Conventional approaches for fat and water discrimination based on chemical-shift fat suppression have reduced ability to characterize fatty infiltration due to poor contrast of microscopic fat. The multiecho Dixon approach to water and fat separation has advantages over chemical-shift fat suppression: 1) water and fat images can be acquired in a single breathhold, avoiding misregistration; 2) fat has positive contrast; 3) the method is compatible with precontrast and late-enhancement imaging, 4) less susceptible to partial-volume effects, and 5) robust in the presence of background field variation; and 6) for the bandwidth implemented, chemical-shift artifact is decreased. The proposed technique was applied successfully in all 28 patients studied. This included 10 studies with indication of coronary artery disease (CAD), of which four cases with chronic myocardial infarction (MI) exhibited fatty infiltration; 13 studies to rule out arrhythmogenic right ventricular cardiomyopathy (ARVC), of which there were three cases with fibrofatty infiltration and two confirmed with ARVC; and five cases of cardiac masses (two lipomas). The precontrast contrast-tonoise ratio (CNR) of intramyocardial fat was greatly improved, by 240% relative to conventional fat suppression. For the parameters implemented, the signal-to-noise ratio (SNR) was decreased by 30% relative to conventional late enhancement

OBJECTIVES The purpose of this study was to prospectively evaluate the diagnostic performance of 3.0T contrast-enhanced whole-heart coronary magnetic resonance angiography (CMRA) in patients with suspected coronary artery disease. BACKGROUND A slow-infusion, contrast-enhanced whole-heart CMRA approach has recently been developed at 3.0T. The accuracy of such technique has not yet been determined among patients with suspected coronary artery disease. METHODS 3.0T contrast-enhanced whole-heart CMRA was performed in 69 consecutive patients. An ECG-triggered, navigator-gated, inversion-recovery prepared, segmented gradient-echo sequence was used to acquire isotropic whole-heart CMRA with slow infusion of 0.2 mmol/kg Gd-BOPTA. The diagnostic accuracy of whole-heart CMRA in detecting significant stenoses (≥50%) was evaluated using x-ray angiography as the reference. RESULTS The MR examinations were successfully completed in 62 patients. Acquisition time of whole-heart CMRA procedure was 9.0 ±1.9 min. 3T whole-heart CMRA correctly identified significant CAD in 32 patients and correctly ruled out CAD in 23 patients. The sensitivity, specificity, and accuracy of whole-heart CMRA for detecting significant stenoses were 91.6% (87/95), 83.1% (570/686), 84.1% (657/781), respectively, on a per-segment basis. These values were 94.1% (32/34), 82.1% (23/28), 88.7% (55/62), respectively, on a per-patient basis. CONCLUSIONS 3.0T contrast-enhanced whole-heart CMRA allows for the accurate detection of coronary artery stenosis with high sensitivity and moderate specificity.

Purpose:To investigate the accuracy of a dual-projection respiratory self-gating (DP-RSG) technique in dynamic heart position measurement and its feasibility for freebreathing whole-heart coronary MR angiography (MRA). Materials and Methods:A DP-RSG method is proposed to enable accurate direct measurement of heart position by acquiring two whole-heart projections. On 14 volunteers we quantitatively evaluated the efficacy of DP-RSG by comparison with diaphragmatic navigator (NAV) and single-projection-based respiratory self-gating (SP-RSG) methods. For DP-RSG we also compared center-of-mass and two profilematching algorithms in deriving heart motion. Coronary imaging was conducted on eight volunteers based on retrospective gating to preliminarily validate the effectiveness of DP-RSG for whole-heart coronary MRA. Comparison of vessel delineation was performed between images reconstructed using different gating methods. Results:The quantitative evaluation shows that DP-RSG more accurately tracks heart motion than NAV with all gating window (GW) values and SP-RSG approaches with GW Ն2.5 mm and profile-matching algorithms are more reliable for motion derivation than center-of-mass calculations with GW Ն1.0 mm. Whole-heart coronary MRA studies demonstrate the feasibility of using DP-RSG to improve overall delineation of the coronary arteries.Conclusion: DP-RSG is a promising approach to better resolve respiratory motion for whole-heart coronary MRA compared to conventional NAV and SP-RSG. CORONARY MR ANGIOGRAPHY (MRA) is emerging as a noninvasive technique for diagnosis of coronary artery diseases. Conventionally, coronary MRA is performed using double-oblique thin slabs targeted at specific coronary artery branches and thus requires precise planning of the imaging plane for each coronary artery branch on each subject (1-3). Due to the tortuous geometry of coronary arteries, visualization is highly dependent on operator skills and ultimately restricted by the slab thickness. Lately, whole-heart coronary MRA was introduced to improve the ease-of-use and the length of vessel depiction (4,5). The complete coronary artery tree is covered in a single measurement and individual branches can be visualized by reformatting the three-dimensional dataset retrospectively. However, whole-heart scans require multifold increases in imaging time compared to volume-targeted scans. Despite recent significant advances in MRA, eg, fast pulse sequences and parallel imaging, the imaging time for high-quality whole-heart coronary MRA is still far beyond breath-hold capabilities and thus necessitates data acquisition during free-breathing.Free-breathing coronary MRA has been mostly relying on diaphragmatic navigator (NAV) approaches (4 -8). By tracking the motion of the right hemidiaphragmatic dome, respiratory motion of the heart along the superior-inferior (SI) direction can be estimated using an empirical correction factor (typically 0.6) and used for gating and slice tracking (9). NAV approaches are reliant on a simplified motion model a...

OBJECTIVES-To evaluate the potential use of a novel 3D turbo spin-echo (TSE) T2-weighted (T2w) technique for assessing the vessel wall in the superficial femoral artery at 3.0T.BACKGROUND-Magnetic resonance imaging (MRI) can be used for the noninvasive assessment of atherosclerotic plaque burden in the peripheral circulation. While black-blood 2D TSE techniques have been used for femoral arterial wall imaging, these techniques require prolonged imaging time to cover a large field of view required to cover the leg. Recently, variable-flip-angle 3D TSE T2w (SPACE) has been introduced as a fast vessel wall imaging technique with submillimeter spatial resolution. A systematic investigation of the application of this technique to femoral arterial wall imaging has yet to be performed.

Free-breathing 3D PSIR turbo FLASH imaging is a promising technique for the assessment of left ventricular scar particularly for scar quantification and the detection of small nonischemic scars in the myocardium.