| Abstract: | Rapid T2 dependent field echo [partial saturation (PS)] sequences were used in 38 patients with brain tumors, intracerebral hematomas, and cerebral infarction as well as other neurological and abdominal disease. Reduction in the radiofrequency excitation angle (alpha) from 90 to 30 degrees produced an increase in lesion contrast as did change of echo time (TE) from 33 to 59 or 120 ms using repetition time (TR) values in the range of 120-500 ms. The PS sequence showing most lesion contrast was compared with conventional spin echo (SE 1,500/80 and SE 1,500/120) and inversion recovery (IR 1,500/500/44 and IR 1,500/100/44) sequences. Although PS sequences with TE = 39 ms were usually inferior to conventional SE sequences, those with TE = 59 or 120 ms were comparable and in some cases (particularly hematomas) superior. The PS sequences with alpha of approximately 30 degrees, TR of 80-250 ms, and TE of 60-120 ms offer considerable savings in time compared with conventional sequences although more work will be required to explore the limits of this approach and to optimize sequences at different field strengths. |
