Correlation of 68Ga-DOTATATE uptake on PET/CT with pathologic features of cellular proliferation in neuroendocrine neoplasms

Objective 68Ga-DOTATATE positron emission tomography/computed tomography (PET/CT) is a useful tool for diagnosing and staging neuroendocrine neoplasms (NEN). Unlike other PET tracers like FDG, the meaningfulness and use of standardized uptake values (SUVs) of 68Ga-DOTATATE is not well-established. This study aimed to determine if a correlation exists between intensity of 68Ga-DOTATATE uptake and markers of cellular proliferation. Methods This retrospective study included 79 patients with positive 68Ga-DOTATATE PET/CT and Ki-67 and/or mitotic index (MI) available on pathology report. SUVmax of the most intense lesion and the most intense organ-matched lesion were determined. Demographics and pathology results for Ki-67 and MI were collected from the electronic medical record. Correlations and trends for correlations of SUVmax to Ki-67 and MI were performed using Kruskal-Wallis and Cuzick trend tests. Results A trend for an association between SUVmax and Ki-67 grade was found; median SUVmax of Ki-67 < 3%, 3-20%, and > 20% was 35.2, 31.8, and 12.8 (p = 0.077), respectively. There was also a trend between SUVmax and Ki-67 categories in organ-matched lesions (p = 0.08). The median organ-matched SUVmax of MI < 2, 2-20, and > 20 lesions was 34.2, 18, and 21.7, respectively, (Cuzick trend test p = 0.066). The median SUVmax for small bowel, pancreatic, and other primary locations was 27.6, 46.9, and 9.3 (p < 0.01), respectively. Conclusions The association between 68Ga-DOTATATE SUVmax, histologic grade, and primary site of NEN demonstrates its potential use for prognostication, or potentially as a surrogate for histologic grading when biopsy is not possible.