Parametric Response Mapping of Co-registered Positron Emission Tomography and Dynamic Contrast Enhanced Computed Tomography to Identify Radio-resistant Sub-volumes in Locally Advanced Cervical Cancer. International journal of radiation oncology, biology, physics Capaldi, D. P., Hristov, D. H., Kidd, E. A. 2020

Abstract

PURPOSE: To identify sub-volumes that may predict treatment response to definitive concurrent chemoradiation therapy (CCRT) using parametric-response-mapping (PRM) of co-registered positron-emission-tomography (PET) and dynamic-contrast-enhanced (DCE) computed-tomography (CT) in locally advanced cervical carcinoma.METHODS AND MATERIALS: Pre- and mid-treatment (after 23±4days of CCRT) DCE CT and PET imaging were performed on 21 cervical cancer patients who were enrolled in a pilot study to evaluate the prognostic-value of CT perfusion for primary cervical cancer (NCT01805141). Three-dimensional co-registered maps of PET/CT standardized-uptake-value (SUV) and DCE CT blood-flow (BF) were generated. PRM was performed using voxel-wise joint histogram analysis to classify voxels within the tumor as highly-metabolic and perfused (SUVhiBFhi), highly-metabolic and hypoxic (SUVhiBFlo), low-metabolically active and hypoxic (SUVloBFlo), or low-metabolically active and perfused (SUVloBFhi) tissue based on thresholds determined from population means of pre-treatment PET SUV and DCE CT BF. Relationships between baseline pre-treatment imaging metrics and relative changes in metabolic-tumor-volume (DeltaMTV), calculated from pre- and during-treatment imaging, were determined using univariable and multivariable linear regression models.RESULTS: The relative volume of three PRM sub-volumes significantly changed during treatment (SUVhiBFhi: p=.04; SUVhiBFlo: p=.0008; SUVloBFhi: p=.02), while SUVloBFlo did not (p=.9). Pre-treatment PET SUVmax (r=-.58,p=.006), PET SUVmean (rho=-.59,p=.005), DCE CT BFmean (r=-.50,p=.02), tumor-volume (rho=-.65,p=.001) and PRM SUVhiBFhi (rho=-.59,p=.004) were negatively correlated with DeltaMTV, while PRM SUVloBFlo was positively-related with DeltaMTV (r=.77,p<.0001). In a multivariable model that predicted DeltaMTV, PRM SUVloBFlo, which combines both PET/CT and DCE CT, was the only significant variable (beta=1.825,p=.03), over both imaging modalities independently.CONCLUSIONS: PRM was applied in locally advanced cervical carcinoma treated definitively with chemoradiation and radioresistant sub-volumes were identified which correlated with changes in MTV and predict treatment-response. Identification of these sub-volumes may assist in clinical decision-making to tailor therapies, such as brachytherapy, in an effort to improve patient outcomes.

View details for DOI 10.1016/j.ijrobp.2020.03.023

View details for PubMedID 32251757