RF21 | PSUN08 Morphologic or Molecular Imaging - Diagnostic Capabilities in von Hippel-Lindau related pheochromocytoma

BACKGROUND: Within a spectrum of cancers implicated by VHL germline pathogenic variants, one rare cancer which may present in patients are pheochromocytomas (PHEOs). These tumors occur in the adrenal glands and predispose patients to a variety of morbid clinical symptoms due to the excess secretion of catecholamines. As a part of these patients’ management, imaging is important to localize the tumors of which there are both morphologic (CT and MRI) and molecular (PET/CT with (18)F-FDG, 68Ga-DOTATATE, (18)F-DOPA, and (18)F-DA) imaging modalities. PURPOSE: To determine which imaging modalities provided the optimal detection of VHL-related PHEO. METHODS: The study compared detection of 19 PHEOs (18 histologically proven and 1 is a contralateral tumor awaiting resection) in 12 patients. The CT and MRI were evaluated by a body radiologist and the PET/CT of(18)F-FDG, 68Ga-DOTATATE, (18)F-DOPA, and (18)F-DA were evaluated by a nuclear medicine physician in a blinded fashion. Both experts graded using a five-point Likert scale (1 – not PHEO and 5 – PHEO). For analysis, the Likert scale was dichotomized with 1-3 designating negative for PHEO and 4-5 positive for PHEO. The findings were reported as detection rates of positive PHEOs found on imaging to the gold standard of pathologically (aside from one contralateral PHEO awaiting surgery) proven PHEOs. The McNemar test was performed to compare the statistical relevance of detection rates between histology and the imaging modalities. Two-sided p values <0.05 were considered significant. RESULTS: The detection rates were CT 17/19 [89.5%, 95% CI = 66.9%-98.7%], MRI 17/17 [100%, 95% CI = 80.5%-100%], (18)F-FDG PET/CT 16/17 [94.1%, 95% CI = 80.5%-100%], 68Ga-DOTATATE 5/9 [55.6%, 95% CI = 21.2%-86.3%], (18)F-DOPA 12/14 [85.7%, 95% CI = 57.2%-98.2%], and (18)F-DA 4/6 [66.7%, 95% CI = 22.3%–95.7%]. All McNemar tests showed p-values greater than 0.05, which were not statistically significant. CONCLUSION: The study was performed in a small patient set with VHL-related PHEO showed MRI, with the highest detection percent followed by (18)F-FDG PET/CT. More trials with a larger patient set are needed to support the statistical relevance as it was not seen in this study. Furthermore, performing a study on a patient cohort with additional VHL associated cancers could prove clinically beneficial for patients. Presentation: Sunday, June 12, 2022 12:30 p.m. - 2:30 p.m., Sunday, June 12, 2022 1:18 p.m. - 1:23 p.m.