Radiotherapy for prostate cancer: Effect of gold fiducial markers on diffusion-weighted magnetic resonance imaging.

PURPOSE There has been an increase in the use of gold fiducial markers to ensure precise radiotherapy delivery in prostate cancer patients. However, metal artifacts may affect the quality of subsequent imaging used to assess disease status following treatment. In this study, we evaluated the effect of gold fiducial markers on magnetic resonance imaging (MRI), particularly on diffusion-weighted imaging (DWI). MATERIAL AND METHODS Among 57 patients with prostate cancer, 21 patients in whom two gold markers were placed in the prostate tumor with abnormal signal intensity on DWI were evaluated. The effect of the markers on DWI was evaluated on a scale of 1-5, with a high score indicating clinical usefulness. Change inapparent diffusion coefficient (ADC; 10-3 mm2 /s) from before to after marker placement was also evaluated. RESULTS The mean effect of the markers on DWI was 4.3 (standard deviation [SD] 1.3, range 2-5) points. The mean change in ADC was 0.045 (SD 0.041, range 0.025-0.089) × 10-3 mm2 /s. CONCLUSIONS The gold fiducial markers demonstrated negligible effect on DWI quality. Therefore, gold markers do not affect MRI quality, particularly DWI, and may be used during follow-up in prostate cancer patients.