Eun Ju Chun

Coronary computed tomography angiography as a screening tool for the detection of occult coronary artery disease in asymptomatic individuals

OBJECTIVES The purpose of this study was to evaluate the prevalence of occult coronary artery disease (CAD) with coronary computed tomography angiography (CTA) to characterize plaque composition and to evaluate the potential of this new technology to impact risk stratification in asymptomatic middle-aged subjects. BACKGROUND There is a paucity of information regarding the role of CTA for the detection of occult CAD in asymptomatic individuals. METHODS We consecutively enrolled 1,000 middle-aged asymptomatic subjects (age 50 +/- 9 years, 63% men) who underwent CTA (64-slice multidetector row computed tomography) as part of a general health evaluation. RESULTS Atherosclerotic plaques were identified in 215 (22%, 2 +/- 1 segments/subject) individuals; 40 individuals (4%) had only noncalcified plaques. Fifty-two (5%) subjects had significant (>or=50%) diameter stenosis and 21 (2%) had severe (>or=75%) stenosis. Thirteen (25%) and 30 (58%) subjects with significant stenosis were classified into National Cholesterol Education Program low-risk and mild coronary calcification (coronary artery calcium scores <100), respectively. Midterm follow-up (17 +/- 2 months) revealed 15 cardiac events only in those with CAD on CTA: 1 unstable angina requiring hospital stay and 14 revascularization procedures. Most (87%) events occurred within 90 days of index CTA. CONCLUSIONS The prevalence of occult CAD in apparently healthy individuals was not negligible, although their midterm prognosis was good. CTA has a potential to provide a better insight about the occult CAD in this population. However, on the basis of our results and considering present radiation exposure data, we cannot recommend that CTA be used as a screening tool for this population at this point.

Radiation Dose Modulation Techniques in the Multidetector CT Era: From Basics to Practice

Radiation exposure to the patient has become a concern for the radiologist in the multidetector computed tomography (CT) era. With the introduction of faster multidetector CT scanners, various techniques have been developed to reduce the radiation dose to the patient; one method is automatic exposure control (AEC). AEC systems make use of different types of control, including patient-size AEC, z-axis AEC, rotational or angular AEC, or a combination of two or more of these types. AEC systems operate on the basis of several methods: standard deviation, noise index, reference milliamperage, and reference image. A clear understanding of how to use different AEC systems on different multidetector CT scanners will allow users to modulate radiation dose, reduce photon starvation artifacts, and maintain image quality throughout the body. Further development of AEC systems and their successful introduction into clinical practice will require user education and good communication between users and manufacturers.

Midterm Change of Descending Aortic False Lumen After Repair of Acute Type I Dissection

BACKGROUND Persistent false lumen in the descending aorta after repair of acute type I dissection adversely affects long-term prognosis. In this study, we investigated changes of the descending aortic false lumen during the midterm postoperative period. METHODS Postoperative computed tomographic (CT) images of 122 patients who underwent conventional ascending with or without arch replacement for acute type I dissection were reviewed. Patency and width of false lumen and maximal diameter of the aorta were compared between early and last follow-up images. Changes were analyzed separately in the thoracic and abdominal segments. RESULTS In early CT, thoracic false lumen was patent in 85 patients (69.7%), and abdominal false lumen was patent in 111 patients (91.0%). Among these, the false lumen remained patent after a mean interval of 33.6 months in 69 patients (81.1%) and 105 patients (94.6%), respectively. In 58 patients (47.5%), the descending aorta dilated by 1 cm or more. Dilatation occurred more frequently in the thoracic aorta and in patients with patent or wide false lumens, larger aortic diameter, Marfan syndrome, younger age, and male sex. Meanwhile, shrinkage of thoracic false lumen occurred in 36 patients (29.5%). Such shrinkage occurred in 23 of 24 patients (95.8%) who had thrombosed and narrow false lumens in the thoracic aorta. CONCLUSIONS Early postoperative characteristics of false lumen were helpful for predicting both dilation and regression. Our data show not only a high incidence of descending aortic dilatation after repair of acute type I dissection, but also shrinkage of thoracic false lumen in some patients. These findings can be used as control data for determining the benefit of more extensive or new surgical approaches.

Effects of Nitroglycerin on the Diagnostic Accuracy of Electrocardiogram-gated Coronary Computed Tomography Angiography

Objectives: To evaluate the effect of nitroglycerin on the diagnostic accuracy of electrocardiogram-gated coronary computed tomography (CT) angiography in patients with suspected coronary artery disease. Methods: Computed tomography angiography was performed on 76 patients using a 16-slice CT scanner. Forty-six patients received a sublingual nitroglycerin 1 minute before CT scanning (the NTG group), but the other 30 did not (the non-NTG group). No statistically significant differences were evident between these 2 groups in terms of clinical and demographic characteristics. Significant stenosis (≥50% diameter reduction) as determined by CT was evaluated according to patient-based and segment-based analyses, and results were compared with conventional coronary angiographic findings. In addition, segments of the coronary artery were reclassified by segment luminal size into proximal, mid, and distal segments, and the diagnostic accuracies of the NTG and non-NTG approaches were evaluated in these segments. Results: Differences in heart rate, and systolic and diastolic blood pressures before and after using nitroglycerin were 1.0 ± 2.4 beats per minute, −8.3 ± 14.4 mm Hg, and −4.6 ± 10.6 mm Hg, respectively. Sensitivity, specificity, and positive and negative predictive values in the NTG group were higher than in the non-NTG group by patient-based analysis (P = 0.25) and by segment-based analysis (P < 0.05). In addition, based on the luminal size of each segment, diagnostic accuracy in the NTG group was significantly higher for proximal segments than in the non-NTG group (96.7% vs 89.7%; P < 0.05). Conclusions: The use of nitroglycerin was found to be safe and to improve the diagnostic accuracy of coronary CT angiography for the evaluation of coronary artery disease.

Usefulness of 64-slice multidetector computed tomography as an initial diagnostic approach in patients with acute chest pain.

BACKGROUND Recently, multidetector computed tomography (MDCT) has been proposed as an accurate diagnostic tool to evaluate for coronary artery disease. However, the role of MDCT as part of the initial diagnostic for evaluating acute chest pain is less well established. METHODS We prospectively enrolled patients presenting with acute chest pain to the emergency department (ED) and risk stratified them based on the pretest probability for an acute coronary syndrome (ACS): (1) very low, (2) low, (3) intermediate, (4) high, and (5) very high or definite. After exclusion of very low and very high risk patients, 268 patients were randomized to either immediate 64-slice cardiac MDCT or a conventional diagnostic strategy. Number of admissions, ED and hospital length of stay (LOS), and major adverse cardiac events over 30 days of follow-up were compared between the strategies based on the pretest probability for ACS. RESULTS The number of patients ultimately diagnosed with an ACS did not differ between the 2 strategies. Emergency department LOS and total admissions were not different between strategies. Patients in the MDCT-based strategy had a decreased hospital LOS (P = .049) and fewer admissions deemed unnecessary (P = .007). Reductions in unnecessary admissions were more prominent in intermediate-risk patients (P = .015). None of the patients discharged from the ED in the MDCT-based strategy experienced major adverse cardiac events at follow-up. CONCLUSION Use of an MDCT-based strategy in the ED as part of the initial diagnostic approach for patients presenting with acute chest pain is safe and efficiently reduces avoidable admissions in patients with an intermediate pretest probability for ACS.

Vitamin D Inadequacy Is Associated with Significant Coronary Artery Stenosis in a Community-Based Elderly Cohort: The Korean Longitudinal Study on Health and Aging

CONTEXT Recent studies suggest an association between vitamin D activity and cardiometabolic risk. OBJECTIVE We investigated vitamin D status and its association with subclinical atherosclerosis in a population-based cohort study, the Korean Longitudinal Study on Health and Aging (KLoSHA). PARTICIPANTS Participants were 439 men and 561 women aged 65 yr or older who were recruited by random stratified sampling for KLoSHA. METHODS Anthropometric and biochemical parameters, the concentration of 25-hydroxyvitamin D (25-OHD), and intact PTH were measured. MAIN OUTCOME MEASURES We evaluated the coronary artery calcium score and stenosis using multidetector-row cardiac computed tomography, the intima-media thickness using carotid sonography, pulse wave velocity, and the ankle-brachial index. RESULTS Among the participants, 49.8, 44.2, and 6.0% had 25-OHD deficiency (<15 ng/ml), insufficiency (15-29.9 ng/ml), and adequacy (≥30 ng/ml), respectively. The frequency of coronary artery stenosis (>50%) differed between 25-OHD categories: 18.5, 12.9, and 1.9% in the 25-OHD-deficient, -insufficient, and -adequate groups, respectively (P < 0.05). After adjusting for cardiometabolic risks and intact PTH concentration, multivariate regression analysis showed that participants with a low 25-OHD concentration had a higher risk of significant coronary artery stenosis; the odds ratios were 2.08 for 25-OHD concentration of 15-29.9 ng/ml vs. at least 30 ng/ml and 3.12 for 25-OHD concentration below 15 ng/ml vs. at least 30 ng/ml (both P < 0.05). CONCLUSIONS The association between 25-OHD inadequacy and subclinical atherosclerosis underscores the clinical implications of vitamin D status. An intervention strategy to increase vitamin D level through vitamin D-fortified diet and adequate sun exposure may mitigate the consequences of vitamin D deficiency.

Detection of occult coronary artery disease in asymptomatic individuals with diabetes mellitus using non-invasive cardiac angiography

INTRODUCTION/OBJECTIVES Cardiovascular disease is the leading cause of death for individuals with diabetes mellitus. Controversy exists regarding the screening of asymptomatic diabetics for occult coronary artery disease (CAD). The purpose of this study is to describe the prevalence of occult CAD in a group of asymptomatic subjects with diabetes using non-invasive coronary angiography, as well as to investigate the predictive accuracy of current guidelines with regards to their recommended criteria for further cardiac diagnostic testing in this patient population. METHODS We prospectively enrolled 217 asymptomatic Korean outpatients with type 2 diabetes who had no prior history of CAD. All underwent non-invasive coronary angiography using a 64-slice multi-detector computed tomography scanner. RESULTS The mean age of the study participants was 59+/-8 years; 66% were men. Diabetes duration was 7+/-7 years, mean Framingham risk score was 13%, and mean hemoglobin A1C level was 7%. Of the 217 outpatients, 138 (64%) had occult CAD based on cardiac computed tomography angiography (CCTA) findings. Thirty-six (36/138; 26%) had a significant stenosis on CCTA. Nearly half of the individuals (62/138; 45%) had a combination of non-calcified and calcified plaques. Only 5 out of 217 (2%) individuals with significant stenosis would have been missed using the American Diabetes Association (ADA) criteria for further cardiac testing. CONCLUSION Almost two thirds of asymptomatic diabetics have occult CAD, including obstructive disease. Based on CCTA findings, the ADA criteria for further cardiac diagnostic testing would identify most individuals who have a significant coronary stenosis.

Association of traditional cardiovascular risk factors with coronary plaque sub-types assessed by 64-slice computed tomography angiography in a large cohort of asymptomatic subjects.

OBJECTIVE Although prior studies have shown that traditional cardiovascular (CV) risk factors are associated with the burden of coronary atherosclerosis, less is known about the relationship of risk factors with coronary plaque sub-types. Coronary computed tomography angiography (CCTA) allows an assessment of both, total disease burden and plaque characteristics. In this study, we investigate the relationship between traditional CV risk factors and the presence and extent of coronary plaque sub-types in a large group of asymptomatic individuals. METHODS The study population consisted of 1015 asymptomatic Korean subjects (53+/-10 years; 64% were males) free of known CV disease who underwent 64-slice CCTA as part of a health screening evaluation. We analyzed plaque characteristics on a per-segment basis according to the modified American Heart Association classification. Plaques in which calcified tissue occupied more than 50% of the plaque area were classified as calcified (CAP), <50% calcified area as mixed (MCAP), and plaques without any calcium as non-calcified (NCAP). RESULTS A total of 215 (21%) subjects had coronary plaque while 800 (79%) had no identifiable disease. Multivariate regression analysis demonstrated that increased age (per decade) and gender are the strongest predictors for the presence of any coronary plaque or the presence of at least one segment of CAP and MCAP (any plaque-age: OR 2.89; 95% CI 2.34, 3.56; male gender: OR 5.21; 95% CI 3.20, 8.49; CAP-age: OR 2.75; 95% CI 2.12, 3.58; male gender: 4.78; 95% CI 2.48, 9.23; MCAP-age: OR 2.62; 95% CI 2.02, 3.39; male gender: OR 4.15; 95% CI 2.17, 7.94). The strongest predictors for the presence of any NCAP were gender (OR 3.56; 95% CI 1.96-6.55) and diabetes mellitus (OR 2.87; 95% CI 1.63-5.08). When looking at the multivariate association between the presence of >/=2 coronary segments with a plaque sub-type and CV risk factors, male gender was the strongest predictor for CAP (OR 7.31; 95% CI 2.12, 25.20) and MCAP (OR 5.54; 95% CI 1.84, 16.68). Alternatively, smoking was the strongest predictor for the presence of >/=2 coronary segments with NCAP (OR 4.86; 95% CI 1.68, 14.07). Low-density lipoprotein cholesterol (LDL-C) was only a predictor for the presence and extent of mixed coronary plaque. CONCLUSION Age and gender are overall the strongest predictors of atherosclerosis as assessed by CCTA in this large asymptomatic Korean population and these two risk factors are not particularly associated with a specific coronary plaque sub-type. Smoking is a strong predictor of NCAP, which has been suggested by previous reports as a more vulnerable lesion. Whether a specific plaque sub-type is associated with a worse prognosis is yet to be determined by future prospective studies.

Impact of Coronary Computed Tomographic Angiography Results on Patient and Physician Behavior in a Low-Risk Population

BACKGROUND The impact of screening coronary computed tomographic angiography (CCTA) on physician and patient behavior is unclear. METHODS We studied asymptomatic patients from a health-screening program. Our study population comprised 1000 patients who underwent CCTA as part of a prior study and a matched control group of 1000 patients who did not. We assessed medication use, secondary test referrals, revascularizations, and cardiovascular events at 90 days and 18 months. RESULTS A total of 215 patients in the CCTA group had coronary atherosclerosis (CCTA positive). Medication use was increased in the CCTA-positive group compared with both the CCTA-negative (no atherosclerosis) and control groups at 90 days (statin use, 34% vs 5% vs 8%, respectively; aspirin use, 40% vs 5% vs 8%, respectively), and 18 months (statin use, 20% vs 3% vs 6%, respectively; aspirin use, 26% vs 3% vs 6%, respectively). After multivariable risk adjustment, the odds ratios for statin and aspirin use in the CCTA-positive group at 18 months were 3.3 (95% confidence interval [CI], 1.3-8.3) and 4.2 (95% CI, 1.8-9.6), respectively. At 90 days, in the total CCTA group vs controls, there were more secondary tests (55 [5%] vs 22 [2%]; P < .001) and revascularizations (13 [1%] vs 1 [0.1%]; P < .001). One cardiovascular event occurred in each group over 18 months. CONCLUSIONS An abnormal screening CCTA result was predictive of increased aspirin and statin use at 90 days and 18 months, although medication use lessened over time. Screening CCTA was associated with increased invasive testing, without any difference in events at 18 months. Screening CCTA should not be considered a justifiable test at this time.

Differentiation between malignancy and inflammation in pulmonary ground-glass nodules: The feasibility of integrated 18F-FDG PET/CT

BACKGROUND (18)F-FDG PET/CT has been used to differentiate malignant solid lung nodules from benign nodules. We assess the feasibility of integrated (18)F-FDG PET/CT for the differentiation of malignancy from inflammation manifested as ground-glass nodules (GGNs) on chest CT. METHODS A total of 68 GGNs in 45 patients (M:F=24:21; mean age, 61) fulfilled the following criteria: (a) nodules composed of >/=50% ground-glass opacity, (b) patients who underwent integrated PET/CT within 1 week following dedicated chest CT, (c) definitive diagnosis determined by pathological specimen or at least 9 months of follow-up, and (d) lesions >/=10mm in diameter. 36 malignant GGNs were pathologically proved as adenocarcinoma (n=20), bronchioloalveolar carcinoma (n=11), low-grade lymphoma (n=3), metastatic mucinous adenocarcinoma (n=1) and unknown low-grade malignancy (n=1). 32 inflammatory GGNs were confirmed as pneumonic infiltration as they had disappeared on follow-up CT and were associated with compatible clinical features (n=26) or as chronic inflammation with fibrosis by VATS biopsy (n=6). Using CT density histogram analysis, 14 were classified as pure GGNs and 54 as part-solid nodules. Integrated PET/CT was evaluated by measuring the maximum standardized uptake value (SUV) at the region of interest located at each lesion. The Mann-Whitney U test was performed to compare the SUV of malignancy and inflammation. The optimal cut-off value of SUV to differentiate malignancy from inflammation was determined using a receiver operating characteristic-based positive test. Sensitivity, specificity, accuracy, and positive predictive values (PPV) and negative predictive values (NPV) were calculated at the level of the optimal cut-off value. SUV showing 100% PPV for inflammatory GGNs was evaluated. RESULTS In part-solid nodules, the maximum SUV was significantly higher in inflammation (2.00+/-1.18; range, 0.48-5.60) than in malignancy (1.26+/-0.71; range, 0.32-2.6) (P=0.018). On the other hand, in pure GGNs, the maximum SUV of malignancy (0.64+/-0.19; range, 0.43-0.96) and inflammation (0.74+/-0.28; range, 0.32-1.00) showed no difference (P=0.37). Using the optimal cut-off value of SUV as 1.2 (P=0.01) sensitivity, specificity, accuracy, PPV and NPV in part-solid nodules were 62.1%, 80.0%, 70.4%, 78.3% and 64.5%, respectively. Six part-solid nodules, which showed a maximum SUV of higher than 2.6, were all inflammations. CONCLUSION The part-solid nodules with positive FDG-PET could be inflammatory nodules rather than malignant nodules. This is a quite paradoxical result when considering the basic knowledge that malignant pulmonary nodules have higher glucose metabolism.