Correlations between cerebral cortical thickness, radiation dose and verbal memory performance
Catharina M.L. Zegers,
The Netherlands
MO-0550
Abstract
Correlations between cerebral cortical thickness, radiation dose and verbal memory performance
Authors: Inge Budé1, Joost de Jong2, Niklas Lackner1, Gerhard S. Drenthen2, Wouter van Elmpt1, Walter Backes3, Alida A. Postma2, Jeanette B. Dijkstra4, Inge Compter5, Daniëlle B.P. Eekers1, Catharina M.L. Zegers1
1Maastricht University Medical Center+, GROW-School for Oncology and Reproduction, Department of Radiation Oncology (Maastro), Maastricht, The Netherlands; 2Maastricht University Medical Center+, MHeNs School for Mental Health and Neuroscience, Department of Radiology & Nuclear Medicine, Maastricht, The Netherlands; 3Maastricht University Medical Center+, MHeNs School for Mental Health and Neuroscience, Maastricht, Department of Radiology & Nuclear Medicine, Maastricht, The Netherlands; 4Maastricht University Medical Center+, Department of Medical Psychology , Maastricht, The Netherlands; 5Maastricht University Medical Center+, GROW-School for Oncology and Reproduction, Maastricht, Department of Radiation Oncology (Maastro), Maastricht, The Netherlands
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Purpose or Objective
Radiotherapy induced impairment of cognitive function can lead to loss of independence and reduced quality of life. Cortical thinning has been observed in patients who have been treated with radiation, which might play a role in cognitive decline. The aim of this study is to explore correlations between cortical thickness, verbal memory function and radiation dose at baseline and one year after radiotherapy.
Material and Methods
Retrospective data collection of patients with a primary brain tumor was performed. Seventy-one patients were included, which all underwent neurocognitive testing and MRI scanning before radiotherapy. Moreover, follow-up data was available at 1 year for neurocognitive performance (N=71) and MRI (N=28). Automatic segmentation and measurement of the cortex was performed for the whole cerebrum, right and left hemisphere, temporal, parietal, occipital and frontal lobes on T1-weighed MR images using Freesurfer software. Automatic rigid registration was used to spatially co-register the MRI and cortex segmentation with the planning CT and dose map using openREGGUI. The mean radiation dose to the cortices was calculated. Verbal learning and memory were measured using the Hopkins verbal learning test (HVLT), from which the total recall and delayed recall were used as primary outcome measures. The spearman correlation coefficient was used to assess significant correlation between cortical thickness, verbal memory and radiation dose, where a p-value <0.05 was assumed statistically significant.
Results
Baseline: At baseline a significant negative correlation between age and cortical thickness of the whole cerebrum was observed (N=71, rho=-0.38, p<0.001). In addition, a significant positive correlation between the cortical thickness of the left temporal lobe and the HVLT total (rho=0.27, p=0.02) as well as the HVLT delayed recall (rho=0.34, p<0.01) was found. For the other lobes, no significant correlation was observed between verbal memory and cortical thickness at baseline.
Follow-up: Radiation dose to the left cerebral cortex was negatively correlated with the reliable change index of the HVLT delayed-recall (baseline vs 1 year; N=69, r=-0.28, p=0.02). An example of changes in cortical thickness is shown in Figure 1. Thinning of the cortex of the whole cerebrum after 1 year was correlated (rho=0.65, p=0.02) with a decrease in HVLT total for the younger (< median of 52 years; N=13), but not for the older patients (> median 52 years; N=15, r=-0.11, p=0.69).
No significant correlation was observed between radiation dose to the cortices and changes in cortical thickness (Figure 2).
Conclusion
There is a negative correlation between the thickness of the cerebral cortex in the left temporal lobe and verbal memory at baseline. The radiation dose to the left cortex can potentially influence verbal memory at 1 year after treatment. In addition, there is a correlation between the changes in cortical thickness and verbal memory after treatment, which is influenced by age.