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. 2019 Jul:136:44-49.
doi: 10.1016/j.radonc.2019.03.024. Epub 2019 Apr 6.

Dose-dependent atrophy of the amygdala after radiotherapy

Minh-Phuong Huynh-Le  1 , Roshan Karunamuni  1 , Vitali Moiseenko  1 , Nikdokht Farid  2 , Carrie R McDonald  3 , Jona A Hattangadi-Gluth  1 , Tyler M Seibert  4
Affiliations

Dose-dependent atrophy of the amygdala after radiotherapy

Minh-Phuong Huynh-Le et al. Radiother Oncol. 2019 Jul.

Abstract

Background and purpose: The amygdalae are deep brain nuclei critical to emotional processing and the creation and storage of memory. It is not known whether the amygdalae are affected by brain radiotherapy (RT). We sought to quantify dose-dependent amygdala change one year after brain RT.

Materials and methods: 52 patients with primary brain tumors were retrospectively identified. Study patients underwent high-resolution, volumetric magnetic resonance imaging before RT and 1 year afterward. Images were processed using FDA-cleared software for automated segmentation of amygdala volume. Tumor, surgical changes, and segmentation errors were manually censored. Mean amygdala RT dose was tested for correlation with amygdala volume change 1 year after RT via the Pearson correlation coefficient. A linear mixed-effects model was constructed to evaluate potential predictors of amygdala volume change, including age, tumor hemisphere, sex, seizure history, and bevacizumab treatment during the study period. As 51 of 52 patients received chemotherapy, possible chemotherapy effects could not be studied. A two-tailed p-value <0.05 was considered statistically significant.

Results: Mean amygdala RT dose (r = -0.28, p = 0.01) was significantly correlated with volume loss. On multivariable analysis, the only significant predictor of amygdala atrophy was radiation dose. The final linear mixed-effects model estimated amygdala volume loss of 0.17% for every 1 Gy increase in mean amygdala RT dose (p = 0.008).

Conclusions: The amygdala demonstrates dose-dependent atrophy one year after radiotherapy for brain tumors. Amygdala atrophy may mediate neuropsychological effects seen after brain RT.

Keywords: Amygdala; Brain radiotherapy; Quantitative MRI.

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Conflict of interest statement

Conflicts of Interest: Drs. Seibert and Hattangadi-Gluth report grant funding from Varian Medical Systems, unrelated to the present study. Dr. Seibert reports grants from Radiological Society of North America during the conduct of the study and honoraria from WebMD, Inc, for providing educational content.

Figures

Figure 1.
Figure 1.
Magnetic resonance images (MRI) with color overlay from two illustrative cases showing automated segmentation of the amygdala in cyan. Images on left and right are MRIs taken pre-radiotherapy and 1-year post-radiotherapy, respectively. Coronal and axial images are shown for both cases. Volume percent change of the amygdala and mean dose to that structure are shown on the post-radiotherapy coronal MRI slices.
Figure 2.
Figure 2.
Amygdala volume changes one year after radiotherapy (RT), reported as percentage change relative to baseline pre-RT volume. Each individual dot corresponds to one amygdala (left or right; 84 amygdalae, in all).
See this image and copyright information in PMC

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