An intra-individual comparison of MRI, [18F]-FET and [18F]-FLT PET in patients with high-grade gliomas

PLoS One. 2014 Apr 23;9(4):e95830. doi: 10.1371/journal.pone.0095830. eCollection 2014.

Abstract

Objectives: Intra-individual spatial overlap analysis of tumor volumes assessed by MRI, the amino acid PET tracer [18F]-FET and the nucleoside PET tracer [18F]-FLT in high-grade gliomas (HGG).

Methods: MRI, [18F]-FET and [18F]-FLT PET data sets were retrospectively analyzed in 23 HGG patients. Morphologic tumor volumes on MRI (post-contrast T1 (cT1) and T2 images) were calculated using a semi-automatic image segmentation method. Metabolic tumor volumes for [18F]-FET and [18F]-FLT PETs were determined by image segmentation using a threshold-based volume of interest analysis. After co-registration with MRI the morphologic and metabolic tumor volumes were compared on an intra-individual basis in order to estimate spatial overlaps using the Spearman's rank correlation coefficient and the Mann-Whitney U test.

Results: [18F]-FLT uptake was negative in tumors with no or only moderate contrast enhancement on MRI, detecting only 21 of 23 (91%) HGG. In addition, [18F]-FLT uptake was mainly restricted to cT1 tumor areas on MRI and [18F]-FLT volumes strongly correlated with cT1 volumes (r = 0.841, p<0.001). In contrast, [18F]-FET PET detected 22 of 23 (96%) HGG. [18F]-FET uptake beyond areas of cT1 was found in 61% of cases and [18F]-FET volumes showed only a moderate correlation with cT1 volumes (r = 0.573, p<0.001). Metabolic tumor volumes beyond cT1 tumor areas were significantly larger for [18F]-FET compared to [18F]-FLT tracer uptake (8.3 vs. 2.7 cm3, p<0.001).

Conclusion: In HGG [18F]-FET but not [18F]-FLT PET was able to detect metabolic active tumor tissue beyond contrast enhancing tumor on MRI. In contrast to [18F]-FET, blood-brain barrier breakdown seems to be a prerequisite for [18F]-FLT tracer uptake.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Aged
  • Aged, 80 and over
  • Female
  • Fluorodeoxyglucose F18
  • Glioma / diagnosis*
  • Humans
  • Magnetic Resonance Imaging / methods*
  • Male
  • Middle Aged
  • Positron-Emission Tomography / methods*

Substances

  • Fluorodeoxyglucose F18

Grants and funding

Martha Nowosielski holds a DOC-fFORTE Fellowship from the Austrian Academy of Science at the Department of Neurology, Innsbruck Medical University. Markus Hutterer holds a grant from the Oesterreichische Nationalbank Jubiläumsfond (project number 14326). Matthew D.DiFranco holds an EU Marie Curie Intra European Fellowship at the Computational Image Analysis and Radiology Lab (CIR), Department of Radiology, Medical University of Vienna (grant number PIEF-GA-2010-275747). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.