Infarct size determined by emission computed tomography using 99mTc-PYP: effect of coronary thrombolysis

Emission computed tomography with 99mTc-PYP was used to estimate infarct size in 38 patients with documented acute myocardial infarction. In the present study, the effect of thrombolysis with Urokinase on infarct size and on left ventricular function was assessed. Fourteen patients with acute myocardial infarction who underwent intracoronary thrombolysis within six hours after the onset of symptoms, and 24 patients who underwent conventional therapy were the subjects of this study. Infarct size was measured by drawing a region of interest around the myocardial pyrophosphate uptake for each tomographic slice. The boundary was then defined as 65% of the maximal count within the region of interest as determined by phantom volume studies. The total number of voxels was obtained by adding those in all slices and multiplying the sum by the voxel volume (0.205 ml per one voxel) to determine the infarct volume. Measurement of the 99mTc-PYP uptake on the tomographic image revealed an average infarct size of 100.1 +/- 36.0 ml (ranged 45 to 198). The calculated infarct volume correlated significantly with sigma CPK (p less than 0.01) and with left ventricular ejection fraction (p less than 0.01), but not with the peak CPK. In patients with acute inferior myocardial infarction, the mean infarct volume was 78.4 +/- 29.1 ml in the coronary thrombolysis group, and 105.1 +/- 33.7 ml in the conventional bypass graft treatment group (p less than 0.05). We concluded that successful intracoronary thrombolysis may reduce infarct size. ECT imaging with 99mTc-PYP to determine infarct size may be clinically applicable in patients with acute myocardial infarction.     

A computed tomography-based coronary lesion score to predict acute coronary syndrome among patients with acute chest pain and significant coronary stenosis on coronary computed tomographic angiogram

We tested the hypothesis that morphologic lesion assessment helps detect acute coronary syndrome (ACS) during index hospitalization in patients with acute chest pain and significant stenosis on coronary computed tomographic angiogram (CTA). Patients who presented to an emergency department with chest pain but no objective signs of myocardial ischemia (nondiagnostic electrocardiogram and negative initial biomarkers) underwent CT angiography. CTA was analyzed for degree and length of stenosis, plaque area and volume, remodeling index, CT attenuation of plaque, and spotty calcium in all patients with significant stenosis (>50% in diameter) on CTA. ACS during index hospitalization was determined by a panel of 2 physicians blinded to results of CT angiography. For lesion characteristics associated with ACS, we determined cutpoints optimized for diagnostic accuracy and created lesion scores. For each score, we determined the odds ratio (OR) and discriminatory capacity for the prediction of ACS. Of the overall population of 368 patients, 34 had significant stenosis and 21 of those had ACS. Scores A (remodeling index plus spotty calcium: OR 3.5, 95% confidence interval [CI] 1.2 to 10.1, area under curve [AUC] 0.734), B (remodeling index plus spotty calcium plus stenosis length: OR 4.6, 95% CI 1.6 to 13.7, AUC 0.824), and C (remodeling index plus spotty calcium plus stenosis length plus plaque volume <90 HU: OR 3.4, 95% CI 1.5 to 7.9, AUC 0.833) were significantly associated with ACS. In conclusion, in patients presenting with acute chest pain and stenosis on coronary CTA, a CT-based score incorporating morphologic characteristics of coronary lesions had a good discriminatory value for detection of ACS during index hospitalization.     

Tomographic plaque imaging with CT: technical considerations and capabilities

X-ray computed tomography (CT) is widely available in the world and has the ability to provide high-definition, thin-section imaging of any body part. In particular, CT over the past decade has been shown in numerous publications to allow for quantitation of coronary calcification, a proven surrogate for coronary artery atheromatous plaque. Electron beam tomography (EBT) and multidetector CT (MDCT) have been studied for these purposes. However, there are methodological differences between types of CT scanners and precision of calcium scoring is a function of their individual technical capabilities and limitations. These technical aspects are detailed here. Although MDCT has shown considerable improvements in recent years, EBT remains the clinical reference standard for noninvasive definition of atherosclerotic plaque.     

Coronary calcification, coronary disease risk factors, C-reactive protein, and atherosclerotic cardiovascular disease events: the St. Francis Heart Study

OBJECTIVES: The purpose of this study was to determine the prognostic accuracy of electron beam computed tomographic (CT) scanning of the coronary arteries and the relationship of coronary calcification to standard coronary disease risk factors and C-reactive protein (CRP) in the prediction of atherosclerotic cardiovascular disease (ASCVD) events in apparently healthy middle-age persons. BACKGROUND: As a screening test for coronary artery disease (CAD), electron beam CT scanning remains controversial. METHODS: In a prospective, population-based study, 4,903 asymptomatic persons age 50 to 70 years underwent electron beam CT scanning of the coronary arteries. RESULTS: At 4.3 years, follow-up was available in 4,613 participants (94%), and 119 had sustained at least one ASCVD event. Subjects with ASCVD events had higher baseline coronary calcium scores (median [interquartile range], Agatston method) than those without events: 384 (127, 800) versus 10 (0, 86) (p < 0.0001). For coronary calcium score threshold > or = 100 versus < 100, relative risk (95% confidence interval) was 9.6 (6.7 to 13.9) for all ASCVD events, 11.1 (7.3 to 16.7) for all CAD events, and 9.2 (4.9 to 17.3) for non-fatal myocardial infarction and death. The coronary calcium score predicted CAD events independently of standard risk factors and CRP (p = 0.004), was superior to the Framingham risk index in the prediction of events (area under the receiver-operating characteristic curve of 0.79 +/- 0.03 vs. 0.69 +/- 0.03, p = 0.0006), and enhanced stratification of those falling into the Framingham categories of low, intermediate, and high risk (p < 0.0001). CONCLUSIONS: The electron beam CT coronary calcium score predicts CAD events independent of standard risk factors, more accurately than standard risk factors and CRP, and refines Framingham risk stratification.     

Detection of coronary calcinosis with multislice spiral computerized tomography: an alternative to electron beam tomography

Electron-beam CT (EBT) has been used for years as the gold standard to quantify coronary artery calcification as a marker of coronary atherosclerosis. With the introduction of Multi-Slice Spiral CT (MSCT) technology in 1999, EBT is now challenged in the determination of coronary calcium. The aim of this study was to determine the diagnostic accuracy of MSCT for the assessment of coronary calcium, comparing this new technique to EBT. The study population consisted of 54 male patients, aged 58 +/- 11 years with suspected coronary artery disease. For EBT, 40 axial slices (scan time = 100 ms, slice thickness = 3 mm) were acquired in one breath-hold (35 +/- 5 s) using an ECG-trigger at 80% of the RR interval. For MSCT, simultaneous acquisition of four axial slices (scan time = 250 ms, slice thickness = 2.5 mm) allowed the entire heart (40 slices) to be covered in one breath-hold (25 +/- 5 s) using a prospective ECG-trigger (R--450 ms). For quantification of coronary calcium the Agatston and the Volumetric calcium score (VCS) were applied. Mean Agatston score of the study group was calculated as 88 +/- 111 (median = 45), which is between the 25th and 75th age-corrected percentile of asymptomatic patients. For the Volumetric calcium score, number of lesions, calcium mass and density, no statistical difference was found between both imaging modalities. Agatston and Volumetric calcium score were statistically different between and within both scans. Mean variability of VCS of the two methods was calculated as 24% and was in the range of repeated EBT studies (14-44.9%). The Multi-Slice Spiral CT scanner is equivalent to EBT for the determination of coronary calcium and can, therefore, be used for calcium screening. Using a prospective ECG-trigger technique, the application of the Agatston method delivers statistically different results in comparison to EBT. With the application of the spiral mode technique, retrospective ECG-trigger and thinner slice thickness, further improvement in variability can be expected, thus allowing for follow-up studies to determine progression or regression of atherosclerosis with high accuracy.     

Accuracy of 64-slice computed tomography for the preoperative detection of coronary artery disease in patients with chronic aortic regurgitation

We studied the diagnostic accuracy of 64-slice computed tomography for the diagnosis of significant coronary artery disease (CAD) compared with conventional coronary angiography (CA) in patients with chronic aortic regurgitation (AR) referred for elective aortic valve surgery. Fifty consecutive patients with chronic AR (38 men, mean age 54 +/- 14 years) scheduled for valve surgery underwent 64-slice computed tomographic (CT) coronary angiography and CA. Significant stenosis was defined as a luminal diameter decrease >50%. Mean heart rate during CT scanning was 65.5 +/- 7.4 beats/min. Mean Agatston score was 136 +/- 278 (range 0 to 1207); prevalence of significant CAD in the study population was 26% (13 of 50 patients). Thirteen of 742 segments (1.8%) in 3 patients were considered nondiagnostic with computed tomography because of motion artifacts (n = 9) or calcium (n = 4). In a patient-based analysis taking nonevaluative segments as falsely positive, sensitivity, specificity, and positive and negative predictive values of computed tomography were 100%, 95%, 87%, and 100%, respectively. Preoperative CA could have been avoided in 70% of patients (35 of 50), CA would have been performed to confirm the CT diagnosis in 26% (13 of 50), and unnecessary CA would have been performed in 4% (2 of 50) on the basis of false-positive CT ratings. In conclusion, 64-slice CT coronary angiography provides high diagnostic accuracy for diagnosing significant CAD in patients with chronic AR and may be used as a filter test before valve surgery to decide whether CA should be performed.     

Comparison of spiral and electron beam tomography in the evaluation of coronary calcification in asymptomatic persons

Recently, investigators have begun evaluating the ability of spiral computed tomography (sequence scan mode-SEQ) to measure coronary calcium. Electron Beam Tomography (EBT) and SEQ studies were performed in 10 women and 23 men, with a mean age of 54+/-9 years. The EBT study was performed within 4 weeks (mean 11+/-4 days) of the SEQ with no clinical interval event (MI, revascularization). The mean EBT calcium score (Agatston method) was 52.1+/-58.6, with a range of 0 to 175. The SEQ mean score was 60.1+/-71.1 (range 0 to 253). There were 7 persons with scores of 0 on both scans, and 9 persons with scores of zero on either EBT or spiral CT, but not both. Three persons had negative EBT studies where SEQ detected calcium, and 6 persons had EBT detected calcium and negative SEQ studies. The six patients with negative SEQ and positive EBT studies had a mean score of 47+/-25.7 (range 9 to 99). The remaining sixteen persons had coronary calcium detected on both studies. As compared to EBT, spiral CT had a sensitivity of 74% and a specificity of 70%, for an overall diagnostic accuracy of 73%. The positive and negative predictive values were 85 and 54%, respectively for SEQ in this study. The absolute difference in scores between the two tests was 29.1+/-28.5 (mean+/-S.D.). The inter-test variability, defined as the mean values of the differences between the calcium scores in the two scans on the same subjects divided by the mean of the two scores (Absolute Difference between tests/mean), was 84.5% in this study. In asymptomatic persons, spiral CT (using SEQ) provides a limited sensitivity (74%) and specificity (70%) for coronary calcium when compared to EBT. Caution should be used when evaluating the results of spiral CT coronary calcium especially in patients with relatively low calcium scores (<200).     

Diagnostic accuracy of noninvasive coronary angiography with 320-detector row computed tomography

We sought to evaluate the diagnostic accuracy of noninvasive coronary angiography using 320-detector row computed tomography, which provides 16-cm craniocaudal coverage in 350 ms and can image the entire coronary tree in a single heartbeat, representing a significant advance from previous-generation scanners. We evaluated 63 consecutive patients who underwent 320-detector row computed tomography and invasive coronary angiography for the investigation of suspected coronary artery disease. Patients with known coronary artery disease were excluded. Computed tomographic (CT) studies were assessed by 2 independent observers blinded to results of invasive coronary angiography. A single observer unaware of CT results assessed invasive coronary angiographic images quantitatively. All available coronary segments were included in the analysis, regardless of size or image quality. Lesions with >50% diameter stenoses were considered significant. Mean heart rate was 63 ± 7 beats/min, with 6 patients (10%) in atrial fibrillation during image acquisition. Thirty-three patients (52%) and 70 of 973 segments (7%) had significant coronary stenoses on invasive coronary angiogram. Seventeen segments (2%) were nondiagnostic on computed tomogram and were assumed to contain significant stenoses on an "intention-to-diagnose" analysis. Sensitivity, specificity, and positive and negative predictive values of computed tomography for detecting significant stenoses were 94%, 87%, 88%, and 93%, respectively, by patient (n = 63), 89%, 95%, 82%, and 97%, respectively, by artery (n = 260), and 87%, 97%, 73%, and 99%, respectively, by segment (n = 973). In conclusion, noninvasive 320-detector row CT coronary angiography provides high diagnostic accuracy across all coronary segments, regardless of size, cardiac rhythm, or image quality.     

无冠脉钙化征象的HIV感染者应用可卡因及使用酶抑制剂对冠脉狭窄的影响

目的 通过招募美国马里兰州巴尔第摩市年龄25~54岁的黑人青年有（无）HIV感染和（或）应用可卡因者使用酶抑制剂（PI）以及长期应用可卡因是否出现冠状动脉狭窄进行研究。方法 对在美国马里兰州巴尔第摩市招募的既往无心血管症状和传统心血管危险因素的109名年龄在25~54岁，有（无）HIV感染和（或）应用可卡因黑人青年，抽血检测血脂、血糖并应用64排多层CT对心脏及冠状动脉进行扫描，并采用Logistic回归模型对可能引起冠状动脉狭窄的因素进行分析。结果 109名被调查者的年龄为25~54岁，39名(35.8%)为女性；胆固醇水平为(4.01±0.88)mmol/L，CT检查见其中35例（32.1%）有冠状动脉钙化。74例CT检查未查见冠状动脉钙化，74例中有8例（11%）的被调查者冠状动脉狭窄>20%，其中5例（7%）冠状动脉狭窄≥50%；44例（59%）患者曾应用可卡因，应用过可卡因的患者中21例（28%）患者应用时间超过15年。109名被调查者，40例（36.7%）曾服用PI，在有和无冠状动脉斑块的被调查者中，血清高密度脂蛋白胆固醇（HDL）、吸食可卡因、年龄和服用PI有显著差异。应用Logistic回归模型分析发现使用PI和长期应用可卡因的时间是引起冠状动脉狭窄的独立相关因素。结论 在HIV感染患者中，长期应用可卡因及同时使用PI可能与非钙化的冠状动脉斑块独立相关。     

Non-invasive computed tomography angiography in the assessment of coronary stent patency: an Australian experience

Background: This study aimed to evaluate the feasibility and accuracy of 16‐slice computed tomography (CT) in the assessment of coronary stent patency. CT coronary angiography (CA) has a high degree of accuracy in the assessment of coronary artery disease compared with invasive selective CA. However, its accuracy in the evaluation of stent patency is not well investigated. Methods: We conducted a retrospective observational study of paired CT coronary angiography (CT–CA) and invasive fluoroscopic coronary angiography (FCA) in 37 patients with 47 coronary stents. CT–CA was carried out with an electrocardiogram‐gated 16‐slice CT (LightSpeed‐16, General Electric (GE), WI, USA). Two CT reporters, blinded to the FCA findings, assessed CT images for stent patency. A cardiologist blinded to CT findings reported FCA. FCA was regarded as the reference standard. Results: A CT–CA could assess 45 of 47 coronary stents (96%). Non‐assessable stents on CT–CA were due to motion artefacts and stent‐blooming effects. Of those 45 assessable stents, CT–CA correctly identified five out of seven stents with binary in‐stent restenosis (ISR) and 37 of 38 stents without binary ISR. The sensitivity and specificity of 16‐slice CT in the evaluation of coronary stents for binary ISR were 71% (95% confidence interval (CI) (29%, 96%)) and 97% (95%CI (86%, 100%)), respectively, exclusive of non‐assessable stents. The positive and negative predictive values of 16‐slice CT were 83% (95%CI (36%, 100%)) and 95% (95%CI (83%, 99%)), respectively. Conclusion: Sixteen‐slice CT has a low sensitivity, but very a high specificity when compared with FCA in the evaluation of coronary stents for ISR.     

Coronary artery quantitation and data management system for paired cineangiograms

A computerized system designed to optimize the quantitation of coronary vessels on 35 mm cineangiograms is described and validated. Because the system has two cine film digitizers, it processes paired coronary arteriograms for the evaluation of serial changes in coronary arteries. A database system was specifically designed for the storage of coronary artery quantitation data which resides on a file server in a local area network and may be accessed by multiple workstations. In radiographic phantom studies of nine contrast-filled lucite cylinders of known size, the overall accuracy and precision for the measured diameters were 0.069 mm and 0.066 mm respectively. Measurements of minimum diameter and percent diameter stenosis of 21 coronary lesions selected from 17 routine cineangiograms showed high degree of intraobserver and interobserver reproduclbllity.     

Coronary artery quantitation and data management system for paired cineangiograms.

A computerized system designed to optimize the quantitation of coronary vessels on 35 mm cineangiograms is described and validated. Because the system has two cine film digitizers, it processes paired coronary arteriograms for the evaluation of serial changes in coronary arteries. A database system was specifically designed for the storage of coronary artery quantitation data which resides on a file server in a local area network and may be accessed by multiple workstations. In radiographic phantom studies of nine contrast-filled lucite cylinders of known size, the overall accuracy and precision for the measured diameters were 0.069 mm and 0.066 mm respectively. Measurements of minimum diameter and percent diameter stenosis of 21 coronary lesions selected from 17 routine cineangiograms showed high degree of intraobserver and interobserver reproducibility.     

Prognostic value of coronary artery calcium and epicardial adipose tissue assessed by non-contrast cardiac computed tomography

Objective

Epicardial adipose tissue (EAT) accumulation is believed to be associated with development of coronary atherosclerosis. We investigated whether EAT volume as assessed by computed tomography (CT) has value in prediction of future cardiac events.

Methods

We studied 722 patients without proven coronary artery disease (CAD) who underwent non-contrast cardiac CT. EAT volume and coronary artery calcium (CAC) score were measured simultaneously. Patients were followed as to the occurrence of coronary events (cardiac death, nonfatal myocardial infarction, unstable angina requiring hospitalization, and late coronary revascularization ≥3 months after CT examination).

Results

During a 3.7 ± 1.7 years follow-up period, 37 coronary events were documented. Annual event rates increased across CAC score categories (0.3%, 1.0%, 2.4%, and 4.3%, in 0, 1–99, 100–399, and ≥400, respectively, p < 0.001); these were significantly higher in the higher EAT volume group (>median; 107.2 mL, 0.7% vs., 2.1%, adjusted hazard ratio; 2.65, p = 0.0090). Cox-proportional hazard analysis demonstrated that a combination of CAC score ≥ 100 and high EAT volume had a significantly higher event rate than CAC score < 100 and low EAT volume group (adjusted hazard ratio 11.6, p < 0.0001). Using Cox regression models, incremental prognostic values were identified by adding high EAT volume to clinical risks plus CAC score ≥ 100 (global χ², 6.7; p = 0.059).

Conclusion

We suggest that high EAT volume may be an independent predictor of future coronary events and increases predictive values of CAC score in patients without proven CAD.     

Imaging of coronary atherosclerosis using computed tomography: Current status and future directions

Computed tomography (CT) imaging of the coronary arteries, using either electron beam tomography (EBT) or multidetector row CT (MDCT), offers two possibilities to assess coronary atherosclerosis. Without injection of contrast agent, coronary calcifications can be detected and quantified. Their presence and extent correlates to the presence and amount of coronary atherosclerotic plaque. Prospective studies have demonstrated a high predictive value concerning the occurrence of coronary artery disease events and overall mortality. An emerging consensus seems to indicate that calcium imaging may be clinically useful in patients at intermediate risk for coronary artery disease events as determined based on traditional risk factors. In addition, recent studies have shown that after injection of contrast agent and using high-resolution scan protocols, the visualization of noncalcified plaque is also possible with CT techniques. However, data on the accuracy of plaque detection, quantification of plaque volume, and characterization of plaque (eg, lipid-rich vs fibrous) is currently limited, and the prognostic significance of noncalcifed coronary atherosclerotic plaque detection is unclear.     

Associations of Coffee,Tea, and Caffeine Intake with Coronary Artery Calcification and Cardiovascular Events

Background

Coffee and tea are 2 of the most commonly consumed beverages in the world. The association of coffee and tea intake with coronary artery calcium and major adverse cardiovascular events remains uncertain.

Multidetector row CT in assessment of coronary artery calcification on hemodialisis

Vascular calcification is a strong predictor of cardiovascular and all-cause mortality. Coronary artery calcification is more frequent, more extensive and progresses more rapidly in CKD than in general population. They are also considered a marker of coronary heart disease, with high prevalence and functional significance. It suggests that detection and surveillance may be worthwhile in general clinical practice. New non-invasive image techniques, like Multi-detector row CT, a type of spiral scanner, assess density and volume of calcification at multiple sites and allow quantitative scoring of vascular calcification using calcium scores analogous to those from electron-beam CT. We have assessed and quantified coronary artery calcification with 16 multidetector row CT in 44 patients on hemodialysis and their relationship with several cardiovascular risk factors. Coronary artery calcification prevalence was of 84 % with mean calcium score of 1580 +/- 2010 ( r 0-9844) with calcium score > 400 in 66% of patients. It was usually multiple, affecting more than two vessels in more than 50%. In all but one patient, left anterior descending artery was involved with higher calcium score level at right coronary artery. Advanced age, male, diabetes, smoking, more morbidity, cerebrovascular disease previous, and calcium-binders phosphate and analogous vitamin D treatment would seem to be associated with coronary artery calcification. Coronary artery calcification is very frequent and extensive, usually multiple and associated to modifiable risk factors in hemodialysis patients. Multi-detector-row CT seems an effective, suitable, readily applicable method to assess and quantify coronary artery calcification.     

Determinants of Transplant-Related Coronary Calcium Detected by Ultrafast Computed Tomography Scanning

Coronary calcium detected by ultrafast computed tomography (CT) has been shown to be a marker of coronary artery disease in heart transplant recipients. The objective of this study was to examine the possible determinants of coronary calcium after heart transplantation. Over a 15-month period, 102 consecutive cardiac transplant recipients (mean age 53 years, 88 men) underwent ultrafast CT scanning of the heart, in addition to coronary angiography, to determine coronary calcium score on their annual follow-up (a median of 4.6 years [range 63 days to 9.1 years] after transplant). The following data were also recorded: the recipient's sex and date of birth, date of transplantation, date of ultrafast computed tomography and coronary angiography; recipient pretransplant diagnosis, history of diabetes mellitus and systemic hypertension, fasting lipid profile, immunosuppression, number of rejection episodes, and donor organ ischemic time. Forty six patients (45.1%) had total calcium scores >0 and 41 (40.2%) had at least 1 major coronary with angiographic narrowing >24%. On univariate analysis, coronary calcium was significantly associated with dyslipoproteinemia, total cholesterol was >6.0 mmol/L (240 mg/dl), triglycerides were >3.0 mmol/L (265 mg/dl), and lipoprotein(a) >30 mg/dl; ≥25% angiographic disease was significantly associated with coronary calcium and dyslipoproteinemia. Logistic regression revealed that dyslipoproteinemia, systemic hypertension, and donor ischemic time were significant predictors of coronary calcium in transplanted hearts. We conclude that the prevalence of coronary calcium in heart transplant recipients is high and is related to recipient dyslipoproteinemia, systemic hypertension, and donor organ ischemic time.

Dyslipoprteinemia, systemic hypertension, and organ ischemic time are determinants of transplant-related coronary calcium.     

低血钙浓度与脑出血患者血肿体积的相关性

目的探讨低血钙浓度与脑出血患者血肿体积的关系。方法前瞻性连续性纳入2012年1月至2014年10月发病24 h内入住四川大学华西医院神经外科脑出血患者870例,完成血清钙浓度实验室检查和头部CT检查,并收集基线资料及实验室检查结果。根据实验室血钙浓度正常参考值,将患者分为低血钙组(2.1 mmol/L)193例,及正常血钙组(2.1~2.7 mmol/L)677例。采用Spearman相关性分析,分析血钙浓度与患者入院时血肿体积的相关性。结果 (1)低血钙组与正常血钙组比较,男性患者比例高[73.6%(142例)比66.0%(447例)],格拉斯哥昏迷评分中位数分值更低(9分比11分),血肿体积中位数更大(33.86 cm3比21.69 cm3),差异均有统计学意义(均P0.05)。(2)Spearman相关性分析显示,脑出血患者入院时低血钙水平与血肿体积呈弱负相关(r=-0.113,P0.01)。结论该研究提示脑出血患者入院时低血钙浓度男性居多、病情重及血肿体积大,并且低血钙浓度与血肿体积呈潜在负相关性。     

Cardiac computed tomography--evidence, limitations and clinical application

Coronary CT angiography and coronary calcium scoring offer a new approach to the diagnosis of coronary artery disease (CAD). They hold significant promise in improving patient outcomes, through identification of atherosclerosis and improved risk assessment. Coronary calcium scoring has proven predictive value concerning the occurrence of future cardiovascular events and outperforms current risk evaluation methods such as the Framingham Risk Score. Coronary CT angiography allows visualisation of the coronary artery lumen, detection of stenoses as well as visualisation of both calcified and non-calcified plaque. The accuracy of coronary CT angiography to detect obstructive coronary artery disease has been established by numerous trials. In particular the negative predictive value of the test approaches 100% in low and intermediate risk groups. Outcomes data demonstrate significant prognostic ability of coronary CT angiography. Modern techniques allow substantial reduction of dose values and radiation exposure of coronary CT angiography has significantly fallen. Coronary CT angiography can be reliably performed with doses similar to the level of annual background radiation, and less than one-third of a Tc Sestamibi scan. Coronary CT angiography has been approved for Medicare reimbursement for specific indications when performed by accredited providers. High quality examinations, experience and careful patient selection and preparation are required to ensure optimal results of coronary CT angiography, and to guide clinical decisions.     

Prevalence of subclinical atherosclerosis in asymptomatic diabetic patients by 64-slice computed tomography

OBJECTIVES: Patients with diabetes have a 2-fold to 4-fold higher risk of a cardiovascular event than nondiabetic patients. Thus there is a need to identify patients with diabetes who are at risk of cardiovascular events before the onset of symptoms. We studied the prevalence of coronary artery disease in asymptomatic diabetic patients compared with asymptomatic nondiabetic patients by 64-slice computed tomography (CT). METHODS: From 425 asymptomatic patients with coronary risk factors but without known coronary artery disease who underwent 64-slice CT, we identified 93 asymptomatic diabetic patients (diabetic group) and 93 age-matched and sex-matched asymptomatic nondiabetic patients. RESULTS: Clinical characteristics were not significantly different between the two groups. Total coronary calcium score was significantly higher in diabetic group than that in nondiabetic group (median 117 vs. 53.5, P<0.0001). No coronary calcium was detected in 30.0% of nondiabetic group compared with 15.1% of diabetic group (P=0.0022). Coronary calcium score more than 400 was detected in 9.7% of nondiabetic group compared with 36.6% of diabetic group (P<0.0001). Coronary plaques were found in 67.7% of nondiabetic group compared with 91.4% of diabetic group (P<0.0001). Multiple plaques were detected in 57.0 and 77.4% of patients in nondiabetic and diabetic group, respectively (P=0.0030). Significant coronary stenosis was found in 16.1% of nondiabetic group compared with 33.3% of diabetic group (P=0.0065). CONCLUSION: Our results show that the prevalence of coronary plaques detectable by 64-slice CT in asymptomatic diabetic patients is very high.