Abstract #2234

Tang L, LI J, CAO K, SUN Y, ZHANG X

Purpose The aim of this study is to investigate how to select the reasonable b values of DWI for displaying rectal cancer.Materials and Methods Thirty-two patients with rectal cancer with single-shot EPI diffusion-weighted sequences (b=300, 500, 800, 1000 and 1300 s/ mm2) at 1.5T MR scanner (GE Healthcare) with an 8-channel body phase-array coil. The mean ADC values and Signal-to-noise ratio (SNR) of tumors, Contrast-to-noise ratio (CNR) of tumors and normal rectal wall, Signal intensity ratio (SIR) of bladder were calculated and compared. .Results The CNR of tumors and normal rectal wall decreases following the ascending of b values, and the CNR in the DWI of rectal cancer with b=300, 500, 1000 s/ mm2 was significantly higher than that in DWI with b=1300 s/ mm2 and T2 weighted imaging (F42.492p0. 001). The SIR of bladder and background noise in DWI ( b=300, 500, 800, 1000 and 1300 s/ mm2) were lower than that in T2 weighted imagingF144.786p0. 05. When b values reached 800 s/ mm2 the