Coronary computer tomographic angiography for preoperative risk stratification in patients undergoing liver transplantation.

The assessment of the cardiovascular risk profile in patients with end-stage liver disease is essential prior to liver transplantation (LT) as cardiovascular diseases are major causes of morbidity and mortality in the posttransplant course. The aim of this study was to evaluate the accuracy of a 64-slice coronary computed tomographic angiography (CTA) and coronary calcium scoring (CCS) to predict the postoperative cardiovascular risk of patients assessed for LT. In this single center, observational study we included 54 consecutive patients who were assessed for LT and consequently transplanted. Twenty-four patients (44%) presented with a high CCS above 300 and/or a significant stenosis (>50% percent narrowing due to stenotic plaques) and were further referred to coronary angiography. Three of these patients had a more than 70% LAD stenosis with subsequent angioplasty (n=1) or conservative therapy (n=2). The other patients showed only diffuse CAD without significant stenosis. The remaining 30 patients with normal CTA findings were listed for LT without further tests. None of the 54 patients developed cardiovascular events peri- and postoperatively. This study indicated that CTA combined with CCS is a useful non-invasive imaging technique for pre-LT assessment of coronary artery disease and safe tool in the risk assessment of peri- and postoperative cardiovascular events in patients undergoing LT.

Differences in coronary plaque composition by noninvasive computed tomography angiography in individuals with and without obstructive coronary artery disease.

BACKGROUND: Coronary CT angiography (CCTA) has emerged as a promising non-invasive tool to detect coronary artery disease (CAD) which provides additional information about atherosclerotic plaque composition. We aimed to assess whether differences in plaque composition and plaque burden exist across patients with more and <50% coronary stenosis. METHODS: 1060 patients (58±11 years, 43% females) with an intermediate risk of CAD referred for 64-slice CCTA were studied. Plaque characteristics and burden was analyzed on CCTA images on a per-segment basis (modified 16-segment AHA classification). Plaques types were classified as: calcified (type 1), mixed (predominantly calcified) (type 2), mixed (predominantly non-calcified) (type 3), and non-calcified (type 4). Plaque types in patients with more and <50% stenosis were compared. RESULTS: Overall 373 (35.2%) patients had normal coronaries without evidence of plaque. In the remaining 687 patients, 353 (33%) and 334 (31%) were found to have luminal narrowing of <50% and ≥50% in at-least one coronary artery segment, respectively. Those with ≥50% stenotic CAD demonstrated were more likely to have segments with mixed plaque subtype and less likely to be exclusively non-calcified (relative distribution of 58%, 22%, 10%, 11% for type 1-4 respectively) compared to those with <50% stenosis with (59%, 11%, 6% and 24%, respectively (p=0.006). In multivariable adjustment models, individuals with significant CAD were 5-fold more likely to have increased burden type 1 plaque (≥3 coronary segments) as compared to those with non-obstructive CAD (OR: 5.00, 95% CI: 1.05-23.78). The respective odds ratio (95% CI) for ≥3 coronary segments of type 2, 3 and 4 were 8.73 (3.01-25.23), 4.62 (2.99-0.22-1.55), respectively. CONCLUSIONS: Plaque composition is different according to severity of CAD with a higher mixed plaque and lesser non-calcified plaque burden among those patients with ≥50% stenotic CAD. These findings should stimulate further investigations to assess the prognostic value of coronary plaque subtypes according to their underlying composition.

Radiation dose reduction by using 100-kV tube voltage in cardiac 64-slice computed tomography: a comparative study.

OBJECTIVE: To evaluate a 100-kilovoltage (kV) tube voltage protocol regarding radiation dose and image quality, in comparison with the standard 120 kV setting in cardiac computed tomography angiography (CCTA). METHODS: 103 patients undergoing retrospective ECG-gated helical 64-slice CCTA were enrolled (100 kV group: 51 patients; 120 kV group: 52 patients). Inclusion criteria were: (1) BMI <28 kg/m(2); (2) weight <85 kg; (3) coronary calcium score <300 Agatston Units (AU). Quantitative image quality parameters were calculated [image noise, contrast-to-noise ratio (CNR), intracoronary CT-attenuation (HU)]. Each coronary artery segment (AHA/ACC-16-segments-classification) was evaluated for image quality on a 4-point scale. RESULTS: There was no statistical difference in age, gender, BMI and eff. tube current (mAs), and the use of ECG-tube current modulation (50.9% vs. 50% of patients) between both groups. 84.2% of patients in the 100 kV group had zero calcium score or less than 100 AU, the remaining had between 100 and 300 AU. The effective radiation dose was significantly lower in the 100 kV group with mean 7.1 mSv+/-2.4 (range, 3.4-11.1) compared to the 120 kV group with 13.4 mSv+/-5.2 (range, 6.3-22.7) (p<0.001) (dose reduction, 47%). In the 100 kV group, the use of ECG-dependent tube current modulation reduced the radiation exposure (by 44.8%) to 5.3 mSv+/-1.1 (range, 3.4-8.5 mSv) (p<0.001), the dose without was 9.6 mSv+/-1.1 (range, 6.3-11.1). Image noise in the coronary arteries was not different between both groups with 29.8 and 30.5 SD [HU], respectively. CNR in the 100 kV group was with 20.9+/-6.8 for the coronary arteries and with 19.9+/-5.9 for the aorta similar to the 120 kV group. Intraluminal CT-attenuation (HU) of the coronary arteries were higher in the 100 kV group (p<0.001). Image quality on 100 kV scans was excellent in 86.3%, good in 9.2%, acceptable in 3.1% of coronary segments; 1.4% were non-interpretable (in 1/4 due to increased image noise because of BMI >25 kg/m(2)). CONCLUSIONS: The 100 kV protocol significantly reduces the radiation dose in CCTA in patients with a low BMI <25 kg/m(2) and a low calcium load while maintaining high image quality and the advantages of helical scan algorithm.

Clinical relevance and scope of accidental extracoronary findings in coronary computed tomography angiography: a cardiac versus thoracic FOV study.

OBJECTIVE: To assess the spectrum and clinical relevance of extracoronary findings in coronary CT angiography (CCTA), and to compare a small (cardiac) field of view (FOV) to a large (thoracic) FOV setting. MATERIAL AND METHODS: 1084 consecutive patients (mean 57 years) with low-to-intermediate risk of coronary artery disease were enrolled. 542 CCTA scans were interpreted with small FOV (160-190mm(2)) encompassing the cardiac region. In another 542 CCTA (patients matched for age and gender), read-out of an additional full FOV (>320mm(2)) covering the thorax was performed. Clinical relevance of extracoronary findings was considered as either "significant" or "non-significant". "Significant" findings were subclassified as either score 1: findings necessitating immediate therapeutic actions, or score 2: findings with undoubted clinical or prognostic relevance, requiring clinical awareness, follow-up or further investigations (non-urgent). "Non-significant" findings were assigned to either score 3: findings not requiring follow-up or further tests, or as score 4: irrelevant incidental findings. RESULTS: Significantly more patients with extracoronary findings were identified by using a full FOV with 43.2% (234/542) compared to a small FOV with 33.6% (182/542) (p=0.001). Similarly, a higher total number of extracoronary findings (n=394) was found on full FOV compared to small FOV (n=250) (p<0.001). The detection rate of clinically significant findings was higher by using full FOV compared to small FOV (25.6% versus 15.4%) (p<0.001), out of those 2.2% versus 1.8% of findings required immediate actions (score 1), and 23.4% versus 13.6% (p=0.0001), respectively were of clinical relevance (non-urgent, score 2). The rate of malign findings was 0.2%, and of acute pulmonary embolism 0.1%. More lung pathologies were observed by using full FOV compared to small FOV (22% versus 7%) (p<0.0001), and the detection rate of intrapulmonary nodules increased by 2.1%. Prevalence of aortic valve calcification (n=72) was 13.3%, out of those 7% had less than 2cm(2) aortic valve orifice area. CONCLUSIONS: The interpretation of extracoronary findings on CCTA scans is mandatory given high prevalence of clinically significant findings by using a full "thoracic" FOV.

Left anterior descending coronary artery myocardial bridging by multislice computed tomography: correlation with clinical findings.

OBJECTIVE: To assess the relationship between left anterior descending (LAD) coronary artery myocardial bridging detected by 64-slice computed tomography (CT) and clinical findings. METHODS: 221 consecutive patients were examined with coronary 64-slice CT angiography. 21 patients with coronary stenosis >50% were excluded. The length, depth, and luminal narrowing of LAD myocardial bridges during systole and diastole were measured. CT findings were compared with the treadmill ECG-stress test, and clinical symptoms. RESULTS: Myocardial bridges of the LAD were found in 23% of patients (51/221) (length, 14.9+/-6.5mm; depth, 2.6+/-1.6mm). A significant difference was noted between the LAD luminal diameter before the intramyocardial course and intramyocardially, for both diastole and systole (p<0.001); with a higher diameter reduction of 27% for end-systole compared to end-diastole with 15% (p=0.006). Systolic LAD intramyocardial luminal narrowing >50% was found in 3/25 (8%). 30/51 (59%) of bridges were "deep" (>2mm myocardial depth), 21/51 (41%) were "superficial". The prevalence of a positive ECG-stress tests for the anterior myocardial region was significantly higher in patients with LAD myocardial bridges (34/50; 68%) compared to those without (28/144; 19.4%) (p<0.001). There was no difference between "superficial" and "deep" LAD myocardial bridges in regard to a positive treadmill ECG-stress test. Typical angina was rare with 6%. CONCLUSION: LAD myocardial bridges are common findings and can possibly explain a positive exercise ECG-stress test for anterior myocardial ischemia. Intramyocardial LAD segments show mild-to-moderate luminal narrowing at rest, which is higher during end-systolic phase.

Diagnostic accuracy of cardiac 64-slice computed tomography in detecting atrial thrombi. Comparative study with transesophageal echocardiography and cardiac surgery.

OBJECTIVES: Atrial thrombi are a potential source for cerebral and peripheral emboli. Objective of this study was to evaluate the diagnostic accuracy of 64-slice cardiac computed tomography (CT) for detection of atrial thrombi in comparison with transesophageal echocardiography (TEE) and cardiac surgery. MATERIAL AND METHODS: Sixty-four patients were examined with ECG-gated multidetector CT coronary or pulmonary vein angiography. All patients underwent TEE. Cardiac surgery was performed in 31 patients. The Hounsfield units (HU) of atrial lesions were measured. RESULTS: The diagnostic accuracy of 64-slice CT for the detection of atrial thrombi was 77%: sensitivity 100% (9/9), specificity 73% (40/55), positive predictive value (PPV) 38% (9/24), and negative predictive value (NPV) 100% (40/40). All 15 false positive (FP) findings by CT were located in the left atrial appendage (LAA). Four characteristic imaging features suggesting incomplete filling of the LAA were noted in FP: "hypostatic layering," 5/15 (33%); "flow phenomenon," 9/15 (60%); "HU-run-off," 8/15 (53%); higher intralesional HU in FP when compared with thrombi (153.8 HU +/- 71 vs. 46.6 HU +/- 10; P < 0.0001). The diagnostic accuracy of CT in detecting atrial thrombi improved significantly (P = 0.03) to 86% after defining "typical filling defects" as "flow phenomenon/>180 HU" (sensitivity 100%; specificity 84%; PPV 50%; NPV 100%). On receiver operating curve (ROC) analysis, a threshold of 60.7 HU showed a specificity of 100% and a sensitivity of 86.7% to distinguish between FP and thrombi. CONCLUSIONS: Cardiac ECG-gated 64-slice CT is accurate to exclude atrial thrombi, which can be applied eg, in patients before radiofrequency (RF) ablation. Left atrial appendage "filling defects" cause a high number of false positive findings, and there are radiologic features, which are helpful to differentiate them from true thrombi.

64-MDCT for diagnosis of aortic regurgitation in patients referred to CT coronary angiography.

OBJECTIVE: In clinical practice, 64-MDCT coronary angiography is increasingly being used for exclusion of coronary artery disease. Therefore, the purpose of this study was to evaluate whether aortic valve regurgitation can be diagnosed with 64-MDCT in comparison with transthoracic echocardiography. MATERIALS AND METHODS: Eighty-one consecutive patients were examined with ECG-gated CT coronary angiography using image reconstruction during end-diastole. The diagnostic criterion for aortic valve regurgitation by CT was an incomplete coadaptation of aortic valve leaflets, the central aortic regurgitation area (ARA), which was quantified. All patients underwent transthoracic echocardiography using semiquantitative grading of aortic valve regurgitation (i.e., mild, moderate, or severe). RESULTS: Of the 81 patients, 45 had aortic valve regurgitation by transthoracic echocardiography. The diagnostic accuracy of CT in detecting aortic valve regurgitation was as follows: sensitivity of 73% (33/45), specificity of 97% (35/36), positive predictive value (PPV) of 97% (33/34), and negative predictive value (NPV) of 74% (35/47). All 12 false-negative findings by CT were graded as mild regurgitation by transthoracic echocardiography and were caused by severe valve calcification (mean, 3,053.1 +/- 1,700 Agatston units; range, 937.7-5,632.5 Agatston units), bicuspid valves, or both. The sensitivity, specificity, PPV, and NPV of CT for the detection of moderate and severe aortic valve regurgitation were 95%, 100%, 100%, and 98%, respectively. Quantification of the ARA by CT (mean, 0.25 cm(2) +/- 0.34 cm(2) [SD]) was significantly correlated with the severity of aortic valve regurgitation by trans thoracic echocardiography (p < 0.001). CONCLUSION: Although 64-MDCT accurately detects moderate and severe aortic regurgitation in patients referred to coronary CT angiography, mild aortic regurgitation can be missed on 64-MDCT in the presence of severe valve calcification or bicuspid valves.

Is there a relation between non-calcifying coronary plaques and acute coronary syndromes? A retrospective study using multislice computed tomography.

OBJECTIVES: The purpose of this study was to assess whether different coronary plaque types as classified by multislice computed tomography (CT) are retrospectively correlated with acute coronary syndromes (ACS) in an unselected study population. METHODS: Sixty-three consecutive patients were examined with 16-slice CT coronary angiography. Coronary plaque types were classified as calcifying type 1, mixed (calcifying > non-calcifying) type 2, mixed (non-calcifying > calcifying) type 3, and non-calcifying type 4. Patients who had an ACS within 17 days were included. All patients underwent invasive coronary angiography. RESULTS: Fifty-eight patients (92%) had coronary plaques evaluated by CT: 18 type 1 (31%), 10 type 2 (17%), 16 type 3 (28%) and 14 type 4 (24%). The presence of a non-calcifying plaque component (types 2-4; 40 of 63 patients, 63%) was correlated with ACS (n = 15; 24%) (p < 0.001). Only type 3 was significantly correlated with ACS (p = 0.01), but plaque types 2 and 4 were not. The diagnostic accuracy of CT for detection of stenosis >50% in proximal segments was: sensitivity 98%, specificity 90%, negative predictive value 97%, positive predictive value 97% per patient. CONCLUSIONS: Mixed calcifying/non-calcifying plaques with a predominantly non-calcifying component (type 3) as classified by multislice CT are retrospectively correlated with ACS.