Comparative study on 16-slice CT coronary angiography vs conventional coronary angiography--a report of 38 cases

The clinical application of 16-slice CT coronary angiography (CTCA) and the impact of plaques differently characterized on assessing coronary artery stenosis were evaluated. Thirty-eight patients with coronary artery disease diagnosed by conventional coronary angiography (CAG) underwent 16-slice CTCA (collimation: 16x0.75 mm; rotation time: 420 msec; kernel: 35f; effective current: 500 mAs; tube voltage: 120 kV). The interval between CTCA and CAG was within one month. CTCA was evaluated by consensus of two independent experienced radiologists unknowing CAG findings. Original images, maximum intensity projections and multiplanar reconstructions were used to assess coronary artery stenosis. For a determined plaque an attenuation value > or = 130 HU was considered as calcified, and <130 HU noncalcified. The plaques were then classified into significant calcification (extensive calcification), medium calcification (small isolated calcification) and noncalcification. The diagnostic accuracy of 16-slice CTCA findings as well as to detect > or = 50% stenoses caused by plaques was evaluated respectively regarding CAG as the standard of reference. In comparison with CAG findings, the sensitivity, specificity, positive and negative predictive value derived from CTCA for mild stenosis (<50%) were 72.7%, 38.5%, 50%, 62.5%, respectively; for moderate stenosis (50%-75%) 82.4%, 72.7%, 70%, 84.2%, respectively; and for severe coronary stenosis (>75%) 85%, 90.5%, 81%, 92.7% respectively. With the increase of stenoses degree, the value of CTCA was greater. For the classification of the plaque calcification with > or = 50% stenosis CTCA attained the sensitivity, specificity, positive and negative predictive value for severe calcification 73.3%, 22.2%, 61.1% and 33.3%, respectively; for moderate calcification 70%, 55.6%, 63.6% and 62.5%, respectively; for noncalcification 93.8%, 85.7%, 93.8% and 85.7% respectively. CTCA was restricted in assessing coronary artery stenosis in the presence of calcification, but CTCA value was much improved in assessing non-calcified stenosis. It was concluded that 16-slice CTCA could provide useful information about coronary artery stenosis, especially for severe stenosis > or = 50%) and non-calcified plaque. Since CTCA is a noninvasive technique, it may be useful in screening coronary artery disease.