Purpose: To evaluate MR coronary angiography using a three-dimensional navigator echo sequence on a MR scanner with a high performance gradient system.
Material and methods: Five healthy volunteers were examined with a 1.5 Tesla MR system, using a high performance prototype gradient system (peak amplitude 50 mT/m, rising time 600 mus). For imaging, a navigated gradient-echo pulse sequence with an in-plane resolution between 0.63 x 0.63 and 0.78 x 0.78 mm2 was used. Per patient two overlapping slabs were acquired. The number of visualized coronary artery segments was estimated (AHA classification). In addition, signal-to-noise measurements were performed in the ascending aorta at the level of the proximal right and left coronary arteries.
Results: In all volunteers the left main, the right coronary artery up to segment 3, the LAD up to segment 8 and the RCX with segment 11 and 13 were clearly visualized. The average signal-to-noise value at the level of the right coronary artery was 11.4 +/- 5.0, at the level of the left coronary artery 12.3 +/- 4.5. One volunteer was measured with an in-place resolution of 0.63 x 0.63 mm2. This resulted in a too low signal-to-noise ratio so that an adequate assessment of coronary arteries was no longer possible.
Conclusion: 3D-MR coronary angiography using the navigator technique is limited by the signal-to-noise ratio.