Feasibility of MR perfusion-weighted imaging by use of a time-spatial labeling inversion pulse.

Perfusion-weighted imaging (PWI) by use of arterial spin labeling (ASL) has been introduced to the clinical setting. However, it is not widely available because it requires specialized pulse sequences. Imaging using a time-spatial labeling inversion pulse (time-SLIP), which is a magnetic resonance angiography (MRA) technique that is based on ASL, can be used in various situations. In this study, we examined the feasibility of time-SLIP PWI. Two types of time-SLIP sequences were evaluated: (1) a single inversion recovery (IR) pulse sequence, which is the same as that used in conventional time-SLIP MRA except for the timing of data acquisition, and (2) a dual IR pulse sequence, where a second, non-selective, IR pulse was added during the inflow time to suppress background signals. Subtraction processing is performed between the "on" and "off" settings of the first IR pulse (time-SLIP tag) to obtain PWI. The average signal intensity was measured in a uniform phantom as the residual of the background, and in five healthy subjects as the perfusion signal. The average signal-to-noise ratio (SNR) was also measured in the five subjects. All imaging was performed with a 1.5-T MR scanner. Images using the dual IR method showed lower background signals and higher perfusion signals compared with images using the single IR method. However, the SNR was lower in images with the dual IR method. These results demonstrate that a time-SLIP, which is an MRA method, can be used for obtaining cerebral PWI simply by adjusting the imaging parameters.