Cerenkov Luminescence Imaging in Prostate Cancer: Not the Only Light That Shines

Cerenkov luminescence imaging (CLI) is a novel imaging technology that might have the ability to assess surgical margins intraoperatively during prostatectomy using ⁶⁸Ga-prostate-specific membrane antigen (⁶⁸Ga-PSMA-11). This study evaluated the accuracy of CLI compared with histopathology and, as an exploratory objective, investigated the characteristics of the identified chemiluminescence signal. Methods: After intravenous injection of a mean ⁶⁸Ga-PSMA-11 activity of 69 MBq intraoperatively, all excised specimens were imaged with CLI. Areas of increased signal were marked for histopathologic comparison and scored for the likelihood of being a positive surgical margin (PSM) using a 5-point Likert scale. In addition, the chemiluminescence signal was investigated in 3 radioactive and 3 nonradioactive specimens using CLI. Results: In 15 patients, the agreement between CLI and histopathology was 60%; this improved to 83% when including close surgical margins (≤1 mm). In 6 hot spots, CLI correctly identified PSMs on histopathology, located at the apex and mid prostate. In all 15 patients, an increased signal at the prostate base was observed, without the presence of the primary tumor in this area in 8 patients. This chemiluminescence signal was also observed in nonradioactive prostate specimens, with a half-life of 48 ± 11 min. The chemiluminescence hampered the visual interpretation of 4 PSMs at the base. Conclusion: CLI was able to correctly identify margin status, including close margins, in 83% of the cases. The presence of a diathermy-induced chemiluminescent signal hampered image interpretation, especially at the base of the prostate. In the current form, CLI is most applicable to detect PSMs and close margins in the apex and mid prostate.