The comparison of three different molecular imaging methods in localization and grading of insulinoma

Front Endocrinol (Lausanne). 2023 Jun 30:14:1163176. doi: 10.3389/fendo.2023.1163176. eCollection 2023.

Abstract

Aims: This cross-sectional study compared the value of molecular imaging (Exendin-4 positron emission tomography/computed tomography [PET/CT], 68Ga-DOTATATE PET/CT, 18F- fluorodeoxyglucose [FDG] PET/CT) in insulinoma localization by stratified tumor size and grading, and explored the correlation of the related the maximum standardized uptake value (SUVmax) with insulinoma grading, Ki-67, maximum tumor diameter, and glucose metabolism.

Methods: In 28 insulinoma patients, the sensitivity of three types of PET/CT for localizing insulinoma was calculated according to tumor size and grade. We compared the SUVmax for different insulinoma grades and analyzed the correlation of SUVmax with Ki-67, maximum tumor diameter, and glucose metabolism indicators.

Results: The study included 12 grade (G) 1 and 16 G2 cases, with maximum tumor diameters ranging from 9 to 40 mm. Without differentiation by size and grade, the sensitivity of Exendin-4 PET/CT to localize insulinoma was 100%, which significantly exceeded that of 68Ga-DOTATATE PET/CT and 18F-FDG PET/CT (75% and 57%, respectively). In tumors with a maximum diameter ≤ 20 mm and ≤ 15 mm, the sensitivity of Exendin-4 (both 100%) significantly exceeded that of 68Ga-DOTATATE PET/CT (74% and 64%, respectively) and 18F-FDG PET/CT (54% and 50%, respectively). In G1 tumors, the sensitivity of Exendin-4 PET/CT was significantly higher than that of 18F-FDG PET/CT, but not that of 68Ga-DOTATATE PET/CT, while in G2 tumors, the sensitivity of Exendin-4 PET/CT was significantly higher than that of both other types. However, all three PET/CT types missed a metastatic lymph node in one patient. The 18F-FDG PET/CT SUVmax was significantly lower than that of the other PET/CT types and that of 68Ga-DOTATATE PET/CT was significantly lower in G2 than in G1. 68Ga-DOTATATE PET/CT SUVmax correlated negatively with Ki-67. A receiver operating characteristic (ROC) curve suggested that 68Ga-DOTATATE PET/CT SUVmax > 19.9 could predict G1 tumors.

Conclusion: Exendin-4 PET/CT was superior to 68Ga-DOTATATE PET/CT and 18F-FDG PET/CT for insulinoma localization, particularly small and G2 tumors, but its diagnostic value in small metastatic lymph nodes requires further exploration. 68Ga-DOTATATE PET/CT SUVmax could be used as an adjunct to pathology, and a value > 19.9 could predict G1 tumors. No PET/CT SUVmax could predict tumor maximum diameter and glucose metabolism.

Keywords: Ki-67; grade; insulinoma; maximum standardized uptake value; molecular imaging; positron emission tomography/computed tomography (PET/CT).

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Cross-Sectional Studies
  • Exenatide
  • Fluorodeoxyglucose F18
  • Gallium Radioisotopes
  • Glucose
  • Humans
  • Insulinoma* / diagnostic imaging
  • Ki-67 Antigen / metabolism
  • Molecular Imaging
  • Neuroendocrine Tumors* / pathology
  • Pancreatic Neoplasms* / diagnostic imaging

Substances

  • Fluorodeoxyglucose F18
  • Ki-67 Antigen
  • Gallium Radioisotopes
  • Exenatide
  • Glucose

Grants and funding

This work was supported by Tianjin Key Medical Discipline(Specialty) Construction Project(grant number TJYXZDXK-030A), Major project of Tianjin Municipal Science and Technology Bureau (grant number 21ZXJBSY00060), the National Natural Science Foundation of China (grant number 82070854), Project of Tianjin Municipal Health Commission(grant number ZC20210) and Project of Tianjin Municipal Health Commission(grant number RC20126).