Prognostic value of diffusion tensor imaging parameters for Gamma Knife radiosurgery in meningiomas

Abstract

OBJECTIVEDiffusion tensor imaging (DTI) parameters are able to differentiate between meningioma subtypes. The hypothesis that there is a correlation between DTI parameters and the change in tumor size after Gamma Knife radiosurgery (GKRS) was analyzed.METHODSDTI parameters were measured using MRI before GKRS in 26 patients with meningiomas. The findings were correlated with the change in tumor size after treatment as measured at the last follow-up (range 12.5–45 months).RESULTSOnly those meningiomas that showed the highest fractional anisotropy (FA), the lowest spherical index of the tensor ellipsoid (Cs), and the lowest radial diffusivity (RD) either increased or remained stable in terms of volume, whereas all other meningiomas decreased in volume. The correlation between the DTI parameters (correlation values of −0.81 for FA, 0.75 for Cs, 0.66 for RD, and 0.66 for mean diffusivity) and the rate of volume change per month was significant (p ≤ 0.001). Other factors, including original tumor size, prescription dose, and patient age, did not correlate significantly.CONCLUSIONSMeningiomas that show high FA values—as well as low Cs, low RD, and low mean diffusivity values—do not respond as well to GKRS in comparison with meningiomas with low FA values. This finding might be due to their higher content level of fibrous tissue. In particular, the meningioma with the highest FA value (0.444) considerably increased in volume (by 32.3% after 37 months), whereas the meningioma with the lowest FA value (0.151) showed the highest rate of reduction (3.3% per month) in this study.

Pretreatment texture analysis of routine MR images and shape analysis of the diffusion tensor for prediction of volumetric response after radiosurgery for meningioma

“…Texture analysis based on MRI data revealed a highly significant correlation between DTI data, mainly FA, Cp, and L3, and the rate of tumor volume reduction per month. In this way, previous results 19 were confirmed by including a larger number of patients, a longer follow-up period, and the application of a different software package for calculating DTI parameters.…”

“…This partially retrospective study was approved by the institutional review board at CEDIMAT hospital and included some pre-GKRS imaging data from the Speckter et al 19 study mentioned earlier. However, tumor volume changes in these patients were updated according to more recent follow-up examination results.…”

“…11,22 Finally, using histograms from 8 different DTI parameters and data from T1-and T2-weighted images, the best model was elaborated statistically to classify meningiomas according to their subtype and grade. 24 Carrying this concept to clinical application in radiosurgery, Speckter et al 19 described a significant predictive value of FA and other DTI parameters, measured before treatment, for volume reduction after Gamma Knife radiosurgery (GKRS) in meningiomas. In their study, only the mean values of 6 different DTI parameters were compared to predict the success of GKRS, and T1-and T2weighted image sequences were not included.…”

Importance of Pre-treatment Fractional Anisotropy Value in Predicting Volumetric Response in Patients with Meningioma Treated with Gamma Knife Radiosurgery

“…Recently, Gamma Knife Radiosurgery (GKR) has been used in even larger meningiomas (> 2.5-3 cm). It has been reported that meningioma growth is controlled between 85% and 99% in patients who have been followed up for more than 3 years after GKR [ 1 , 4 - 8 ]. The location of the meningioma may affect the response of the tumor after radiosurgery.…”

“…In parasagittal meningiomas close to critical structures that are sensitive to radiation, such as optic pathways, brainstem, and cochlea, radiosurgery should be planned more carefully. The volume shrinkage in meningiomas after radiosurgery is affected by several factors such as initial tumor volume, radiation dose, patient age, and follow-up time [ 4 , 9 - 11 ].…”