Recent topics of brain MRI. Arterial spin labeling and new diffusion analysis

The implementation of 3T MR imager enabled us the use of many attractive techniques in daily clinical setting, including arterial spin labeling, Diffusion Tensor Imaging (DTI), MR spectroscopy, high resolution MR angiography (MRA) and etc. Increased signal-to-noise ratio (SNR) and T1 value allows us to obtain practical Arterial Spin Labeling (ASL) images within a few minutes. Cerebral blood flow images by ASL might potentially replace brain single photon emission computed tomography (SPECT) and positron emission tomography (PET). Increased SNR also provides clinical use of diffusion tensor images and beyond-tensor diffusion analysis such as diffusional kurtosis image or Q-space images. In addition to the precise anatomical information by structural MRI, ASL and diffusional analysis (DTI, q-space imaging (QSI)/diffusion kurtosis imaging (DKI)) is capable of assessing functional and physiological information. These will be useful not only in pre- or intraoperative structural evaluation such as tractography, but also in the evaluation of cognitive or behavioral changes. (author)