[Clinical evaluation of intracoronary in-stent stenosis by electron-beam CT single flow mode study]

To investigate the diagnostic accuracy and clinical value of electron-beam CT (EBCT) single flow mode study (EBCTSF) in combination with EBCT coronary angiography (EBCTCA) and three dimensional reconstruction using medial axis reformation (MAR) for diagnosis of coronary in-stent stenosis.

Electrocardiogram-gated EBCT single coronary scanning (without and with contrast medium) was performed in 25 consecutive coronary heart disease (CHD) patients during a short breathhold. EBCTSF was then performed at the level nearly distal to stent. Three-dimensional coronary images were reformed using MAR. EBCT findings were compared with that of conventional coronary angiography (CAG).

Thirty-five intracoronary stents were implanted in thirty-one diseased vessel segments. EBCTSF procedure was unsuccessful in 2 patients (successful rate was 92.0%, 23/25). There was a significant decrease in flow peak value (Dp), increased value (Deltad) and area under curve (A), and a significant increase in prolonged peak time (Td) in stenosed stents compared to normal stents (P < 0.05). EBCTCA was successful for all patients. Seven stenosed stents (5 in left anterior descending branch and 2 in right coronary) were correctly evaluated with EBCT. Compared with CAG, EBCTSF in combination with EBCTCA images and MAR reconstruction images had a diagnostic sensitivity of 85.0% (6/7) and a specificity of 92.9% (26/28) for detecting significant in-stent stenosis (> 50% lumen diameter). Positive and negative predictive value were 75.0% (6/8) and 96.5% (26/27) respectively. Compared with EBCT cross-section images alone, or cross-section images and three-dimensional images, the diagnostic accuracy increased from 80.0% and 88.6% to 91.4% (32/35).

Noninvasive EBCTSF can be used to quantitatively analyze coronary flow characteristics. This technique, used in combination with EBCTCA and three dimensional reconstruction using MAR, seems to be an effective imaging modality in identifying coronary in-stent stenosis. For stent-implanted patients with atypical and nonischemic chest pain after coronary intervention, the above-mentioned technique is of important value for evaluating therapeutic effect and follow-up results.