68Ga-DOTATATE PET/CT compared to standard imaging in metastatic neuroendocrine tumors: a more sensitive test to detect liver metastasis?

Abstract

68Ga-DOTATATE PET is becoming a popular imaging technique for detecting neuroendocrine tumors (NETs). The sensitivity and specificity of 68Ga-DOTATATE PET compared to standard cross-sectional imaging with triple phase CT or MRI with Eovist has not been studied extensively. 68Ga-DOTATATE PET scans ordered at our institution between 11/2017 and 7/2018 were reviewed. Patients with evidence of liver metastases were sorted and cross-sectional imaging results were reviewed. Specifically, the number of lesions detected by standard cross-sectional imaging versus 68Ga-DOTATATE PET was compared. 32 patients with 68Ga-DOTATATE PET scans and a corresponding MRI or CT were identified. Primary tumors were pancreatic (43.8%), small bowel (25%), hepatic (9.4%), gastric (6.3%), appendiceal (3.1%), and not localized (12.5%). 26/32 (81%) patients had CT scans and 17/32 (53%) had MRI scans. 25/32 (78%) patients had at least equal or increased number of lesions identified on 68Ga-DOTATATE PET when compared with CT or MRI. 7/32 (21.9%) had fewer lesions on 68Ga-DOTATATE PET compared to CT or MRI. However, 3 of these cases had numerous liver lesions. The overall sensitivity and specificity of 68Ga-DOTATATE PET are 92.9% and 75% respectively. 68Ga-DOTATATE PET appears to have superior sensitivity in detecting metastatic NET to the liver. Further studies are needed to determine if it should be considered the test of choice for evaluating patients with metastatic NET to the liver. While standard cross-sectional imaging will be needed for surgical planning, 68Ga-DOTATATE PET will identify lesions that may not be seen on other imaging modalities.