High‐resolution selective three‐dimensional magnetic resonance coronary angiography with navigator‐echo technique: Segment‐by‐segment evaluation of coronary artery stenosis

Abstract

Purpose:To investigate the feasibility of high-resolution selective three-dimensional (3D) magnetic resonance coronary angiography (MRCA) in the evaluation of coronary artery stenoses. Materials and Methods:In 12 patients with coronary artery stenoses, MRCA of the coronary artery groups, including the coronary segments with stenoses of 50% or greater based on conventional x-ray coronary angiography (CAG), was performed with double-oblique imaging planes by orienting the 3D slab along the major axis of each right coronary artery-left circumflex artery (RCA-LCX) group and each left main trunk-left anterior descending artery (LMT-LAD) group. Ten RCA-LCX and five LMT-LAD MR angiograms were obtained, and the results were compared with those of conventional x-ray angiography.Results: Among 70 coronary artery segments expected to be covered, a total of 49 (70%) segments were fully demonstrated in diagnostic quality. The identification of segmental location of stenoses showed as high an accuracy as 96%. The retrospective analysis for stenosis of 50% or greater yielded the sensitivity, specificity, and accuracy of 80%, 85%, and 84%, respectively. Conclusion:Selective 3D MRCA has the potential for segment-by-segment evaluation of major portions of the right and left coronary arteries with high accuracy. THE DESIRE TO REPLACE CONVENTIONAL x-ray coronary angiography (CAG) by a less invasive imaging method is commonplace. Magnetic resonance coronary angiography (MRCA) has been evaluated by many authors since the late 1980s (1-16). Electrocardiography (ECG)-gated breath-hold and navigator-echo guided data acquisition have been evaluated to overcome image blurring due to cardiac and respiratory motion during the relatively long MR data acquisition process. Many imaging strategies have focused on the detection and quantification of the stenoses of only the proximal coronary arteries, but detection and quantification of the stenoses still remain unreliable (4,8,12,15).Transaxial sections used in those studies usually cover only the proximal segments of the major coronary arteries (8,12). However, not only the proximal coronary arteries, but also the mid and distal coronary arteries can be involved in the ischemic heart diseases. If all of the coronary arteries are covered with the transaxial imaging plane (12)(13)(14), the imaging time would be prolonged in association with large volume acquisition, and the right coronary artery could not be obtained with high spatial resolution because it runs in the through-plane direction. Thus, by orienting the threedimensional (3D) imaging slab along the major axis of the coronary vessels, coronary coverage can be more optimal with smaller imaging volumes (16). Recently, some investigators have used axial orientations for the left main trunk (LMT), proximal and mid left anterior descending artery (LAD), and proximal left circumflex artery (LCX), and oblique orientations for the right coronary artery (RCA) (17,18). However, two double-oblique scan volumes, when oriented along the atrioventri...

Coronary artery abnormalities in Kawasaki disease: Comparison between CT and MR coronary angiography

“…In this study, the absent segments on target-volume MRCA (91 of 638 segments) mainly comprised the distal segments of the coronary arteries: the distal LAD artery (28 segments, 30.8%), the PDA (27 segments, 30%), and the distal LCx artery (25 segments, 27.5%). This observation is comparable with results from previous studies using target volume MRCA (26,27). The per-patient analysis, after excluding the absent segments in group B, also showed that coronary artery assessibility was comparable between CTCA and MRCA.…”

Efficacy of Cardiac MRI in the Evaluation of Ischemic Heart Disease

“…3D acquisition techniques, which acquire some amount of volume data in a single acquisition, were soon developed, and data acquisition with 3D sequences is now the mainstream in coronary MRA. [5][6][7][8][9][10][11][12][13] In 3D acquisition, data is acquired over a wide range at one time, and respiratory gating, such as the navigator echo technique, is therefore used to directly monitor the position of the diaphragm. 6 Respiratory gating enables MRA with high spatial resolution while the patient breathes quietly.…”

“…Results reported for coronary MRA have varied widely, with sensitivity values ranging from 40z to 90z as compared to those for CAG. [2][3][4][5]10,11 It is thought that this variation can be attributed to the diŠerent MRI systems and acquisition sequences employed as well as to diŠerences in the target segments of the coronary arteries. A multicenter study using MRI systems of the same model and the same acquisition technique (3D-segmented k-space gradient-echo sequence with respiratory gating employing the navigator echo technique) has recently been conducted.…”

Optimization of acquisition trajectories for 3D rotational coronary venography

“…In contrast to non-invasive imaging of the coronary vessels as computed tomography (CT) (e.g., [1,2]) or magnetic resonance imaging (e.g., [3,4]), X-ray imaging generates projections in real-time. The working views are traditionally operator selected in order to subjectively minimize vessel overlap and foreshortening [5,6].…”