Detection Rate and Localization of Prostate Cancer Recurrence Using 68Ga-PSMA-11 PET/MRI in Patients with Low PSA Values ≤ 0.5 ng/mL

J Nucl Med. 2020 Feb;61(2):194-201. doi: 10.2967/jnumed.118.225276. Epub 2019 Aug 2.

Abstract

A first analysis of simultaneous 68Ga-prostate-specific membrane antigen (PSMA)-11 PET/MRI showed some improvement in the detection of recurrent disease at low serum prostate specific antigen (PSA) values below 0.5 ng/mL compared with the already high detection rate of 68Ga-PSMA-11 PET/CT. We therefore focused on all patients with biochemical recurrence and PSA values no higher than 0.5 ng/mL to assess the detection rate for 68Ga-PSMA-11 PET/MRI. Methods: We retrospectively analyzed a cohort of 66 consecutive patients who underwent 68Ga-PSMA-11 PET/MRI for biochemical recurrence with a PSA value no higher than 0.5 ng/mL at our institution. Median PSA level was 0.23 ng/mL (range, 0.03-0.5 ng/mL). Detection of PSMA-positive lesions within the prostate fossa, local and distant lymph nodes, bones, or visceral organs was recorded. In addition, all scans with 68Ga-PSMA-11 PET/MRI-positive lesions were retrospectively assessed to analyze if lesions were detected inside or outside a standard salvage radiotherapy volume. Results: Overall, in 36 of 66 patients (54.5%) PSMA-positive lesions were detected; in 26 of 40 (65%) patients with a PSA level between 0.2 and 0.5 ng/mL and in 10 of 26 (38.5%) patients with a PSA level less than 0.2 ng/mL. Even at those low PSA values, only 8 of 66 (12.1%) patients had exclusive local recurrence. Lymph nodes were detected in 23 patients and bone metastases in 5 on 68Ga-PSMA-11 PET/MRI. In 26 of 66 patients (39.4%), PSMA-positive lesions were located outside a standard salvage radiotherapy volume. Conclusion: Our data confirm that 68Ga-PSMA-11 PET/MRI has a high detection rate for recurrent prostate cancer, even at low PSA levels no higher than 0.5 ng/mL. In addition, we show that 68Ga-PSMA-11 PET/MRI detected PSMA-positive lesions outside a standard salvage radiotherapy volume in 39.4% of all patients.

Keywords: 68Ga-PSMA-11; PET; PSMA antigen; prostate cancer; prostate-specific antigen.

MeSH terms

  • Aged
  • Edetic Acid / analogs & derivatives*
  • Gallium Isotopes
  • Gallium Radioisotopes
  • Humans
  • Magnetic Resonance Imaging*
  • Male
  • Middle Aged
  • Multimodal Imaging*
  • Oligopeptides*
  • Positron-Emission Tomography*
  • Prostate-Specific Antigen / metabolism*
  • Prostatic Neoplasms / diagnostic imaging*
  • Prostatic Neoplasms / metabolism*
  • Prostatic Neoplasms / pathology
  • Recurrence
  • Retrospective Studies

Substances

  • Gallium Isotopes
  • Gallium Radioisotopes
  • Oligopeptides
  • gallium 68 PSMA-11
  • Edetic Acid
  • Prostate-Specific Antigen