Identification and Localization of Functioning Gastroenteropancreatic Neuroendocrine Tumors Using [18F]F-NOTA-octreotide PET/CT

Summary

These two case reports demonstrate the use of [¹⁸F]F-NOTA-octreotide positron emission tomography/computed tomography (PET/CT) to identify and localize functioning gastroenteropancreatic neuroendocrine tumors (F-GEP-NETs) and highlight its role in guiding clinical diagnosis and treatment planning.

Abstract

Accurate identification and localization are crucial for determining surgical strategies in patients with F-GEP-NETs, as these tumors often cause specific clinical syndromes due to hormone overproduction. However, conventional anatomical imaging techniques, such as computed tomography (CT) and magnetic resonance imaging (MRI), exhibit low sensitivity and accuracy in detecting and localizing F-GEP-NETs. This limitation stems from the frequent small size and inherent imaging heterogeneity of such tumors, which often lead to inconclusive or false-negative results. Herein, we present two illustrative cases of F-GEP-NETs (one gastrinoma and one VIPoma) that were either not visualized or yielded undefined findings on contrast-enhanced CT (CE-CT). In both instances, [¹⁸F]F-NOTA-octreotide PET/CT subsequently enabled precise identification and anatomical localization of the primary tumors. This molecular imaging technique leverages the overexpression of somatostatin receptors on the surface of most neuroendocrine tumor cells, providing superior functional characterization. These cases underscore the potential diagnostic value of [¹⁸F]F-NOTA-octreotide PET/CT in the clinical workup of patients with biochemically confirmed F-GEP-NETs in whom conventional imaging is non-diagnostic, thereby aiding in the formulation of optimal treatment strategies and personalized management plans.

Introduction

Neuroendocrine tumors (NETs) are a diverse group of neoplasms arising in neuroendocrine cells throughout the body, particularly in the gastrointestinal tract, pancreas, and lungs¹. Gastroenteropancreatic NETs (GEP-NETs) are located throughout the gastrointestinal (GI) tract or pancreas, accounting for 55-70% of NETs². Based on their ability to secrete hormones and biogenic amines, GEP-NETs are classified as functional or non-functional GEP-NETs. Although non-functional GEP-NETs (NF-GEP-NETs) account for approximately 60% of GEP-NETs, the incidence of F-GEP-NETs has surged in the last 10 years². NF....

Protocol

The protocol followed the Institutional Ethics Committee guidelines of The First Affiliated Hospital, Zhejiang University School of Medicine. Approval was obtained from the ethics committee (ClinicalTrials.gov identifier: IIT202110004C) before initiating the study procedures. Written informed consent was obtained from all enrolled patients prior to their [¹⁸F]F-NOTA-octreotide PET/CT examination.

1. Study design and participant recruitment

1. A retrospective review was conducted of patients who underwent [¹⁸F]F-NOTA-octreotide PET/CT imaging at the Department of Nuclear Medicine between Novemb....

Results

[¹⁸F]F-NOTA-octreotide PET/CT was performed in two patients with suspected F-GEP-NETs. The clinical and imaging details of the two cases are summarized in Supplementary Table 1. Image interpretation was performed independently by two experienced nuclear medicine physicians, and concordant findings were obtained in both cases. In Case 1, no abnormal lesions were identified on CE-CT or CE-MRI. [¹⁸F]F-NOTA-octreotide PET/CT showed a focal lesion with markedly increased radiotracer upta.......

Discussion

The incidence of neuroendocrine tumors (NETs), once considered rare diseases, has increased steadily worldwide in recent years in most countries and has garnered increasing attention⁸. Although F-GEP-NETs represent a minority of NETs, their incidence has increased in recent decades⁸. Since F-GEP-NETs present with a wide variety of clinical signs and symptoms related to inappropriately elevated hormonal levels secreted by the tumor, which may affect different organs, their m.......

Materials

List of materials used in this article

Name	Company	Catalog Number	Comments
Aluminum chloride (AlCl3)	Alfa Aesar	88488.06
Biograph Vision 600 PET/CT	Siemens Healthineers	N/A
HLB Light Cartridge	Waters	186001879
Iohexol Injection	Yangtze River Pharmaceutical Group	NMPA Approval No.H10970358
Lauromacrogol Injection	Shaanxi Tianyu Pharmaceutical	NMPA Approval No.H20080445
MedEx Nuclear Medical Information System	MedEx Technology	N/A
NOTA-octreotide	Beijing PET Technology	BJA-025
QMA Cartridge	Waters	186000805
Sodium Acetate	Sigma-Aldrich	S2889-250G
Sterile Filter (0.22 μm )	Millipore	SLGV033RS
Brilliance iCT (Slice scanner)	Philips Healthcare, Germany	4535 674 80181
VG76B Reconstruction Software	Siemens Healthineers	N/A