Measurements of T1-relaxation in ex vivo prostate tissue at 132 μT

The proton T1 was measured at 132 mu T in ex vivo prostate tissue specimens from radical prostatectomies of 35 patients with prostate cancer. Each patient provided two specimens. The NMR and MRI measurements involved proton repolarization, a field of typically 150 mT and detection of the 5.6-kHz signal with a superconducting quantum interference device. Values of T1 varied from 41 to 86 ms. Subsequently, the percentages of tissue types were determined histologically. The theoretical image contrast is quantified for each case by d = [1 T1(more cancer)/T1(less cancer)]. A linear fit of d versus difference in percentage cancer yields T1 (100% cancer)/T1 (0% cancer) = 0.70 +/- 0.05 with correlation coefficient R2 = 0.30. Two-dimensional T1 maps for four specimens demonstrate variation within a single specimen. These results suggest that MR images with T1 contrast established at ultra-low fields may discriminate prostate cancer from normal prostate tissue in vivo without a contrast agent. Magn Reson Med, 2012. (C) 2012 Wiley Periodicals, Inc.