Current utilization of cardiac computed tomography in mainland China: A national survey.

BACKGROUND: Surveys that describe the utilization of cardiac CT are available for the United States, Germany, and Taiwan, but not mainland China. OBJECTIVES: To analyze the clinical utilization of cardiac CT in mainland China. METHODS: A 25-item questionnaire was created and 240 tertiary hospitals were randomly selected to participate. Survey data were collected and confirmed by email as well as phone interviews. RESULTS: In total, 237 (99%) hospitals consented to this survey, but 85 were excluded because of lack of cardiac CT patient volume or advanced technology. Finally, 152 (64%) questionnaires were available for analysis. Median patient volume was 1,037 patients (range: 150-8,072) annually. The most common clinical indications for coronary CT angiography were exclusion of coronary artery disease in patients with low to intermediate pretest likelihood, asymptomatic individuals with cardiovascular risk factors, and follow-up after coronary bypass grafting. The median heart rate threshold for beta blocker administration was >70 beats/min; most centers (86%) used sublingual nitroglycerin. Prospectively ECG triggered acquisition was the predominant technique in 44% of hospitals. Most (59%) providers adjusted the tube current to the body mass, but few (16%) adjusted the contrast injection rate. Per case, the mean examination duration was 14.2 min; post-processing time 13.6 min; and reporting time 18.0 min. CONCLUSIONS: Cardiac CT is widely established in clinical practice in mainland China but there is a need for more uniform standards regarding performance and clinical utilization.

MESA: the NIH-sponsored study that validates atherosclerosis imaging for primary prevention.

Coronary artery calcium (CAC) score correlates strongly with the burden of atherosclerotic plaques in the coronary arteries. It is the strongest predictor of future coronary events in asymptomatic individuals, being stronger than all traditional risk factors combined. It is also a better predictor of future events than carotid intima-media thickness (CIMT) measurement for the prediction of coronary artery disease but slightly weaker than CIMT for the prediction of cerebrovascular events such as stroke. These findings have been validated by the Multi-Ethnic Study of Atherosclerosis (MESA), a prospective epidemiologic study sponsored by the National Institutes of Health (NIH) investigating the prevalence, correlates, and progression of atherosclerosis in an asymptomatic, ethnically diverse population. That is why the US national guidelines have recently elevated their recommendation levels to Class IIa for use of CAC and CIMT in risk stratification of the asymptomatic intermediate-risk population.

Comparison of coronary artery calcium scores between electron beam computed tomography and 64-multidetector computed tomographic scanner.

OBJECTIVE: Because almost all data currently available with coronary calcium scanning are from electron beam tomography (EBT), we assessed whether scores obtained with 64-multidetector computed tomography (CT; MDCT) are similar. We evaluated the interscan variation in coronary artery calcium (CAC), Agatston score (AS), and volume score (VS) between EBT and 64-MDCT (VCT; GE, Milwaukee, Wis). MATERIALS AND METHODS: One hundred two patients (mean age, 61.1 years; 27 women) underwent dual CAC scanning with both EBT and 64-MDCT. The AS and VS were measured with the Aquarius workstation (TeraRecon, Inc, San Mateo, Calif). The correlation coefficient, Bland-Altman analysis, interscanner variation, and agreement in AS and VS scores between EBT and 64-MDCT were computed. RESULTS: Interscan agreement for presence of CAC was 99%. Median values were 286 and 268 mm for AS and 243 and 213 mm for VS with EBT and 64-MDCT, respectively (P > 0.05). There was significant linear relationship between scores from the 2 scanners (R = 0.98 in AS and R = 0.99 in VS; P < 0.001). The interscanner variability between EBT and 64-MDCT was 20.9% and 17.6% in AS and VS, respectively (P = NS). Bland-Altman analysis demonstrated a mean difference in scores of 8.3% for AS and 7.8% by VS. When compared with EBT, there were larger and more prevalent motion artifacts (P < 0.001) and larger mean Hounsfield units using 64-MDCT (P < 0.001). CONCLUSIONS: At CAC scanning, 64-MDCT and EBT were comparable in AS and VS. The interscan variability between scanners is similar to interscan variability of 2 calcium scores done on the same equipment. However, heart rate control was achieved for this study for calcium scores. Whether these results are repeatable without heart rate control needs to be further assessed.

Reproducibility of coronary artery calcified plaque with cardiac 64-MDCT: the Multi-Ethnic Study of Atherosclerosis.

OBJECTIVE: The Multi-Ethnic Study of Atherosclerosis is a longitudinal study evaluating determinants of future cardiac events and progression of atherosclerosis. Emerging data are showing that coronary artery calcification (CAC) is a robust independent predictor of future cardiac events and that measurement of progression depends on reproducibility of the measure. Reproducibility previously was reported on baseline scans obtained with both electron-beam tomography (EBT) and MDCT. The aim of this study was to compare the interscan variability for both Agatston and volume scores derived with newer (16- and 64-MDCT) scanners with that derived with older scanners in the Multi-Ethnic Study of Atherosclerosis. SUBJECTS AND METHODS: The participants in this study were 4,054 persons who underwent dual scanning with EBT (n = 1,716), 4-MDCT (n = 370), 16-MDCT (n = 1,245), or 64-MDCT (n = 723). Agreement on the presence or absence of CAC was assessed with logistic regression models adjusted for age, sex, body mass index, and scanner type. Among participants with CAC, the log-transformed interscan difference was regressed on log-transformed amount of CAC, age, sex, and body mass index. RESULTS: The percentage agreement for the presence or absence of CAC was high and similar across scanner groups (EBT, 16-MDCT, and 64-MDCT). The greatest adjusted average absolute CAC differences between scans were found with the Aquilion 64 (24%; 95% CI, 20.9-27.6) and LightSpeed Pro 16 (19%; 95% CI, 17.4-21.0) scanners, both differences being significantly greater than with the EBT scanner (16%; 95% CI, 15.4-17.5) (p < 0.05). No differences were found between the EBT, Sensation 16, and Sensation 64 scanners. For volume score, the Aquilion 64 was the only scanner with significantly greater average absolute interscan differences than the EBT scanner (p < 0.001). Volume scoring resulted in lower rescan differences for all scanners. CONCLUSION: For CAC scoring, interscan variability with newer-generation MDCT scanners was similar to but not superior to that with the EBT scanner.

Multiphase contrast medium injection for optimization of computed tomographic coronary angiography.

RATIONALE AND OBJECTIVES: Electron beam angiography is a minimally invasive imaging technique. Adequate vascular opacification throughout the study remains a critical issue for image quality. We hypothesized that vascular image opacification and uniformity of vascular enhancement between slices can be improved using multiphase contrast medium injection protocols. MATERIALS AND METHODS: We enrolled 244 consecutive patients who were randomized to three different injection protocols: single-phase contrast medium injection (Group 1), dual-phase contrast medium injection with each phase at a different injection rate (Group 2), and a three-phase injection with two phases of contrast medium injection followed by a saline injection phase (Group 3). Parameters measured were aortic opacification based on Hounsfield units and uniformity of aortic enhancement at predetermined slices (locations from top [level 1] to base [level 60]). RESULTS: In Group 1, contrast opacification differed across seven predetermined locations (scan levels: 1st versus 60th, P < .05), demonstrating significant nonuniformity. In Group 2, there was more uniform vascular enhancement, with no significant differences between the first 50 slices (P > .05). In Group 3, there was greater uniformity of vascular enhancement and higher mean Hounsfield units value across all 60 images, from the aortic root to the base of the heart (P < .05). CONCLUSIONS: The three-phase injection protocol improved vascular opacification at the base of the heart, as well as uniformity of arterial enhancement throughout the study.