Faculty Bibliography

In patients with metallic hip implants, distortions, and other artifacts relating to the echo-planar imaging acquisition may render prostate diffusion-weighted imaging (DWI) nondiagnostic. Reduced field-of-view (rFOV) acquisition, using parallel transmission and focused excitation, is a novel DWI approach that reduces distortions and improves images quality. This article presents images from both standard and rFOV DWI acquisitions in 2 prostate cancer patients with hip implants, showing the effect of rFOV DWI for improving tumor localization. The findings have implications for the potential application of magnetic resonance imaging for guiding targeted biopsy and planning focal therapy in the growing population of patients with hip implants.

OBJECTIVE:The purpose of this study was to compare image quality and tumor assessment at prostate magnetic resonance imaging (MRI) between reduced field-of-view diffusion-weighted imaging (rFOV-DWI) and standard DWI (st-DWI). METHODS:A total of 49 patients undergoing prostate MRI and MRI/ultrasound fusion-targeted biopsy were included. Examinations included st-DWI (field of view [FOV], 200 × 200 mm) and rFOV-DWI (FOV, 140 × 64 mm) using a 2-dimensional (2D) spatially-selective radiofrequency pulse and parallel transmission. Two readers performed qualitative assessments; a third reader performed quantitative evaluation. RESULTS:Overall image quality, anatomic distortion, visualization of capsule, and visualization of peripheral/transition zone edge were better for rFOV-DWI for reader 1 (P ≤ 0.002), although not for reader 2 (P ≥ 0.567). For both readers, sensitivity, specificity, and accuracy for tumor with a Gleason Score (GS) of 3 + 4 or higher were not different (P ≥ 0.289). Lesion clarity was higher for st-DWI for reader 2 (P = 0.008), although similar for reader 1 (P = 0.409). Diagnostic confidence was not different for either reader (P ≥ 0.052). Tumor-to-benign apparent diffusion coefficient ratio was not different (P = 0.675). CONCLUSIONS:Potentially improved image quality of rFOV-DWI did not yield improved tumor assessment. Continued optimization is warranted.