Development of a PET/EPRI combined imaging system for assessing tumor hypoxia

TL;DR

This paper presents the development of a combined PET/EPRI imaging system to accurately assess tumor hypoxia, aiming to improve radiation therapy planning by providing precise oxygen measurements as ground truth.

Contribution

The study introduces a novel integrated PET/EPRI system for simultaneous tumor hypoxia imaging, validating PET results with EPRI measurements in animal models.

Findings

Successful construction of the PET/EPRI system.

Initial imaging demonstrated feasibility in tumor hypoxia assessment.

EPRI provides precise oxygen partial pressure measurements.

Abstract

Precise quantitative delineation of tumor hypoxia is essential in radiation therapy treatment planning to improve the treatment efficacy by targeting hypoxic sub-volumes. We developed a combined imaging system of positron emission tomography (PET) and electron para-magnetic resonance imaging (EPRI) of molecular oxygen to investigate the accuracy of PET imaging in assessing tumor hypoxia. The PET/EPRI combined imaging system aims to use EPRI to precisely measure the oxygen partial pressure in tissues. This will evaluate the validity of PET hypoxic tumor imaging by (near) simultaneously acquired EPRI as ground truth. The combined imaging system was constructed by integrating a small animal PET scanner (inner ring diameter 62 mm and axial field of view 25.6 mm) and an EPRI subsystem (field strength 25 mT and resonant frequency 700 MHz). The compatibility between the PET and EPRI subsystems were tested with both phantom and animal imaging. Hypoxic imaging on a tumor mouse model using $^{18}$F-fluoromisonidazole radio-tracer was conducted with the developed PET/EPRI system. We report the development and initial imaging results obtained from the PET/EPRI combined imaging system.