A fast Look-Locker method for T 1 mapping of the head and neck region

A sequence for T (1) relaxation time measurements that allows a high-resolution image to be obtained within a short acquisition time is described. Its application to the orofacial region is investigated. The sequence is based on the Look-Locker (LL) method and employs a magnetization-preparation pulse prior to data acquisition, with either a turbo-field echo (TFE) or turbo-field echo echo-planar imaging (TFEPI) sequence. We applied the multiple LL sequence by synchronizing the data acquisition with the virtual electrocardiogram. T (1) results from the LL sequence were compared with those from the inversion recovery (IR) sequence. In an in vitro study, we evaluated the T (1) maps of contrast medium at different concentrations. In an in vivo study, we evaluated the T (1) maps in seven volunteers. In the in vitro study, the correlation between the T (1) values obtained from the LL sequence and those from the IR sequence was high, with an R (2) of more than 0.99. For T (1) values between 200 and 1,500 ms, the difference between the two methods was less than 7%. In the in vivo study, a high correlation was observed between the T (1) values from the IR sequence and those from the LL sequence. The scan duration for the LL sequence was less than 3 min. Our method, based on the LL sequence, was found to be clinically useful for producing a T (1) map.