68Ga-DOTATATE PET/CT imaging of indeterminate pulmonary nodules and lung cancer.
OBJECTIVE
18F-FDG PET/CT is widely used to evaluate indeterminate pulmonary nodules (IPNs). False positive results occur, especially from active granulomatous nodules. A PET-based imaging agent with superior specificity to 18F-FDG for IPNs, is badly needed, especially in areas of endemic granulomatous nodules. Somatostatin receptors (SSTR) are expressed in many malignant cells including small cell and non-small cell lung cancers (NSCLCs). 68Ga-DOTATATE, a positron emitter labeled somatostatin analog, combined with PET/CT imaging, may improve the diagnosis of IPNs over 18F-FDG by reducing false positives. Our study purpose was to test this hypothesis in our region with high endemic granulomatous IPNs.


METHODS
We prospectively performed 68Ga-DOTATATE PET/CT and 18F-FDG PET/CT scans in the same 30 patients with newly diagnosed, treatment-naïve lung cancer (N = 14) or IPNs (N = 15) and one metastatic nodule. 68Ga-DOTATATE SUVmax levels at or above 1.5 were considered likely malignant. We analyzed the scan results, correlating with ultimate diagnosis via biopsy or 2-year chest CT follow-up. We also correlated 68Ga-DOTATATE uptake with immunohistochemical (IHC) staining for SSTR subtype 2A (SSTR2A) in pathological specimens.


RESULTS
We analyzed 31 lesions in 30 individuals, with 14 (45%) being non-neuroendocrine lung cancers and 1 (3%) being metastatic disease. McNemar's result comparing the two radiopharmaceuticals (p = 0.65) indicates that their accuracy of diagnosis in this indication are equivalent. 68Ga-DOTATATE was more specific (94% compared to 81%) and less sensitive 73% compared to 93%) than 18F-FDG. 68Ga-DOTATATE uptake correlated with SSTR2A expression in tumor stroma determined by immunohistochemical (IHC) staining in 5 of 9 (55%) NSCLCs.


CONCLUSIONS
68Ga-DOTATATE and 18F-FDG PET/CT had equivalent accuracy in the diagnosis of non-neuroendocrine lung cancer and 68Ga-DOTATATE was more specific than 18F-FDG for the diagnosis of IPNs. IHC staining for SSTR2A receptor expression correlated with tumor stroma but not tumor cells.
Medical Imaging Service, Tennessee Valley VA Healthcare System, Nashville, Tennessee, United States of America.|Department of Radiology and Radiological Sciences, Vanderbilt University Medical Center, Nashville, Tennessee, United States of America.|Vanderbilt-Ingram Cancer Center, Nashville, Tennessee, United States of America.
Ronald
R
Walker
Department of Surgery, Vanderbilt University Medical Center, Nashville, Tennessee, United States of America.
Stephen
S
Deppen
Medical Imaging Service, Tennessee Valley VA Healthcare System, Nashville, Tennessee, United States of America.|Department of Radiology and Radiological Sciences, Vanderbilt University Medical Center, Nashville, Tennessee, United States of America.
Gary
G
Smith
Department of Pathology, Microbiology and Immunology, Vanderbilt University Medical Center, Nashville, Tennessee, United States of America.
Chanjuan
C
Shi
Department of Medicine, Division of Hematology/Oncology, Vanderbilt University Medical Center, Nashville, Tennessee, United States of America.
Jonathan
J
Lehman
Department of Radiology and Radiological Sciences, Vanderbilt University Medical Center, Nashville, Tennessee, United States of America.
Jeff
J
Clanton
Medical Imaging Service, Tennessee Valley VA Healthcare System, Nashville, Tennessee, United States of America.
Brandon
B
Moore
Vanderbilt-Ingram Cancer Center, Nashville, Tennessee, United States of America.
Rena
R
Burns
Department of Surgery, Vanderbilt University Medical Center, Nashville, Tennessee, United States of America.|Department of Surgery, Tennessee Valley Healthcare System, Nashville, Tennessee, United States of America.
Eric L
EL
Grogan
Vanderbilt-Ingram Cancer Center, Nashville, Tennessee, United States of America.|Department of Medicine, Division of Pulmonary, Allergy and Critical Care Medicine, Vanderbilt University Medical Center, Nashville, Tennessee, United States of America.|Pulmonary Critical Care Section, Medical Service, Tennessee Valley Healthcare System, Nashville, Tennessee, United States of America.
Pierre P
PP
Massion
D000328:Adult; D000368:Aged; D001706:Biopsy; D002289:Carcinoma, Non-Small-Cell Lung / Q000175:diagnosis* / Q000473:pathology; D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D008175:Lung Neoplasms / Q000175:diagnosis* / Q000473:pathology; D008297:Male; D008875:Middle Aged; D064847:Multimodal Imaging / Q000379:methods; D055613:Multiple Pulmonary Nodules / Q000175:diagnosis* / Q000473:pathology; D009362:Neoplasm Metastasis; D009942:Organometallic Compounds; D000072078:Positron Emission Tomography Computed Tomography / Q000379:methods*
D009942:Organometallic Compounds; C513399:gallium Ga 68 dotatate