title: Correlation of contrast-enhanced MR images with the histopathology of minimally invasive thermal and cryoablation cancer treatments in normal dog prostates.
abstract: Magnetic Resonance Imaging (MRI) is a promising tool for visualizing the delivery of minimally invasive cancer treatments such as high intensity ultrasound (HUS) and cryoablation. We use an acute dog prostate model to correlate lesion histopathology with contrast-enhanced (CE) T1 weighted MR images, to aid the radiologists in real time interpretation ofin vivolesion boundaries and pre-existing lesions. Following thermal or cryo treatments, prostate glands are removed, sliced, stained with the vital dye triphenyl tetrazolium chloride, photographed, fixed and processed in oversized blocks for routine microscopy. Slides are scanned by Trestle Corporation at .32 microns/pixel resolution, the various lesions traced using annotation software, and digital images compared to CE MR images. Histologically, HUS results in discrete lesions characterized by a "heat-fixed" zone, in which glands subjected to the highest temperatures are minimally altered, surrounded by a rim or "transition zone" composed of severely fragmented, necrotic glands, interstitial edema and vascular congestion. The "heat-fixed" zone is non-enhancing on CE MRI while the "transition zone" appears as a bright, enhancing rim. Likewise, the CE MR images for cryo lesions appear similar to thermally induced lesions, yet the histopathology is significantly different. Glands subjected to prolonged freezing appear totally disrupted, coagulated and hemorrhagic, while less intensely frozen glands along the lesion edge are partially fragmented and contain apoptotic cells. In conclusion, thermal and cryo-induced lesions, as well as certain pre-existing lesions (cystic hyperplasia - non-enhancing, chronic prostatitis - enhancing) have particular MRI profiles, useful for treatment and diagnostic purposes.
authors: Comparative Medicine, Stanford University, Stanford, CA.
authors: D M
authors: DM
authors: Bouley
authors: Radiology, Stanford University, Stanford, CA.
authors: B
authors: B
authors: Daniel
authors: Radiology, Stanford University, Stanford, CA.
authors: K Butts
authors: KB
authors: Pauly
authors: Radiology, Stanford University, Stanford, CA.
authors: E
authors: E
authors: Liu
authors: Radiation Oncology, UCSF, San Francisco, CA.
authors: A
authors: A
authors: Kinsey
authors: Radiation Oncology, UCSF, San Francisco, CA.
authors: W
authors: W
authors: Nau
authors: Radiation Oncology, UCSF, San Francisco, CA.
authors: C J
authors: CJ
authors: Diederich
authors: Radiology, Stanford University, Stanford, CA.
authors: G
authors: G
authors: Sommer
keywords: Prostate; canine model; cryoablation; high intensity ultrasound; histopathology