University of Pennsylvania Medical Center
School of Medicine
Philadelphia, Pennsylvania
Michael Feldman, MD, PhD

M. Feldman, R. Nadgir, A. Wright, M. Rosen, M. Schnall, and J. Tomaszewski

Background: High resolution magnetic resonance imaging (MRI) has the potential capacity to image tissues at 10-20 microns of spatial resolution. Currently, clinical MR imaging is done with 1.5 T magnets at a resolution of 3 to 5 mm. MR imaging which approaches the resolution of a low power microscope lens requires strong magnetic field gradients ¡Ý 4T and optimized receiver coils.

Design: Radical prostatectomy specimens were imaged using a custom-designed bird-cage receiver at 4T using a whole body magnet equipped with high strength imaging gradients. T1 and T2 weighted gradient-echo and spin-echo images were collected and correlated with histopathologic changes in serially sectioned and completely embedded prostatectomy specimens sectioned at ¡Ü3 mm intervals.

Results: MRI (at 100-150 micron spatial resolution) imaging of prostatectomy specimens under a 4T magnet allowed for the separation of BPH, infiltrating carcinoma and benign mimics of carcinoma including sclerosing adenosis. Signal characteristics associated with carcinoma include distortion of normal prostate architecture, bright T2-weighted signal, and irregular architectural contours. As in-plane resolution and slice thickness decreased, additional architectural details were revealed which include the ability to discriminate small prostatic ducts and macroacinar patterns within BPH nodules. An image essay of discriminant MR signals and their histological correlates will be presented.

Conclusion: High resolution MR imaging of prostate tissue with a 4T magnet can provide morphologic data at the level of resolution of a 2-4 X optical lens.