CT Coronary Angiography to Detect Coronary Artery Disease: low dose radiation in high risk individuals

Coronary atherosclerosis is a frequently encountered chronic disease of the arteries of the heart with very high mortality rates worldwide. It occurs predominantly in individuals with acquired risk factors and a genetic predisposition. Progression of atherosclerosis develops from early asymptomatic stages to advanced stages that may cause cardiac symptoms already starting in the 2nd or 3rd decades in life. In the last one and a half decades Computed Tomography Coronary Angiography (CTCA) has emerged as modality for imaging of the coronary arteries of the heart. A non-enhanced scan shows the total amount of coronary calcium; while a contrast-enhanced CT coronary angiography permits evaluation of narrowing of the vessel lumen as well as detection of both calcified and non-calcified atherosclerotic plaques. Radiation exposure for the patient is inherent to CT technique and the related risk of cancer is of major concern. The average radiation dose of a CTCA has decreased over the years from 20-30 mSv to <3 mSv which is below the dose of nuclear cardiac imaging techniques or conventional invasive coronary angiography Several studies acknowledge the high diagnostic accuracy of CTCA compared to the gold standard invasive coronary angiography. CTCA reliably detects, and especially rules out significant stenosis in stable patients with a low or intermediate pre-test probability of having coronary artery disease (CAD). Besides these direct diagnostic purposes, CTCA has incremental prognostic value over traditional risk factors (i.e. hypertension, diabetes mellitus, smoking, cholesterol blood values etc.) to predict adverse cardiac events in symptomatic patients. Nevertheless clinical guidelines only recommend CTCA as first choice diagnostic modality in a limited number of specified symptomatic patients. Further lowering of radiation dose and improvement of the diagnostic performance of CTCA will probably expand the number of appropriate indications for CTCA. This might even include screening of high risk individuals when supported by extended research in the future

豪雨による自然斜面の表層崩壊メカニズムおよび対策に関する研究

博士（工学）神戸大

Diagnostic performance of exercise bicycle testing and single-photon emission computed tomography: Comparison with 64-slice computed tomography coronary angiography

To conduct a comparison of the diagnostic performance of exercise bicycle testing and singlephoton emission computed tomography (SPECT) with computed tomography coronary angiography (CTCA) for the detection of obstructive coronary artery disease (CAD) in patients with stable angina. 376 symptomatic patients (254 men, 122 women, mean age 60.4 ± 10.0 years) referred for noninvasive stress testing (exercise bicycle test and/or SPECT) and invasive coronary angiography were included. All patients underwent additional 64-slice CTCA. The diagnostic performance of exercise bicycle testing (ST segment depression), SPECT (reversible perfusion defect) and CTCA (≥50% lumen diameter reduction) was presented as sensitivity, specificity, positive and negative predictive value (PPV and NPV) to detect or rule out obstructive CAD with quantitative coronary angiography as reference standard. Comparisons of exercise bicycle testing versus CTCA (n = 334), and SPECT versus CTCA (n = 61) were performed. The diagnostic performance of exercise bicycle testing was significantly (P value0.05): 77% (95% CI, 50-92) vs. 82% (95% CI, 56-95). We observed a PPV of 91% (95% CI, 77-97) vs. 93% (95% CI, 81-98); andNPVof 72% (95%, 46-89) vs. 93% (95%, 66-100). SPECT and CTCA yielded higher diagnostic performance compared to traditional exercise bicycle testing for the detection and rule out of obstructive CAD in patients with stable angina

Computed tomography coronary angiography accuracy in women and men at low to intermediate risk of coronary artery disease

Objectives To investigate the diagnostic accuracy of CT coronary angiography (CTCA) in women at low to intermediate pre-test probability of coronary artery disease (CAD) compared with men. Methods In this retrospective study we included symptomatic patients with low to intermediate risk who underwent both invasive coronary angiography and CTCA. Exclusion criteria were previous revascularisation or myocardial infarction. The pre-test probability of CAD was estimated using the Duke risk score. Thresholds of less than 30 % and 30-90 % were used for determining low and intermediate risk, respectively. The diagnostic accuracy of CTCA in detecting obstructive CAD (≥50 % lumen diameter narrowing) was calculated on patient level. P<0.05 was considered significant. Results A total of 570 patients (46 % women [262/570]) were included and stratified as low (women 73 % [80/109]) and intermediate risk (women 39 % [182/461]). Sensitivity, specificity, PPV and NPV were not significantly different in and between women and men at low and intermediate risk. For women vs. me

Small coronary calcifications are not detectable by 64-slice contrast enhanced computed tomography

Recently, small calcifications have been associated with unstable plaques. Plaque calcifications are both in intravascular ultrasound (IVUS) and multi-slice computed tomography (MSCT) easily recognized. However, smaller calcifications might be missed on MSCT due to its lower resolution. Because it is unknown to which extent calcifications can be detected with MSCT, we compared calcification detection on contrast enhanced MSCT with IVUS. The coronary arteries of patients with myocardial infarction or unstable angina were imaged by 64-slice MSCT angiography and IVUS. The IVUS and MSCT images were registered and the arteries were inspected on the presence of calcifications on both modalities independently. We measured the length and the maximum circumferential angle of each calcification on IVUS. In 31 arteries, we found 99 calcifications on IVUS, of which only 47 were also detected on MSCT. The calcifications missed on MSCT (n = 52) were significantly smaller in angle (27° ± 16° vs. 59° ± 31°) and length (1.4 ± 0.8 vs. 3.7 ± 2.2 mm) than those detected on MSCT. Calcifications could only be detected reliably on MSCT if they were larger than 2.1 mm in length or 36° in angle. Half of the calcifications seen on the IVUS images cannot be detected on contrast enhanced 64-slice MSCT angiography images because of their size. The limited resolution of MSCT is the main reason for missing small calcifications