of (right-sided) selective cannulation and may in combination with adapted hormone indices, offer a successful alternative to previously published AVS analysis algorithms with lower radiation exposure compared to a full-FOV CACT.

Do the cardiovascular risk profile and the degree of arterial wall calcification influence the performance of MDCT angiography of lower extremity arteries?

OBJECTIVES: To retrospectively assess the influence of arterial wall calcifications on the accuracy of run-off computed tomographic angiography (CTA) and to analyse whether cardiovascular risk factors are predictors of compromising calcifications. METHODS: In 200 consecutive patients who underwent run-off CTA, calcifications were assessed in pelvic, thigh and calf arteries using a four-point scale. Fifty-nine patients with digital subtraction angiography (DSA) were assessed by both techniques to estimate a threshold of compromising calcifications, defined as a decrease of sensitivity, specificity, PPV or NPV below the lower 95% confidence interval of overall results. Regression analysis was performed to investigate a potential relationship between compromising calcifications and presence of cardiovascular risk factors, advanced patient age and severe peripheral arterial disease (PAD). RESULTS: The highest Ca(++)-score was chosen as the cut-off for the regression analysis, as a relevant decrease of specificity (0.91; overall: 0.95) above the knee and of sensitivity (0.66; overall: 0.83), specificity (0.65; overall: 0.93), positive predictive value (PPV) and negative predictive value (NPV) below the knee was observed. In the pelvic and thigh arteries, severe PAD (Fontaine Stage >or=III) showed the highest odds ratio for compromising calcifications (2.9), followed by diabetes mellitus (2.4), renal failure (2.1) and smoking (1.7). In the calf, renal failure (12.2) and diabetes mellitus (3.3) were the strongest predictors. CONCLUSIONS: Patients with diabetes and renal failure should be considered as candidates for alternative vessel imaging in order to avoid inconclusive examination results.

COMPARISON OF EXPERIMENTAL AND NUMERICAL METHODS OF PATIENT DOSE ESTIMATIONS IN CT USING ANTHROPOMORPHIC MODELS.

The common methods for patient dose estimations in computed tomography (CT) are thermoluminescence dosemeter (TLD) measurements or the usage of software packages based on Monte Carlo simulations like CT-Expo or the newer CTVoxDos, which uses the ICRP Reference Adult Male (ICRP 110). Organ (OD) and effective doses of a CT protocol of the upper abdomen are compared. Compared to CTVoxDos, ODs inferred by TLD measurement using an anthropomorphic phantom differ by $\mathbf{(19\pm 16)\,\%}$ inside the primary radiation field, $\mathbf{(14\pm 2)\,\%}$ for partially primary irradiated organs and $\mathbf{(34\pm 38)\,\%}$ in the scattered radiation field. ODs estimated by CT-Expo show a mean deviation of $\mathbf{(16\pm 9)\,\%}$ (primary irradiated) and $\mathbf{(28\pm 31)\,\%}$ (scatter irradiated) from ODs estimated by CTVoxDos.

Comparison of health-related quality of life after transarterial chemoembolization and transarterial radioembolization in patients with unresectable hepatocellular carcinoma.

PURPOSE: The purpose of this study was to compare quality of life (QoL) after two different transarterial therapies [transarterial chemoembolization (TACE) and transarterial radioembolization (TARE)] for patients with unresectable hepatocellular carcinoma (HCC) to assess tumor therapy in palliative situation additional to traditional aims like survival or image response. MATERIAL AND METHODS: QoL was evaluated with two validated questionnaires (EORTC QLQ-30 and EORTC HCC18) before and 14d after treatment in 94 initial therapies (TACE n = 67; TARE n = 27). QoL changes after treatment were analyzed. Tumor response was evaluated using RECIST/WHO/mRECIST/EASL criteria. A multivariate linear regression was undertaken to identify potential influence factors on change of QoL. RESULTS: Mean return rate of questionnaires was 71.3% allowing analysis of 67 therapies (TACE n = 46; TARE n = 21). Initial global health status/QoL was significantly higher in TACE (62.5%) compared to TARE with 50.8%. Absolute global health decrease was higher in TACE (- 10.5%) compared to TARE (- 4.8%, p = 0.396). Also relative global health decrease was higher in TACE (- 16.82%) compared to TARE (- 9.37%). Findings for other items were corresponding, as less impairment was found for TARE compared to TACE for physical/social functioning, fatigue and pain. Objective mRECIST response rate was 22.8% in TACE and 21.1% in TARE. CONCLUSION: Neither TACE nor TARE showed a major decrease in QoL after first treatment. TACE showed a slightly but not significantly higher decrease, so this study is not clearly in favor for one treatment. But with the addition that TARE showed less decrease even in patients with higher tumor burden and lower baseline.

Virtual single source CT using dual source acquisition: Clinical applicability in run-off CT-angiography for intra-individual comparison of different scan protocols.

PURPOSE: Virtual single source computed tomography (VSS-CT) acquisition on a dual source CT (DSCT) has been demonstrated to allow for dose-neutral intra-individual comparison of three acquisition protocols at different radiation dose levels (RDL) within one acquisition in a phantom. The purpose of this study was twofold: first to evaluate the applicability of VSS-CT in patients and second to optimize the task-dependent trade-off between radiation dose and image quality of lower extremity CT angiography (run-off CTA). MATERIAL AND METHODS: In this IRB-approved prospective study 52 patients underwent run-off CTA between 06/2012 and 06/2013. VSS-CT acquisition was conducted using a first generation DSCT applying equal X-ray tube settings (120 kVp), collimation (2 × 32 × 0.6 mm), and slice thickness (1.0 mm) but different effective tube current-time products (tube A: 80 mAs, tube B: 40 mAs). Three different image datasets representing three different radiation dose levels (RDL40, RDL80, RDL120) were reconstructed using a soft kernel from the raw data of tube B, tube A or both tubes combined. Dose length products (DLP) of each raw data set were documented. Quantitative image quality (IQ) was assessed for five anatomical levels using image noise and contrast-to-noise ratio (CNR). To investigate dose efficiency of each acquisition, the dose-weighted CNR (CNRD) was determined. Qualitative IQ was evaluated by two blinded readers in consensus using a 5-point Likert scale and compared with a Friedman- and posthoc Wilcoxon test. RESULTS: Mean DLP was 200 ±â€¯40, 400 ±â€¯90 and 600 ±â€¯130 mGy·cm for the RDL40, RDL80 and RDL120, respectively. Image noise and CNR were best for RDL120 and decreased significantly for RDL80 and RDL40, independent of the anatomic level (p < 0.001). CNRD showed no significant differences at the abdominal and pelvic level between the investigated radiation dose levels. However, for thigh to foot level a significant increase of CNRD was noted between RDL120, RDL80 and RDL40. Significant differences of qualitative IQ were observed between RDL120 and RDL40 from the abdominal to the foot level, whereas no difference was seen for the other dose levels. CONCLUSION: Radiation dose splitting with VSS-CT can be applied to run-off CTA facilitating intra-individual comparison of different acquisition protocols without additional radiation exposure. Furthermore, a radiation dose reduction potential for run-off CTA of approximately 1/3 as compared to the acquisition protocol recommended by the manufacturer could be identified in this study.

Quality of life in patients undergoing repetitive TACE for the treatment of intermediate stage HCC.

PURPOSE: With a limited overall survival (OS) of 20 months in patients diagnosed with intermediate stage hepatocellular carcinoma (HCC), the preservation of quality of life (QoL) during transarterial chemoembolization (TACE) procedures remains a primary goal. The aim of our study was to evaluate the change in QoL amongst patients undergoing repetitive TACE and to identify specific risk factors that may predict change in QoL. METHODS: QoL was assessed in 82 patients undergoing at least two TACE, before and 14 days after TACE, using validated EORTC QLQ-C30 and EORTC HCC18 questionnaires. Tumour response was assessed using established response criteria. Laboratory and clinical parameters were analysed. RESULTS: Functional scores decreased due to first TACE treatment (p < 0.01), conversely symptom scores increased significantly (p < 0.01). During repetitive TACE no statistically significant changes were observed. Higher Global Health- and Physical Functioning scores at baseline were identified as independent prognostic factors for greater decrease in QoL. Tumour response did not alter QoL at all. Furthermore higher symptom scales including pain (p = 0.00), nausea and vomiting (p = 0.00) and fever (p < 0.01 for repetitive TACE) at baseline were predictive of a significantly lesser increase of symptom severity, and a greater reduction in pain during a course of TACE. Higher C-reactive protein (CRP) at baseline and female gender were associated with a greater decrease of functional scales and increase of symptom scales. CONCLUSION: QoL amongst patients receiving repetitive TACE showed neither significant nor clinically relevant changes over time. Pre-treatment assessment of QoL-scores, clinical and laboratory parameters can improve patient selection for TACE whilst optimizing QoL.

Impact of CT parameters on the physical quantities related to image quality for two MDCT scanners using the ACR accreditation phantom: A phantom study.

INTRODUCTION: To evaluate the image quality provided by MDCT scanners using an ACR phantom an to find out the relationship between CT parameters and physical quantities related to image quality. METHODS: A GE Lightspeed VCT and a GE Lightspeed Pro 16 are used. The ACR phantom consists of four modules for evaluating physical parameters. The image quality parameters, such as CT number, linearity, CNR, image uniformity, SNR and at least spatial resolution using MTF, by different sets of image acquisition protocols (IAPs) are characterized. The influences of the IAPs on the physical quantities are also discussed. RESULTS: The CT numbers behaved linearly relative to material density for all tube voltages. The impact of the tube current on the CT numbers is neglectable. However, the variation of the tube current reflects in the CT number uncertainties. The CNR are altered by changing the IAPs. 50% MTF decreases from 6.2 to 3.6 lp/cm and from 6.5 to 3.7 lp/cm using Lung and Soft kernel for the Lightspeed VCT and Lightspeed Pro 16 scanner, respectively. CONCLUSION: The dependence of the image quality parameters on reconstruction kernels, tube peak voltages, tube currents and the slice thicknesses has been discussed. The tube peak voltage has the most influence on the CT numbers. The results indicate that the reconstruction kernel has the main impact on the spatial resolution. The spatial resolution dependence on the tube voltages, tube currents and slice thicknesses can be ignored.

[Dual energy CT of the peripheral arteries: a phantom study to assess the effect of automatic plaque removal on stenosis grading]. / Dual-Energy-CT der peripheren Arterien: eine Phantomstudie zur Bestimmung des Einflusses der automatischen Plaqueentfernung auf die Stenosegradbestimmung.

PURPOSE: To evaluate the accuracy of dual energy (DE)-based plaque removal in a vessel phantom. MATERIALS AND METHODS: Acrylic vessel phantoms of different diameters (3, 5, 8 mm), degrees of stenoses (25 - 100%) and plaque densities (300 - 750 HU) were filled with contrast-enhanced blood (150 - 450 HU). Dual source CT was used for simultaneous image acquisition at 80 and 140 kV. Beside a DE-based plaque-subtracted dataset (DE-PS), a virtual 120 kV non-plaque subtracted dataset (N-PS) was generated. Agreement between the known and measured luminal diameter in both datasets was determined using Lin's concordance correlation coefficient (kappaLin). RESULTS: A total of 8260 measurements were taken. The correlation of measured diameter in DE-PS images was excellent (kappaLin = 0.83 - 0.96) for 5 - 8 mm vessel phantoms with high luminal enhancement (300 - 450 HU) and plaque density (500 - 750 HU), moderate (kappaLin = 0.6 - 0.67) for 5 mm vessels with lower luminal enhancement and plaque density and poor (kappaLin = 0.10 - 0.64) in the 3 mm vessels. The correlation of N-PS-based stenosis quantification was excellent (kappaLin = 0.86 - 0.99) for 5 - 8 mm vessel phantoms if the contrast between lumen and plaque was above 100 HU. The correlation decreased in 3 mm vessels (kappaLin = 0.45 - 0.93), while the lowest correlation was observed for the lowest contrast between plaque and vessel lumen. CONCLUSION: Automatic DE-based plaque removal is highly effective for heavily calcified plaques and high luminal enhancement in larger diameter vessels > or = 5 mm). However, accuracy is limited for low density calcified plaque, lower luminal enhancement and smaller caliber vessels mainly due to poor specificity.

Dual energy CT of peripheral arteries: effect of automatic bone and plaque removal on image quality and grading of stenoses.

PURPOSE: To evaluate the effect of automatic bone and plaque removal on image quality and grading of steno-occlusive lesions in patients undergoing dual energy CT angiography (CTA) of lower extremity. MATERIALS AND METHODS: Dual energy (DE) runoff CTA was performed in 50 patients using the following parameters: collimation 2 x 32 x 0.6; tube potentials, 80 kV and 140 kV; reconstructed slice thickness 1mm. 100 mL iomeprol 400 and 50 mL saline were injected at 4 mL/s. Separate datasets were calculated for each of the two tubes and used to generate automatically bone-subtracted images (ABS) as well as bone and plaque subtracted images (ABPS). Residual bone in the ABS dataset was removed manually (=ABS-B dataset). In addition, a weighted average dataset from both dual energy acquisitions resembling a routine 120 kV CT acquisition was used for standard manual bone subtraction (MBS). Operator time for bone removal was measured. Effectiveness of bone subtraction and presence of vessel erosions was assessed by two readers in consensus. Stenosis grading in plaque subtracted and unsubtracted images was assessed and correlated. RESULTS: Residual bone fragments (ribs: 46%, patella: 25%, spine: 4%, pelvis: 2%, tibia 2% of patients) were only observed with ABS. The time needed to manually remove these residual bones was 2.1+/-1.1 min and was significantly lower than the duration of manual bone removal (6.8+/-2.0 min, p<0.0001, paired t-test). A total of 1159 arteries were analyzed. Compromising vessel erosions were observed less frequently in the ABS-B dataset (10.6%) than in the MBS dataset (15.2%, p<0.001, wilcoxon's signed rank test). A total of 817 steno-occlusive lesions were assessed. While the agreement of grading of steno-occlusive lesions was good at the levels of the aorta and the pelvic arteries (kappa=0.70 in both, Cohen's kappa statistics), it was moderate at the level of the thigh arteries (kappa=0.57) and poor at the level of the calf (kappa=0.16). CONCLUSION: DE CTA has substantial advantages over conventional CTA. Automatic bone subtraction is more time efficient and reliable. Automatic plaque subtraction for the first time provides a true CTA-luminogram which is easy to interpret and reduces the need for further post-processing. DE CTA provides best results in arteries of the thigh; below the knee, plaque subtraction is less accurate.