RT Journal Article
SR Electronic
T1 68Ga-exendin-4 PET/CT is both sensitive and specific in diagnosing insulinomas
JF Journal of Nuclear Medicine
JO J Nucl Med
FD Society of Nuclear Medicine
SP 237
OP 237
VO 58
IS supplement 1
A1 Yaping Luo
A1 Shaobo Yao
A1 Fang Li
YR 2017
UL http://jnm.snmjournals.org/content/58/supplement_1/237.abstract
AB 237Objectives: Glucagon-like peptide-1 receptor (GLP-1R) imaging, using radiolabeled exendin-4, has proven to be a sensitive method for preoperative localization of insulinomas. Clinical studies with 111In-, 99mTc- and 68Ga-labeled exendin-4 showed high sensitivity (95%-100%) in detecting insulinomas with SPECT and PET. However, there wasn’t much evidence on its specificity, which might be quite important in differentiation of etiologies of hyperinsulinism. Therefore, we assessed the diagnostic value of 68Ga-exendin-4 PET/CT in patients with hypoglycemia in order to evaluate its clinical relevance as a screening test for insulinomas in clinical practice.Methods: A prospective cohort study was performed in 180 consecutive patients with hypoglycemia. All patients underwent 68Ga-exendin-4 PET/CT. They were hospitalized and carefully examined for hypoglycemic etiologies. Surgical removal was performed if insulinoma was highly suspected.Results: 114 patients were positive for insulinomas in 68Ga-exendin-4 PET/CT with intense radioactivity in the tumor. Multiple lesions were found in 10 patients with 68Ga-exendin-4 PET/CT, and 3 patients had multiple metastases in the liver and lymph nodes. 90 patients underwent surgical removal of 96 insuliniomas, and 3 patients had liver biopsy due to distant metastasis. EUS-guided ethanol ablation or radiofrequency ablation of insulinoma was performed in 2 patients. 19 patients who were highly suspicious for insulinoma have declined surgery so far. 66 patients were negative for insulinomas in 68Ga-exendin-4 PET/CT. Only 1 patient was confirmed to be insulinoma which was surgically removed, additionally, this tumor was positive in 99mTc-HYNIC-TOC SPECT/CT. In the remaining 65 patients, insulin autoimmune hypoglycemia (13), congenital hyperinsulinism (5), post gastric bypass hypoglycemia (3), noninsulinoma pancreatogenous hypoglycemia (2), insulin secretagogue (2), reactive hypoglycemia of insulin-deficient diabetes mellitus or impaired glucose tolerance (21), non-islet cell tumor hypoglycemia (1), type A insulin resistance (1) were clinically diagnosed. Endogenous hyperinsulinism was finally excluded during hospitalization in 9 patients. 8 patients were unknown for the cause of hyperinsulinism. The sensitivity, specificity, accuracy, positive predictive value, and negative predictive value of 68Ga-exendin-4 PET/CT in diagnosing insulinoma were 99.0%, 100%, 99.3%, 100%, and 98.3%, respectively.Conclusion: 68Ga-exendin-4 PET/CT is both sensitive and specific in diagnosing insulinomas. It might be an accurate screening test for insulinomas in patients with hypoglycemia.