CTA shows promise for myocardial perfusion imaging

A preliminary study suggests that CTA can play the role cardiac MRI has been playing for detecting and quantifying myocardial infarction to estimate the potential success of coronary bypass graft surgery.

Establishing the feasibility of perfusion CT to do what cardiac MRA does for delayed-enhancement myocardial imaging could eliminate the need for cardiac MRA in this important function and help speed therapy decision-making for surgical candidates.

Dr. Yoon Jin Lee and colleagues working in Seoul, Korea, were encouraged by the results of 10-minute delayed-enhancement, ECG-gated examinations performed with dual-source CT and cardiac MR for 29 patients requiring pre-coronary artery bypass graft surgery workups.

Delayed-enhancement and infarction volumes over total myocardial volume were evaluated by two radiologists using a 19-segment model for dual-source CT and cardiac MR. Ventricular function measures were also acquired using both techniques. The myocardium was considered viable when delayed enhancement failed to reveal any transmural deficit of greater than 50%.

Delayed enhancement was observed in 17 patients with both cardiac MR and dual-source CT. Cardiac MR caught a delayed-enhancement void in one patient that was not seen with dual-source CT.

Lee noted that the percentage of infarction volume was not significantly different between the two modalities, though the correlation was strongest for patients with ventricular ejection fractions greater than 40%.

The sensitivity and specificity of dual-source CT for detecting transmural infarctions greater than 50% were 95% and 77% respectively.

Though larger multicenter randomized trials are needed to validate the findings, Lee’s work strongly suggests that perfusion CT will eventually challenge cardiac MR for this application.