Navigator echo-based respiratory gating for three-dimensional MR coronary angiography: Reduction of scan time using a slice interpolation technique

Purpose: The aim of the study was to compare a conventional respiratory-gat ed 3D MR coronary angiographic technique (conventional MRCA) with a respira tory-fated 3D MR coronary angiographic technique that includes a slice inte rpolation technique (slice interpolation MRCA). Both MRCA techniques were c ompared based on the quality of visualization of the coronary arteries and the diagnostic accuracy in identifying hemodynamically significant coronary artery stenoses. Method: Forty patients with known proximal coronary artery stenosis after c onventional CA were examined on a 1.5 T scanner, that is, 20 patients with each sequence. A 6 point grading system (0 = worst quality, 5 = best qualit y) was used to evaluate and compare the image quality. The length and proxi mal diameter of the depicted coronary arteries were measured. Detection of coronary artery stenoses was compared with that obtained by conventional CA by two blinded readers. Results: With the slice interpolation technique, the average scan time of t he entire heart was reduced by approximate to 40%. With use of conventional MRCA, 69% of all proximal and middle coronary artery segments were visuali zed with a sufficient image quality; with the slice interpolation technique , 79% of these segments were depicted adequately. For the assessment of ste noses, sensitivity was 71% and specificity was 53% for conventional MRCA an d 72 and 60% for slice interpolation MRCA, respectively. These differences in sensitivity and specificity were statistically not significant. Conclusion: The application of a slice interpolation technique reduces the scan time, maintains a comparable sensitivity and specificity for the asses sment of coronary artery stenoses, and increases the number of completely i dentified coronary artery segments compared with the conventional technique .