Preliminary findings suggest increased value for DK imaging compared with standard DW imaging in prostate cancer assessment.

http://radiology.rsna.org/lookup/suppl/doi:10.1148/radiol.12111281/-/DC1.

ADC entropy showed significantly greater accuracy than the more traditional metric of mean ADC for distinguishing benign and malignant adnexal lesions. Although whole-lesion ADC entropy provides a straightforward and objective measurement, its potential benefit decreases with greater reader experience.

Use of a b-value of 2000 s/mm(2) compared with a b-value of 1000 s/mm(2) resulted in improved tumor sensitivity and higher tumor-to-PZ contrast on the acquired DW images, although performance of the ADC maps corresponding with the two b-values was similar. Correlation with tumor size was greater for either ADC map than for either acquired DW image set.

The sensitivity and PPV of multiparametric MRI for index lesion localization were moderate, although they improved in the setting of more aggressive pathologic features and a greater number of abnormal MRI parameters, respectively.

Although high malignancy rates were observed for both Bosniak category III and IV lesions, our results suggest that such malignant cysts are usually early-stage tumors with a low histologic grade. Lesions that underwent follow-up remained unchanged on control examinations. These findings may indicate low aggressiveness of these lesions, supporting the idea that more conservative approaches may be used.

No abstract

Background Evaluation of interobserver agreement of the PI‐RADS v2 lexicon is important to validate the uniformity of this widely used classification. Purpose To determine the interobserver agreement of PI‐RADS v2 lexicon among eight radiologists with varying levels of experience. Study Type Retrospective. Population In all, 160 consecutively imaged men with confirmatory targeted biopsy. Field Strength/Sequence 3T scanner without an endorectal coil. T2‐weighted imaging (T2w), diffusion‐weighted imaging (DWI), apparent diffusion coefficient (ADC) map and dynamic contrast‐enhanced sequence were performed. Assessment Eight radiologists (two highly experienced, two moderately experienced, and four less experienced) independently read 130 lesions in the peripheral zone (PZ) and 30 lesions in the transition zone (TZ), blinded to clinical MRI indication and biopsy results. The features described in PI‐RADS v2 for TZ and PZ lesions were evaluated. Statistical Tests Conger's kappa, percentage of concordance, and first‐order agreement coefficient (AC1) were used to evaluate interobserver agreement. Results From the features evaluated on PZ lesions, definite extraprostatic extension (EPE) / invasive behavior on T2w had good agreement (AC1 = 0.80), and the others had fair agreement (AC1 = 0.32–0.40). From the features evaluated on TZ lesions, two had good agreement: definite EPE/invasive behavior (AC1 = 0.77) and moderate/marked hypointensity (AC1 = 0.67) on T2w. Encapsulation and lenticular shape on T2w, focal (not indistinct) on DWI and ADC map, and marked hypointensity on ADC map (AC1 = 0.45 to 0.60) had moderate agreement, whereas heterogeneous and circumscribed (not obscured margins) on T2w, marked hyperintensity on high‐b‐value DWI, and the presence or not of early enhancement in the lesion/region of the lesion (AC1 = 0.30 to 0.38) had fair agreement. Data Conclusion Interobserver agreement in PI‐RADS v2 lexicon ranges from fair to good among radiologists and improves with increasing experience. Level of Evidence: 2 Technical Efficacy: Stage 2 J. Magn. Reson. Imaging 2020;51:593–602.