Original Research Anatomical and Metabolic Assessment of Prostate Using a 3-Tesla MR Scanner With a Custom-Made External Transceive Coil: Healthy Volunteer Study Yasushi Kaji, MD, 1–3 Kagayaki Kuroda, PhD, 3,4 Takaki Maeda, MD, 1 Yuri Kitamura, MD, 1 Toshitaka Fujiwara, MD, 5 Yuichiro Matsuoka, PhD, 3 Mitsuru Tamura, PE, 6 Naoyuki Takei, PhD, 7 Tsuyoshi Matsuda, RT, 7 and Kazuro Sugimura, MD 1 Purpose: To examine the possibility of using a 3 Tesla (T) magnetic resonance (MR) scanner with a custom-made ex- ternal coil to obtain ductal details of the prostate, high- quality spectra, and metabolite mapping corresponding to prostate zonal anatomy in healthy volunteers. Materials and Methods: MRI and two-dimensional (2D) chemical shift imaging (CSI) were performed in 16 healthy volunteers using a 3T scanner with a custom-made exter- nal transmit-receive (transceive) coil. Visualization of the prostatic duct-like structure was analyzed on T2-weighted (T2W) images. The resolution of the metabolite peaks and the distribution of metabolites in CSI were also assessed. Results: In the axial plane, 3-mm-thick images were better than 4-mm-thick images with the same voxel volume for assessing duct-like structures and prostatic urethra. Dif- ferentiation between inner and outer citrate (Cit) peaks was frequently observed (29 out of 30). The mean peak area ratio of choline (Cho) plus creatine (Cr) over Cit in the peripheral zone (PZ) was significantly lower than in the transition zone (TZ) (P = 0.014). Conclusion: 3T MR examinations of the prostate using an external coil allow information to be collected about the details of duct-like structures, the high-quality spectra of Cit, and the zone-specific distribution of metabolites. Key Words: 3 Tesla; MR spectroscopy; MR coils; prostate; citrate J. Magn. Reson. Imaging 2007;25:517–526. © 2007 Wiley-Liss, Inc. DETECTION OF PROSTATE CANCER, especially in its early stages, is increasing due to serum prostate spe- cific antigen (PSA) screening and systematic prostate biopsy (1). It has been reported that early T1c cancer tends to distribute in the anterior part of the apex and midgland prostate (2), and awareness of the importance of assessing the whole prostate (both the peripheral zone (PZ) and transition zone (TZ)) is increasing as a result. MRI with an endorectal surface coil is a useful mo- dality for staging prostate cancer (3); however, false results may occur in differentiating cancer from benign changes (4 –7). Proton MR spectroscopy (MRS) of the prostate can diagnose prostate cancer in the PZ based on citrate (Cit) and choline (Cho) levels using an endo- rectal surface coil (8 –10), but the voxel volume and spatial resolution are not sufficient to diagnose small prostate cancers. A strong magnetic field strength scanner (3T) can improve the signal-to-noise ratio (SNR) and thus pro- vide better spectral resolution compared to a 1.5T clin- ical scanner. Two recent studies of prostate MRI using a 3T endorectal surface coil have been reported (11,12). Prostate MRI and MRS using an external coil at high magnetic field strength is also expected to have greater efficacy than the conventional 1.5T scanner with an external coil. There is only one report in the literature about 3T MRI and single-voxel spectroscopy of the pros- tate using an external coil, and little has been reported about the anatomical structure of the prostate and the characteristics of prostate metabolites (13). In this study we assessed the ability of a 3T scanner with a custom-made external coil to provide ductal de- tails of prostate structures, high-quality spectra, and 1 Department of Radiology, Kobe University, Graduate School of Medi- cine, Kobe, Japan. 2 Department of Radiology, Dokkyo Medical University, School of Med- icine, Mibu, Japan. 3 Department of Image-Based Medicine, Institute of Biomedical Re- search and Innovation, Kobe, Japan. 4 Department of Human and Information Sciences, Faculty of Informa- tion and Electronics, Tokai University, Hiratsuka, Japan. 5 Department of Radiology, Kyoto University, Graduate School of Med- icine, Kyoto, Japan. 6 Tamura Artistic Research, Tokyo, Japan. 7 GE Yokogawa Medical Systems, Tokyo, Japan. Contract grant sponsor: New Energy and Industrial Technology Develop- ment Organization (NEDO), Japan; Contract grant number: 1999-2003. Presented at the 11th Annual Meeting of ISMRM, Toronto, Canada, 2003. Address reprint requests to: Y.K., Department of Radiology, Dokkyo Medical University, School of Medicine, 880 Kita-kobayashi, Mibu, Tochigi 321-0293, Japan. E-mail: ykaji@dokkyomed.ac.jp Received August 16, 2005; Accepted September 27, 2006. DOI 10.1002/jmri.20829 Published online 5 February 2007 in Wiley InterScience (www. interscience.wiley.com). JOURNAL OF MAGNETIC RESONANCE IMAGING 25:517–526 (2007) © 2007 Wiley-Liss, Inc. 517