Proton and sodium MR imaging of in vivo human prostate using dual-tuned body and endorectal coils at 7 T

[Introduction] Prostate cancer is the most frequently diagnosed male malignancy and the second most common cause of cancer death among men in the United States [1]. Prostate cancer typically appears as a low intensity mass against the bright peripheral zone on T2-weighted MR images. Despite its high sensitivity, T2-weighted MR imaging lacks adequate specificity for prostate cancer detection. In order to improve diagnostic accuracy, a combination of endorectal MR imaging and MR spectroscopy (MRS) has been advocated. MRS, however, is not widely used in daily clinical practice because of the challenges related to images acquisition and interpretation. Sodium (Na) MRI also provides useful information that reflects the physiological and biochemical characteristics of normal and cancerous tissues [2]. Prostate cancer from excised specimen was found to have low Na concentrations [3, 4]. Although Na MRI may improve the detection and characterization of prostate cancer, the image quality is poor compared to proton imaging because of its intrinsic low concentration in tissues. Therefore, it is highly desirable to image both H and Na MRI using a dual-tuned coil without changing coils. The dual-tuned imaging will maximize the benefits of acquiring both morphologic (H) and functional information (Na) for accurate diagnosis of prostate cancer in a clinical setting. To achieve this objective, we have recently developed a dual-tuned body coil with a sodium-only endorectal receiver. Thus, the purpose of this study was to assess the feasibility and performance of a dual-tuned RF coil for in-vivo H and Na MR imaging of human prostate at 7T.