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World J Clin Oncol. Oct 24, 2021; 12(10): 897-911
Published online Oct 24, 2021. doi: 10.5306/wjco.v12.i10.897
Current update on imaging for pancreatic neuroendocrine neoplasms
Nicole Segaran, Catherine Devine, Mindy Wang, Dhakshinamoorthy Ganeshan
Nicole Segaran, Department of Radiology, Mayo Clinic Arizona, Phoenix, AZ 85259, United States
Catherine Devine, Mindy Wang, Department of Diagnostic Radiology, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, United States
Dhakshinamoorthy Ganeshan, Department of Diagnostic Radiology, Abdominal Imaging, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, United States
Author contributions: Segaran N drafted the review article and contributed to the design of the manuscript; Devine C contributed to the design of the manuscript and edited the draft; Wang M contributed to manuscript design and edited the manuscript; Ganeshan D designed the structure of the overall manuscript and made critical revisions related to important intellectual content of the manuscript; all authors approved the final version of the manuscript.
Conflict-of-interest statement: Authors declare no conflict of interests for this manuscript.
Open-Access: This article is an open-access article that was selected by an in-house editor and fully peer-reviewed by external reviewers. It is distributed in accordance with the Creative Commons Attribution NonCommercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial. See: http://creativecommons.org/Licenses/by-nc/4.0/
Corresponding author: Dhakshinamoorthy Ganeshan, MD, Associate Professor, Department of Diagnostic Radiology, Abdominal Imaging, The University of Texas MD Anderson Cancer Center, 1400 Pressler Street, Unit 1473, Houston, TX 77030, United States. dganeshan@mdanderson.org
Received: March 31, 2021
Peer-review started: March 31, 2021
First decision: June 7, 2021
Revised: June 21, 2021
Accepted: August 27, 2021
Article in press: August 27, 2021
Published online: October 24, 2021
Processing time: 204 Days and 16.6 Hours
Abstract

Pancreatic neuroendocrine neoplasms (panNEN) are a heterogeneous group of tumors with differing pathological, genetic, and clinical features. Based on clinical findings, they may be categorized into functioning and nonfunctioning tumors. Adoption of the 2017 World Health Organization classification system, particularly its differentiation between grade 3, well-differentiated pancreatic neuroendocrine tumors (panNET) and grade 3, poorly-differentiated pancreatic neuroendocrine carcinomas (panNEC) has emphasized the role imaging plays in characterizing these lesions. Endoscopic ultrasound can help obtain biopsy specimen and assess tumor margins and local spread. Enhancement patterns on computed tomography (CT) and magnetic resonance imaging (MRI) may be used to classify panNEN. Contrast enhanced MRI and diffusion-weighted imaging have been reported to be useful for characterization of panNEN and quantifying metastatic burden. Current and emerging radiotracers have broadened the utility of functional imaging in evaluating panNEN. Fluorine-18 fluorodeoxyglucose positron emission tomography (PET)/CT and somatostatin receptor imaging such as Gallium-68 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid–octreotate PET/CT may be useful for improved identification of panNEN in comparison to anatomic modalities. These new techniques can also play a direct role in optimizing the selection of treatment for individuals and predicting tumor response based on somatostatin receptor expression. In addition, emerging methods of radiomics such as texture analysis may be a potential tool for staging and outcome prediction in panNEN, however further investigation is required before clinical implementation.

Keywords: Pancreatic neuroendocrine neoplasms; Computed tomography; Ultrasound; Positron emission tomography; Magnetic resonance imaging; Peptide receptor radionuclide therapy

Core Tip: Imaging plays a critical role in the diagnosis and management of pancreatic neuroendocrine neoplasms. Enhancement patterns and diffusion-weighted imaging aid the detection and classification of these lesions. Contrast-enhanced magnetic resonance imaging is useful for the evaluation of hepatic metastases. Dual-tracer positron emission tomography/computed tomography with Gallium-68 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid–octreotate and Fluorine-18 fluorodeoxyglucose may be particularly useful for distinguishing grade 3 pancreatic neuroendocrine tumor from pancreatic neuroendocrine carcinoma. Furthermore, these advanced imaging techniques can help in the staging and detection of distant metastases. Evaluation of somatostatin receptor expression and metabolic activity with functional imaging can help select optimal treatment.