Multislice CTA outshines MRA in coronary arteries

Researchers at the 2005 SCMR meeting presented documented evidence showing that multislice CT angiography is superior to two leading MR angiography protocols for detecting coronary artery disease.

Dr. Murat Ozgun and colleagues at the University of Munster in Germany described their head-to-head comparison of 16-detector CT and two popular MRA protocols performed on a 1.5T scanner. Their findings indicate that MR can help overcome the shortcomings of contrast-enhanced CTA, but the two protocols are second and third best for diagnosing coronary artery disease.

The good news for MR was that the steady-state free precession (SSFP) sequence allowed readers to examine more coronary artery segments than MSCTA. Among 104 imaged sequences of 21 patients with suspected CAD, only 12 segments interrogated with SSFP were set aside because of misregistration and motion artifact. That performance stacked up well against CTA, which was unable to evaluate nine segments because of calcium accumulation and had five set aside because of trigger/motion artifacts. A navigator-gated turbo field-echo (TFE) sequence performed least well, with 20 segments set aside.

But the two MR protocols did not match CTA in spatial resolution or diagnostic power. Ozgun calculated that the in-plane resolution of CTA was 0.4 x 0.4 mm2 compared with 1 x 1 mm2 for SSFP MR and 0.7 x 1 mm2 for the TFE technique. The sensitivity and specificity rates for the three approaches were 90% and 81% for CTA, 79% and 74% for SSFP MRA, and 82% and 62% for TFE MRA.

Nearly one-fourth of calcified coronary artery segments could not be assessed with CT, however, while SSFP MRA led to successful diagnoses in two-thirds of those calcified segments.

"As a consequence, MRA may be used as a problem-solving tool in segments with extensive calcifications," Ozgun said.