Use of18F-DOPA PET/MRI for the Detection and Localization of Focal Forms of Hyperinsulinism

Congenital hyperinsulinism (CHI) is a clinically and genetically heterogeneous disorder that is the most common cause of permanent hypoglycemia in infants and children. More than 50% of the medically-unresponsive patients have focal disease. Which is characterized by a distinct region of Beta-cell hyperplasia in the pancreas, due to a somatic loss of a gene that regulates cell proliferation. Resection of the involved region cures most cases of focal HI. Therefore, preoperative identification and localization of focal HI lesions is useful for diagnostic confirmation and surgical guidance of patients with HI that fail pharmacological therapy and are being considered for surgery.

Insulinomas are benign insulin secreting neuroendocrine neoplasms located in the pancreas. They are the most common cause of endogenous hyperinsulinemic hypoglycemia in adults. Approximately 90% are solitary, benign and < 2cm in diameter and therefore represent a challenge to localize. The small size of insulinomas makes detection by conventional imaging techniques such as contrast-enhanced CT (ceCT) and contrast-enhanced MRI challenging. As surgery appears to be the only available treatment option, it remains very critical to localize the tumor to facilitate pancreas preserving surgery. Endoscopic ultrasound is well established in the detection of insulinomas. However, this technique is operator dependent, invasive, and the visualization of the pancreas tail is not always possible. Therefore better imaging techniques to detect these lesions are needed for surgical planning.

Though not FDA approved, noninvasive imaging with 18F-fluoro-L-DOPA (FDOPA) is considered an integral part of standards of care management to identify focal lesions in CHI and potentially insulinomas. This is based on the fact that 18F-DOPA is selectively taken up by neuroendocrine cells, and thus, in focal HI, dense collections of endocrine cells can be visualized by an experienced radiologist. This study aims to determine if using combined positron emission tomography and magnetic resonance imaging will better localize the lesions and help the investigators determine which areas of the pancreas are affected, and assist with the surgical plan.