DOI: 10.1007/s00259-018-4154-5Pages: 206-216

A prospective study of the feasibility of FDG-PET/CT imaging to quantify radiation-induced lung inflammation in locally advanced non-small cell lung cancer patients receiving proton or photon radiotherapy

1. University of Pennsylvania, Department of Radiology

2. University of Pennsylvania, Department of Radiation Oncology

3. University of Maryland School of Medicine, Department of Radiation Oncology

Correspondence to:
Charles B. Simone
Tel: 410-369-5215
Email: CharlesSimone@umm.edu

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Abstract

Purpose

This prospective study assessed the feasibility of 18F-2-fluoro-2-deoxy-D-glucose (FDG) positron emission tomography/computed tomography (PET/CT) to quantify radiation-induced lung inflammation in patients with locally advanced non-small cell lung cancer (NSCLC) who received radiotherapy (RT), and compared the differences in inflammation in the ipsilateral and contralateral lungs following proton and photon RT.

Methods

Thirty-nine consecutive patients with NSCLC underwent FDG-PET/CT imaging before and after RT on a prospective study. A novel quantitative approach utilized regions of interest placed around the anatomical boundaries of the lung parenchyma and provided lung mean standardized uptake value (SUVmean), global lung glycolysis (GLG), global lung parenchymal glycolysis (GLPG) and total lung volume (LV). To quantify primary tumor metabolic response to RT, an adaptive contrast-oriented thresholding algorithm was applied to measure metabolically active tumor volume (MTV), tumor uncorrected SUVmean, tumor partial volume corrected SUVmean (tumor-PVC-SUVmean), and total lesion glycolysis (TLG). Parameters of FDG-PET/CT scans before and after RT were compared using two-tailed paired t-tests.

Results

All tumor parameters after either proton or photon RT decreased significantly (p < 0.001). Among the 21 patients treated exclusively with proton RT, no significant increase in PVC-SUVmean or PVC-GLPG was observed in ipsilateral lungs after the PVC parameters of primary tumor were subtracted (p = 0.114 and p = 0.453, respectively). Also, there were no significant increases in SUVmean or GLG of contralateral lungs of patients who received proton RT (p = 0.841, p = 0.241, respectively). In contrast, among the nine patients who received photon RT, there was a statistically significant increase in PVC-GLPG of ipsilateral lung (p < 0.001) and in GLG of contralateral (p = 0.036) lung. In the subset of nine patients who received a combined proton and photon RT, there was a statistically significant increase in PVC-GLPG of ipsilateral lung (p < 0.001).

Conclusion

Our data suggest less induction of inflammatory response in both the ipsilateral and contralateral lungs of patients treated with proton compared to photon or combined proton-photon RT.

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  • Accepted: Aug 29, 2018
  • Online: Sep 18, 2018

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