CTA demonstrates advantages

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The 64-slice CT angiography (CTA) is noninvasive, can diagnose vein graft disease at an early stage and complementary evaluation of extracardiac anatomic features provide useful information before coronary artery bypass grafting is redone, according to new study results published in the October issue of the American Journal of Roentgenology. This journal is published by the American Roentgen Ray Society.

Researchers from the radiology and cardiac departments at Innsbruck Medical University in Innsbruck, Austria, examined 41 patients (70 grafts: 46 arterial and 24 venous), who underwent CTA. Among the participants, there was a mean of 2.6 years after minimally invasive or conventional coronary artery bypass surgery.

None of the grafts were excluded from the analysis because all 70 were assessable.

For the detection of 50 to 90 percent graft stenosis, the sensitivity of CT was 75 percent, the specificity was 95 percent, the positive predictive value was 67 percent and the negative predictive value was 97 percent.

Assessed together, more than 50 percent graft stenosis and occlusion were detected with a sensitivity of 85 percent, specificity of 95 percent, a positive predictive value of 80 percent and a negative predictive value of 96 percent.

Vein graft disease was found in eight, or 42 percent, of 19 patient vein grafts.

Although a 64-slice CTA can be used for accurate exclusion of greater than 50 percent graft stenosis, detection of distal anastomotic stenosis is limited and the degree of stenosis can be overestimated. Yet, the researchers believe that CTA’s advantages make its usage important.