A fast 3D approach for coronary MRA

Two-dimensional (2D)-breathhold coronary magnetic resonance angiography (MR A) has been shown to be a fast and reliable method to depict the proximal c oronary arteries. Recent developments, however, allow for free-breathing na vigator gated and navigator corrected three-dimensional (3D) coronary MRA. These 3D approaches have potential for improved signal-to-noise ratio (SNR) and allow for the acquisition of adjacent thin slices without the misregis tration problems known from 2D approaches. Still, a major impediment of a 3 D acquisition is the increased scan time. The purpose of this study was the implementation of a free-breathing navigator gated and corrected ultra-fas t 3D coronary MRA technique, which allows for scan times of less than 5 min utes, Twelve healthy adult subjects were examined in the supine position us ing a navigator gated and corrected ECG triggered ultra-fast 3D interleaved gradient echo planar imaging sequence (TFE-EPI). A 3D slab, consisting of 20 slices with a reconstructed slice thickness of 1.5 mm, was acquired with free-breathing. The diastolic TFE-EPI acquisition block was preceded by a T2prep pre-pulse, a diaphragmatic navigator pulse, and a fat suppression pr e-pulse. With a TR of 19 ms and an effective TE of 5.4 ms, the duration of the data acquisition window duration was 38 ms. The in-plane spatial resolu tion was 1.0-1.3 mm*1.5-1.9 mm, In all cases, the entire left main (LM) and extensive portions of the left anterior descending (LAD) and right coronar y artery (RCA) could be visualized with an average scan time for the entire 3D-volume data set of 2:57 +/- 0:51 minutes. Average contiguous vessel len gth visualized was 53 +/- 11 mm (range: 42 to 75 mm) for the LAD and 84 +/- 14 mm (range: 62 to 112 mm) for the RCA. Contrast-to-noise between coronar y blood and myocardium was 5.0 +/- 2.3 for the LM/LAD and 8.0 +/- 2.9 for t he RCA, resulting In an excellent suppression of myocardium. We present a n ew approach for free-breathing 3D coronary MRA, which allows for scan times superior to corresponding 2D coronary MRA approaches, and which takes adva ntage of the enhanced SNR of 3D acquisitions and the post-processing benefi ts of thin adjacent slices. The robust image quality and the short average scanning time suggest that this approach may be useful for screening the ma jor coronary arteries or identification of anomalous coronary arteries. (C) 1999 Wiley-Liss, Inc.