Room: Exhibit Hall | Forum 8
Purpose: To minimize the complication of radiosurgery for critically located lesions, we integrated diffusion tensor tractography into treatment planning for Gamma-knife radiosurgery(GKRS) for trigeminal neuralgia. Assessment of treatment effectiveness is primarily clinical, given the paucity of investigational tools to assess trigeminal nerve (TN) changes. The efficiency of radiosurgery is related to its highly precise targeting. We assessed clinically the targeting accuracy of GKRS. We hypothesized that TN tractography provides more information, allowing detection of the target.
Methods: Sixteen trigeminal neuralgia patients (12 females, 4 male, average age 65.3 years) were underwent 1.5T MRI and treated with the GKRS. All patients were treated with a single 4-mm isocenter, treatment dose rates ranged from 1.54 to 3.56 Gy/min. Target accuracy was assessed from deviation of the coordinates of the target compared with the center of enhancement on post MRI. Radiation dose delivered at the borders of contrast enhancement was evaluated.
Results: The median deviation of the coordinates between the intended target and the center of contrast enhancement was within 1mm. The radiation doses fitting within the borders of the contrast enhancement the target ranged from 38 to 43 Gy. Trigeminal tractography accurately detected the radiosurgical target. GKRS resulted in 47% drop in FA values at the target with no significant change in FA outside the target, suggesting that radiosurgery primarily affects myelin. Tractography was more sensitive, since FA changes were detected regardless of TN enhancement.
Conclusion: The median deviation found in clinical assessment of GKRS is compatible with its high rate of efficiency. Diffusion tensor imaging (DTI) parameters accurately detect the effects of focal radiosurgery on the trigeminal neuralgia, serving as an in vivo imaging tool. This study is a proof of principle for further assessment of DTI parameters to understand the pathophysiology of trigeminal neuralgia and treatment effects.