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A Journal on Nuclear Medicine and Molecular Imaging
Affiliated to the and to the International Research Group of Immunoscintigraphy
Indexed/Abstracted in: Current Contents/Clinical Medicine, EMBASE, PubMed/MEDLINE, Science Citation Index (SciSearch), Scopus
Impact Factor 2,413
Online ISSN 1827-1936
Punit SHARMA 1, Saurabh ARORA 1, Sellam KARUNANITHI 1, Rajesh KHADGAWAT 2, Prashant DURGAPAL 3, Raju SHARMA 4, Devasenathipathy KANDASAMY 4, Chandrasekhar BAL 1, Rakesh KUMAR 1
1 Department of Nuclear Medicine, All India Institute of Medical Sciences, New Delhi, India; 2 Department of Endocrinology and Metabolism, All India Institute of Medical Sciences, New Delhi, India; 3 Department of Pathology, All India Institute of Medical Sciences, New Delhi, India; 4 Department of Radiodiagnosis, All India Institute of Medical Sciences, New Delhi, India
BACKGROUND: Localization of primary tumor in insulinoma is often difficult. We evaluated the role of 68Ga-DOTA-Nal3-Octreotide (DOTANOC) PET/CT for localization of primary tumor in patients with clinical and biochemical suspicion of insulinoma.
METHODS: Data of 35 patients (age: 38.4±16.5 years) who underwent 68Ga-DOTANOC PET/CT for clinical and biochemical suspicion of insulinoma (hypoglycemia, raised serum insulin and C-peptide levels) were retrospectively analyzed. PET/CT images were evaluated visually and semiquantitatively (SUV) by two experienced nuclear medicine physicians. A definite lesion in pancreas on non contrast CT showing increased 68Ga-DOTANOC was taken as positive. In the absence of CT lesion focal 68Ga-DOTANOC uptake in the pancreas more than liver was taken as positive. All patients had also undergone conventional imaging (CIM) (CT/MRI/endosonography) and their reports were retrieved for comparison. Histopathology and/or imaging/clinical/biochemical follow up (minimum 6 months) was used as reference standard.
RESULTS: The mean serum insulin levels was 51.6±54 µIU/mL and C-peptide level was 6.9±7.3 ng/mL. 68Ga-DOTANOC PET/CT was interpreted as positive in 11 patients (31.5%) and negative in 24 (68.5%). PET/CT demonstrated total 16 pancreatic lesions in 11 patients. In two patients it also showed both liver and lymph nodal metastases. 68Ga-DOTANOC PET/CT was true positive in 8, true negative in 1, false positive in 3 and false negative in 23 patients. Per patient based sensitivity of PET/CT was 25.8% (95% CI: 11.8-44.6), specificity was 25% (95% CI: 0.6-80.5) and accuracy was 25.7%. The mean SUVmax of pancreatic lesions was 13.8±11.1. On comparison no significant difference was seen between CIM and PET/CT on patient based (P=1.00) or lesion based comparison (P=0.790).
CONCLUSION: 68Ga-DOTANOC PET/CT has limited utility for localizing the primary tumor in patients with clinical and biochemical suspicion of insulinoma. However, it might be useful for differentiating benign and malignant insulinoma. Further prospective comparative studies are warranted.