Assessment of uveal melanomas using advanced diffusion-weighted imaging techniques: value of reduced field of view DWI ("zoomed DWI") and readout-segmented DWI (RESOLVE)

Background Diffusion-weighted imaging (DWI) has become an important tool for lesion characterization. Advanced techniques of DWI may be used to improve image quality. Purpose To evaluate multi-shot segmented DWI (rs-EPI, RESOLVE) and reduced field-of view DWI (rFOV-EPI, "zoomed" EPI) in patients with ocular melanoma and to compare image quality and diagnostic performance in differentiation of melanoma from retinal detachment. Material and Methods In this prospective and IRB-approved trial, we examined 26 patients using methods including conventional single-shot echo-planar DWI (ss-EPI), rs-EPI, and rFOV-EPI. Subjective image quality was compared using a four-point score and the maximum tumor length was measured in all sequences. Apparent diffusion coefficient (ADC) measurements were performed using a region-of interest analysis. Tumor delineation and differences in ADC values between melanomas and retinal detachments were compared. Results Diffusion restriction was markedly reduced in melanomas in all applied image techniques. Subjective image quality was significantly higher for rFOV-EPI (score = 3.5 +/- 0.5) compared with rs-EPI (score = 3.3 +/- 0.6) and ss-EPI (score = 2.5 +/- 0.9). Regarding tumor diameter measurements, rFOV-EPI showed the best agreement compared with high-resolution conventional sequences. ADC measurements of the tumor and retinal detachment differed significantly (P < 0.001) with the rFOV-EPI performing best (sensitivities and specificities compared with T1-weighted ss-EPI 61%/82%; rFOV-EPI 86%/92%; rs-EPI 79%/92%, respectively). Conclusion rFOV-EPI showed improved image quality compared with ss-EPI and rs-EPI, the most accurate tumor delineation and the best differentiation from retinal detachments in our patients.