MAGNETIZATION-TRANSFER MR OF THE NORMAL ADULT BRAIN

PURPOSE: To establish a normal baseline of the percent magnetization t ransfer of gray (cortical and deep) and white matter structures in the brain in healthy adults and to determine whether there are adult age- related differences in these measurements. METHODS: Axial TI-weighted scans (800/20 [repetition time/echo time]) with and without magnetizat ion transfer were prospectively performed on a 1.5-T MR imaging unit o n 68 healthy patients (aged 20 to 76 years). Presaturation and postsat uration magnetization transfer images were obtained using an on-resona nce binomial pulse. All patients had normal MR scans on all pulse sequ ences. A calculated ''difference'' image was used to calculate the per cent magnetization transfer in multiple specific regions of the brain. In each hemisphere, 9 discrete areas of cortical and deep gray matter and 29 areas of white matter were measured in 68 patients to generate age-related changes in percent magnetization transfer in these anatom ic regions. Ranges of normal percent magnetization transfer in each of the 38 measures were established. RESULTS: The percent magnetization transfer of the gray matter (28% +/- 2%) was lower than that of the wh ite matter (36% +/- 2%). There was no statistically significant differ ence in the percent magnetization transfer in different areas of gray matter. Deep white matter in the different lobes (percent magnetizatio n transfer, 31% to 38%) also showed no differences by age. Percent mag netization transfer was the highest in the genu of the corpus callosum (42%), and this was statistically significant compared with other whi te matter measurements. CONCLUSION: There were no statistically signif icant age-related variations in the percent magnetization transfer in healthy adults in gray or white matter. These percent magnetization tr ansfer measurements provide baseline normative data, which can be used to measure the extent and severity of white matter changes in disease states.