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Abstract #0469

Susceptibility of the Optic Nerve and the Involvement of Retrograde Neuronal Degeneration in a Delayed Radiation Induced Injury Model: Evidence from a Diffusion Tensor Imaging Study

Deqiang Qiu1, Silun Wang1,2, Kwok-Fai So3, Ed Xuekui Wu4, Lucullus Hing-Tong Leung5, Pek-Lan Khong1

1Diagnostic Radiology, The University of Hong Kong, Hong Kong, China; 2Radiology, Johns Hopkins University, Baltimore, MD, United States; 3Anatomy, The University of Hong Kong; 4Laboratory of Biomedical Imaging and Signal Processing, The University of Hong Kong; 5Oncology, Princess Margaret Hospital, Hong Kong, China

In the present study, we evaluated changes of multiple white matter tracts following radiation using diffusion tensor imaging. A novel finding of severe changes in FA in the contralateral optic nerve as compared to the ipsilateral optic nerve was observed, and these changes were confirmed by histological evaluation. These findings cannot be explained by difference in radiation dose and suggests, for the first time, an important role of retrograde neuronal degeneration in the underlying mechanism for radiation induced injury to the visual pathway. The results also suggest susceptibility of the optic nerve relative to the cerebral peduncle.