MR imaging-guided percutaneous cryoablation of the prostate in an animal model: in vivo imaging of cryoablation-induced tissue XXXX with immediate histopathologic correlation.

@entity235 @entity4 @entity548 @entity39
PURPOSE: To evaluate the feasibility of magnetic resonance (MR) imaging-guided percutaneous cryoablation of normal @entity235 prostates and to identify MR imaging features that accurately predict the area of tissue damage at a microscopic level. MATERIALS AND METHODS: Six adult male mixed-breed @entity235 were anesthetized, intubated, and placed in a 0.5-T open MR imaging system. A receive-only endorectal coil was placed, and prostate location and depth were determined on T1-weighted fast spin-echo (FSE) MR imaging. After placement of cryoprobes and temperature sensors, three freezing protocols were used to ablate prostate tissue. Ice ball formation was monitored with T1-weighted FSE imaging. Tissue @entity39 area was assessed with contrast-enhanced weighted MR imaging and compared with histopathologic findings. RESULTS: A total of 12 cryolesions (mean size, 1.2 cm) were bilaterally created in six prostates. Ice ball formation was oval and signal-free on T1-weighted FSE sequences in all cases. Postprocedural contrast-enhanced MR imaging typically showed a nonenhancing area of low signal intensity centrally located within the frozen area, surrounded by a bright enhancing rim in all cases. On histopathologic examination, two distinct zones were identified within cryolesions. Centrally, a necrotic zone with complete cellular destruction and @entity548 was found. Between this necrotic zone and normal glandular tissue, a zone of fragmented and intact glands, @entity4 , and rare acute inflammatory cells was seen. Correlation between nonenhancement on contrast-enhanced weighted MR images and tissue @entity39 on pathologic examination was consistent within all six @entity235 . CONCLUSIONS: MR imaging-guided cryoablation of the prostate is technically feasible. The nonenhancing area on postablation contrast-enhanced weighted MR imaging accurately predicts the area of cryoablation-induced tissue @entity39 on pathologic analysis.
