Article
Loss of fractional anisotropy of supratentorial tracts correlates significantly with impaired cognitive and fine motor function
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Published: | September 16, 2010 |
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Objective: Tumor and therapy-associated neurotoxic effects including local pressure and hypoperfusion, internal hydrocephalus, surgery, and adjuvant treatment cause brain damage in pediatric patients with posterior fossa tumors. Treatment related toxicity factors are resection in pilocytic astrocytoma (PA) and additionally cranio-spinal irradiation together with chemotherapy in medulloblastoma (MB) patients. We tested whether MR Diffusion Tensor Imaging (DTI) derived fractional anisotropy (FA) of white matter tracts correlates with functional results of ataxia, IQ, and kinematic parameters of handwriting in pediatric posterior fossa tumor patients.
Methods: 23 MB and 17 PA survivors (mean age ±SD, 14y±5) were subjected to DTI (b=1000, 25 directions, in-plane resolution 1 mm) on a 3T-MR system equipped with an 8-channel headcoil (GE Healthcare). Skeletonized FA-maps excluding the cerebellum were generated using FMRIB Software Library. Mean FA of the supratentorial tracts was determined. Ataxia was quantified using the International Cooperative Ataxia Rating Scale (ICARS). Wechsler Intelligence Scale for Children was applied to determine IQ. Movements of handwriting were analyzed using a digitizing graphic tablet. Speed and automation were determined employing CSWIN software.
Results: Mean FA correlated significantly (Spearman correlation) with movement parameters of handwriting (speed: r=0.48, p=0.012, automation: r=-0.4, p=0.038). Furthermore, a significant correlation was found of mean FA and IQ (r: 0.39, p=0.038), but no correlation between mean FA and ICARS scores were detected. All significant correlations indicated functional loss when supratentorial mean FA was decreased.
Conclusions: DTI is a useful tool to quantify tumor and therapy-associated cortical damage in patients who had tumors in the posterior fossa. It is linked with the functional outcome of this patient group. Mean FA of supratentorial tracts may be a representative marker for cognitive and motor deterioration of these patients. This study was supported by the “Kind-Philipp” foundation.