Imaging and evaluation of coronary artery bypass graft patency by 16-slice multidetector computed tomography.

INTRODUCTION

The purpose of this study was to evaluate the patency of coronary artery bypass grafts (CABGs) while assessing the capabilities and limitations of 16-slice multidetector computed tomography.

METHODS

We studied retrospectively 19 patients (13 men, 6 women), over an 18-month period. All patients had undergone CABG surgery 3 months to 7 years earlier. Two patients were examined on an emergency basis for chest pain and their CABGs were evaluated simultaneously. The number of CABGs in each patient ranged from one to three. A total of 44 grafts were assessed. All scans were performed by a 16-row multislice scanner (Toshiba Aquilion). Maximum intensity projections, multiplanar reformations, and volume rendering techniques were performed on a Vitrea workstation. All 19 patients also underwent invasive catheter coronary angiography for confirmation of their status.

RESULTS

Of the 44 grafts evaluated, 26 were classified as patent, 13 as not patent, and 5 as stenotic. In the bypass grafts with stenosis > or = 50% there was a difference in the mean level of enhancement before and after the stenosis (265.38 +/- 35.82 and 178.56 +/- 9.32, respectively). Seventeen arterial and 27 venous grafts were imaged. Of the 13 non-patent grafts, 8 were venous. In 3 cases of arterial grafts the distal anastomoses were not delineated. The assessment of venous grafts was easier because of their larger diameter and lack of surrounding clips. One case of a carotid-subclavian shunt with a distal anastomosis of the left internal mammary artery to the left anterior descending branch was reported. Sensitivity, specificity, positive and negative predictive values for stenosis were evaluated.

CONCLUSIONS

Multidetector computed tomography is a fast and non-invasive modality for evaluating CABG patency that is gaining acceptance as an alternative method to invasive coronary angiography. Sensitivity and specificity are determined by the available and evolving technology.