Yaping Luo

Glucagon-Like Peptide-1 Receptor PET/CT with 68Ga-NOTA-Exendin-4 for Detecting Localized Insulinoma: A Prospective Cohort Study

Preoperative localization of insulinoma is a clinical dilemma. We aimed to investigate whether glucagon-like peptide-1 receptor (GLP-1R) PET/CT with 68Ga-NOTA-MAL-cys40-exendin-4 (68Ga-NOTA-exendin-4) is efficient in detecting insulinoma. Methods: In our prospective cohort study, patients with endogenous hyperinsulinemic hypoglycemia were enrolled. CT, MRI, endoscopic ultrasound, and 99mTc-hydrazinonicotinamide-TOC SPECT/CT were done according to standard protocols. GLP-1R PET/CT was performed 30–60 min after the injection of 68Ga-NOTA-exendin-4. The gold standard for diagnosis was the histopathologic results after surgery. Results: Of 52 recruited patients, 43 patients with histopathologically proven insulinomas were included for the imaging studies. Nine patients did not undergo surgical intervention. 68Ga-NOTA-exendin-4 PET/CT correctly detected insulinomas in 42 of 43 patients with high tumor uptake (mean SUVavg ± SD, 10.2 ± 4.9; mean SUVmax ± SD, 23.6 ± 11.7), resulting in sensitivity of 97.7%. In contrast, 99mTc-hydrazinonicotinamide-TOC SPECT/CT showed a low sensitivity of 19.5% (8/41) in this group of patients; however, it successfully localized the tumor that was false-negative with GLP-1R PET/CT. The sensitivities of CT, MR, and endoscopic ultrasonography were 74.4% (32/43), 56.0% (14/25), and 84.0% (21/25), respectively. Conclusion: 68Ga-NOTA-exendin-4 PET/CT is a highly sensitive imaging technique for the localization of insulinoma.

68Ga-NOTA-exendin-4 PET/CT in detection of occult insulinoma and evaluation of physiological uptake

A 52-year-old man who had hypoglycaemia for 8 years was found to have endogenous hyperinsulinism indicating an insulinoma. Abdominal MRI, CT perfusion, endoscopic ultrasonography, and Tc-HYNIC-TOC SPECT/CT were negative. Thus, the patient was referred for Ga-NOTA-exendin-4 PET/CT with the approval of the Institutional Review Board of our hospital. As well as the intense physiological distribution in the kidneys and bladder due to urinary excretion, moderately elevated uptake is apparent in the proximal duodenum (a–c long arrows, SUVmax 5.2) and pancreas (SUVmax 2.9) at 1 h after injection of Ga-NOTAexendin-4. Because visualization of the pancreas tail was significantly influenced by the intense radioactivity in the left kidney, the patient was reimaged at 2 h after injection. A lesion with intense uptake (SUVmax 20.7) was clearly seen in the pancreas tail (d, e short arrows). Interestingly, radioactivity in the proximal duodenum significantly decreased (d, e long arrows, SUVmax 2.3) while the appearance of the normal pancreas remained unchanged. The patient recovered from hypoglycemia after surgical removal of the pancreas tail insulinoma (WHO grade 1). Intraoperative ultrasonography excluded a duodenal tumor. Glucagon-like peptide-1 receptor (GLP-1R) is highly overexpressed in insulinoma [1, 2]. SPECT/CT imaging of GLP-1R using In-labelled or Tc-labelled exendin-4 has been shown to be highly accurate in the detection of insulinoma [2–4]. However, PET/CT imaging of GLP-1R has rarely been reported [5]. We present the first successful use of Ga-NOTA-exendin-4 PET/ CT for the identification of an occult insulinoma that could not be detected by other standard imaging methods. Ga-NOTAexendin-4 also shows great potential for evaluation of pancreatic physiology due to its uptake, presumably, by islet cells. Yaping Luo and Miao Yu contributed equally to the article.

Unexpected primary osseous lymphoma as the cause of lactic acidosis in a patient suffering from pancreatitis.

A 45-year-old man was admitted due to acute pancreatitis. A severe lactic acidosis was found. Following active therapy, the signs and symptoms from pancreatitis was improved, but acidosis was exacerbated. FDG PET/CT images were acquired to investigate the etiology of lactic acidosis and/or other unknown pathology. The images showed widespread abnormal FDG activity in the bone marrows throughout the body, suggestive of hematologic malignancy, which was confirmed as primary osseous non-Hodgkin lymphoma following a histopathological examination of the bone marrow. Chemotherapy against lymphoma was initiated and status of the lactic acidosis was rapidly corrected.

68Ga-NOTA-Exendin-4 PET/CT in Localization of an Occult Insulinoma and Appearance of Coexisting Esophageal Carcinoma.

A 61-year-old woman with biochemically proven endogenous hyperinsulinemic hypoglycemia and negative conventional imaging underwent 68Ga-NOTA-exendin-4 PET/CT for localization of insulinoma. Focal intense radioactivity in the tail of the pancreas was observed that was subsequently confirmed as insulinoma pathologically after surgical resection. In addition, esophageal carcinoma with lymph node and hepatic metastases was found by FDG PET/CT in the same patient. Neither the primary carcinoma nor the metastases showed increased radioactivity on 68Ga-NOTA-exendin-4 PET/CT.

Acinar cell carcinoma of the pancreas presenting as diffuse pancreatic enlargement: Two case reports and literature review

Rationale: Pancreatic acinar cell carcinoma (ACC) is a rare malignant tumor of exocrine pancreas. It is typically a well-marginated large solid mass arising in a certain aspect of the pancreas. Diffuse involvement of ACC in the pancreas is very rare, and may simulate pancreatitis in radiological findings. We report 2 cases of ACC presenting as diffuse enlargement of the pancreas due to tumor involvement without formation of a distinct mass. Patient concerns: The patients consisted of a 41-year-old man with weight loss and a 77-year-old man who was asymptomatic. Diagnoses: Computed tomography (CT) and 18F-fluorodeoxyglucose (FDG) positron emission tomography (PET)/CT showed diffuse enlargement of the pancreas forming a sausage-like shape with homogenously increased FDG activity. Interventions: Endoscopic ultrasound (EUS)-guided fine needle aspiration (FNA) biopsy of the pancreatic lesion was performed. Outcomes: Histopathology results from the pancreas confirmed the diagnosis of pancreatic ACC. Lessons: Because diffuse enlargement of the pancreas is a common imaging feature of pancreatitis, recognition of this rare morphologic pattern of ACC is important for radiological diagnosis of this tumor.

Epstein-Barr Virus–Associated Hemophagocytic Lymphohistiocytosis Mimicking Lymphoma on FDG PET/CT

A 15-year-old boy with fever, pancytopenia, and hepatosplenomegaly was diagnosed as hemophagocytic lymphohistiocytosis (HLH). F-FDG PET/CT showed hypermetabolic foci in the liver, spleen, and bone marrow, as well as multiple FDG-avid lymph nodes, which were highly suggestive of lymphoma. Specimens from splenectomy depicted a large number of macrophages/histiocytes with hemophagocytosis of erythrocytes, without evidence of malignancy. Considering increased Epstein-Barr virus (EBV) DNA in peripheral blood and positive staining for EBV-encoded RNA in the spleen, EBV-associated HLH was confirmed. This case indicates that FDG-avid foci in the liver, spleen, and bone marrow may also be seen in EBV-associated HLH.

Primary Neuroendocrine Carcinoma of the Kidney on FDG PET/CT.

A 28-year-old woman presented gradually worsening intermittent right groin pain for 10 months. FDG PET/CT was performed to evaluate the suspected renal malignancy. The images demonstrated a large hypermetabolic tumor occupying the entire right kidney. Pathological examination demonstrated a primary neuroendocrine carcinoma of the kidney.