Author: Robert Fucetola, Jiayi Huang, Zhihua Liu, Chongliang Luo, Tong Zhu 👨🔬
Affiliation: Washington University School of Medicine, Washington University in St. Louis, School of Medicine 🌍
Purpose:
This prospective observational study investigates radiation-induced white matter (WM) injuries using longitudinal diffusion tensor imaging (DTI) in patients with diffuse glioma following radiotherapy (RT). We aim to not only quantify dose response pattern of WM injuries, quantified by axial/radial diffusivity (AD/RD) of DTI, but also evaluate spatial pattern of WM injuries that correlate with neurocognitive function (NCF) changes.
Methods:
32 adult glioma patients underwent NCF testing using the NIH Toolbox Cognitive Function Battery (NIHTB-CFB) at baseline and 6 months post-RT, specifically the five fluid tests: dimension change card sort test (executive function), flanker test (attention), picture sequence test (episodic memory), list sorting test (working memory), and pattern comparison test (processing speed). Longitudinal changes of five test scores were calculated as the percent change at 6 months relative to the baseline. Longitudinal DTI were acquired on 3T MRIs coinciding with the NCF tests. An automated WM fiber segmentation approach was applied to generate 20 major WM tracts. Dosimetric characteristic of each tract was described by the mean value of top 95%, 90%, 80% percentile of the DVH. WM injury was quantified by the percentage of changes comparing to pre-RT values, of fractional anisotropy (FA), mean, axial and radial diffusivity (MD/AD/RD), at locations of dose range abovementioned. Correlation of longitudinal DTI changes with neurocognitive decline was evaluated through a linear fixed-effect model.
Results:
Dose- and age-dependent WM injury, quantified as increased AD and RD, were observed post-RT, especially in WM regions of elderly patients receiving high dose (>46Gy). Radiation injuries of several WM tracts significantly correlate with NCF scores of multiple domains, especially episodic memory (EM) and processing speed (PS). More importantly, many tracts are known to be part of EM and PS domains.
Conclusion:
Post-RT longitudinal changes of AD/RD from DTI may be promising imaging biomarkers for radiation-induced neurocognitive decline.