Arterial Calcium Stimulation with Hepatic Venous Sampling in the Localization Diagnosis of Endogenous Hyperinsulinism

Qualitative and Quantitative Analyses of Noninvasive Diagnosis of Insulinoma Using [18F]FB(ePEG12) 12-Exendin-4 PET/CT

CONTEXT

This study represents the first interim report from a phase 2 clinical trial. Accurate localization of insulinomas remains a clinical challenge despite the availability of various imaging modalities.

OBJECTIVE

The current study aimed to evaluate the efficacy of positron emission tomography/computed tomography (PET/CT) using [18F]FB(ePEG12)12-exendin-4 (18F-exendin-4), a novel 18F-labeled PEGylated glucagon-like peptide 1 (GLP-1) receptor-targeted imaging probe, for the noninvasive detection of insulinomas.

METHODS

This prospective single-center study enrolled patients with biochemically confirmed hyperinsulinemic hypoglycemia suggestive of insulinoma. All patients underwent 18F-exendin-4 PET/CT, with scans performed at 60 and 120 minutes after injection. The findings of 18F-exendin-4 PET/CT were then compared with those of conventional imaging modalities performed before and after 18F-exendin-4 PET/CT in actual clinical settings, with all findings being verified through surgical and pathological findings.

RESULTS

18F-exendin-4 PET/CT successfully identified insulinomas in all 12 patients (100% sensitivity), showing significantly higher uptake in tumor tissues than in the surrounding pancreatic tissues and organs. The detection rate of 18F-exendin-4 PET/CT exceeded that of the conventional imaging modalities (CT, 83%; magnetic resonance imaging, 63%; endoscopic ultrasonography, 90%; selective arterial calcium stimulation, 89%). All identified lesions were surgically confirmed to be insulinomas, with complete clinical resolution of hypoglycemia after resection.

CONCLUSION

18F-exendin-4 PET/CT demonstrated effective sensitivity for noninvasive insulinoma detection, offering a reliable and practical diagnostic alternative to invasive procedures for precise and prompt preoperative localization with functional evaluation. This novel imaging approach may therefore improve the management of patients with suspected insulinomas.

Refractory Hyperinsulinemic Hypoglycemia as a Complication of Roux-en-Y Gastric Bypass Surgery

This case involves a 45-year-old woman with severe obesity who underwent Roux-en-Y gastric bypass (RYGB) surgery. After one year, she developed daily episodes of severe hypoglycemia, presenting with symptoms of palpitations, diaphoresis, and syncope. The patient was diagnosed with endogenous hyperinsulinemic hypoglycemia, a condition characterized by abnormally high insulin levels leading to low blood glucose, commonly associated with insulinoma. In rare instances, this can be due to nesidioblastosis, an overgrowth of pancreatic beta cells, which is more prevalent in individuals who have undergone bariatric surgery. Diagnostic evaluations included blood tests, abdominal computed tomography and magnetic resonance imaging, continuous glucose monitoring, and hepatic venous sampling to exclude insulinoma. This report details the diagnosis and unsuccessful treatment of endogenous hyperinsulinemic hypoglycemia following RYGB surgery. Interventions included dietary modifications (small, frequent, low-carbohydrate meals), medical management with acarbose 100 mg three times daily, diazoxide 150 mg three times daily, verapamil 40 mg twice daily, and surgical reversal of the RYGB. Ultimately, a percutaneous gastrostomy tube was placed for 24-hour continuous parenteral feeding. Despite these extensive treatment efforts, the patient continues to experience frequent hypoglycemic episodes four years after the bariatric procedure.

Occult insulinoma with treatment refractory, severe hypoglycaemia in multiple endocrine neoplasia type 1 syndrome; difficulties faced during diagnosis, localization and management; a case report

BACKGROUND

Multiple endocrine neoplasia type 1 (MEN 1) syndrome is a rare, complex genetic disorder characterized by increased predisposition to tumorigenesis in multiple endocrine and non-endocrine tissues. Diagnosis and management of MEN 1 syndrome is challenging due to its vast heterogeneity in clinical presentation.

CASE PRESENTATION

A 23-year-old female, previously diagnosed with Polycystic Ovarian Syndrome (PCOS) and pituitary microprolactinoma presented with drowsiness,confusion and profuse sweating developing over a period of one day. It was preceded by fluctuating, hallucinatory behavior for two weeks duration. There was recent increase in appetite with significant weight gain. There was no fever, seizures or symptoms suggestive of meningism. Her Body mass index(BMI) was 32 kg/m2.She had signs of hyperandrogenism. Multiple cutaneous collagenomas were noted on anterior chest and abdominal wall. Her Glasgow Coma Scale was 9/15. Pupils were sluggishly reactive to light. Tendon reflexes were exaggerated with up going planter reflexes. Moderate hepatomegaly was present. Rest of the clinical examination was normal. Laboratory evaluation confirmed endogenous hyperinsulinaemic hypoglycaemia suggestive of an insulinoma. Hypercalcemia with elevated parathyroid hormone level suggested a parathyroid adenoma. Presence of insulinoma, primary hyperparathyroidism and pituitary microadenoma, in 3rd decade of life with characteristic cutaneous tumours was suggestive of a clinical diagnosis of MEN 1 syndrome. Recurrent, severe hypoglycaemia complicated with hypoglycaemic encephalopathy refractory to continuous, parenteral glucose supplementation and optimal pharmacotherapy complicated the clinical course. Insulinoma was localized with selective arterial calcium stimulation test. Distal pancreatectomy and four gland parathyroidectomy was performed leading to resolution of symptoms.

CONCLUSIONS

Renal calculi or characteristic cutaneous lesions might be the only forewarning clinical manifestations of an undiagnosed MEN 1 syndrome impending a life-threatening presentation. Comprehensive management of MEN 1 syndrome requires multi-disciplinary approach with advanced imaging modalities, advanced surgical procedures and long-term follow up due to its heterogeneous presentation and the varying severity depending on the disease phenotype.

Glucagon-like Peptide-1 Receptor as Emerging Target: Will It Make It to the Clinic?

The glucagon-like peptide-1 receptor (GLP-1R) is an emerging target due to its high expression in benign insulinomas as well as in islet cell hypertrophia/hyperplasia (nesidioblastosis) and pancreatic β-cells. In 2008, occult insulinomas were localized for the first time in men using the metabolically stable radiolabeled glucagon-like peptide-1 (GLP-1) agonist [Lys40(Ahx-DTPA-111In)NH2]-exendin-4 (111In-DTPA-exendin-4). Afterward, several radiopharmaceuticals for GLP-1R PET/CT imaging were synthesized and evaluated, for example, [Nle14,Lys40(Ahx-DOTA-68Ga)NH2]-exendin-4 (68Ga-DOTA-exendin-4), [Cys40(MAL-NOTA-68Ga)NH2]-exendin-4 (68Ga-NOTA-exendin-4), and [Lys40(NODAGA-68Ga)NH2]-exendin-4 (68Ga-NODAGA-exendin-4). Several prospective comparison studies provided evidence that GLP-1R PET/CT is significantly more sensitive than contrast-enhanced MRI (ceMRI), contrast-enhanced CT (ceCT), GLP-1R SPECT/CT, somatostatin receptor PET/CT, and SPECT/CT in the detection of benign insulinomas, and insulinomas in the context of multiple endocrine neoplasia type 1. As a result, the European Neuroendocrine Tumor Society guidelines recommend GLP-1R imaging or selective intraarterial calcium stimulation and venous sampling (ASVS) in patients for whom there is a clinical suspicion of having an insulinoma but who have a negative ceMRI/ceCT or negative endoscopic ultrasound. Furthermore, there is growing evidence that GLP-1R PET/CT can visualize and localize adult nesidioblastosis. This is clinically relevant as the distinction between focal and diffuse nesidioblastosis is critical in directing a therapeutic strategy in these patients. Prospective studies have proven the clinical relevance of GLP-1R imaging as it is often the only imaging modality able to localize the insulinoma or nesidioblastosis. It is therefore likely that this noninvasive imaging modality will replace the invasive localization of insulinomas using ASVS. More experimental indications for GLP-1R imaging include the diagnosis of an insulinoma/nesidioblastosis in patients with postprandial hypoglycemia after bariatric bypass surgery and monitoring β-cells in patients with brittle type 1 diabetes after islet-cell transplantation. We believe that these indications and possibly future indications will bring GLP-1R imaging to the clinic.

Multimodality Imaging Review of Multiple Endocrine Neoplasia

OBJECTIVE. The purpose of this article is to review the clinical manifestations, endocrine tumors types, and multimodality diagnostic tools available to physicians involved in the management of patients with multiple endocrine neoplasia (MEN) syndrome, in addition to discussing relevant imaging findings and appropriate imaging follow-up. CONCLUSION. Thorough knowledge of the spectrum of tumors associated with MEN gene mutations aids in the screening, diagnostic workup, and posttreatment monitoring of patients with MEN-related gene mutations.

Adrenal and Hepatic Venous Sampling in a Case of Aldosterone-Producing Adrenocortical Carcinoma with Hepatic Metastasis

Background

Adrenocortical carcinoma (ACC) is a rare and highly aggressive malignancy. ACCs often secrete adrenal steroid hormones including cortisol and androgens; however, aldosterone-producing ACC is very rare. Although adrenal production of aldosterone is assessed by adrenal venous sampling, the use of sampling from the relevant vein to assess aldosterone production from a tumor arising from ACC metastasis has not been previously reported. Case Presentation. We report the case of a 69-year-old Japanese man with aldosterone-producing ACC with hepatic metastasis. He presented with a history of treatment-resistant hypertension and hypokalemia. Endocrinological examination showed markedly increased plasma aldosterone concentration and suppressed plasma renin activity. Serum cortisol concentration was not suppressed by administration of dexamethasone 1 mg, and normal circadian variation of cortisol secretion was disrupted. Abdominal computed tomography showed a large tumor in the left adrenal gland and multiple tumors in the liver. Together, these results strongly suggested ACC with multiple liver metastases causing primary aldosteronism and subclinical Cushing syndrome. Adrenal and hepatic venous sampling showed markedly increased aldosterone concentration in the left adrenal vein but no increase in the hepatic vein, despite a pathological diagnosis of ACC with hepatic metastasis, with immunohistochemical investigation showing both primary and secondary tumors to have synthetic capability for aldosterone. The patient received mitotane but declined combination chemotherapy and died 2 months later.

Conclusion

This is the first report of adrenal and hepatic venous sampling in a case of aldosterone-producing ACC with hepatic metastasis. The case suggests that hepatic venous sampling is unable to detect aldosterone production from liver metastases arising from ACC.

Perspectives on the current pharmacotherapeutic strategies for management of functional neuroendocrine tumor syndromes

Introduction: In the past, controlling the hormone-excess-state was the main determinant of survival in Functional-Neuroendocrine-Neoplasm-syndromes (F-NENs). This was difficult because the pharmacological-armamentarium available was limited. Recently, new therapeutic strategies have increased but it also generated controversies/uncertainties.Areas covered: The authors briefly review: established/proposed F-NENs; the rationale for treatments; the recommended initial-pharmacotherapeutic-approach to controlling F-NENs hormone-excess-state; the secondary-approaches if the initial approach fails or resistance develops; and the approach to deal with the malignant nature of the NEN. Also discussed are controversies/uncertainties related to new treatments.Expert opinion: Unfortunately, except for patients with insulinomas (>90-95%), gastrinomas (<20-40%), a minority with the other F-panNENs and 0-<1% with Carcinoid-syndrome is curative-surgery possible. Except for insulinomas, gastrinomas, and ACTHomas, long-acting somatostatin-analogs are the initial-pharmacological-treatments for hormone-excess-state. For insulinomas prior to surgery/malignancy, diazoxide is the initial drug-treatment; for gastrinomas, oral PPIs; and for ACTHomas, steroidogenesis inhibitors. There are now several secondary pharmacotherapeutic treatments. Surgery and liver-directed therapies also have a role in selected patients. Particularly promising is the recent results with PRRT for the hormone-excess-state, independent of its anti-growth effect. The sequence to use various agents and the approach to syndrome diagnosis while taking various agents remains unclear/controversial in many cases.

Innovative imaging of insulinoma: the end of sampling? A review

Receptors for the incretin glucagon-like peptide-1 (GLP-1R) have been found overexpressed in selected types of human tumors and may, therefore, play an increasingly important role in endocrine gastrointestinal tumor management. In particular, virtually all benign insulinomas express GLP-1R in high density. Targeting GLP-1R with indium-111, technetium-99m or gallium-68-labeled exendin-4 offers a new approach that permits the successful localization of small benign insulinomas. It is likely that this new non-invasive technique has the potential to replace the invasive localization of insulinomas by selective arterial stimulation and venous sampling. In contrast to benign insulinomas, malignant insulin-secreting neuroendocrine tumors express GLP-1R in only one-third of the cases, while they more often express the somatostatin subtype 2 receptors. Importantly, one of the two receptors appears to be always overexpressed. In special cases of endogenous hyperinsulinemic hypoglycemia (EHH), that is, in the context of MEN-1 or adult nesidioblastosis GLP-1R imaging is useful whereas in postprandial hypoglycemia in the context of bariatric surgery, GLP-1R imaging is probably not helpful. This review focuses on the potential use of GLP-1R imaging in the differential diagnosis of EHH.

Diagnostic value of ASVS for insulinoma localization: A systematic review and meta-analysis

BACKGROUND

Previous studies on the diagnostic value of arterial calcium stimulation with hepatic venous sampling (ASVS) for the localization of insulinoma have reported inconsistent results. Here, we performed a meta-analysis of the relevant published studies.

METHODS

PubMed, Embase, Web of Science, the Cochrane Library, and Wanfang Data were searched for studies on the diagnostic value of ASVS in insulinoma localization published up to May 2019. We calculated the sensitivity, specificity, positive likelihood ratio (PLR), negative likelihood ratio (NLR), diagnostic odds ratio (DOR), and receiver operating characteristic (ROC) curve of ASVS in the localization of insulinoma.

RESULTS

We included ten studies involving 337 patients in the study. The pooled sensitivity, specificity, PLR, and NLR were 0.93 (95% confidence interval [CI]: 0.83-0.97), 0.86 (95%CI: 0.75-0.93), 6.8(95%CI: 3.7-12.7), and 0.08 (95%CI: 0.03-0.19), respectively. The DOR was 84 (95%CI: 30-233), and the area under the ROC curve was 0.96 (95%CI: 0.94-0.97).The results of the heterogeneity of the studies (P = 0.00, I2 = 80.17) were calculated using forest plots of the DOR.

CONCLUSION

ASVS is of significant value in localization of insulinoma. If a qualitative diagnosis of insulinoma is definite and the imaging examination results are negative, ASVS should be performed to confirm the localization of insulinoma.

Imaging of pancreatic neuroendocrine tumors: recent advances, current status, and controversies

Recently, there have been a number of advances in imaging pancreatic neuroendocrine tumors (panNETs), as well as other neuroendocrine tumors (NETs), which have had a profound effect on the management and treatment of these patients, but in some cases are also associated with controversies. Areas covered: These advances are the result of numerous studies attempting to better define the roles of both cross-sectional imaging, endoscopic ultrasound, with or without fine-needle aspiration, and molecular imaging in both sporadic and inherited panNET syndromes; the increased attempt to develop imaging parameters that correlate with tumor classification or have prognostic value; the rapidly increasing use of molecular imaging in these tumors and the attempt to develop imaging parameters that correlate with treatment/outcome results. Each of these areas and the associated controversies are reviewed. Expert commentary: There have been numerous advances in all aspects of the imaging of panNETs, as well as other NETs, in the last few years. The advances are leading to expanded roles of imaging in the management of these patients and the results being seen in panNETs/GI-NETs with these newer techniques are already being used in more common tumors.

Should the Selective Arterial Secretagogue Injection Test for Insulinoma Localization Be Evaluated at 60 or 120 Seconds?

Objective The selective arterial secretagogue injection (SASI) test is considered indispensable for the accurate localization of insulinoma. However, the optimum timing of the post-injection evaluation is controversial, as some studies recommend 60 seconds [SASI (60 seconds)] while others support 120 seconds [SASI (120 seconds)]. The aim of this study was to determine the optimum timing for the SASI test evaluation for insulinoma localization. Methods Thirteen patients with surgically proven insulinoma were studied retrospectively. For the SASI test, immunoreactive insulin (IRI) was determined at baseline and at 30, 60, 90, and 120 seconds after calcium gluconate injection. A two-fold or greater increase in IRI over the baseline value was considered positive. The localization abilities of SASI (60 seconds) and SASI (120 seconds) were then compared. Results In 13 patients, a secretagogue was injected into 40 arteries supplying the pancreas. In the SASI (60 seconds) and SASI (120 seconds), the respective findings were as follows: positive predictive value, 72.2% and 68.2%; false positive rate, 25.0% and 35.0%; and rate of positivity in the head and body/tail, 38.5% and 46.2%. When the artery with the largest change was taken as the dominant artery, the localization detection sensitivity was 76.9% for SASI (60 seconds) and 92.3% for SASI (120 seconds). The sensitivity of morphological imaging techniques for localization ranged from 61.5-91.7%. Conclusion Compared with SASI (60 seconds) or morphological imaging, the insulinoma localization ability of SASI (120 seconds) was superior. Given these findings, we believe that the IRI level should be measured at 120 seconds in the SASI test.