Multidetector computed tomography angiography of the celiac trunk and hepatic arterial system: normal anatomy and main variants

Abstract Although digital angiography remains as the gold standard for imaging the celiac arterial trunk and hepatic arteries, multidetector computed tomography in association with digital images processing by software resources represents a useful tool particularly attractive for its non invasiveness. Knowledge of normal anatomy as well as of its variations is helpful in images interpretation and to address surgical planning on a case-by-case basis. The present essay illustrates several types of anatomical variations of celiac trunk, hepatic artery and its main branches, by means of digitally reconstructed computed tomography images, correlating their prevalence in the population with surgical implications.

Left ventricular thrombus attenuation characterization in cardiac computed tomography angiography

BACKGROUND: Because of their similar visual appearance, differentiation of left ventricular thrombotic material and myocardial wall can be difficult in contrast-enhanced coronary computed tomography (CT) angiography. OBJECTIVE: We identified typical thrombi attenuation of left ventricular thrombi with the use of CT measurement. METHODS: Over a time period of 6 years; we retrospectively identified 31 patients who showed a left ventricular thrombus in CT angiography datasets. Patients underwent routine contrast cardiac CT to investigate coronary artery disease. CT attenuation of each thrombus was assessed in the 4-chamber view. CT densities were also determined in the ascending aorta, left ventricle, and myocardial wall both in the mid-septal and mid-lateral segments. The mean CT attenuation of thrombi and the difference between attenuation in thrombi, left ventricular cavity, and myocardial wall were determined. The ratio of attenuation values in thrombus versus aorta and myocardium versus aorta were also determined. RESULTS: Mean (+/- SD) CT attenuation of all left ventricular thrombi in 31 patients was 43.2 +/- 15.3 HU (range, 25-80 HU). Mean CT densities of septal and lateral myocardial wall were 102.9 +/- 23.1 HU (range, 63-155 HU) and 99.3 +/- 28.7 HU (range, 72-191 HU), respectively, and were thus significantly higher than the CT attenuation of thrombi (P < 0.001). A threshold of 65 HU yielded a sensitivity, specificity, and positive and negative predictive values of 94%, 97%, 94%, and 97%, respectively, to differentiate thrombus from the myocardial wall. The mean ratio between CT attenuation of thrombus and CT attenuation within the ascending aorta was 0.11 +/- 0.05 (range, 0.04-0.23), which was significantly lower compared with the mean ratio between CT attenuation of the myocardial wall and the CT attenuation within the ascending aorta. CONCLUSION: CT attenuation within left ventricular thrombi was significantly lower than myocardial attenuation in CT angiography datasets. Assessment of CT attenuation may contribute to the differentiation of thrombi. (C) 2012 Society of Cardiovascular Computed Tomography. All rights reserved.

Postmortem whole-body computed tomography angiography visualizing vascular rupture in a case of fatal car crash

In addition to the increasingly significant role of multislice computed tomography in forensic pathology, the performance of whole-body computed tomography angiography provides outstanding results. In this case, we were able to detect multiple injuries of the parenchymal organs in the upper abdomen as well as lesions of the brain parenchyma and vasculature of the neck. The radiologic findings showed complete concordance with the autopsy and even supplemented the autopsy findings in areas that are difficult to access via a manual dissection (such as the vasculature of the neck). This case shows how minimally invasive computed tomography angiography can serve as an invaluable adjunct to the classic autopsy procedure.

Computed tomography angiography (CTA) to prove circulatory arrest for the diagnosis of brain death in the context of organ transplantation

For the determination of brain death (BD) in potential organ donors, confirmatory tests that show cessation of cerebral circulation are used in many countries. Conventional angiography is considered the golden standard among these ancillary examinations. In recent years other angiographic techniques such as CT angiography (CTA) have been increasingly employed to establish the diagnosis of BD. We report our experience with CTA in this setting.

Meta-analysis: diagnostic performance of low-radiation-dose coronary computed tomography angiography

A new radiation dose-saving technique for noninvasive coronary artery imaging with computed tomography (CT) is available.

Image quality in low-dose coronary computed tomography angiography with a new high-definition CT scanner

A new generation of high definition computed tomography (HDCT) 64-slice devices complemented by a new iterative image reconstruction algorithm-adaptive statistical iterative reconstruction, offer substantially higher resolution compared to standard definition CT (SDCT) scanners. As high resolution confers higher noise we have compared image quality and radiation dose of coronary computed tomography angiography (CCTA) from HDCT versus SDCT. Consecutive patients (n = 93) underwent HDCT, and were compared to 93 patients who had previously undergone CCTA with SDCT matched for heart rate (HR), HR variability and body mass index (BMI). Tube voltage and current were adapted to the patient's BMI, using identical protocols in both groups. The image quality of all CCTA scans was evaluated by two independent readers in all coronary segments using a 4-point scale (1, excellent image quality; 2, blurring of the vessel wall; 3, image with artefacts but evaluative; 4, non-evaluative). Effective radiation dose was calculated from DLP multiplied by a conversion factor (0.014 mSv/mGy × cm). The mean image quality score from HDCT versus SDCT was comparable (2.02 ± 0.68 vs. 2.00 ± 0.76). Mean effective radiation dose did not significantly differ between HDCT (1.7 ± 0.6 mSv, range 1.0-3.7 mSv) and SDCT (1.9 ± 0.8 mSv, range 0.8-5.5 mSv; P = n.s.). HDCT scanners allow low-dose 64-slice CCTA scanning with higher resolution than SDCT but maintained image quality and equally low radiation dose. Whether this will translate into higher accuracy of HDCT for CAD detection remains to be evaluated.

Effect of X-ray tube parameters, iodine concentration, and patient size on image quality in pulmonary computed tomography angiography: a chest-phantom-study

OBJECTIVES: The aim of this phantom study was to evaluate the contrast-to-noise ratio (CNR) in pulmonary computed tomography (CT)-angiography for 300 and 400 mg iodine/mL contrast media using variable x-ray tube parameters and patient sizes. We also analyzed the possible strategies of dose reduction in patients with different sizes. MATERIALS AND METHODS: The segmental pulmonary arteries were simulated by plastic tubes filled with 1:30 diluted solutions of 300 and 400 mg iodine/mL contrast media in a chest phantom mimicking thick, intermediate, and thin patients. Volume scanning was done with a CT scanner at 80, 100, 120, and 140 kVp. Tube current-time products (mAs) varied between 50 and 120% of the optimal value given by the built-in automatic dose optimization protocol. Attenuation values and CNR for both contrast media were evaluated and compared with the volume CT dose index (CTDI(vol)). Figure of merit, calculated as CNR/CTDIvol, was used to quantify image quality improvement per exposure risk to the patient. RESULTS: Attenuation of iodinated contrast media increased both with decreasing tube voltage and patient size. A CTDIvol reduction by 44% was achieved in the thin phantom with the use of 80 instead of 140 kVp without deterioration of CNR. Figure of merit correlated with kVp in the thin phantom (r = -0.897 to -0.999; P < 0.05) but not in the intermediate and thick phantoms (P = 0.09-0.71), reflecting a decreasing benefit of tube voltage reduction on image quality as the thickness of the phantom increased. Compared with the 300 mg iodine/mL concentration, the same CNR for 400 mg iodine/mL contrast medium was achieved at a lower CTDIvol by 18 to 40%, depending on phantom size and applied tube voltage. CONCLUSIONS: Low kVp protocols for pulmonary embolism are potentially advantageous especially in thin and, to a lesser extent, in intermediate patients. Thin patients profit from low voltage protocols preserving a good CNR at a lower exposure. The use of 80 kVp in obese patients may be problematic because of the limitation of the tube current available, reduced CNR, and high skin dose. The high CNR of the 400 mg iodine/mL contrast medium together with lower tube energy and/or current can be used for exposure reduction.

Adequacy of an early arterial phase low-volume contrast protocol in 64-detector computed tomography angiography for aortoiliac aneurysms

PURPOSE: This retrospective study was conducted to determine whether a low-volume contrast medium protocol provides sufficient enhancement for 64-detector computed tomography angiography (CTA) in patients with aortoiliac aneurysms. METHODS: Evaluated were 45 consecutive patients (6 women; mean age, 72 +/- 6 years) who were referred for aortoiliac computed tomography angiography between October 2005 and January 2007. Group A (22 patients; creatinine clearance, 64.2 +/- 8.1 mL/min) received 50 mL of the contrast agent. Group B (23 patients; creatinine clearance, 89.4 +/- 7.3 mL/min) received 100 mL of the contrast agent. The injection rate was 3.5 mL/s, followed by 30 mL of saline at 3.5 mL/s. Studies were performed on the same 64-detector computed tomography scanner using a real-time bolus-tracking technique. Quantitative analysis was performed by determination of mean vascular attenuation at 10 regions of interest from the suprarenal aorta to the common femoral artery by one reader blinded to type and amount of contrast agent and compared using the Student t test. Image quality according to a 4-point scale was assessed in consensus by two readers blinded to type and amount of contrast medium and compared using the Mann-Whitney test. Multivariable adjustments were performed using ordinal regression analysis. RESULTS: Mean total attenuation did not differ significantly between both groups (196.5 +/- 33.0 Hounsfield unit [HU] in group A and 203.1 +/- 44.2 HU in group B; P = .57 by univariate and P > .05 by multivariable analysis). Accordingly, attenuation at each region of interest was not significantly different (P > .35). Image quality was excellent or good in all patients. No significant differences in visual assessment were found comparing both contrast medium protocols (P > .05 by univariate and by multivariable analysis). CONCLUSIONS: Aortoiliac aneurysm imaging can be performed with substantially reduced amounts of contrast medium using 64-detector computed tomography angiography technology.

Patient exposure and image quality of low-dose pulmonary computed tomography angiography: comparison of 100- and 80-kVp protocols

OBJECTIVE: Measures to reduce radiation exposure and injected iodine mass are becoming more important with the widespread and often repetitive use of pulmonary CT angiography (CTA) in patients with suspected pulmonary embolism. In this retrospective study, we analyzed the capability of 2 low-kilovoltage CTA-protocols to achieve these goals. MATERIALS AND METHODS: Ninety patients weighing less than 100 kg were examined by a pulmonary CTA protocol using either 100 kVp (group A) or 80 kVp (group B). Volume and flow rate of contrast medium were reduced in group B (75 mL at 3 mL/s) compared with group A (100 mL at 4 mL/s). Attenuation was measured in the central and peripheral pulmonary arteries, and the contrast-to-noise ratios (CNR) were calculated. Entrance skin dose was estimated by measuring the surface dose in an ovoid-cylindrical polymethyl methacrylate chest phantom with 2 various dimensions corresponding to the range of chest diameters in our patients. Quantitative image parameters, estimated effective dose, and skin dose in both groups were compared by the t test. Arterial enhancement, noise, and overall quality were independently assessed by 3 radiologists, and results were compared between the groups using nonparametric tests. RESULTS: Mean attenuation in the pulmonary arteries in group B (427.6 +/- 116 HU) was significantly higher than in group A (342.1 +/- 87.7 HU; P < 0.001), whereas CNR showed no difference (group A, 20.6 +/- 7.3 and group B, 22.2 +/- 7.1; P = 0.302). Effective dose was lower by more than 40% with 80 kVp (1.68 +/- 0.23 mSv) compared with 100 kVp (2.87 +/- 0.88 mSv) (P < 0.001). Surface dose was significantly lower at 80 kVp compared with 100 kVp at both phantom dimensions (2.75 vs. 3.22 mGy; P = 0.027 and 2.22 vs. 2.73 mGy; P = 0.005, respectively). Image quality did not differ significantly between the groups (P = 0.151). CONCLUSIONS: Using 80 kVp in pulmonary CTA permits reduced patient exposure by 40% and CM volume by 25% compared with 100 kVp without deterioration of image quality in patients weighing less than 100 kg.

True four-dimensional analysis of thoracic aortic displacement and distension using model-based segmentation of computed tomography angiography.

Previous analyses of aortic displacement and distension using computed tomography angiography (CTA) were performed on double-oblique multi-planar reformations and did not consider through-plane motion. The aim of this study was to overcome this limitation by using a novel computational approach for the assessment of thoracic aortic displacement and distension in their true four-dimensional extent. Vessel segmentation with landmark tracking was executed on CTA of 24 patients without evidence of aortic disease. Distension magnitudes and maximum displacement vectors (MDV) including their direction were analyzed at 5 aortic locations: left coronary artery (COR), mid-ascending aorta (ASC), brachiocephalic trunk (BCT), left subclavian artery (LSA), descending aorta (DES). Distension was highest for COR (2.3 ± 1.2 mm) and BCT (1.7 ± 1.1 mm) compared with ASC, LSA, and DES (p < 0.005). MDV decreased from COR to LSA (p < 0.005) and was highest for COR (6.2 ± 2.0 mm) and ASC (3.8 ± 1.9 mm). Displacement was directed towards left and anterior at COR and ASC. Craniocaudal displacement at COR and ASC was 1.3 ± 0.8 and 0.3 ± 0.3 mm. At BCT, LSA, and DES no predominant displacement direction was observable. Vessel displacement and wall distension are highest in the ascending aorta, and ascending aortic displacement is primarily directed towards left and anterior. Craniocaudal displacement remains low even close to the left cardiac ventricle.

Accuracy of computed tomography angiography in the detection of pulmonary embolism in patients with high body weight

BACKGROUND The accuracy of CT pulmonary angiography (CTPA) in detecting or excluding pulmonary embolism has not yet been assessed in patients with high body weight (BW). METHODS This retrospective study involved CTPAs of 114 patients weighing 75-99 kg and those of 123 consecutive patients weighing 100-150 kg. Three independent blinded radiologists analyzed all examinations in randomized order. Readers' data on pulmonary emboli were compared with a composite reference standard, comprising clinical probability, reference CTPA result, additional imaging when performed and 90-day follow-up. Results in both BW groups and in two body mass index (BMI) groups (BMI <30 kg/m(2) and BMI ≥ 30 kg/m(2), i.e., non-obese and obese patients) were compared. RESULTS The prevalence of pulmonary embolism was not significantly different in the BW groups (P=1.0). The reference CTPA result was positive in 23 of 114 patients in the 75-99 kg group and in 25 of 123 patients in the ≥ 100 kg group, respectively (odds ratio, 0.991; 95% confidence interval, 0.501 to 1.957; P=1.0). No pulmonary embolism-related death or venous thromboembolism occurred during follow-up. The mean accuracy of three readers was 91.5% in the 75-99 kg group and 89.9% in the ≥ 100 kg group (odds ratio, 1.207; 95% confidence interval, 0.451 to 3.255; P=0.495), and 89.9% in non-obese patients and 91.2% in obese patients (odds ratio, 0.853; 95% confidence interval, 0.317 to 2.319; P=0.816). CONCLUSION The diagnostic accuracy of CTPA in patients weighing 75-99 kg or 100-150 kg proved not to be significantly different.

Evaluation of subclinical atherosclerosis by computed tomography coronary angiography and its association with risk factors in familial hypercholesterolemia

Background: Increasing age and cholesterol levels, male gender, and family history of early coronary heart disease (CHD) are associated with early onset of CHD in familial hypercholesterolemia (FH). Objective: Assess subclinical atherosclerosis by computed tomography coronary angiography (CTCA) and its association with clinical and laboratorial parameters in asymptomatic FH subjects. Methods: 102 FH subjects (36% male, 45 +/- 13 years, LDL-c 280 +/- 54 mg/dL) and 35 controls (40% male, 46 +/- 12 years, LDL-c 103 +/- 18 mg/dL) were submitted to CTCA. Plaques were divided into calcified, mixed and non-calcified; luminal stenosis was characterized as >50% obstruction. Results: FH had a greater atherosclerotic burden represented by higher number of patients with: plaques (48% vs. 14%, p = 0.0005), stenosis (19% vs. 3%, p = 0.015), segments with plaques (2.05 +/- 2.85 vs. 0.43 +/- 1.33, p = 0.0016) and calcium scores (55 perpendicular to 129 vs. 38 perpendicular to 140, p = 0.0028). After multivariate analysis, determinants of plaque presence were increasing age (OR = 2.06, for age change of 10 years, CI95%: 1.38-3.07, p < 0.001) and total cholesterol (OR = 1.86, for cholesterol change by 1 standard deviation, CI95%: 1.09-3.15, p = 0.027). Coronary calcium score was associated with the presence of stenosis (OR = 1.54; CI95%: 1.27-1.86, p < 0.001, for doubling the calcium score). Male gender was directly associated with the presence of non-calcified plaques (OR: 15.45, CI95% 1.72-138.23, p = 0.014) and inversely with calcified plaques (OR = 0.21, CI95%: 0.05-0.84, p = 0.027). Family history of early CHD was associated with the presence of mixed plaques (OR = 4.90, CI95%: 1.32-18.21, p = 0.018). Conclusions: Patients with FH had an increased burden of coronary atherosclerosis by CTCA. The burden of atherosclerosis and individual plaque subtypes differed with the presence of other associated risk factors, with age and cholesterol being most important. A coronary calcium score of zero ruled out obstructive disease in this higher risk population. (C) 2010 Elsevier Ireland Ltd. All rights reserved.

Relation between visceral fat and coronary artery disease evaluated by multidetector computed tomography

Visceral abdominal fat has been associated to cardiovascular risk factors and coronary artery disease (CAD). Computed tomography (CT) coronary angiography is an emerging technology allowing detection of both obstructive and nonobstructive CAD adding information to clinical risk strati. cation. The aim of this study was to evaluate the association between CAD and adiposity measurements assessed clinically and by CT. We prospectively evaluated 125 consecutive subjects (57% men, age 56.0 +/- 12 years) referred to perform CT angiography. Clinical and laboratory variables were determined and CT angiography and abdominal CT were performed in a 64-slice scanner. CAD was defined as any plaque calcified or not detected by CT angiography. Visceral and subcutaneous adiposity areas were determined at different intervertebral levels. CT angiography detected CAD in 70 (56%) subjects, and no association was found with usual anthropometric adiposity measurements (waist and hip circumferences and body mass index). Otherwise, CT visceral fat areas (VFA) were significantly related to CAD. VFA T12-L1 values >= 145 cm(2) had an odds ratio of 2.85 (95% CI 1.30-6.26) and VFA L4-L5 >= 150 cm(2) had a 2.87-fold (95% CI 1.31-6.30) CAD risk. The multivariate analysis determined age and VFA T12-L1 as the only independent variables associated to CAD. Visceral fat assessed by CT is an independent marker of CAD determined by CT angiography. (C) 2009 Elsevier Ireland Ltd. All rights reserved.

Dipyridamole stress myocardial perfusion by computed tomography in patients with left bundle branch block

Abstract Background: Functional tests have limited accuracy for identifying myocardial ischemia in patients with left bundle branch block (LBBB). Objective: To assess the diagnostic accuracy of dipyridamole-stress myocardial computed tomography perfusion (CTP) by 320-detector CT in patients with LBBB using invasive quantitative coronary angiography (QCA) (stenosis ≥ 70%) as reference; to investigate the advantage of adding CTP to coronary computed tomography angiography (CTA) and compare the results with those of single photon emission computed tomography (SPECT) myocardial perfusion scintigraphy. Methods: Thirty patients with LBBB who had undergone SPECT for the investigation of coronary artery disease were referred for stress tomography. Independent examiners performed per-patient and per-coronary territory assessments. All patients gave written informed consent to participate in the study that was approved by the institution’s ethics committee. Results: The patients’ mean age was 62 ± 10 years. The mean dose of radiation for the tomography protocol was 9.3 ± 4.6 mSv. With regard to CTP, the per-patient values for sensitivity, specificity, positive and negative predictive values, and accuracy were 86%, 81%, 80%, 87%, and 83%, respectively (p = 0.001). The per-territory values were 63%, 86%, 65%, 84%, and 79%, respectively (p < 0.001). In both analyses, the addition of CTP to CTA achieved higher diagnostic accuracy for detecting myocardial ischemia than SPECT (p < 0.001). Conclusion: The use of the stress tomography protocol is feasible and has good diagnostic accuracy for assessing myocardial ischemia in patients with LBBB.