Is there a diagnostic benefit of late-phase abdomino-pelvic PET/CT after urination as part of whole-body 68 Ga-PSMA-11 PET/CT for restaging patients with biochemical recurrence of prostate cancer after radical prostatectomy?

Janna Morawitz; Julian Kirchner; Johannes Hertelendy; Christina Loberg; Lars Schimmöller; Mardjan Dabir; Lena Häberle; Eduards Mamlins; Christina Antke; Christian Arsov; Gerald Antoch; Lino M Sawicki

doi:10.1186/s13550-022-00885-z

Is there a diagnostic benefit of late-phase abdomino-pelvic PET/CT after urination as part of whole-body ⁶⁸ Ga-PSMA-11 PET/CT for restaging patients with biochemical recurrence of prostate cancer after radical prostatectomy?

EJNMMI Res. 2022 Mar 4;12(1):12. doi: 10.1186/s13550-022-00885-z.

Affiliations

¹ Department of Diagnostic and Interventional Radiology, Medical Faculty, University Dusseldorf, Moorenstrasse 5, 40225, Düsseldorf, Germany.
² Department of Diagnostic and Interventional Radiology, Medical Faculty, University Dusseldorf, Moorenstrasse 5, 40225, Düsseldorf, Germany. julian.kirchner@med.uni-duesseldorf.de.
³ Department of Nuclear Medicine, Medical Faculty, University Dusseldorf, 40225, Düsseldorf, Germany.
⁴ Institute of Pathology, Medical Faculty, Heinrich-Heine-University and University Hospital Duesseldorf, Duesseldorf, Germany.
⁵ Department of Urology, Medical Faculty, University Dusseldorf, 40225, Düsseldorf, Germany.

Abstract

Background: To assess the diagnostic value of an additional late-phase PET/CT scan after urination as part of ⁶⁸ Ga-PSMA-11 PET/CT for the restaging of patients with biochemically recurrent prostate cancer (BCR).

Methods: This retrospective trial included patients with BCR following radical prostatectomy, who underwent standard whole-body early-phase PET/CT performed 105 ± 45 min and an additional late-phase PET/CT performed 159 ± 13 min after injection of ⁶⁸ Ga-PSMA-11. Late-phase PET/CT covered a body volume from below the liver to the upper thighs and was conducted after patients had used the bathroom to empty their urinary bladder. Early- and late-phase images were evaluated regarding lesion count, type, localisation, and SUVmax. Reference standard was histopathology and/or follow-up imaging.

Results: Whole-body early-phase PET/CT detected 93 prostate cancer lesions in 33 patients. Late-phase PET/CT detected two additional lesions in two patients, both local recurrences. In total, there were 57 nodal, 28 bone, and 3 lung metastases, and 7 local recurrences. Between early- and late-phase PET/CT, lymph node metastases showed a significant increase of SUVmax from 14.5 ± 11.6 to 21.5 ± 17.6 (p = 0.00007), translating to a factor of + 1.6. Benign lymph nodes in the respective regions showed a significantly lower increase of SUVmax of 1.4 ± 0.5 to 1.7 ± 0.5 (p = 0.0014, factor of + 1.2). Local recurrences and bone metastases had a SUVmax on late-phase PET/CT that was + 1.7 and + 1.1 times higher than the SUVmax on early-phase PET/CT, respectively.

Conclusion: In patients with BCR following radical prostatectomy, an additional abdomino-pelvic late-phase ⁶⁸ Ga-PSMA-11 PET/CT scan performed after emptying the urinary bladder may help to detect local recurrences missed on standard whole-body ⁶⁸ Ga-PSMA-11 PET/CT. Lymph node metastases show a higher SUVmax and a stronger increase of SUVmax than benign lymph nodes on late-phase PET/CT, hence, biphasic ⁶⁸ Ga-PSMA-11 PET/CT might help to distinguish between malignant and benign nodes. Bone metastases, and especially local recurrences, also demonstrate a metabolic increase over time.

Keywords: Biochemical recurrence; Lesion detection; PET/CT; PSMA; Prostate cancer.