Congenital hyperinsulinism: Role of fluorine-18L-3, 4 hydroxyphenylalanine positron emission tomography scanning

F-18 DOPA PET/CT in pediatric patients with hyperinsulinemic hypoglycemia: A correlation with genetic analysis

AIM

Persistent hyperinsulinemic hypoglycemia is a rare but life-threatening disease of infancy and childhood. 18F-DOPA PET/CT has been shown to be a useful modality in the localization of focal pancreatic lesions in these patients. We aimed to assess the role of 18F-DOPA PET/CT in such patients at our institution.

MATERIALS AND METHODS

In this prospective study, 18F-DOPA PET/CT scans and clinical details of 20 children with clinical diagnosis of hyperinsulinemic hypoglycemia were reviewed. Scans were acquired at 5 min postinjection of 2-3 mCi of 18F-DOPA on dedicated PET/CT scanners (Biograph mCT, Siemens Inc and Discovery PET/CT, GE). Abdominal spot images over 1-2 bed positions were acquired. Additionally, genetic mutation status, where available, was correlated to the scan findings.

RESULTS

Out of 20 children (7 female and 13 male), 13 were infants. The age of the children ranged from 3 months to 8 years. Fifteen children had undergone gene analysis, 12 were positive for mutation in ABCC8, 1 for GLUD-1, 1 for GCK mutations and 1 had not shown any mutation. 18F-DOPA PET/CT scan showed 5 focal pancreatic lesions in 5 children (1 in each), two focal lesions in 1 child and diffuse pancreatic uptake in 14 children.

CONCLUSION

18F-DOPA PET/CT is a useful modality for localizing focal pancreatic lesions in children with persistent hyperinsulinemic hypoglycemia. The detection rate is significantly higher in patients with ABCC8 paternal monoallelic recessive gene mutation. 18F-DOPA PET/CT scan consequent to findings on genetic analysis appears to be useful in planning the management of children with hyperinsulinism.

Early diagnosis of focal congenital hyperinsulinism: A fluorine-18-labeled l-dihydroxyphenylalanine positron emission tomography/computed tomography study

Congenital hyperinsulinism (CHI) is responsible for hyperinsulinemic hypoglycemia which needs aggressive treatment in order to prevent neurological damages. Recent advances in genetics have linked CHI to mutations in many different genes that play a key role in regulating insulin secretion from pancreatic ß-cells. Furthermore, histopathological lesions, diffuse and focal, have been associated with these different genetic alterations. This short manuscript describes how the advent of fluorine-18-labeled L-dihydroxyphenylalanine-positron emission tomography/computed tomography (¹⁸F-DOPA-PET/CT) scanning has changed the management of patients with CHI. ¹⁸F-DOPA PET/CT imaging differentiates focal from diffuse disease and is 100% accurate in localizing the focal lesion. In these patients, the lesion can be surgically removed allowing complete resolution of clinical alterations. We report a case in which clinical experience together with rapid genetic analysis and imaging with ¹⁸F-DOPA-PET/CT, were able to guide the correct clinical management of this condition. We confirm that advances in molecular genetics, imaging methods (¹⁸F-DOPA PET-CT), medical therapy, and surgical approach have completely changed the management and improved the outcome of these children.

18F-FDOPA and 68Ga-dotatate PET imaging in congenital hyperinsulinism

Congenital hyperinsulinism (CHI) occurs most commonly in infants but may also be discovered in older children. It presents with recurrent episodes of hypoglycemia due to high endogenous insulin levels. There is a focal and diffuse form of the disease depending on the extent of pancreatic involvement. Hyperplasia of the islet cells results in hyperfunctioning pancreatic β cells and the ensuing clinical disease. Medical treatment fails in several patients and surgery has been shown to be very effective in improving prognosis and even resolution of disease in the focal form. Several genetic mutations have been uncovered and these may also be predictive of prognosis. Anatomical imaging alone including ultrasound, CT and MRI are rarely able to detect any abnormality in the pancreas. PET plays a major role in the distinction between the focal and diffuse forms of the disease. It also guides surgical intervention by providing information on the location of the focal hyperfunctioning islet cells. Imaging children and infants in this disease is quite challenging. We propose to show the benefit of using two PET tracers in this disease. ¹⁸F-FDOPA has been used quite successfully in the evaluation of CHI. ⁶⁸Ga-DOTATATE has also been described to be helpful although inferior to ¹⁸F-FDOPA. We illustrate imaging of CHI patients in 3 different scans and briefly review the literature. ¹⁸F-FDOPA as described in the literature is superior but when unavailable ⁶⁸Ga-DOTATATE may be a reasonable alternative.

Case report: contradictory genetics and imaging in focal congenital hyperinsulinism reinforces the need for pancreatic biopsy

Background

Congenital Hyperinsulinism (CHI) is an important cause of severe hypoglycaemia in infancy due to excessive, dysregulated insulin secretion. In focal CHI, a localised lesion within the pancreas hypersecretes insulin and, importantly, hypoglycaemia resolution is possible through limited surgical resection of the lesion. Diagnosis of focal CHI is based on a crucial combination of compatible genetics and specialised imaging. Specifically, a focal lesion arises due to a paternal mutation in one of the ATP-sensitive potassium channel genes, KCNJ11 or ABCC8, in combination with post-zygotic loss of maternal heterozygosity within the affected pancreatic tissue. 6-[18F]Fluoro-L-3,4-dihydroxyphenylalanine (¹⁸F-DOPA) positron emission tomography (PET)/computed tomography (CT) imaging is used to detect and localise the lesion prior to surgery. However, its accuracy is imperfect and needs recognition in individual case management.

Case presentation

We report the case of an infant with hypoglycaemia due to CHI and a paternally inherited KCNJ11 mutation, c.286G > A (p.Ala96Thr), leading to a high probability of focal CHI. However,¹⁸F-DOPA PET/CT scanning demonstrated diffuse uptake and failed to conclusively identify a focal lesion. Due to unresponsiveness to medical therapy and ongoing significant hypoglycaemia, surgery was undertaken and a small 4.9 × 1.7 mm focal lesion was discovered at the pancreatic neck. This is the second case where this particular KCNJ11 mutation has been incorrectly associated with diffuse ¹⁸F-DOPA uptake, in contrast to the correct diagnosis of focal CHI confirmed by pancreatic biopsy.

Conclusions

Identifying discrepancies between genetic and imaging investigations is crucial as this may negatively impact upon the diagnosis and surgical treatment of focal CHI. This case highlights the need for pancreatic biopsy when a strong suspicion of focal CHI is present even if ¹⁸F-DOPA imaging fails to demonstrate a discrete lesion.

Molecular imaging of β-cells: diabetes and beyond

Since diabetes is becoming a global epidemic, there is a great need to develop early β-cell specific diagnostic techniques for this disorder. There are two types of diabetes (i.e., type 1 diabetes mellitus (T1DM) and type 2 diabetes mellitus (T2DM)). In T1DM, the destruction of pancreatic β-cells leads to reduced insulin production or even absolute insulin deficiency, which consequently results in hyperglycemia. Actually, a central issue in the pathophysiology of all types of diabetes is the relative reduction of β-cell mass (BCM) and/or impairment of the function of individual β-cells. In the past two decades, scientists have been trying to develop imaging techniques for noninvasive measurement of the viability and mass of pancreatic β-cells. Despite intense scientific efforts, only two tracers for positron emission tomography (PET) and one contrast agent for magnetic resonance (MR) imaging are currently under clinical evaluation. β-cell specific imaging probes may also allow us to precisely and specifically visualize transplanted β-cells and to improve transplantation outcomes, as transplantation of pancreatic islets has shown promise in treating T1DM. In addition, some of these probes can be applied to the preoperative detection of hidden insulinomas as well. In the present review, we primarily summarize potential tracers under development for imaging β-cells with a focus on tracers for PET, SPECT, MRI, and optical imaging. We will discuss the advantages and limitations of the various imaging probes and extend an outlook on future developments in the field.

PET/MR Imaging of the Pancreas

PET/MR imaging has the potential to markedly alter pancreatic care in both the malignant, and premalignant states with the ability to perform robust, high-resolution, quantitative molecular imaging. The ability of PET/MR imaging to monitor disease processes, potentially correct for motion in the upper abdomen, and provide novel biomarkers that may be a combination of MR imaging and PET biomarkers, offers a unique, precise interrogation of the pancreatic milieu going forward.

Clinical practice guidelines for congenital hyperinsulinism

Congenital hyperinsulinism is a rare condition, and following recent advances in diagnosis and treatment, it was considered necessary to formulate evidence-based clinical practice guidelines reflecting the most recent progress, to guide the practice of neonatologists, pediatric endocrinologists, general pediatricians, and pediatric surgeons. These guidelines cover a range of aspects, including general features of congenital hyperinsulinism, diagnostic criteria and tools for diagnosis, first- and second-line medical treatment, criteria for and details of surgical treatment, and future perspectives. These guidelines were generated as a collaborative effort between The Japanese Society for Pediatric Endocrinology and The Japanese Society of Pediatric Surgeons, and followed the official procedures of guideline generation to identify important clinical questions, perform a systematic literature review (April 2016), assess the evidence level of each paper, formulate the guidelines, and obtain public comments.

Targets and probes for non-invasive imaging of β-cells

β-cells, located in the islets of the pancreas, are responsible for production and secretion of insulin and play a crucial role in blood sugar regulation. Pathologic β-cells often cause serious medical conditions affecting blood glucose level, which severely impact life quality and are life-threatening if untreated. With 347 million patients, diabetes is one of the most prevalent diseases, and will continue to be one of the largest socioeconomic challenges in the future. The diagnosis still relies mainly on indirect methods like blood sugar measurements. A non-invasive diagnostic imaging modality would allow direct evaluation of β-cell mass and would be a huge step towards personalized medicine. Hyperinsulinism is another serious condition caused by β-cells that excessively secrete insulin, like for instance β-cell hyperplasia and insulinomas. Treatment options with drugs are normally not curative, whereas curative procedures usually consist of the resection of affected regions for which, however, an exact localization of the foci is necessary. In this review, we describe potential tracers under development for targeting β-cells with focus on radiotracers for PET and SPECT imaging, which allow the non-invasive visualization of β-cells. We discuss either the advantages or limitations for the various tracers and modalities. This article concludes with an outlook on future developments and discuss the potential of new imaging probes including dual probes that utilize functionalities for both a radioactive and optical moiety as well as for theranostic applications.

A compound heterozygous mutation of ABCC8 gene causing a diazoxide-unresponsive congenital hyperinsulinism with an atypical form: Not a focal lesion in the pancreas reported by ¹⁸F-DOPA-PET/CT scan

Congenital hyperinsulinism (CHI) is a severe heterogeneous disorder due to dysregulation of insulin secretion from the pancreatic β-cells leading to severe hypoglycemia in infancy. 18-fluoro-l-3,4-dihydroxyphenylalanine positron emission tomography ((18)F‑DOPA‑PET)/CT is a useful tool in distinguishing between focal and diffuse disease preoperatively. But recent studies have suggested that the scanning may not be accurate as initially estimated. In this study we characterize a case of CHI with a compound heterozygous mutation of ABCC8 gene. The results of clinical investigation, gene mutation analysis, (18)F‑DOPA‑PET/CT scan, and pathological examination showed some new characteristics that have never been reported. The patient was unresponsive to medical therapy with diazoxide and received pancreatectomy twice. Genetic analysis identified a compound heterozygous mutation in ABCC8 genes. Imaging with (18)F‑DOPA‑PET/CT indicated a focal lesion in the head of the pancreas. The pathological diagnosis was an atypical form of CHI. The patient presented with a phenotype of atypical CHI unresponsive to diazoxide. It is considered that a relationship existed between the compound heterozygous mutation and the atypical form. (18)F‑DOPA‑PET/CT is a useful tool in distinguishing between focal and diffuse forms preoperatively but the accuracy is not 100%. The scan result is best combined with genetic analysis and intra-operative biopsy to confirm the histological subtypes. The combination will provide the optimal strategy for the surgical treatment of patients with CHI.