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Purpose: To evaluate the effectiveness of blood suppression and the quality of black-blood cardiac images acquired at 3.0 Tesla using a double-inversion recovery fast spinecho sequence by comparing data acquired at 3.0T to data acquired at 1.5T. Materials and Methods:Black-blood T2-weighted fast spinecho images of the heart were acquired from five normal volunteers at 1.5T and five normal volunteers at 3.0T. Regionof-interest signal intensity measurements were performed at several locations in the suppressed blood regions of the left and right ventricles and around the left ventricle walls to assess the effectiveness and uniformity of the blood suppression, the myocardial signal-to-noise ratio (SNR), and the signal uniformity at both field strengths. B1 field maps were produced in phantoms and in subjects at both field strengths.Results: Blood suppression performance is equivalent at 1.5T and 3.0T. The improvement in SNR at 3.0T compared with 1.5T is less than has been predicted in previous studies. The signal uniformity is significantly poorer at 3.0T than at 1.5T due to dielectric effects and shorter radio frequency wavelengths (P Ͻ 0.005). Conclusion:Spin-echo and spin-echo echo-train sequences that perform well at 1.5T will produce large signal variations in the chest cavity at 3.0T without modifications. B1 insensitive methods must be explored and implemented for spin-echo sequences to fully realize the advantages of using these sequences for high-field MRI.

OBJECTIVE -To characterize structural changes and the metabolic profile of foot muscles and correlate them with diabetic neuropathy measurements using phosphorus-31 ( 31 P) rapid acquisition with relaxation enhancement (RARE) magnetic resonance imaging (MRI).RESEARCH DESIGN AND METHODS -We studied 12 control subjects, 9 nonneuropathic diabetic patients, and 12 neuropathic diabetic patients using 31 P RARE and proton ( 1 H) MRI at 3 Tesla. The ratio of the total cross-sectional area of the foot to that of the muscle tissue was calculated from transaxial 1 H and 31 P images. The average 31 P concentration across the metatarsal head region was measured from the 31 P images.RESULTS -The muscle areaϪtoϪtotal area ratio differed among all three groups (means Ϯ SD): 0.55 Ϯ 0.04 vs. 0.44 Ϯ 0.05 vs. 0.06 Ϯ 0.06 for control, nonneuropathic, and neuropathic subjects, respectively (P Ͻ 0.0001). The average 31 P concentration also differed among all groups: 27.7 Ϯ 3.8 vs. 21.7 Ϯ 4.8 vs. 7.9 Ϯ 8.8 mmol/l for control, nonneuropathic, and neuropathic subjects (P Ͻ 0.0001). The muscle areaϪtoϪtotal area ratio strongly correlated with clinical measurements: Neuropathy Disability Score, r ϭ Ϫ0.83, P Ͻ 0.0001; vibration perception threshold, r ϭ Ϫ0.79, P Ͻ 0.0001; and Semmes-Weinstein monofilaments, r ϭ Ϫ0.87, P Ͻ 0.0001.CONCLUSIONS -Small muscle atrophy is present in diabetes before clinical peripheral neuropathy can be detected using standard clinical techniques. The 31 P RARE MRI method evaluates the severity of muscle atrophy, even in the early stages when neuropathy is absent. This technique may prove to be a useful diagnostic tool in identifying early-stage diabetic foot problems. Diabetes Care 28:1425-1430, 2005A trophy of the small muscles of the foot is common in diabetes and is related to peripheral motor neuropathy (1). The atrophy is believed to be the main factor responsible for the development of an imbalance between the flexor and extensor muscles, which results in clawing of the toes, prominent metatarsal heads, and the development of high foot pressures that play a direct role in the development of foot ulceration (2). Currently, there are no established methods to evaluate and follow the progress of small muscle atrophy in diabetic patients. As a result, little information is available regarding the onset of muscle changes and the natural history of their progression in diabetes.Concentrations of phosphorus-31 ( 31 P) cellular metabolites in skeletal muscle change immediately with the onset of ischemia and return quickly to normal levels in viable muscle tissue after reperfusion (3,4). Thus a method that accurately quantifies 31 P metabolite concentrations in foot muscles in vivo and spatially maps the resulting values to an anatomic, radiological image of the foot would be a sensitive, direct indicator of the health of muscle tissue in the diabetic foot. Magnetic resonance imaging (MRI) and magnetic resonance spectroscopy (MRS) provide data for the noninvasive assessment of deep-lying soft tissue anatomy (5-7). R...