Seven tesla (T) MR imaging is potentially promising for the morphologic evaluation of coronary arteries because of the increased signal-to-noise ratio compared to lower field strengths, in turn allowing improved spatial resolution, improved temporal resolution, or reduced scanning times. However, there are a large number of technical challenges, including the commercial 7 T systems not being equipped with homogeneous body radiofrequency coils, conservative specific absorption rate constraints, and magnified sample-induced amplitude of radiofrequency field inhomogeneity. In the present study, an initial attempt was made to address these challenges and to implement coronary MR angiography at 7 T. A singleelement radiofrequency transmit and receive coil was designed and a 7 T specific imaging protocol was implemented, including significant changes in scout scanning, contrast generation, and navigator geometry compared to current protocols at 3 T. With this methodology, the first human coronary MR images were successfully obtained at 7 T, with both qualitative and quantitative findings being presented. Coronary magnetic resonance angiography (MRA) has been shown to be a promising tool for the noninvasive identification of significant proximal coronary artery disease (1,2). The most commonly used magnetic field strength for coronary MRA is 1.5 T, involving many years of sequence, parameter, and radiofrequency (RF) coil optimization. In common with many MRI applications, the use of higher magnetic field strengths for coronary MRA is attractive, with advantages arising from increases in signal-to-noise ratio (SNR), smaller voxel sizes, a higher temporal resolution, and/or shortened scanning times. Individually or in combination, these improvements are likely to result in improved image quality and ultimately better access to small diameter and branching vessels. As a first step in this direction, implementation of coronary MRA at 3 T has been found to result in increased SNR, increased contrast-to-noise ratio, and increased measured coronary vessel lengths compared to 1.5 T (3-5). Voxel sizes as low as 0.35 ϫ 0.35 ϫ 1.5 mm 3 have been obtained at 3 T (6) in selected cases. Although initial studies comparing 1.5 T coronary MRA with 3 T coronary MRA and the gold standard x-ray coronary angiography showed little advantage of 3 T for the identification of significant luminal coronary artery disease, a more recent report (4) appears much more promising, and other studies that take advantage of new high-field specific improvements are ongoing. Notably, the increase in magnetic field strength between 1.5 and 3 T produces a series of challenges, including adequate electrocardiograph (ECG) triggering (7), sophisticated higherorder shimming (8) to account for increased magnetic field susceptibility, and spatially homogeneous magnetization preparation for contrast generation (9).Given the promising indicators at 3 T, the recent availability of commercial human whole-body high-field 7 T MR systems might offer great potential for c...
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