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Purpose To prospectively evaluate contemporary indications, safety and diagnostic impact of cardiac CTA in patients undergoing cardiac CTA examinations for non-coronary clinical indications. Method We analyzed 1097 consecutive patients from the German Cardiac CT Registry who underwent cardiac CTA between 2009 and 2014 due to clinically indicated non-coronary reasons using 64-slice or newer CT systems in twelve tertiary German heart centers in order to evaluate the impact of clinical indications on procedure-associated parameters. All participating centers electronically submitted patient and examination data including detailed indications, clinical symptoms, procedural parameters, complications and diagnostic results in a predefined template. Results The most frequent indication for non-coronary cardiac CTA was the evaluation of pulmonary vein anatomy (65.9 %, 723/1097). In the remaining cases, most frequent indications were planning before TAVI (44.5 %, 69/155), evaluation of valvular disease (31.6 %, 49/155), and evaluation of implants (5.8 %, 9/155). Non-coronary cardiac CTA required a median amount of iodinated contrast agent of 100.0 mL (IQR 95.0–110.0 mL). Prospectively ECG-triggered acquisition was the most frequently used protocol (74.0 %), followed by retrospectively ECG-gated acquisition with and without tube current modulation (19.9 % and 6.0 %, respectively), resulting in a mean estimated effective dose of 5.2 mSv (IQR 2.9−9.5 mSv, average conversion factor k = 0.026). Overall, complication rate was very low (1.5 %). Non-coronary cardiac CTA revealed a new clinical diagnostic aspect in 3.2 % of all patients, and a new main clinical diagnosis in 2.2 %. Conclusions Non-coronary cardiac CTA as a routinely applied diagnostic modality is associated with a very low procedure-related rate of complications and reasonably low radiation exposure using contemporary CT systems.

PURPOSE: South Asian (SA) have been observed to have higher cardiovascular mortality rates compared to East Asians (EA) and Caucasians. Pericoronary adipose tissue (PCAT) attenuation around the right coronary artery (RCA) from coronary CT angiography (CTA) has been associated with coronary inflammation and cardiac death. We aimed to investigate i) the relationship between plaque characteristics and PCAT attenuation and ii) to assess gender and ethnic differences in PCAT attenuation using a matched cohort of SA, EA and Caucasians. METHOD: Three-hundred symptomatic patients who underwent CTA were matched for age, gender, BMI and diabetes (100 in each ethnic group). Semi-automated software was used to quantify the total volumes and burden of non-calcified plaque (NCP), low-density non-calcified plaque (LD-NCP) and calcified plaque (CP) in blinded core-lab analysis. PCAT CT attenuation was measured around the RCA (10–50 mm from RCA ostium), the most standardized model for PCAT analysis. RESULTS: The total volumes and burden of NCP, LD-NCP and CP were comparable in the ethnic groups (each p > 0.05). PCAT attenuation was higher in patients with coronary plaque. PCAT attenuation correlated with the total volumes and burden of NCP, LD-NCP and CP (r > 0.17; p < 0.003). Within the RCA this correlation persisted only for NCP features (r > 0.39;p < 0.001). Males showed higher PCAT attenuation (p < 0.001). PCAT attenuation was similar between Caucasian, EA and SA (p = 0.32). CONCLUSIONS: PCAT CT attenuation correlated most with its surrounded NCP features further highlighting its role as surrogate measure of coronary inflammation. As coronary plaque burden and RCA PCAT attenuation did not differ between ethnic groups, causes of increased cardiac mortality in South Asians needs further investigations.

While computed tomography (CT) is frequently used to quantify epicardial adipose tissue (EAT), the effect of different acquisition parameters on EAT volume has not been systematically reported. We assessed the influence of low-voltage acquisition and contrast enhancement on EAT quantification.Two independent cohorts (100 and 127 patients) referred for routine coronary CT were included. One cohort received a low-voltage and a standard voltage non-contrast acquisition (120 and 100 kV), the other cohort underwent non-contrast and contrast-enhanced CT. EAT volume was quantified using a semi-automated analysis software. Whereas the lower EAT threshold was consistently set at -190 Hounsfield Units (HU), different upper thresholds for EAT were analyzed. Bland-Altman analysis was used to analyze the agreement of EAT volume between scans with different acquisition parameters. We referred to a non-enhanced 120 kV acquisition with an upper threshold of -30 HU.Mean EAT volume was 159 ± 76 ml as measured in 120 kV non-contrast data sets with an upper threshold of -30 HU. For 100 kV data sets, an upper threshold of -40 HU showed the best correlation (r = 0.961, p 0.05). Significant overestimation was found for upper thresholds of -20 and -30 HU and significant underestimation for -50 HU. In non-contrast vs. contrast-enhanced acquisitions, there was a significant underestimation of EAT volume for contrast-enhanced scans (mean difference 31 ml, 95% limits of agreement 27 to -89 ml).CT-based EAT volume quantification in low-voltage and contrast-enhanced images is feasible. However, adjustment of the upper threshold for detection of fat is mandatory.

To determine the application of advanced coronary computed tomography angiography (CCTA) plaque analysis for predicting invasive fractional flow reserve (FFR) in intermediate coronary lesions.Sixty-one patients with 71 single intermediate coronary lesions (≥ 50-80% stenosis) on CCTA prospectively underwent coronary angiography and FFR. Advanced anatomical and morphometric plaque analysis was performed based on CCTA data set to determine optimal criteria for significant flow impairment. A significant stenosis was defined as FFR ≤ 0.80.FFR averaged 0.85 ± 0.09, and 19 lesions (27%) were functionally significant. FFR correlated with minimum lumen area (MLA) (r=0.456, p0.001), minimum lumen diameter (MLD) (r=0.326, p=0.006), reference lumen diameter (RLD) (r=0.245, p=0.039), plaque burden (r=-0.313, p=0.008), lumen area stenosis (r=-0.305, p=0.01), lesion length (r=-0.692, p0.001), and plaque volume (r=-0.668, p0.001). There was no relationship between FFR and CCTA morphometric plaque parameters. By multivariate analysis the independent predictors of FFR were lesion length (beta=-0.581, p0.001), MLA (beta=0.360, p=0.041), and RLD (beta=-0.255, p=0.036). The optimal cutoffs for lesion length, MLA, MLD, RLD, and lumen area stenosis were18.5mm, ≤ 3.0mm(2), ≤ 2.1mm, ≤ 3.2mm, and69%, respectively (max. sensitivity: 100% for MLA, max. specificity: 79% for lumen area stenosis).CCTA predictors for FFR support the mathematical relationship between stenosis pressure drop and coronary flow. CCTA could prove to be a useful rule-out test for significant hemodynamic effects of intermediate coronary stenoses.

Objectives To evaluate an automated attenuation-based kV-selection in computed tomography of the chest in respect to radiation dose and image quality, compared to a standard 120kV protocol. Materials and methods 104 patients were examined using a 128-slice scanner. Fifty examinations (58±15 years, study group) were performed using the automated adaption of tube potential (100–140kV), based on the attenuation profile of the scout scan, 54 examinations (62±14 years, control group) with fixed 120kV. Estimated CT dose index (CTDI) of the software-proposed setting was compared with a 120kV protocol. After the scan CTDI volume (CTDIvol) and dose length product (DLP) were recorded. Image quality was assessed by region of interest (ROI) measurements, subjective image quality by two observers with a 4-point scale (3 – excellent, 0 – not diagnostic). Results The algorithm selected 100kV in 78% and 120kV in 22%. Overall CTDIvol reduction was 26.6% (34% in 100kV) overall DLP reduction was 22.8% (32.1% in 100kV) (all p Conclusion The attenuation based kV-selection algorithm enables relevant dose reduction (∼27%) in chest-CT while keeping image quality parameters at high levels.

Purpose An extensive number of protocols have been suggested to allow for functional diagnostics; however, no data is available about the minimal amount of contrast medium to achieve reliable imaging properties. None of the plethora of existing studies report a rational why the specific concentration was chosen. Materials and methods A total of 40 patients were included in this prospective, controlled study. They were divided up into four equal groups getting a different concentration (10%, 20%, 30% or 40%) of a second contrast medium bolus. Corresponding septal and right ventricular ROIs were compared. A visual score was established. Coronary attenuation was measured in the right and left coronary artery. Streak artifacts in the right atrium/ventricle were assessed. Results In the 10% contrast medium (CM) group only in 5/10 (50%) patients full septal delineation was reached. In all other groups full septal visualization was obtained. No group showed a relevant difference of mean density measured in HU units of the left ventricle or the coronary arteries. All study groups except of group 1 (10% CM) showed streak artifacts in the right atrium. Conclusion The dual flow protocol with a minimum concentration of 20% improves septal visualization as basis for left ventricular functional assessment, however, does not allow for reliable right ventricular or atrial visualization. There is no significant difference between the different concentration protocols in terms of coronary attenuation.

Aim of this study was to compare DNA double-strand breaks (DSBs) in blood lymphocytes of patients undergoing high-pitch helical, low-pitch helical and sequential coronary CT angiography.66 patients were examined with various scan protocols and modes (low-pitch helical scan: 100-120 kV, 320-438 mAs/rot, pitch 0.18-0.39, with or without ECG-pulsing, n=35; prospectively ECG-triggered high-pitch helical scan: 100-120 kV, 320-456 mAs/rotation, pitch 3.2-3.4, n=19; prospectively ECG-triggered sequential scan: 100-120 kV, 150-300 mAs or 320-370 mAs/rotation, n=12) either using a 64-slice or 128-slice dual-source CT or a 128-slice single source CT scanner. Blood samples were obtained before and 30 min after CT and DSBs were analyzed in isolated lymphocytes using γ-H2AX immunofluorescence microscopy. A significant increase of DSBs was measurable 30 min after CTA (range 0.01-0.71/cell). CT induced DSBs showed a significant correlation with the estimated effective dose (ρ=0.90, p0.00001). Both prospectively ECG-triggered sequential (0.10 DSBs/cell, 176 mGy cm, p0.00001) and high-pitch helical scan protocols (0.03 DSBs/cell, 109 mGy cm, p0.00001) led to a significant reduction of median DLP and DSB levels compared to low-pitch helical scans (0.34 DSBs/cell, 828 mGy cm). A reduction of the tube voltage resulted in significantly lower whereas additional calcium scoring resulted in elevated DLP and DNA damages (p0.05 each).In coronary CTA, data acquisition protocols have a significant influence on the X-ray induced DSB levels. Using γ-H2AX immunofluorescence microscopy different scan modes in different CT generations can be compared concerning their biological impact.

Objective To determine the accuracy of dual-source CT (DSCT) to quantify coronary stenosis compared to intravascular ultrasound (IVUS) and quantitative coronary angiography (QCA). Methods 21 patients (23 vessels) were examined with DSCT, IVUS and invasive coronary angiography. Coronary minimal luminal diameter (MLD) and area (MLA) were measured in cross-sectional multi-planar reformatted images perpendicular to the vessel long-axis. The vessel cross-sectional area stenosis (MLA/CSA ratio) was calculated. DSCT results were compared with IVUS and QCA. Results A good correlation between DSCT and IVUS was noted for diameter and area stenosis (r = 0.69 and r = 0.73), with an overestimation of MLD stenosis by DSCT (+9.1%) and an underestimation of MLA stenosis (−5.8%). For MLD and MLA, high correlation coefficients (r = 0.78 and r = 0.90, respectively) were found between DSCT and IVUS; and the bias was almost zero (−0.41 mm and +0.1 mm2, respectively). The correlation between DSCT and QCA was moderate (r = 0.60) for MLD stenosis with minor overestimation by DSCT (+4.0%) and moderate (r = 0.59) for MLD (bias, +0.01 mm). The cross-sectional area stenosis showed a moderate correlation (r = 0.59) between DSCT and IVUS (+0.00). Conclusions DSCT allows accurate quantification of coronary stenosis as compared to IVUS. An excellent correlation was found for the MLA between DSCT and IVUS.

Objective To evaluate, whether semi-automated vessel extraction and curved planar reformations (“automated vessel extraction”) increases diagnostic accuracy in the detection of relevant coronary artery lesions compared to manual, interactive multiplanar interpretation (“manual approach”). Materials and methods 50 coronary CT angiography datasets were evaluated by four independent readers (two experienced, two novice) for the presence of stenoses exceeding 50% diameter reduction. One experienced and one novice reader each used the “manual approach” for cases 1–25 and “automated vessel extraction” for cases 26–50, while the other two readers used the complementary method. Results were compared to those of invasive coronary angiography. Results Using the “manual approach”, 37 of 42 stenoses were correctly detected by experienced as well as novice readers. 14 vs. 17 lesions were false positive (sensitivity 88%, specificity 91% vs. 89%, PPV 73% vs. 69%, NPV 97%, n.s.). Using “automated vessel extraction”, experienced readers detected 35/42 stenoses compared to 31/42 for novice readers. 7 vs. 11 lesions were missed and 17 vs. 15 false-positive lesions reported (sensitivity 83% vs. 74%, specificity 89% vs. 90%, PPV 67%, NPV 95% vs. 93%, n.s.).In patient-based analysis, for novice readers sensitivity was higher using the “manual approach” (97%, 29/30 pts. vs. 80%, 24/30 pts., p = 0.069). Conclusions Semi-automated vessel extraction and curved multiplanar reconstructions do not improve the diagnostic accuracy of coronary CT angiography compared to the use of interactive multiplanar reformations. Especially for less experienced readers, the use of automatically rendered curved multiplanar reconstructions alone cannot be recommended.

Multi-detector computed tomography (CT) scanners, by virtue of their high temporal and spatial resolution, permit imaging of the coronary arteries. However, motion artifacts, especially in patients with higher heart rates, can impair image quality. We thus evaluated the performance of a new dual-source CT (DSCT) with a heart rate independent temporal resolution of 83ms for the visualization of the coronary arteries in 14 consecutive patients. Methods Fourteen patients (mean age 61 years, mean heart rate 71min −1 ) were studied by DSCT. The system combines two arrays of an X-ray tube plus detector (64 slices) mounted on a single gantry at an angle of 90° With a rotation speed of 330ms, a temporal resolution of 83ms (one-quarter rotation) can be achieved independent of heart rate. For data acquisition, intraveous contrast agent was injected at a rate of 5ml/s. Images were reconstructed with 0.75 slice thickness and 0.5mm increment. The data sets were evaluated concerning visibility of the coronary arteries and occurrence of motion artifact. Results Visualization of the coronary arteries was successful in all patients. Most frequently, image reconstruction at 70% of the cardiac cycle provided for optimal image quality (50% of patients). Of a total of 226 coronary artery segments, 222 (98%) were visualized free of motion artifact. In summary, DSCT constitutes a promising new concept for cardiac CT. High and heart rate independent temporal resolution permits imaging of the coronary arteries without motion artifacts in a substantially increased number of patients as compared to earlier scanner generations. Larger and appropriately designed studies will need to determine the method's accuracy for detection of coronary artery stenoses.

The present study investigated the threshold-dependent variability of coronary artery calcification (CAC) measurements and the potential to quantify CAC in contrast-enhanced multi-detector row-computed tomography (MDCT).We compared the mean CT attenuation of CAC to luminal contrast enhancement of the coronary arteries in 30 patients (n = 30) undergoing standard coronary contrast-enhanced spiral MDCT. The modified Agatston score [AS], calcified plaque volume [CV], and mineral mass [MM]) at four different thresholds (130, 200, 300, and 400 HU) were measured in 50 patients who underwent non-contrast-enhanced MDCT.Mean CT attenuation of CAC was similar to the attenuation of the contrast-enhanced coronary lumen (CAC 297.1 +/- 68.7 HU versus 295 +/- 65 HU (p0.0001), respectively). Above a threshold of 300 HU CAC measurements significantly varied to standard measurements obtained at a threshold of 130 HU (p0.0001). The threshold-dependent variation of MM measurements was significantly smaller than for AS and CV (130 HU versus 400 HU: 63, 75, and 81, respectively; p0.001). These differences resulted in a change of age and gender based percentile category for AS in 78% of subjects.We demonstrated that CAC measurements are threshold dependent with MM measurements having significantly less variation than AS or CV. Due to the similarity of mean CT attenuation of CAC and the contrast-enhanced coronary lumen accurate quantification of CAC may be difficult in standard coronary contrast-enhanced spiral MDCT.

To compare the measurement variability for coronary artery calcium (CAC) measurements using mineral mass compared with a modified Agatston score (AS) or volume score (VS) with multi-detector CT (MDCT) scanning, and to estimate the potential impact of these methods on the design of CAC progression studies.We studied 162 consecutive subjects (83 women, 79 men, mean age 51 +/- 11 years) from a general Caucasian community-based cohort (Framingham Heart Study) with duplicate runs of prospective electrocardiographically-triggered MDCT scanning. Each scan was independently evaluated for the presence of CAC by four experienced observers who determined a "modified" AS, VS and mineral mass.Of the 162 subjects, CAC was detected in both scans in 69 (42%) and no CAC was detected in either scan in 72 (45%). Calcium scores were low in the 21/162 subjects (12%) for whom CAC was present in one but not the other scan (modified AS20 in 20/21 subjects, mean AS 4.6 +/- 1.9). For all three quantification algorithms, the inter- and intraobserver correlation were excellent (r0.96). However, the mean interscan variability was significantly different between mineral mass, modified AS, and VS (coefficient of variation 26 +/- 19%, 41 +/- 28% and 34 +/- 25%, respectively; p0.04), with significantly smaller mean differences in pair-wise comparisons for mineral mass compared with modified AS (p0.002) or with VS (p0.03). The amount of CAC but not heart rate was an independent predictor of interscan variability (r = -0.638, -0.614 and -0.577 for AS, VS, and mineral mass, respectively; all p0.0001). The decreased interscan variability of mineral mass would allow a sample size reduction of 5.5% compared with modified AS for observational studies of CAC progression and for randomized clinical trials.There is significantly reduced interscan variability of CAC measurements with mineral mass compared with the modified AS or VS. However, the measurement variability of all quantification methods is predicted by the amount of CAC and is inversely correlated to the extent of partial volume artifacts. Moreover, the improvement of measurement reproducibility leads to a modest reduction in sample size for observational epidemiological studies or randomized clinical trials to assess the progression of CAC.

Purpose To investigate the ability of 16-slice multidetector-row computed tomography (MDCT) to visualize coronary artery bypass graft (CABG) patency and to detect bypass stenoses. Materials and methods Thirty-two patients with 94 grafts (20 mammary artery grafts, 74 venous grafts) were investigated by 16-slice MDCT using a scan protocol with 12×0.75mm slice collimation (pitch 0.3), 420ms rotation time and simultaneous electrocardiogram (ECG)-registration. One hundred milliliters iodinated contrast agent were injected with a delay according to the individually determined contrast agent transit time. Patients with heart rates above 60bpm received oral beta-blockade. Cross-sectional images with a slice width of 1.0mm (0.5mm increment) were reconstructed using an ECG-gated half-scan reconstruction or a multisegment reconstruction algorithm depending on the heart rate. Bypass grafts were evaluated concerning patency and presence of stenoses ≥50% diameter reduction on cross-sectional images, multiplanar reformations and maximum intensity projections by two independent observers. Results were compared to coronary bypass angiography. Results Sixteen-slice MDCT results were compared to those of invasive coronary angiography concerning absence or presence of bypass graft occlusion or relevant stenosis ≥50% lumen reduction. Coronary CT angiography (CTA) permitted detection of bypass occlusion with 100% sensitivity (28/28) and 98% specificity (64/65). Seventy-eight percent (observer 1) and 84% (observer 2) of all patent grafts were found to be evaluable concerning presence or absence of stenosis. In 34 of 40 (observer 1) and 38 of 43 (observer 2) bypass grafts, high-grade stenoses were correctly ruled out (specificity 85% versus 88%, sensitivity 80% and 82%). Yet, if all patients with either unevaluable grafts/graft anastomosis or relevant graft stenosis were excluded, only 8/32 patients (25%) had fully diagnostic "negative" graft-CTA. According to Kappa statistics, agreement between the observers was 1.0 and 0.93 concerning occlusion and relevant stenosis, respectively. Conclusion Sixteen-slice coronary CTA with sub-millimeter spatial resolution and premedication with oral beta-blockade permits non-invasive assessment of coronary artery bypass grafts with decreasing numbers of unevaluable graft segments. However, patient-based analysis reveals that only a relatively small number of patients ("negative" and completely evaluable graft-CTA) truly profits from noninvasive work-up and could be spared invasive angiography.

a b s t r a c t Introduction: The geometry of the aortic annulus and implanted transcatheter aortic valve prosthesis might influence valve function. We investigated the influence of valve type and aortic valve calcification on post-implant geometry of catheter-based aortic valve prostheses. Methods: Eighty consecutive patients with severe aortic valve stenosis (mean age 82 ± 6 years) underwent computed tomography before and after TAVI. Aortic annulus diameters were determined. Influence of prosthesis type and degree of aortic valve calcification on post-implant eccentricity were analysed. Results: Aortic annulus eccentricity was reduced in patients after TAVI (0.21 ± 0.06 vs. 0.08 ± 0.06, p < 0.0001). Post-TAVI eccentricity was significantly lower in 65 patients following implantation of a balloon-expandable prosthesis as compared to 15 patients who received a self-expanding prosthesis (0.06 ± 0.05 vs. 0.15 ± 0.07, p < 0.0001), even though the extent of aortic valve calcification was not dif- ferent. After TAVI, patients with a higher calcium amount retained a significantly higher eccentricity compared to patients with lower amounts of calcium. Conclusions: Patients undergoing TAVI with a balloon-expandable prosthesis show a more circular shape of the implanted prosthesis as compared to patients with a self-expanding prosthesis. Eccentricity of the deployed prosthesis is affected by the extent of aortic valve calcification. © 2015 Published by Elsevier Ireland Ltd.

Objectives Coronary computed tomography angiography (CTA) allows the detection of obstructive coronary artery disease. However, its ability to predict the hemodynamic significance of stenoses is limited. We assessed differences in plaque characteristics and contrast density difference between hemodynamically significant and non-significant stenoses, as defined by invasive fractional flow reserve (FFR). Methods Lesion characteristics of 59 consecutive patients (72 lesions) in whom invasive FFR was performed in at least one coronary artery with moderate to high-grade stenoses in coronary CTA were evaluated by two experienced readers. Coronary CTA data sets were acquired on a second-generation dual-source CT scanner using retrospectively ECG-gated spiral acquisition or prospectively ECG-triggered axial acquisition mode. Plaque volume and composition (non-calcified, calcified), remodeling index as well as contrast density difference (defined as the percentage decline in luminal CT attenuation/cross-sectional area over the lesion) were assessed using a semi-automatic software tool (Autoplaq). Additionally, the transluminal attenuation gradient (defined as the linear regression coefficient between intraluminal CT attenuation and length from the ostium) was determined. Differences in lesion characteristics between hemodynamically significant (invasively measured FFR ≤0.80) and non-significant lesions (FFR >0.80) were determined. Results Mean patient age was 64 ± 11 years with 44 males (75%). 21 out of 72 coronary artery lesions (29%) were hemodynamically significant according to invasive FFR. Mean invasive FFR was 0.66 ± 0.12 vs. 0.91 ± 0.05 for hemodynamically significant versus non-significant lesions. Hemodynamically significant lesions showed a significantly greater percentage of non-calcified plaque compared to non-hemodynamically relevant lesions (51.3 ± 15.3% vs. 43.6 ± 16.5%, p = 0.021). Contrast density difference was significantly increased in hemodynamically relevant lesions (26.0 ± 20.2% vs. 16.6 ± 10.9% for non-significant lesions; p = 0.013). At a threshold of ≥24%, the contrast density difference predicted hemodynamically significant lesions with a specificity of 75%, sensitivity of 33%, PPV of 35% and NPV of 73%. The transluminal attenuation gradient showed no significant difference between hemodynamically significant and non-significant lesions (−1.4 ± 1.4 HU/mm vs. −1.1 ± 1.3 HU/mm, p = n.s.). Conclusions Quantitative contrast density difference across coronary lesions in coronary CTA data sets may be applied as a non-invasive tool to identify hemodynamically significant stenoses.

An extensive number of protocols have been suggested to allow for functional diagnostics; however, no data is available about the minimal amount of contrast medium to achieve reliable imaging properties. None of the plethora of existing studies report a rational why the specific concentration was chosen.A total of 40 patients were included in this prospective, controlled study. They were divided up into four equal groups getting a different concentration (10%, 20%, 30% or 40%) of a second contrast medium bolus. Corresponding septal and right ventricular ROIs were compared. A visual score was established. Coronary attenuation was measured in the right and left coronary artery. Streak artifacts in the right atrium/ventricle were assessed.In the 10% contrast medium (CM) group only in 5/10 (50%) patients full septal delineation was reached. In all other groups full septal visualization was obtained. No group showed a relevant difference of mean density measured in HU units of the left ventricle or the coronary arteries. All study groups except of group 1 (10% CM) showed streak artifacts in the right atrium.The dual flow protocol with a minimum concentration of 20% improves septal visualization as basis for left ventricular functional assessment, however, does not allow for reliable right ventricular or atrial visualization. There is no significant difference between the different concentration protocols in terms of coronary attenuation.

Computed tomography angiography (CTA) is a well-accepted imaging modality to evaluate the supraaortic vessels. Initial reports have suggested that dual energy CTA (DE-CTA) can enhance diagnosis by creating bone-free data sets, which can be visualized in 3D, but a number of limitations of this technique have also been addressed. We sought to describe the performance of DE-CTA of the supraaortic vessels with a novel dual source CT system with special emphasis on image quality and post-processing related artifacts.Thirty-three patients underwent carotid CT angiography on a second generation dual source CT system. Simultaneous acquisitions of 100 and 140kV data sets in arterial phase were performed. Two examiners evaluated overall bone suppression with a 3-point scale (1=poor; 3=excellent) and image quality regarding integrity of the vessel lumen of different vessel segments (n=26) with a 5-point scale (1=poor; 5=excellent), CTA source data served as the reference.Excellent bone suppression could be achieved in the head and neck. Only minor bone remnants occurred, mean score for bone removal was 2.9. Mean score for vessel integrity was 4.3. Eight hundred fifty-seven vessel segments could be evaluated. Six hundred thirty-five segments (74%) showed no lumen alteration, 65 segments (7.6%) lumen alterations10%, 27 segments (3.1%) lumen alterations10% resulting in a total luminal reduction50%, 17 segments (2%) lumen alterations of more than 10% resulting in a total luminal reduction50%, and 113 segments (13.2%) showed a gap in the vessel course (100% total lumen reduction). Artificial gaps of the vessel lumen occurred in 28 vessel segments due to artifacts caused by dental hardware and in all but one (65) ophthalmic arteries.Excellent bone suppression could be achieved, DE imaging with 100 and 140kV lead to improved image quality and vessel integrity in the shoulder region than previously reported. The ophthalmic artery still cannot be adequately visualized.

Purpose Evaluation of a new protocol for Dual-source CT contrast-enhanced cardiac imaging for better visualization of right ventricle structures. Methods A total of 106 patients were included in this prospective, controlled study. The control group ( n =53) underwent our clinic's standard procedure for contrast-enhanced imaging of coronary arteries. The study group ( n =53) was imaged using a protocol with the dual flow injection protocol in which the saline chaser bolus contained 20% contrast media. The images were analyzed for mean density values using defined ROIs in the septum and both ventricles. In addition the data sets were semi-quantitatively evaluated for visual delineation between right ventricle and septum. To investigate whether this new protocol influenced the visualization of coronary arteries, mean density was also measured in the right and left coronary artery. Results The dual flow concept allows for a statistically significant better delineation of the septum in Dual-source cardiac computed tomography for both the quantitative and semi-quantitative analyses. Also, the dual flow concept allows for statistically relevant higher coronary attenuation. Conclusion Using a saline chaser containing 20% contrast medium improves septal delineation for functional ventricular analysis as well as unimpaired coronary visualization.

We explored quantitative parameters of image quality in consecutive patients undergoing 64-slice multi-detector computed tomography (MDCT) coronary angiography for clinical reasons. Forty-two patients (36 men, mean age 61 +/- 11 years, mean heart rate 63 +/- 10 bpm) underwent contrast-enhanced MDCT coronary angiography with a 64-slice scanner (Siemens Sensation 64, 64 mm x 0.6 mm collimation, 330 ms tube rotation, 850 mAs, 120 kV). Two independent observers measured the overall visualized vessel length and the length of the coronary arteries visualized without motion artifacts in curved multiplanar reformatted images. Contrast-to-noise ratio was measured in the proximal and distal segments of the coronary arteries. The mean length of visualized coronary arteries was: left main 12 +/- 6 mm, left anterior descending 149 +/- 25 mm, left circumflex 89 +/- 30 mm, and right coronary artery 161 +/- 38 mm. On average, 97 +/- 5% of the total visualized vessel length was depicted without motion artifacts (left main 100 +/- 0%, left anterior descending 97 +/- 6%, left circumflex 98 +/- 5%, and right coronary artery 95 +/- 6%). In 27 patients with a heart rateor = 65 bpm, 98 +/- 4% of the overall visualized vessel length was imaged without motion artifacts, whereas 96+/-6% of the overall visualized vessel length was imaged without motion artifacts in 15 patients with a heart rate65 bpm (p0.001). The mean contrast-to-noise ratio in all measured coronary arteries was 14.6 +/- 4.7 (proximal coronary segments: range 15.1 +/- 4.4 to 16.1 +/- 5.0, distal coronary segments: range 11.4 +/- 4.2 to 15.9 +/- 4.9). In conclusion, 64-slice MDCT permits reliable visualization of the coronary arteries with minimal motion artifacts and high CNR in consecutive patients referred for non-invasive MDCT coronary angiography. Low heart rate is an important prerequisite for excellent image quality.

Multi-detector computed tomography (MDCT) permits detection of coronary plaque. However, noise and blurring impair accuracy and precision of plaque measurements. The aim of the study was to evaluate MDCT post-processing based on non-linear image deblurring and edge-preserving noise suppression for measurements of plaque size. Contrast-enhanced MDCT coronary angiography was performed in four subjects (mean age 55 +/- 5 years, mean heart rate 54 +/- 5 bpm) using a 16-slice scanner (Siemens Sensation 16, collimation 16 x 0.75 mm, gantry rotation 420 ms, tube voltage 120 kV, tube current 550 mAs, 80 mL of contrast). Intravascular ultrasound (IVUS; 40 MHz probe) was performed in one vessel in each patient and served as a reference standard. MDCT vessel cross-sectional images (1 mm thickness) were created perpendicular to centerline and aligned with corresponding IVUS images. MDCT images were processed using a deblurring and edge-preserving noise suppression algorithm. Then, three independent blinded observers segmented lumen and outer vessel boundaries in each modality to obtain vessel cross-sectional area and wall area in the unprocessed MDCT cross-sections, post-processed MDCT cross-sections and corresponding IVUS. The wall area measurement difference for unprocessed and post-processed MDCT images relative to IVUS was 0.4 +/- 3.8 mm2 and -0.2 +/- 2.2 mm2 (p0.05), respectively. Similarly, Bland-Altman analysis of vessel cross-sectional area from unprocessed and post-processed MDCT images relative to IVUS showed a measurement difference of 1.0 +/- 4.4 and 0.6 +/- 4.8 mm2, respectively. In conclusion, MDCT permitted accurate in vivo measurement of wall area and vessel cross-sectional area as compared to IVUS. Post-processing to reduce blurring and noise reduced variability of wall area measurements and reduced measurement bias for both wall area and vessel cross-sectional area.

Sixteen-slice multi-detector computed tomography (MDCT) permits reliable noninvasive detection of significant coronary stenosis based on qualitative visual assessment. The purpose of this study was to determine the accuracy of MDCT to quantify the degree of coronary stenosis as compared to quantitative coronary angiography (QCA) using two different reconstruction methods.We studied 69 coronary artery lesions from 38 consecutive patients that underwent 16-slice MDCT as a part of research study, which enrolled consecutive subjects scheduled for clinically indicated invasive coronary angiography. Nine coronary artery lesions with motion artifacts, heavily calcified plaques or stents were excluded from the analysis. The degree of stenosis was calculated by two independent readers non-blinded to the location of the stenosis, but blinded to the results of the QCA. MDCT luminal diameters were measured in cross-sectional multi-planar reformatted (CS-MPR) images created perpendicular to the centerline of the vessel and in 5 mm thin-slab maximum intensity projections (MIP) parallel to the long axis of the vessel. Both MDCT methods were compared against QCA.The mean degree of stenosis as measured by MDCT was closely correlated to QCA for both methods (CS-MPR versus QCA: 61 +/- 23% versus 64 +/- 29%; r2 = 0.83, p0.001 and MIP versus QCA: 64 +/- 22% versus 64 +/- 29%; r2 = 0.84, p0.001 for MIP. Bland-Altman analysis demonstrated a negative bias of the degree of stenosis of -2.8 +/- 12% using CS-MPR and a minimally positive bias of 0.6 +/- 12% for MIP. In stratified analysis for lesion severity (mild, 0-40%; moderate, 41-70% or severe,70%) the agreement between both CS-MPR and MIP was high when compared to QCA (kappa = 0.74 and 0.71, respectively).Multi-detector spiral CT permits accurate quantitative assessment of the degree of coronary stenosis in selected data sets of sufficient quality using both cross-sectional and longitudinal vessel reconstructions.