Original Research Multiparametric MRI for Prostate Cancer Localization in Correlation to Whole-Mount Histopathology Sofie Isebaert, PhD, 1 * Laura Van den Bergh, MD, 1 Karin Haustermans, MD, PhD, 1 Steven Joniau, MD, 2 Evelyne Lerut, MD, PhD, 3 Liesbeth De Wever, MD, 4 Frederik De Keyzer, MSc, 4 Tom Budiharto, MD, PhD, 1 Pieter Slagmolen, PhD, 5,6 Hendrik Van Poppel, MD, PhD, 2 and Raymond Oyen, MD, PhD 4 Purpose: To prospectively evaluate multiparametric mag- netic resonance imaging (MRI) for accurate localization of intraprostatic tumor nodules, with whole-mount histopa- thology as the gold standard. Materials and Methods: Seventy-five patients with biopsy-proven, intermediate, and high-risk prostate can- cer underwent preoperative T2-weighted (T2w), dynamic contrast-enhanced (DCE) and diffusion-weighted (DW) MRI at 1.5T. Localization of suspicious lesions was recorded for each of 24 standardized regions of interest on the different MR images and correlated with the patho- logic findings. Generalized estimating equations (GEE) were used to estimate the sensitivity, specificity, accu- racy, positive, and negative predictive value for every MRI modality, as well as to evaluate the influence of Gleason score and pT-stage. Tumor volume measurements on his- topathological specimens were correlated with those on the different MR modalities (Pearson correlation). Results: DW MRI had the highest sensitivity for tumor localization (31.1% vs. 27.4% vs. 44.5% for T2w, DCE, and DW MRI, respectively; P < 0.005), with more aggres- sive or more advanced tumors being more easily detected with this imaging modality. Significantly higher sensitivity values were obtained for the combination of T2w, DCE, and DW MRI (58.8%) as compared to each modality alone or any combination of two modalities (P < 0.0001). Tumor volume can most accurately be assessed by means of DW MRI (r ¼ 0.75; P < 0.0001). Conclusion: Combining T2w, DCE, and DW imaging sig- nificantly improves prostate cancer localization. Key Words: prostate cancer; dynamic contrast-enhanced (DCE) MRI; diffusion-weighted (DW); MRI; whole-mount histopathology J. Magn. Reson. Imaging 2013;37:1392–1401. V C 2012 Wiley Periodicals, Inc. FOCAL THERAPY is becoming an attractive alternative for whole-gland treatment of prostate cancer, as it aims to reduce whole-gland treatment-related side effects by selectively ablating the tumor lesion while at the same time sparing the surrounding nonmalignant paren- chyma and organs at risk (1). As for external beam radiotherapy, the development of high-precision radia- tion delivery techniques, eg, intensity-modulated radio- therapy, has paved the way for focal boost radiation treatment (2,3). Since whole-gland dose-escalation is limited due to a high probability of normal tissue com- plications, escalating the radiation dose only to the macroscopic tumor nodule(s) would be a valuable al- ternative without a significantly increased risk of nor- mal tissue injury (2,4). An additional argument for focal dose-escalation is the fact that local recurrences usually initiate at the primary tumor site (5,6). The implementation of this focal treatment strategy obvi- ously necessitates accurate imaging (7). Magnetic resonance imaging (MRI) is an ideal tool to guide focal therapy. Conventional T2-weighted MRI (T2w MRI) provides anatomical and morphological 1 Department of Radiation Oncology, University Hospitals Leuven, Leuven, Belgium. 2 Department of Urology, University Hospitals Leuven, Leuven, Belgium. 3 Department of Histopathology, University Hospitals Leuven, Leuven, Belgium. 4 Department of Radiology, University Hospitals Leuven, Leuven, Belgium. 5 Department of Electrical Engineering, Katholieke Universiteit Leuven, Leuven, Belgium. 6 IBBT-KULeuven Future Health Department, Katholieke Universiteit Leuven, Leuven, Belgium. The first two authors contributed equally to this work. Contract grant sponsor: Institute for the Promotion of Innovation by Science and Technology in Flanders, Belgium; Contract grant number: IWT TBM 060793; Contract grant sponsor: National Cancer Plan Action 29, Belgium; Contract grant sponsor: Research Foundation-Flanders, Belgium (research fellowship to S.I.); Contract grant sponsor: Emmanuel van der Schueren research grant from the Flemish League against Cancer, Belgium (to S.I); K.H. is a fundamental clinical researcher of the Research Foundation-Flanders, Belgium. *Address reprint requests to: S. Isebaert, University Hospitals Leuven, Campus Gasthuisberg, Department of Radiation Oncology, Box 7003, Herestraat 49, 3000 Leuven, Belgium. E-mail: sofie.isebaert@med.kuleuven.be Received September 6, 2011; Accepted October 4, 2012. DOI 10.1002/jmri.23938 View this article online at wileyonlinelibrary.com. JOURNAL OF MAGNETIC RESONANCE IMAGING 37:1392–1401 (2013) CME V C 2012 Wiley Periodicals, Inc. 1392