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Purpose Our goal was to evaluate the usefulness of apparent diffusion coefficient (ADC) ratios in discriminating true from false positives in multiparametric (mp) prostate MRI in clinical practice. Methods We retrospectively evaluated 98 prostate lesions in a series of 73 patients who had undergone prostate mpMRI and standard 12-core prostatic biopsy in our institution from 2016 to 2018. Two experienced radiologists performed double blind ADC value quantifications of both MRI-identified lesions and apparently benign contralateral prostatic parenchyma in a circular region of interest (ROI) of ∼10 mm2. The ratios between the mean values of both measurements (i.e., ADC ratio mean) and between the minimum value of the lesion and the maximum value of the benign parenchyma (i.e., ADC ratio min-max) were automatically calculated. The malignancy of all lesions was determined through biopsy according to Gleason score (GS ≥ 6) and localization. Results For Reader 1, the area under the ROC curve (AUC) of ADC ratio mean and ADC ratio min-max were 0.72 and 0.67, respectively, whereas for Reader 2 these values were 0.74 and 0.71, respectively. The best cut-off values for ADC ratio means were ≥ 0.5 (Reader 1) and ≥ 0.6 (Reader 2), with a sensitivity of 76.3 % and 84.2 % and a specificity of 51.7 % and 50 %, respectively. Moreover, based on a threshold of 0.6, no clinically significant prostate cancer (csPCa) was missed by Reader 1, while only one went unnoticed by Reader 2. Conclusion The ADC ratio is a useful and moderately accurate complementary tool to diagnose prostate cancer in the mp-MRI.

Objective To assess the efficacy of single, double and triple doses of 1M gadolinium in the magnetic resonance (MR) evaluation of multiple sclerosis (MS) lesions in order to establish the best trade-off in terms of dose and number of injections. Materials and methods Twenty-three patients with relapsing remitting or secondary progressive MS underwent MR scans of the brain, spine or both. Signal intensity, the number of enhancing lesions and the areas of MS plaque were measured in T1-weighted images before and after single, double or triple doses of contrast medium. Wilcoxon's two-sample test and the Mann–Whitney U -test were used to evaluate the differences between the groups, and between doses in the same patient. Results There was no significant difference in area signal intensity or the number of enhancing lesions between the group examined after a single injection of double-dose (DD) contrast medium and the group examined after multiple injections of a triple dose (TD). The difference in the areas of enhancement and signal intensity between a single dose (SD) and TD significantly increased after the second bolus. Conclusion Gadolinium injections in MS patients can be optimised by giving a single DD bolus, which leads to the same results as a TD administered as two boli.