Tumor Detection of ¹⁸F-PSMA-1007 in the Prostate Gland in Patients with Prostate Cancer Using Prostatectomy Specimens as Reference Method

Abstract

Prostate-specific membrane antigen (PSMA) radiopharmaceuticals used with PET/CT are a promising tool for managing patients with prostate cancer. This study aimed to determine the accuracy of ¹⁸F-PSMA-1007 PET/CT for detecting tumors in the prostate gland using radical prostatectomy specimens as a reference method and to determine whether a correlation exists between ¹⁸F-PSMA-1007 uptake and the International Society of Urological Pathology grade and prostate specific antigen (PSA) level at diagnosis. <b>Methods:</b> Thirty-nine patients referred for ¹⁸F-PSMA-1007 PET/CT for initial staging and who underwent radical prostatectomy within 4 mo were retrospectively included. Uptake of ¹⁸F-PSMA-1007 indicative of cancer was assessed, and SUV_max and total lesion uptake were calculated for the index tumor. Histopathology was assessed from radical prostatectomy specimens. True-positive, false-negative, and false-positive lesions were calculated. <b>Results:</b> In 94.9% of patients, the index tumor was correctly identified with PET. SUV_max was significantly higher in the tumors than in the normal prostate tissue, but no significant differences were found between different International Society of Urological Pathology grades and SUV_max. There was a poor correlation between PSA at diagnosis and SUV_max (<i>r</i> = 0.23) and moderate agreement between PSA at diagnosis and total lesion uptake (<i>r</i> = 0.67). When all tumors (also nonindex tumors) were considered, many small tumors (∼1–2 mm) were not detected with PET. <b>Conclusion:</b>¹⁸F-PSMA-1007 PET/CT performs well in correctly identifying the index tumor in patients with intermediate- to high-risk prostate cancer. Approximately 5% of the index tumors were missed by PET, a finding that agrees with previous studies.

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