The Effectiveness of Diffusion Tensor Imaging in Determining Radiological Response after Radiosurgery in Patients with Vestibular Schwannoma

Abstract

Background: The effectiveness of Diffusion Tensor Imaging (DTI) in demonstrating functional changes in the tumor in determining the response to treatment after radiosurgery in patients with vestibular schwannoma (VS) is not clear yet. Objective: The study aimed to determine the change total in tumor volume (TTV) in terms of radiological response in patients who had VS and were treated with radiosurgery and investigate the relationship between the TTV, follow-up times and DTI parameters. Methods: Thirty-one patients were assessed using DTI and MRI. TTV, apparent diffusion coefficient (ADC), and fractional anisotropy (FA) were calculated. Patients were divided into tree groups: those who responded to the treatment (group 1) (n=11), who did not (group 0) (n=9) and who remained stable (group 2) (n=11). Background: The effectiveness of Diffusion Tensor Imaging (DTI) in demonstrating functional changes in the tumor in determining the response to treatment after radiosurgery in patients with vestibular schwannoma (VS) is not clear yet. Objective: The study aimed to determine the change total in tumor volume (TTV) in terms of radiological response in patients who had VS and were treated with radiosurgery and investigate the relationship between the TTV, follow-up times and DTI parameters. Methods: Thirty-one patients were assessed using DTI and MRI. TTV, apparent diffusion coefficient (ADC), and fractional anisotropy (FA) were calculated. Patients were divided into tree groups: those who responded to the treatment (group 1) (n=11), who did not (group 0) (n=9) and who remained stable (group 2) (n=11). Results: The mean duration of follow-up was 28.81±14 months. ADC values increased in patients with VS after radiosurgery (p=0.004). There was no statistical difference in the FA values. A significant reduction in TTV after radiosurgery was detected in group 1 (p=0.003). ADC values increased significantly after radiosurgery in group 2 (p=0.04). Although there were no significant differences, ADC values after radiosurgery increased in group 1 and group 0. Conclusions: ADC values continuously increase due to radiation damage in the period before the tumor volume shrinks after radiosurgery. We think that it is not appropriate to diagnose inadequate treatment or progression only when TTV is evaluated in terms of response to treatment in the early period after radiosurgery.