68Ga-PSMA PET/CT Imaging Predicting Intraprostatic Tumor Extent, Extracapsular Extension and Seminal Vesicle Invasion Prior to Radical Prostatectomy in Patients with Prostate Cancer

Christoph-Alexander J von Klot; Axel S Merseburger; Alena Böker; Sebastian Schmuck; Tobias L Ross; Frank M Bengel; Markus A Kuczyk; Christoph Henkenberens; Hans Christiansen; Hans-Jürgen Wester; Wiebke Solass; Marcel Lafos; Thorsten Derlin

doi:10.1007/s13139-017-0476-7

⁶⁸Ga-PSMA PET/CT Imaging Predicting Intraprostatic Tumor Extent, Extracapsular Extension and Seminal Vesicle Invasion Prior to Radical Prostatectomy in Patients with Prostate Cancer

Nucl Med Mol Imaging. 2017 Dec;51(4):314-322. doi: 10.1007/s13139-017-0476-7. Epub 2017 Mar 7.

Affiliations

¹ Department of Urology and Urological Oncology, Hannover Medical School, Hannover, Germany.
² Department of Urology, Campus Lübeck University Hospital Schleswig-Holstein, Lübeck, Germany.
³ Department of Nuclear Medicine, Hannover Medical School, Hannover, Germany.
⁴ Department of Radiation Oncology, Hannover Medical School, Hannover, Germany.
⁵ Radiopharmaceutical Chemistry, Technical University Munich, Garching, Germany.
⁶ Institute for Pathology, Hannover Medical School, Hannover, Germany.

Abstract

Purpose: ⁶⁸Ga-labeled prostate-specific membrane antigen (PSMA) ligand positron emission tomography/computed tomography (PET/CT) has shown promising results in patients with biochemical recurrence after primary therapy for prostate cancer. In this study, we evaluated the usefulness of PSMA I&T (imaging and therapy) PET/CT prior to radical prostatectomy.

Methods: The study population consisted of 21 patients with prostate cancer who underwent ⁶⁸Ga-PSMA I&T PET/CT before either open or laparoscopic radical prostatectomy. Intraprostatic tumor extent, extracapsular extension (ECE) and seminal vesicle invasion (SVI) were assessed on the PET/CT scans. Tracer uptake was quantified in terms of standardized uptake values (SUVs). Imaging findings were correlated with final whole-gland histopathology.

Results: Of the 21 patients, two had T stage 2b disease, nine stage 2c, six stage 3a and four stage 3b. The median Gleason score was 7. The SUV_mean of the primary tumors was 9.5 ± 8.8. SUV_mean was higher in tumors with ECE than in organ-confined tumors (13.8 ± 11.0 vs. 5.6 ± 3.2, p = 0.029). Peak tracer uptake was significantly positively correlated with Gleason score (r_s = 0.49, p = 0.025). Sensitivity, specificity, positive predictive value and negative predictive value were, respectively, 94.7%, 75.0%, 97.3% and 60.0% for tumor infiltration of an individual prostate lobe, 75.0%, 100.0%, 100.0% and 97.4% for SVI, and 90.0%, 90.9%, 90.0% and 90.9% for ECE, using an angulated contour of the prostate as the criterion. Tumor volume derived from ⁶⁸Ga-PSMA I&T PET/CT was significantly correlated with preoperative prostate-specific antigen value (r_p = 0.75, p < 0.001) and tumor volume on histopathology (r_p = 0.45, p = 0.039).

Conclusions: ⁶⁸Ga-PSMA I&T PET/CT prior to radical prostatectomy can contribute to presurgical local staging of prostate cancer. In this pilot study, ⁶⁸Ga-PSMA I&T PET/CT showed promising results for prediction of lobe infiltration, ECE and SVI.

Keywords: Extracapsular extension; PET/CT; Prostate cancer; Prostate-specific membrane antigen (PSMA); Seminal vesicle; Staging.