Impact of initial imaging with gallium-68 dotatate PET/CT on diagnosis and management of patients with neuroendocrine tumors (NETs): A sequential case series.

Abstract

379 Background: Somatostatin analogue functional imaging with Ga-68 Dotatate PET/CT has demonstrated superiority in lesion detection in patients with NETs. The effect of this novel imaging modality on US clinical practice and its usefulness in different types of NETs is not well described. We describe the impact of initial NETSPOT imaging on diagnosis and management in NET patients at a large urban medical center. Methods: Consecutive patients diagnosed with NETs and referred to our institution who received an initial Ga-68 Dotatate PET/CT between 07/2017-09/2018 were included. Imaging was reviewed and compared to prior available CT, MRI, and/or In-111 Pentetreotide scans. Results: Among 101 patients, 51/50 were female/male, tumor origins were gastroenteropancreatic (GEP) (75%), Unknown Primary (UP) (13%), lung (8%), thymic (2%), and other (2%). All tumors were histologically well/moderately differentiated and 37/51/3/10 were G1/G2/G3/Unknown, respectively. Initial imaging with Ga-68 Dotatate PET/CT revealed additional metastatic disease in 37 of 77(48%) patients with prior evidence of metastatic disease. Most common sites were distant lymph nodes (18), bone (15) and liver (9), peritoneal/pleural (4). A previously UP tumor was identified in 3 patients. No patients with metastatic lung carcinoids (6 atypical, 2 typical) or thymic NETs (2 atypical/G2) NETs had evidence of Ga-68 Dota PET/CT uptake above reference liver SUV levels. Results of imaging altered patient management as follows: 14 initiated systemic therapy due to documentation of progression, in 6 surgical therapy was altered, in 4 biopsy/other management was changed. In 11 patients with no tumor Ga-68 Dotatate uptake, decisions about use of PRRT and somatostatin analogues was altered. Conclusions: In this series, Ga-68 Dotatate PET/CT altered diagnosis and management in 35/101 NET patients. Among GEP and UP NETs, Dotatate imaging diagnosed primarily new nodal, bone, liver and pleural/peritoneal metastases missed by other imaging modalities. Results support the routine use of Ga-68 Dotatate PET/CT in the care of patients with advanced and early stage NETS.