Effects of low-tube voltage coronary CT angiography on plaque and pericoronary fat assessment: intraindividual comparison.

OBJECTIVES: To investigate the effects of low tube voltage on coronary plaques and pericoronary fat assessment, and to compare their extent among various levels of low voltage. MATERIALS AND METHODS: Patients were recommended for high-pitch low-tube voltage coronary computed tomography angiography (CCTA), and they were included if they had poor image quality and were referred to a conventional CCTA. The patients were classified into a low-voltage group (with 70-kV, 80-kV, and 90-kV subgroups) and a conventional group (100/120 kV). Their total plaque and subcomponent volumes and pericoronary fat attenuation index (FAI) were measured. RESULTS: A total of 1002 image slices (from 65 patients and 74 plaques) were included, including 21, 31, 13, 4, and 61 patients in the 70-kV, 80-kV, 90-kV, 100-kV, and 120-kV groups respectively. The CT values of noncalcified plaques in the conventional and low-voltage groups were 54.6 ± 21.3 HU and 31.5 ± 22.6 HU, respectively (p < 0.05). Compared with the conventional group, the necrotic core and calcification volume were increased, and the fibrolipid volume, periplaque, and right coronary artery FAI were decreased in the low-voltage group and its subgroups (p < 0.001). The magnitude of changes in fibrous and calcification volumes increased in the 70-kV subgroup compared with that in the 90-kV subgroup (p < 0.05). CONCLUSION: Low tube voltages, particularly of 70 kV, have a significant effect on coronary plaque and FAI. The effect of low voltage on plaque composition is characterized by a polarization pattern, i.e., a decrease in fibrolipid (medium density) and an increase in necrotic core (low density) and calcification (high density). CLINICAL RELEVANCE STATEMENT: Our results highlight the comparability and repeatability of plaque and pericoronary fat assessments facilitated by the same or a similar tube voltage. It is necessary to carry out studies on the specificity threshold of low tube voltage at each level. KEY POINTS: • Low tube voltage had a significant effect on coronary plaque and pericoronary fat, particularly 70 kV. • The effect of low tube voltage on plaque composition shows the shift from medium-density mixed components to low- and high-density components. • It is necessary to correct the specificity threshold or attenuation difference for low tube voltage at each level.

Image quality and diagnostic value of ultra low-voltage, ultra low-contrast coronary CT angiography.

OBJECTIVE: To explore the image quality (IQ) and diagnostic value of 70 kVp turbo high-pitch coronary CT angiography (THP-CCTA) using automated tube voltage selection (ATVS) and 30 mL of low-concentration contrast agent. METHODS: Patients who underwent 70 kVp THP-CCTA using ATVS with 30 mL of contrast agent (group A) were prospectively enrolled, and those who underwent conventional CCTA (100/120 kVp, prospective sequential mode with 65-75 mL of contrast agent) (group B) were retrospectively selected for study. IQ was assessed subjectively on a 5-point scale, and diagnostic value was assessed based on invasive coronary angiography as the gold standard. Heart rate (HR), HR fluctuation (HRF), body mass index (BMI), effective radiation dose (ED), and iodine uptake (IU) were recorded. RESULTS: A total of 796 patients (398/398 in groups A/B) were included. Between-group differences in age, gender, BMI, HR, HRF, and IQ values were not significant. The ED/IU values were 0.3 ± 0.1 mSv/9.0 ± 0.0 g and 5.8 ± 1.8 mSv/22.9 ± 1.0 g in groups A and B, respectively (p < 0.01). The sensitivity, specificity, positive and negative predictive values, and accuracy of THP-CCTA for the diagnosis of ≥ 50% stenosis were 94.8%, 97.5%, 92.0%, 98.4%, and 96.9% respectively. The mean HR and coronary calcium score were independent predictors of diagnostic image quality, and the best cutoff values were 71.5 bpm and 444.1 respectively. CONCLUSION: This third-generation dual-source CT imaging modality, a 70-kVp THP-CCTA system using ATVS with 30 mL of low-concentration contrast agent, produces high-quality images with high diagnostic accuracy for significant stenosis, with ultra low ED and IU. This technique was most promising in individuals with an HR < 71.5 bpm and coronary calcium score < 444.1. KEY POINTS: • Turbo high-pitch CCTA using 70 kVp via automated tube voltage selection and 30 mL of low-concentration contrast agent is feasible. • This protocol provides high diagnostic accuracy for significant coronary stenosis and reduces radiation doses and iodine uptake significantly. • This protocol was most promising in individuals with an HR < 71.5 bpm and coronary calcium score < 444.1.

Accuracy of cardiac CT in evaluating severity of left atrial appendage spontaneous echo contrast: comparison with transesophageal echocardiography.

To investigate the capacity of biphasic cardiac CT (CCT) for qualitative and quantitative evaluation of different grades of left atrial appendage spontaneous echo contrast (LAASEC). The study included 267 inpatients with confirmed atrial fibrillation who underwent both CCT and transesophageal echocardiography (TEE). CT numbers for LAA, ascending aorta (AA), and left atrium (LA) were identified, and ROC curves for LAA, LAA/AA, and LAA/LA were plotted. With TEE as the standard, the sensitivity, specificity, PPV, NPV, and accuracy of CCT for LAASEC grade ≥ 1 were 60.3, 92.9, 92.4, 64.8, and 75.7%; and for grade ≥ 2 were 100.0, 84.4, 71.4, 100.0, and 88.8% respectively. The values of LAA, LAA/AA, and LAA/LA were significantly larger in LAASEC grade 0 versus 1 and in grade 1 versus 2, but were similar in grades 2 and 3 or in grades 3 and 4. The values of LAA/AA were larger in grade 2 versus 4. When the cutoff value for LAA/AA = 0.897, sensitivity, specificity, PPV, NPV, and accuracy of CCT for LAASEC grade ≥ 1 was 89.6, 83.2, 87.9, 85.5, and 86.9% and with a cutoff for LAA/AA of 0.524, the sensitivity, specificity, PPV, NPV, and accuracy for LAASEC grade ≥ 2 was 98.7, 92.7, 84.1, 99.4, and 94.4%. Although CCT showed limited diagnostic accuracy for grade 1 LAASEC, grade ≥ 2 LAASEC could be excluded when there was no LAA filling defect on first-phase CCT, and TEE can be avoided. CCT has an excellent accuracy in diagnosing LAASEC, and quantitative analysis (in particular LAA/AA) is superior.

Ascending aortic distensibility and target organ damage in primary hypertension without diabetes.

To investigate the relationship between ascending aortic distensibility (AAD) and hypertensive target organ damage (TOD) and its potential value in prediction. One hundred and sixty seven primary hypertension inpatients who underwent coronary CTA examination were enrolled into our study. Retrospective ECG-triggering scanning mode were applied and the images were reconstructed every 5% phase in the entire R-R interval. Maximum and minimum ascending aortic areas as well as the AAD value were calculated on the interested slice. AAD (P < 0.001) and brachial-ankle pulse wave velocity (baPWV, P < 0.05) were changed significantly as the deterioration of TOD. Multivariate logistic regression analysis between TOD and its possible influence factors indicated that AAD was the only independent risk factor for the presence and severity of TOD. One standard deviation decrease on AAD would increase the risk of TOD significantly: TOD1 (odds ratio 0.45, P < 0.05), TOD2 (odds ratio 0.23, P < 0.05), and TOD3 (odds ratio 0.01, P < 0.05). The odds ratio of TOD in the third tertile group was found 5.47 times higher than that in the second tertile group, and the second tertile group TOD odds ratio was 6.4 times higher than that in the first tertile group. Decline of AAD can be taken as the independent predict factor for TOD in primary hypertension patients, superior to baPWV method and other conventional predictors. Without additional contrast media consumption and radiation dose, AAD derived from coronary CTA may provide early detection for hypertensive TOD.

Ascending Aortic Elasticity and Related Risk Factors Study on Prehypertension Patients.

BACKGROUND: A new feature of coronary computed tomography angiography (CTA) is to estimate ascending aortic elasticity without additional cost, but its applicable benefit for prehypertension patients is still unclear. The aim of this study is to discuss the characteristic of ascending aortic elasticity for specific prehypertension patients and its risk factors. METHODS: Coronary CTA examinations of 398 participants were performed using a 128 slicer CT scanner. The differences of 3 ascending aortic elasticity related indices, including aortic distensibility (AD), aortic compliance (AC), and aortic stiffness (ASI), and anatomical measurements were analyzed among the normal, prehypertension, and primary hypertension groups. RESULTS: No difference was found for normalized minimum cross-sectional diameter and area for the ascending aorta between prehypertension and normal groups. AD, AC, and ASI were significantly different in 3 groups. Between prehypertension and normal groups, AD and AC were found much smaller but no difference were found for ASI; while between prehypertension and hypertension groups, significant differences were found in AD and ASI, and AC was found to a lesser extent. Risk factor study for prehypertension patients indicated that age and systolic pressure were the independent risk factors for AD decline. CONCLUSION: As a byproduct, coronary CTA can provide multiple aortic elasticity related indices for the prehypertension patients, without additional contrast media consumption and radiation dose. It is proofed that the early detection of ascending aortic elasticity index changes, especially for AD are essential for identifying the high-risk individuals in the prehypertension populations. CLINICAL TRIALS REGISTRATION: Our public trials registry number ChiCTR-RIC-15007482.

Use of Dual-Source Computed Tomography to Evaluate Renal Cortical Perfusion in Patients With Essential Hypertension Without Diabetes: Preliminary Results.

OBJECTIVES: To assess renal cortical perfusion parameter changes using computed tomography (CT) renal perfusion examination in patients with essential hypertension (EH), especially those with EH-related target organ damage (TOD), and to correlate renal perfusion parameters with clinical and laboratory data. METHODS: Consecutive patients with EH (without exclusion criteria) and healthy controls underwent 128-slice dual-source CT perfusion imaging. Quantitative perfusion analysis of renal cortex parameters [blood flow (BF), blood volume, time to peak, and mean transit time] was performed. RESULTS: Ninety-one participants (60 patients with EH, 31 healthy controls) underwent renal perfusion CT imaging, and 84 participants (92.3%) were eligible for perfusion analysis. The BF values were lower in patients with EH than that in controls. Blood flow was correlated with age (P < 0.01), duration of hypertension (P < 0.01), estimated glomerular filtration rate (eGFR; P < 0.01), pulse pressure (P < 0.05), and body mass index (BMI; P < 0.05). Duration of hypertension, eGFR, and BMI were independently associated with BF. No parameter differed between control subjects and those with EH but not. Blood flow was lower in patients with TOD than in control subjects (P < 0.01), but no other parameter differed. Blood flow was lower (P < 0.01) and mean transit time and time to peak were higher (P < 0.05) in the TOD than that in the non-TOD group. CONCLUSIONS: Essential hypertension, especially EH-related TOD, alters renal cortical perfusion parameters, especially BF. Four-dimensional spiral CT renal perfusion examination showed that duration of hypertension, eGFR, and BMI were independently associated with decreased BF.

Prospective evaluation of unsuspected pulmonary embolism on coronary computed tomographic angiography.

OBJECTIVE: This study aimed to analyze patients with unsuspected pulmonary embolism (PE) in coronary computed tomographic angiography (CCTA) and to draw some conclusions regarding their characteristics. METHODS: All patients suspected of coronary heart disease undergoing CCTA between May 2006 and December 2010 were prospectively analyzed. Patients with previous or suspected current PE were excluded. The CCTA images were reviewed, and the degree of contrast enhancement and the presence or absence of PE were recorded. Where PE was found, the level of the most proximal thrombus was identified. Patients' demographics were recorded. RESULTS: Of 7287 patients, 65 had unsuspected PE--an overall incidence of 0.9% (1.3% among inpatients and 0.3% among outpatients). Unsuspected PE was more common with increasing age, occurring in 0.4% of all patients younger than 60 years and 1.2% (52/4203) of those older than 60 years (P < 0.05). Of the 65 scans positive for disease, 43 (66.2%) were at the segmental or the subsegmental level. Patients with paroxysmal atrial fibrillation (AF) or AF history and cardiac insufficiency (3.2% and 4.1%) were more likely to have an unsuspected PE compared with those without (0.7%), and this was supported by the statistics. Deep vein thrombosis of the lower extremity was found in 8 (13.1%) of 61 patients with PE and in 12 (19.4%) of 62 patients with a D-dimer level of 500 ng/mL or higher. CONCLUSIONS: Unsuspected PE was found in 0.9% of all patients undergoing CCTA, and this kind of PE has its own characteristics compared with the typical PE from the literature. Radiologists should routinely analyze the pulmonary arteries in all patients undergoing CCTA, especially for older patients and the patients with AF or AF history and cardiac insufficiency.

[Value and limitations of multislice spiral CT in diagnosing coronary artery stenoses].

OBJECTIVE: To evaluate the value and limitations of multislice spiral CT in diagnosing coronary artery stenoses. METHODS: A total of 65 patients with known or suspected coronary artery disease were examined by multislice spiral CT (retrospectively ECG-gating; 0.5 s rotation; one-sector reconstruction algorithm; intravenous contrast agent) and the results were compared with quantitative coronary angiography. RESULTS: In the 889 coronary artery segments of 65 patients, 795 could be evaluated by CT (89.4%), 148 out of 167 coronary artery segments with significant stenoses (> or = 50% reduction of vessel diameter) were correctly detected by CT, 597 out of 628 coronary artery segments with normal or mild stenosis (< 50% reduction of vessel diameter) were correctly detected by CT. These values correspond to a sensitivity of 88.6%, specificity of 95.1%, positive predictive value of 82.7%, and negative predictive value of 96.9% for the detection of significant coronary artery stenosis by CT. Adding the 23 coronary artery segments with significant stenosis which could not be judged by CT, the sensitivity of CT for diagnosing coronary stenosis was 77.9%. In the 795 evaluable coronary artery segments, 78 out of 86 coronary artery segments with high-grade stenosis (> or = 75% reduction of vessel diameter) were correctly detected by CT, 692 of 709 coronary artery segments with normal or mild stenosed (< 75% reduction of vessel diameter) were correctly detected by CT. These values correspond to a sensitivity of 90.7%, specificity of 97.6%, positive predictive value of 82.1%, and negative predictive value of 98.9% for the detection of high-grade coronary artery segments stenosis by CT. Adding 13 coronary artery segments with high-grade stenosis which could not be judged by CT, the sensitivity was 78.8%. CONCLUSION: Multislice spiral CT permits the visualization of significant coronary artery stenosis with high accuracy in case of sufficient image quality.