Preliminary Study On Reconstruction Of The Arcuate Fasciculus Withtwo-tensor Unscented Kalman Filter Tractography

Backgroud Arcuate fasciculus (AF) is a crucial bundle of white matter fibers related with human language function. Diffusion imaging tractography is increasingly used to trace arcuate fasciculus before and in resection of tumors involving language areas. However, conventional tractography using the single-tensor model has limitations in reconstruction of AF in regions of peritumoral edema and the branching fibers of AF. The aim of this study is to investigate the feasibility of a novel technique named as two-tensor unscented Kalman filter tractography (UKFT) to track AF in regions of peritumoral edema and the feasibility of predicting language lateralization via asymmetry of the AF reconstructed by UKFT by contrast with Wada test.Methods The first part retrospectively investigated the feasibility of AF reconstruction in regions of significant peritumoral edema of malignant intracranial tumors by UKFT in 16 right-handed patients who suffered from the lesions involving language areas at left hemisphere and underwent 1.5-Tesla magnetic resonance imaging including a diffusion-weighted data set with 20 gradient directions. AF tracking was performed by both single-tensor streamline tractography (STST) and UKFT. Results from the two different tractography were compared visually and analyzed statistically by paired-samples T test. The second part retrospectively investigated the feasibility of predicting language lateralization via asymmetry of AF reconstructed by UKFT in 11 patients who underwent Wada test, a golden standard method in predicting language lateralization. No studies focused on patients with low grade gliomas before. Lateralization index of AF volume from UKFT was calculated to predict language dominance and concordance between UKFT and Wada test was obtained. And the operator who performed the UKFT was blind to the results of Wada test.Results In the first part, the AF reconstructed by STST appeared disrupted or incomplete in seven patients and only in three by UKFT. Moreover, the volume of AF reconstructed by UKFT was significantly larger than that by STST (t=7.269, p<0.001) in nine patients whose AF could be traced successfully by both STST and UKFT, and the branching fibers of AF delineated by UKFT seemed significantly more than that of STST. In the second part, the language dominant hemisphere predicted by asymmetry of volume of AF through UKFTwas completely concordant with that of the Wada test, whose results showed that the language dominant side was left in nine patients and two in right patients.Conclusions UKFT can trace the AF in regions of peritumoral edema more completely than STST in patients with malignant brain tumor and it owned potential value in predicting language dominant hemisphere preoperatively in patients with low-grade gliomas. However, both of the sample size of two parts in the present study are small, thus it needs further larger sample studies on the validity of UKFT in the two aspects above.