Prostate Imaging-Reporting and Data System Version 2: Beyond Prostate Cancer Detection

Abstract

The main purpose of Prostate Imaging-Reporting and Data System Version 2 (PI-RADSv2) is to effectively detect clinically significant prostate cancers (csPCa) using multiparametric magnetic resonance imaging. Since the first introduction of PI-RADSv2, researchers have validated its diagnostic performance in identifying csPCa, and these promising data have influenced biopsy and treatment schemes. However, in this article, we focused on the potential of PI-RADSv2 in relation to various aspects of PCa such as Gleason score, tumor volume, extraprostatic extension, lymph node metastasis, and postoperative biochemical recurrence, beyond prostate cancer detection.

Keywords: Magnetic resonance imaging; PI-RADS; Prognosis; Prostate cancer; Recurrence.

Fig. 1. 69-year-old man with serum PSA level of 18.6 ng/mL and biopsy-proven GS 6 PCa.

A. T2WI showed focal hypointense area in anterior TZ of prostate gland (arrow). PI-RADSv2 score on T2WI was 5. B, C. High b-value DWI and ADC map consistently showed focal area of diffusion restriction at corresponding site (arrow). Final PI-RADSv2 score on DWI was 5. Thus, final PI-RADSv2 score was 5 for TZ lesion. D. In surgical specimen, GS 7 PCa was confirmed (dotted area). This is case of GS upgrading, which was suspected by PI-RADSv2. ADC = apparent diffusion coefficient, DWI = diffusion-weighted imaging, GS = Gleason score, PCa = prostate cancer, PI-RADSv2 = Prostate Imaging-Reporting and Data System Version 2, PSA = prostate-specific antigen, TZ = transition zone, T2WI = T2-weighted imaging

Fig. 2. DWI and ADC maps of two different patients.

A, B. 53-year-old man with serum PSA level of 7.6 ng/mL and PCa. High b-value DWI and ADC map showed focal area of diffusion restriction, measuring 0.9 cm, in left PZ of prostate gland (arrow). DWI and final PI-RADSv2 scores were 4 each. Mean tumor ADC was 0.91 × 10^-3 mm²/s. Surgery revealed GS 6 PCa. C, D. 65-year-old man with serum PSA level of 13.2 ng/mL and PCa. High b-value DWI and ADC map showed focal area of diffusion restriction, measuring 1.0 cm, in left PZ of prostate gland (arrow). DWI and final PI-RADSv2 scores were 4 each. Mean tumor ADC was 0.71 × 10^-3 mm²/s. Surgery revealed GS 7 PCa. These are cases of PCa with different GS, whose PI-RADSv2 scores were same, but tumor ADCs were different. PZ = peripheral zone

Fig. 3. 67-year-old man with serum PSA level of 22.4 ng/mL and PCa.

A, B. High b-value DWI and ADC map showed focal, indistinct area of mild diffusion restriction in right PZ of prostate gland (arrow). DWI score was 2. C. DCE MRI showed diffuse, gradual enhancement around corresponding site (arrow), which is suggestive of negative findings. Thus, final PI-RADSv2 score on DWI was 2 for PZ lesion. D. In surgical specimen, GS 6 PCa with tumor volume of 0.8 cm3 was confirmed (dotted area). According to Epstein criteria, this is case of csPCa underestimated by PI-RADSv2. CsPCa = clinically significant prostate cancer, DCE = dynamic contrast-enhanced, MRI = magnetic resonance imaging

Fig. 4. 54-year-old man with serum PSA level of 6.2 ng/mL and PCa.

A, B. High b-value DWI and ADC map showed focal area of marked diffusion restriction, measuring 1.5 cm, in right PZ of prostate gland (arrow). Overt protrusion of lesion into right extraprostatic area was also seen. DWI score was consistently 5 as measured by two independent, experienced radiologists. C. T2WI also demonstrated focal hypointense lesion with high suspicion of right EPE (arrow). Thus, final PI-RADSv2 score on DWI was also consistently 5 for PZ lesion as measured by two independent, experienced radiologists. D. In surgical specimen, GS 8 PCa with right EPE was confirmed (dotted area). EPE = extraprostatic extension

Fig. 5. 44-year-old man with serum PSA level of 22.0 ng/mL and PCa.

A, B. High b-value DWI and ADC map showed focal area of marked diffusion restriction, measuring 1.1 cm, in right PZ of prostate gland (arrow). Broad tumor-capsule contact was also seen. DWI score was 4 and 5 as measured by two independent, experienced radiologists, respectively, due to different interpretation regarding definite EPE. C. T2WI also demonstrated focal hypointense lesion with broad tumor-capsule contact (arrow). Thus, final PI-RADSv2 score on DWI was also 4 and 5 as measured by two independent, experienced radiologists, respectively. D. In surgical specimen, GS 7 PCa without EPE was confirmed (dotted area).

Fig. 6. 69-year-old man with serum PSA level of 19.7 ng/mL and PCa.

A, B. High b-value DWI and ADC map showed focal area of marked diffusion restriction, measuring 1.8 cm, in right PZ of prostate gland (arrow). Overt protrusion of lesion into right extraprostatic area was also seen. DWI score was 5. C. DCE MRI also showed positive findings (arrow). Thus, final PI-RADSv2 score was 5. D. In surgical specimen, GS 9 PCa with right EPE was confirmed (dotted area). In this patient, normal-sized (e.g., short-axis diameter < 0.8 cm) pelvic lymph node metastasis was proven surgically.