No abstract

Ocular melanoma shows a marked diffusion restriction with an ADC of less than 1000 mm/s, which is in concordance with other malignant tumor entities. Diffusion-weighted imaging helps differentiating ocular tumors from retinal detachment and should therefore be included in the ocular magnetic resonance imaging protocol if an ocular mass is suspected.

Purpose of this study was to evaluate the diagnostic performance of T1 relaxation time (T1) for differentiating prostate cancer (PCa) from benign tissue as well as high-from low-grade PCa. Twentythree patients with suspicion for PCa were included in this prospective study. 3 T MRI including a Modified Look-Locker inversion recovery sequence was acquired. Subsequent targeted and systematic prostate biopsy served as a reference standard. T1 and apparent diffusion coefficient (ADC) value in PCa and reference regions without malignancy as well as high-and low-grade PCa were compared using the Mann-Whitney U test. The performance of T1, ADC value, and a combination of both to differentiate PCa and reference regions was assessed by receiver operating characteristic (ROC) analysis. T1 and ADC value were lower in PCa compared to reference regions in the peripheral and transition zone (p < 0.001). ROC analysis revealed high AUCs for T1 (0.92; 95%-CI, 0.87-0.98) and ADC value (0.97; 95%-CI, 0.94 to 1.0) when differentiating PCa and reference regions. A combination of T1 and ADC value yielded an even higher AUC. The difference was statistically significant comparing it to the AUC for ADC value alone (p = 0.02). No significant differences were found between high-and low-grade PCa for T1 (p = 0.31) and ADC value (p = 0.8). T1 relaxation time differs significantly between PCa and benign prostate tissue with lower T1 in PCa. It could represent an imaging biomarker for PCa. Magnetic resonance imaging (MRI) has proven its potential to detect clinically significant prostate cancer (PCa) with high accuracy and provide information regarding local tumor staging 1-4. According to current guidelines, multiparametric MRI (mpMRI) combining high-resolution T2-weighted imaging (T2WI), diffusion-weighted imaging (DWI), and dynamic contrast-enhanced (DCE) MRI should be evaluated semi-quantitatively using the prostate imaging-reporting and data system (PI-RADS) 5. In addition, DWI and DCE can be evaluated quantitatively, and selected derived parameters have proven promising imaging biomarkers for the characterization of cancerous tissues within the prostate 6-9. Non-contrast-enhanced T1-weighted imaging (T1WI) currently only is used for detection of hemorrhage and no information regarding tumor characterization is derived from this sequence type 5,10. T1 mapping enables the reliable evaluation of the spin-lattice relaxation time (T1) and thus provides reproducible data on intrinsic