Intraindividual Comparison of 3D Coronary MR Angiography and Coronary CT Angiography

Rationale and Objectives

To compare the diagnostic value of magnetic resonance (MR) and computed tomography (CT) for the detection of coronary artery disease (CAD) with special regard to calcifications.

Materials and Methods

Twenty-seven patients with known CAD were examined with a targeted, navigator-gated, free-breathing, steady-state free precession MR angiography sequence (repetition time = 5.6 milliseconds, echo time = 2.8 milliseconds, flip angle 110°) and 16-slice coronary CT angiography. Segment-based sensitivity, specificity, and accuracy for the detection of stenoses larger than 50% were determined as defined by the gold standard catheter coronary angiography along with the subjective image quality (Grade 1–4). The degree of calcifications in each segment was quantified using a standard calcium scoring tool.

Results

Of 115 possible segments, 7% had to be excluded in MR imaging because of poor image quality. In CT, 3% were nondiagnostic because of image quality and 15% were not evaluable because of calcifications. Values for the detection of relevant coronary artery stenoses in the evaluated segments were: sensitivity: MR imaging 85% versus CT 96%; specificity: 88% versus 96%; accuracy: 87% versus. 96%. Average subjective image quality was 1.8 for MR imaging and 1.6 for CT. Of the 15% of segments that had to be excluded from CT evaluation because of calcifications, MR imaging provided the correct diagnosis segments in 67%.

Conclusions

CT provided a better image quality with superior accuracy for the detection of CAD. Despite its overall inferiority, MR imaging proved to be helpful method in interpreting coronary stenosis in severely calcified segments.

Key Words: Coronary arteries, coronary angiography, coronary calcification, coronary artery disease, magnetic resonance imaging, computed tomography