Fractional Anisotropy And Mean Diffusivity As Outcome Predictor Parameters For Gk Radiosurgery In Malignant Lesions.

Israel Roberto Foroni1, Giuseppe Kenneth Ricciardi1, Francesco Lupidi1, Antronio Nicolato1, Michele Longhi1, Antonio De Simone2, Francesca Pizzini1, Alberto Beltramello1, massimo a. gerosa3

1Verona University, Verona, Italy 2Vr, Italy 3University of Verona- Italy

Keywords: glioblastoma multiforme, Imaging, gamma knife, magnetic resonance imaging, diffusion tensor imaging

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       Assessment of brain tumor characteristics should be a requirement for better management of pre surgical or radio surgical planning and consequent follow up. Different techniques allow insights concerning information of tumor cell density within tumor resulting in better grading of malignancy and better target definition. Diffusion Tensor Imaging (DTI) modality is among others useful technique enabling this information although the current literature on this subject is mostly related to white matter delineation in close proximity of tumor.
     This research aims to provide information of fractional anisotropy (FA) and mean diffusivity (MD) parameters in relation to cell tumor density as outcome predictors in patients suffering of malignant lesions candidates to radiosurgery with Gamma Knife.
     As initial trial starting from January 2009 till October 2009 a total of 23 patients (13 M, 10 F; age range 22-75) were collected. 20 out of 23 metastases (9 lung, 4 kidney, 3 colon, 4 others) while 3 out of 23 were gliomas (2 pylocitic astrocytoma, 1 anaplastic astrocytoma).
     The day before the radiosurgery DTI was performed using 3 T MR scanner: patients were imaged with parallel imaging technique and a 4 channel coil; a diffusion weighted single-shot spin echo, echo planar sequence with 2.1x2.1x2.1 mm voxel size. Motion-probing gradients were applied along 18 non-colinear directions with a b factor of 700 sec/mm2 after one non-diffusion weighted image (b = 0 sec/mm2) was obtained. High resolution T1 weighted isotropic volumetric data set with a 3D-magnetization rapid gradient echo sequence with 1x1x1 mm voxel size was acquired.
     11 patients have been examined that way revealing for FA a good positive correlation with tumor cell density (r=0.71) , MD seems to have good negative correlation (r=0.7).
     This is a retrospective study.
     On the base of very preliminary results fractional anisotropy and mean diffusivity are serious parameters of outcome prediction highlighting sufficient correlation to malignancy and cell tumor density.


Project Roles:

I. Foroni (), G. Ricciardi (), F. Lupidi (), A. Nicolato (), M. Longhi (), A. De Simone (), F. Pizzini (), A. Beltramello (), m. gerosa ()