68Ga-PSMA ligand PET/CT integrating indocyanine green-guided salvage lymph node dissection for lymph node metastasis after radical prostatectomy

Abstract

To efficiently remove all recurrent lymph nodes (rLNs) and minimize complications, we developed a combination approach that consisted of 68 Gallium prostate-specific membrane antigen (PSMA) ligand positron emission tomography (PET)/computed tomography (CT) and integrated indocyanine green (ICG)-guided salvage lymph node dissection (sLND) for rLNs after radical prostatectomy (RP). Nineteen patients were enrolled to receive such treatment. 68 Ga-PSMA ligand PET/CT was used to identify rLNs, and 5 mg of ICG was injected into the space between the rectum and bladder before surgery. Fluorescent laparoscopy was used to perform sLND. While extensive LN dissection was performed at level I, another 5 mg of ICG was injected via the intravenous route to intensify the fluorescent signal, and laparoscopy was introduced to intensively target stained LNs along levels I and II, specifically around suspicious LNs, with 68 Ga-PSMA ligand PET/CT. Next, both lateral peritonea were exposed longitudinally to facilitate the removal of fluorescently stained LNs at levels III and IV. In total, pathological analysis confirmed that 42 nodes were rLNs. Among 145 positive LNs stained with ICG, 24 suspicious LNs identified with 68 Ga-PSMA ligand PET/CT were included. The sensitivity and specificity of 68 Ga-PSMA ligand PET/CT for detecting rLNs were 42.9% and 96.6%, respectively. For ICG, the sensitivity was 92.8% and the specificity was 39.1%. At a median follow-up of 15 (interquartile range [IQR]: 6–31) months, 15 patients experienced complete biochemical remission (BR, prostate-specific antigen [PSA] <0.2 ng ml −1 ), and 4 patients had a decline in the PSA level, but it remained >0.2 ng ml −1 . Therefore, 68 Ga-PSMA ligand PET/CT integrating ICG-guided sLND provides efficient sLND with few complications for patients with rLNs after RP.