Imaging of hypoxia in human glioblastoma with dynamic 18F-fluoromisonidazole PET.

Redha-Alla Abdo,Philippe Fernandez,Frédéric Lamare,M’Hamed Bentourkia

doi:10.20517/cdr.2018.21

Abstract

Aim: The purpose of this study was to locate the levels of hypoxia in glioblastoma PET images measured with 18F-fluoromisonidazole in human subjects. It is recognized that tumors with hypoxia are resistant to treatment by radiotherapy and chemotherapy.Methods: The images were acquired in dynamic mode for 15 min or 30 min and in static mode for two single scans at 2 h and 3 h to allow the accumulation of the radiotracer in the tumor. The images were analyzed at the voxel basis with compartmental analysis (CA) and with the usual tumor-to-blood uptake ratio (TBR). Kmeans algorithm was applied to cluster the levels of hypoxia in the images.Results: TBR at a threshold of 1.2 at imaging times of 15 min, 2 h and 3 h produced images with different clusters. Also, the comparison of TBR with the distribution volume obtained with CA had a similarity index of 0.61 ± 0.05.Conclusion: We found some differences in defining the hypoxic volume within a tumor using TBR. The compartmental analysis allowed discrimination of the tumor hypoxic sub-volumes which can be useful for a better treatment with radiotherapy.

Highlights

Glioblastoma multiforme (GBM) is known as the most common tumor in the central nervous system
The difficulty of treating GBM tumors lies in its inherent histological complexity and to various mechanisms leading to treatment resistance
The objectives of this study were to demonstrate the variation of to-blood uptake ratio (TBR) with PET acquisition time, and to decompose the dynamic 18F-FMISO PET images into clusters describing hypoxia sub-volumes

Summary

Introduction

Glioblastoma multiforme (GBM) is known as the most common tumor in the central nervous system. The current techniques of treatment for GBM include surgery, chemotherapy and radiotherapy. These strategies of treatment have done minimum outcomes in extending the life expectancies of patients diagnosed with GBM. The patients’ median survival is ranging from 1 to 1.5 years, and only 5% of the patients reach five years survival[1]. The difficulty of treating GBM tumors lies in its inherent histological complexity and to various mechanisms leading to treatment resistance. One of these mechanisms is hypoxia, which is defined as low oxygenation levels inside the tumor

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Conclusion