A Dual Tracer 18F-FCH/18F-FDG PET Imaging of an Orthotopic Brain Tumor Xenograft Model

PLoS One. 2016 Feb 4;11(2):e0148123. doi: 10.1371/journal.pone.0148123. eCollection 2016.

Abstract

Early diagnosis of low grade glioma has been a challenge to clinicians. Positron Emission Tomography (PET) using 18F-FDG as a radio-tracer has limited utility in this area because of the high background in normal brain tissue. Other radiotracers such as 18F-Fluorocholine (18F-FCH) could provide better contrast between tumor and normal brain tissue but with high incidence of false positives. In this study, the potential application of a dual tracer 18F-FCH/18F-FDG-PET is investigated in order to improve the sensitivity of PET imaging for low grade glioma diagnosis based on a mouse orthotopic xenograft model. BALB/c nude mice with and without orthotopic glioma xenografts from U87 MG-luc2 glioma cell line are used for the study. The animals are subjected to 18F-FCH and 18F-FDG PET imaging, and images acquired from two separate scans are superimposed for analysis. The 18F-FCH counts are subtracted from the merged images to identify the tumor. Micro-CT, bioluminescence imaging (BLI), histology and measurement of the tumor diameter are also conducted for comparison. Results show that there is a significant contrast in 18F-FCH uptake between tumor and normal brain tissue (2.65 ± 0.98), but with a high false positive rate of 28.6%. The difficulty of identifying the tumor by 18F-FDG only is also proved in this study. All the tumors can be detected based on the dual tracer technique of 18F-FCH/18F-FDG-PET imaging in this study, while the false-positive caused by 18F-FCH can be eliminated. Dual tracer 18F-FCH/18F-FDG PET imaging has the potential to improve the visualization of low grade glioma. 18F-FCH delineates tumor areas and the tumor can be identified by subtracting the 18F-FCH counts. The sensitivity was over 95%. Further studies are required to evaluate the possibility of applying this technique in clinical trials.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Brain Neoplasms / diagnostic imaging*
  • Cell Line, Tumor
  • Choline / analogs & derivatives*
  • Disease Models, Animal
  • Fluorodeoxyglucose F18*
  • Glioblastoma / diagnostic imaging
  • Heterografts
  • Humans
  • Image Processing, Computer-Assisted
  • Luminescent Measurements / methods
  • Mice
  • Positron-Emission Tomography*
  • Radiopharmaceuticals*

Substances

  • Radiopharmaceuticals
  • Fluorodeoxyglucose F18
  • fluorocholine
  • Choline

Grants and funding

The authors acknowledge the funding support from Biomedical Research Council (BMRC), A*STAR under the grant numbers BMRC/07/1/21/19/508. CHW and WZ acknowledge the support from the National Research Foundation (NRF), Prime Minister’s Office, Singapore under its Campus for Research Excellence and Technological Enterprise (CREATE) programme. Grant Number R-706-001-101-281, National University of Singapore.