Prospective comparison of PI-RADS version 2 and qualitative in-house categorization system in detection of prostate cancer.
BACKGROUND
Prostate Imaging-Reporting and Data System v. 2 (PI-RADSv2) provides standardized nomenclature for interpretation of prostate multiparametric MRI (mpMRI). Inclusion of additional features for categorization may provide benefit to stratification of disease.


PURPOSE
To prospectively compare PI-RADSv2 to a qualitative in-house system for detecting prostate cancer on mpMRI.


STUDY TYPE
Prospective.


POPULATION
In all, 338 patients who underwent mpMRI May 2015-May 2016, with subsequent MRI/transrectal ultrasound fusion-guided biopsy.


FIELD STRENGTH
3T mpMRI (T2 W, diffusion-weighted [DW], apparent diffusion coefficient [ADC] map, b-2000 DWI acquisition, and dynamic contrast-enhanced [DCE] MRI).


ASSESSMENT
One genitourinary radiologist prospectively read mpMRIs using both in-house and PI-RADSv2 5-category systems.


STATISTICAL TEST
In lesion-based analysis, overall and clinically significant (CS) tumor detection rates (TDR) were calculated for all PI-RADSv2 and in-house categories. The ability of each scoring system to detect cancer was assessed by area under receiver operator characteristic curve (AUC). Within each PI-RADSv2 category, lesions were further stratified by their in-house categories to determine if TDRs can be increased by combining features of both systems.


RESULTS
In 338 patients (median prostate-specific antigen [PSA] 6.5 [0.6-113.6] ng/mL; age 64 [44-84] years), 733 lesions were identified (47% tumor-positive). Predictive abilities of both systems were comparable for all (AUC 76-78%) and CS cancers (AUCs 79%). The in-house system had higher overall and CS TDRs than PI-RADSv2 for categories 3 and 4 (P < 0.01 for both), with the greatest difference between the scoring systems seen in lesions scored category 4 (CS TDRs: in-house 65%, PI-RADSv2 22.1%). For lesions categorized as PI-RADSv2 = 4, characterization of suspicious/indeterminate extraprostatic extension (EPE) and equivocal findings across all mpMRI sequences contributed to significantly different TDRs for both systems (TDR range 19-75%, P < 0.05).


DATA CONCLUSION
PI-RADSv2 behaves similarly to an existing validated system that relies on the number of sequences on which a lesion is seen. This prospective evaluation suggests that sequence positivity and suspicion of EPE can enhance PI-RADSv2 category 4 cancer detection.


LEVEL OF EVIDENCE
1 Technical Efficacy: Stage 3 J. Magn. Reson. Imaging 2018;47:1326-1335.
['Gaur|Sonia|S|', 'Harmon|Stephanie|S|', 'Mehralivand|Sherif|S|', 'Bednarova|Sandra|S|', 'Calio|Brian P|BP|', 'Sugano|Dordaneh|D|', 'Sidana|Abhinav|A|', 'Merino|Maria J|MJ|', 'Pinto|Peter A|PA|', 'Wood|Bradford J|BJ|', 'Shih|Joanna H|JH|', 'Choyke|Peter L|PL|', 'Turkbey|Baris|B|']
D000328:Adult D000368:Aged D000369:Aged, 80 and over D019540:Area Under Curve D001706:Biopsy D003287:Contrast Media D003936:Diagnosis, Computer-Assisted D038524:Diffusion Magnetic Resonance Imaging D055088:Early Detection of Cancer D006801:Humans D061705:Image-Guided Biopsy D008297:Male D008875:Middle Aged D011446:Prospective Studies D011467:Prostate D017430:Prostate-Specific Antigen D011471:Prostatic Neoplasms D014463:Ultrasonography
detection prostate cancer PI-RADSv2 mpMRI