Basic and Translational Science Feasibility of 3.0T Magnetic Resonance Imaging-guided Laser Ablation of a Cadaveric Prostate David A. Woodrum, Krzysztof R. Gorny, Lance A. Mynderse, Kimberly K. Amrami, Joel P. Felmlee, Haraldur Bjarnason, Oscar I. Garcia-Medina, Roger J. McNichols, Thomas D. Atwell, and Matthew R. Callstrom OBJECTIVES To demonstrate the feasibility of 3.0T magnetic resonance imaging (MRI)-guided laser ablation of the prostate. METHODS MRI-guided laser ablations in the intact prostate gland were performed in 5 cadavers. The cadavers were brought into the MRI suite and placed in a supine headfirst position. A needle guide grid was placed against the perineum, and MRI was performed to co-localize the grid with the prostate imaging data set. Using the guidance grid and 14-gauge Abbocath catheters, the laser applicators were placed in the prostate with intermittent MRI guidance. After confirmation of the position of the laser applicators, 2-minute ablations were performed with continuous MRI temperature feedback. Using the relative change in temperature and the Arrhenius model of thermal tissue ablation, the ablation margins were calculated. RESULTS Laser ablation was successfully performed in all 5 cadaveric prostates using 15- and 30-W laser generators. Thermal mapping in the axial, sagittal, and coronal planes was performed with calculated ablation margins projected back onto the magnitude MR images. Deviations of the needles from the template projections ranged from 1.0 to 4.1 mm (average 2.1) at insertion depths of 75.5-116.5 mm (average 98.2). In the 2 cadavers for which histologic correlation was available, the extent of the ablation zone corresponded to the temperature mapping findings and the ablation transition zones were identifiable on hematoxylin-eosin staining. CONCLUSIONS Transperineal laser ablation of the prostate gland is possible using 3.0T MRI guidance and thermal mapping and offers the potential for precise image-guided focal targeting of prostate cancer. UROLOGY 75: 1514.e1–1514.e6, 2010. © 2010 Elsevier Inc. I n 2009, the American Cancer Society estimated that 192 280 new cases of prostate cancer will have been diagnosed in the United States. 1 Many men 75 years of age undergo aggressive therapy, including radio- therapy, surgery, and/or androgen deprivation. No matter how expertly done, these therapies carry significant risk and morbidity to the patient’s health-related quality of life with effects on sexual, urinary, and bowel function. 2 Active screening programs for prostate cancer have iden- tified increasing numbers of patients with low-risk pros- tate cancer, which has encouraged regimens of active surveillance to delay treatment until cancer progression. 3 Although active debate continues regarding the suitabil- ity of focal or regional therapy for these patients with low-risk prostate cancer, many unresolved issues remain that have complicated this management approach, in- cluding prostate cancer multifocality, the limitations of current biopsy strategies, suboptimal staging using ac- cepted imaging modalities, and the less than robust pre- diction models for indolent prostate cancers. Despite these restrictions, focal therapy continues to confront the current paradigm of therapy for low-risk disease. 4 In these patients with low-volume and low-risk disease, magnetic resonance imaging (MRI) technology is evolving to play a critical role in patient risk stratification, targeting treat- ments, and verifying treatment success. 5–7 With addi- tional development of accurate staging and characteriza- tion using MRI, focal therapy might become a viable option for the management of low-volume and low-risk prostate cancer. Laser-induced thermal therapy (LITT) is a minimally invasive ablation technique that uses laser light to de- posit high-energy photons locally in tissue, causing tissue destruction through rapid heating. The laser energy is This study was supported by a small grant from Mayo Clinic. R. McNichols is an employee of, and equity owner in, Visualase, Incorporated. Departments of Radiology and Urology, Mayo Clinic College of Medicine, Rochester, Minnesota; and BioTex, Incorporated, Houston, Texas Reprint requests: David A. Woodrum, Ph.D., Department of Radiology, Mayo Clinic, 200 First Street, Southwest, Rochester, MN 55905. E-mail: woodrum.david@ mayo.edu Submitted: September 23, 2009; accepted (with revisions): January 19, 2010 © 2010 Elsevier Inc. 0090-4295/10/$34.00 1514.e1 All Rights Reserved doi:10.1016/j.urology.2010.01.059