Two healthy volunteers who had inhaled approximately 0.75 L of laser-polarized helium-3 gas underwent magnetic resonance imaging at 1.5 T with fast gradient-echo pulse sequences and small flip angles ( < 10 degrees). Thick-section (20 mm) coronal images, time-course data (30 images collected every 1.8 seconds), and thin-section (6 mm) images were acquired. Subjects were able to breathe the gas (12% polarization) without difficulty. Thick-section images were of good quality and had a signal-to-noise ratio (S/N) of 32:1 near the surface coil and 16:1 farther away. The time images showed regional differences, which indicated potential value for quantitation. High-resolution images showed greater detail and a S/N of approximately 6:1.

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Objective. Quantitative magnetic resonance imaging (MRI) of articular cartilage represents a powerful tool in osteoarthritis (OA) research, but has so far been confined to a field strength of 1.5T. The aim of this study was to evaluate the precision of quantitative MRI assessments of human cartilage morphology at 3.0T and to correlate the measurements at 3.0T with validated measurements at 1.5T.Methods. MR images of the knee of 15 participants with OA and 15 healthy control subjects were acquired using Siemens 1.5T and 3.0T scanners. Double oblique coronal scans were obtained at 1.5T with a 1.5-mm partition thickness, at 3.0T with a 1.5-mm partition thickness, and at 3.0T with a 1.0-mm partition thickness. Cartilage volume, thickness, and surface area of the femorotibial cartilage plates were quantified using proprietary software.Results. For 1.5-mm partition thickness at 1.5T, the precision error was 3.0% and 2.6% for cartilage volume and cartilage thickness, respectively. The error was smaller for a 1.5-mm partition thickness at 3.0T (2.6% and 2.5%) and still smaller for a 1.0-mm partition thickness at 3.0T (2.1% and 2.0%). Correlation coefficients between values obtained at 3.0T and 1.5T were high (r > 0.96), with no significant deviation between the two field strengths.Conclusion. Quantitative MRI measurement of cartilage morphology at 3.0T (partition thickness 1 mm) was found to be accurate and tended to be more reproducible than at 1.5T (partition thickness 1.5 mm). Imaging at 3.0T may therefore provide superior ability to detect changes in cartilage status over time and to determine responses to treatment with structuremodifying drugs.

These preliminary results suggest that donepezil may have a potentially protective effect in Alzheimer's disease. Larger, longer-term confirmatory studies of the medication's effects are warranted.

Four patients with cystic fibrosis (CF) were examined with combined hyperpolarized helium 3-enhanced and conventional proton magnetic resonance (MR) imaging. After inhalation of the polarized 3He gas, single breath-hold, gradient-echo images (resonant frequency of 3He) were obtained to depict lung ventilation. Conventional T2-weighted fast spin-echo (hydrogen) images were also obtained to depict morphologic abnormalities. 3He images were successfully and reproducibly generated that showed both morphologic abnormalities and, often more extensive, ventilation abnormalities. 3He MR imaging may provide a method for evaluating progression of pulmonary disease in patients with CF.