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Spiral CT evaluation of coronary artery bypass graft patency
1Department of Radiology, New England Deaconess Hospital, Boston, MA 02215.
Insights
Spiral CT (SCT) provides detailed visualization of coronary artery bypass grafts. This imaging technique demonstrates high accuracy in assessing graft patency, comparable to traditional angiography.
Area of Science:
- Cardiovascular Imaging
- Radiology
Background:
- Conventional CT has limitations in visualizing coronary artery bypass grafts.
- Spiral CT (SCT) allows rapid, whole-heart imaging with contrast material.
Purpose of the Study:
- To evaluate the accuracy of contrast-enhanced Spiral CT (SCT) in assessing coronary artery bypass graft patency.
- To compare SCT findings with selective graft angiography.
Main Methods:
- 14 patients with 43 coronary artery bypass grafts underwent contrast-enhanced SCT.
- Timing of SCT was optimized using dynamic scanning for patient-specific transit times.
- SCT results were compared against selective graft angiography.
Main Results:
- SCT showed 85.7% sensitivity and 100% specificity for graft patency.
- Angiography demonstrated 96.4% sensitivity and 100% specificity.
- No significant difference in patency rates was found between SCT and angiography (McNemar test).
Conclusions:
- Contrast-enhanced SCT is a reliable method for assessing coronary artery bypass graft patency.
- Optimized timing using dynamic scanning is crucial for SCT accuracy.
- SCT offers a valuable alternative to angiography for bypass graft assessment.
Abstract:
Spiral CT (SCT) differs from conventional CT in that the entire heart can be rapidly imaged in the axial plane following the peripheral infusion of small quantities of contrast material. As contrast material travels through coronary artery bypass graft segments, good image detail is achieved, allowing visualization of entire coronary artery graft segments during a single injection. The patency of 43 coronary artery bypass grafts in 14 patients on contrast enhanced SCT, with timing tailored to patient-specific transit times, was compared with that obtained by selective graft angiography. With use of 5 or 8 mm/s table feed and 24 s volumetric acquisitions, SCT established graft patency with 85.7% sensitivity and 100% specificity compared to angiographic examination (96.4% sensitivity and 100% specificity). The mean time between angiography and SCT was 2.1 days, with 86% of SCT studies done within 24 h after angiography. The utilization of dynamic scanning to establish the patient-specific time delay prior to initiation of SCT proved crucial in improving the quality and reliability of SCT bypass graft patency assessment. The paired McNemar test indicates no significant difference between angiography and SCT in establishing patency rates.