Signal intensity of motor and sensory cortices on T2-weighted and FLAIR images: intraindividual comparison of 1.5T and 3T MRI.

We compared the signal intensity of motor and sensory cortices on T2-weighted and FLAIR images obtained at 3T and 1.5T. MR images of 101 consecutive neurologically normal patients who underwent both 1.5T and 3T MRI were retrospectively evaluated. The signal intensities of motor and sensory cortices were analyzed both visually and quantitatively in comparison with superior frontal cortex. On T2-weighted images, decreased signal intensity of the motor cortex was seen in 6 (32%) of 19 patients aged 61-70 years and 14 (48%) of 29 at 71 years and older at 3T, compared with only 1 (5%) and 2 (7%) at 1.5T, respectively. On FLAIR images, the decreased signal intensity in the motor cortex was also more frequently seen at 3T than at 1.5T. The mean CNRs of motor and sensory cortices were significantly higher at 3T than at 1.5T on both T2-weighted and FLAIR images. The decreased signal intensity in the motor cortex was frequently seen at 3T compared with 1.5T. Knowledge of the finding at 3T can help the recognition of abnormalities of the motor cortex caused by various pathologic conditions.