A Bayesian Hierarchical Model for the Analysis of a Longitudinal Dynamic Contrast-Enhanced MRI Cancer Study

TL;DR

This paper introduces a Bayesian hierarchical model for analyzing longitudinal DCE-MRI data in cancer studies, enabling comprehensive voxel-level and patient-level inference and improving the evaluation of treatment effects.

Contribution

It proposes a novel Bayesian hierarchical framework that models all voxel time courses simultaneously, capturing treatment, patient, and voxel effects in longitudinal DCE-MRI analysis.

Findings

Validated with breast cancer data showing clinical utility

Allows hypothesis testing for treatment effects at study level

Provides detailed random effects at patient and voxel levels

Abstract

Imaging in clinical oncology trials provides a wealth of information that contributes to the drug development process, especially in early phase studies. This paper focuses on kinetic modeling in DCE-MRI, inspired by mixed-effects models that are frequently used in the analysis of clinical trials. Instead of summarizing each scanning session as a single kinetic parameter -- such as median $\ktrans$ across all voxels in the tumor ROI -- we propose to analyze all voxel time courses from all scans and across all subjects simultaneously in a single model. The kinetic parameters from the usual non-linear regression model are decomposed into unique components associated with factors from the longitudinal study; e.g., treatment, patient and voxel effects. A Bayesian hierarchical model provides the framework in order to construct a data model, a parameter model, as well as prior distributions. The posterior distribution of the kinetic parameters is estimated using Markov chain Monte Carlo (MCMC) methods. Hypothesis testing at the study level for an overall treatment effect is straightforward and the patient- and voxel-level parameters capture random effects that provide additional information at various levels of resolution to allow a thorough evaluation of the clinical trial. The proposed method is validated with a breast cancer study, where the subjects were imaged before and after two cycles of chemotherapy, demonstrating the clinical potential of this method to longitudinal oncology studies.