Diagnostic accuracy of 68 Ga-prostate-specific membrane antigen (PSMA) positron-emission tomography (PET) and multiparametric (mp)MRI to detect intermediate-grade intra-prostatic prostate cancer using whole-mount pathology: impact of the addition of 68 Ga-PSMA PET to mpMRI

BJU Int. 2019 Nov:124 Suppl 1:42-49. doi: 10.1111/bju.14794. Epub 2019 Jul 9.

Abstract

Objective: To evaluate the ability of prostate-specific membrane antigen (PSMA)-positron-emission tomography (PET)/computed tomography (CT) to detect intermediate-grade intra-prostatic prostate cancer (PCa), and to determine if PSMA-PET improves the diagnostic accuracy of multiparametric magnetic resonance imaging (mpMRI).

Patients and methods: A total of 56 consecutive patients with International Society of Urological Pathology (ISUP) grade 2-3 PCa after radical prostatectomy, who underwent both mpMRI and PSMA-PET CT (hereafter PSMA-PET) preoperatively, were enrolled in this study. The accuracy of PSMA-PET, mpMRI alone, and the two procedures in combination was analysed for identifying ISUP grades 1-3 within a 12-segment model. The accuracy of a combined predictive model (PSMA-PET and mpMRI) was determined. Receiver-operating characteristic curve analysis to determine the optimal standardized uptake value (SUVmax ) for PSMA-PET in discriminating between ISUP grades 1 and ≥2 was performed.

Results: On a per-patient basis, the sensitivities for PSMA-PET and mpMRI in identifying ISUP grades 2-3 PCa were 100% and 97%, respectively. Assessing ISUP grade ≥2 PCa using a 12-segment analysis, PSMA-PET demonstrated greater diagnostic accuracy (area under the curve), sensitivity, specificity, negative predictive value (NPV) and positive predictive value (PPV), with values of 0.91, 88%, 93%, 95% and 85%, respectively, than did mpMRI (Prostate Imaging Reporting and Data System [PI-RADS] 3-5), at 0.79, 68%, 91%, 87%, and 75%, respectively. When used in combination (PSMA-PET and mpMRI PIRADS 4-5), sensitivity, specificity, NPV and PPV were 92%, 90%, 96% and 81%, respectively. The sensitivity for both techniques reduced markedly when assessing ISUP grade 1 PCa (18% for PSMA-PET, 10% for mpMRI). An SUVmax value of 3.95 resulted in 94% sensitivity and 100% specificity.

Conclusion: PSMA-PET is accurate in detecting segments containing intermediate-grade intra-prostatic PCa (ISUP grade ≥ 2), compared with and complementary to mpMRI. By contrast the detection rate for ISUP grade 1 disease for both PSMA-PET and mpMRI was low.

Keywords: PSMA; #PCSM; #ProstateCancer; PET-CT; diagnostic imaging; mpMRI; prostate cancer.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Aged
  • Dimensional Measurement Accuracy
  • Gallium Radioisotopes / pharmacology*
  • Health Care Surveys
  • Humans
  • Male
  • Middle Aged
  • Multiparametric Magnetic Resonance Imaging*
  • Positron Emission Tomography Computed Tomography*
  • Prostate / diagnostic imaging
  • Prostate / pathology*
  • Prostate-Specific Antigen / analysis
  • Prostatectomy*
  • Prostatic Neoplasms / diagnostic imaging
  • Prostatic Neoplasms / pathology*
  • ROC Curve
  • Radiopharmaceuticals / pharmacology*
  • Reproducibility of Results
  • Sensitivity and Specificity

Substances

  • Gallium Radioisotopes
  • Radiopharmaceuticals
  • Prostate-Specific Antigen