In a subpopulation of patients with newly diagnosed prostate cancer, staged with F18-PSMA-1007 PET/CT, 128 patients accepted to have a masked Na[18F]-PET/CT performed for research purposes only. We aimed to compare the diagnostic accuracy of the two examinations for staging, the effect on patients' (T)NM classification, and whether the expected different staging led to a change in treatment offered to the patients. For these analyses, we established a research Multi-Disciplinary Team.
We showed that the sensitivity for staging lymph node metastases was higher with PSMA-PET/CT than with NaF-PET/CT. In contrast, there was no significant difference in the detection of bone metastases between the two scanning procedures.
For most patients, the (T)NM classification was the same in both examinations (83%). Still, due to higher sensitivity in detecting lymph node metastases, more lymph nodes were identified with PSMA-PET/CT than with NaF-PET/CT, thereby detecting more patients with lymph node metastatic disease. As radiotherapy to the pelvic lymph nodes was included in the suggested field of radiation in some of these patients, it did not change the treatment offered to all these patients. However, in 14% of patients, PSMA-PET/CT staging changed the treatment strategy compared with NaF-PET/CT.
We examined a cohort of patients undergoing radical prostatectomy with lymph node dissection who had no lymph node metastases on preoperative PSMA imaging. Among the 31 patients, three microscopic lymph node metastases (≤1 mm) were identified in two individuals, underscoring the high sensitivity and accuracy of PSMA PET/CT for lymph node staging
18F-PSMA-1007 PET/CT detecting lymph node metastases, not visualized with CT.
Written by: Karen Middelbo Buch-Olsen, Board-certified specialist, Department of Nuclear Medicine, OUH Odense, Denmark
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