Applicability of automated tractography during acute care stroke rehabilitation

Abstract

To assess the clinical applicability of a novel automated tractography tool named XTRACT during acute stroke rehabilitation. [Participants and Methods] Three patients with left hemisphere stroke were sampled. Diffusion tensor images were acquired on the second week, and automated tractography was then applied. Tractography images and fractional anisotropy (FA) values in the corticospinal tract (CST) and arcuate fasciculus (AF) were assessed in relation to hemiparesis and aphasia. [Results] Patient 1 was nearly asymptomatic; FA in the left CST was 0.610 and that in the AF was 0.509. Patient 2 had severe hemiparesis and mild motor aphasia. Tractography images of the CST and AF were blurred; FA in the left CST was 0.295 and that in the AF was 0.304. Patient 3 showed no hemiparesis or aphasia at initial assessment. Tractography image of the CST was intact but that of the AF was less clear; FA in the left CST was 0.586 and that in the AF was 0.338. Considering the less clear images of the AF and lower FA value in Patients 2 and 3, further examinations for aphasia were performed, which revealed agraphia. [Conclusion] Visualization and quantification of neural fibers using automated tractography promoted planning acute care rehabilitative treatment in patients with stroke.

Clinical applicability of automated tractography for stroke rehabilitation: Z-score conversion of fractional anisotropy

“…Stroke management followed the Japanese Guidelines for the Management of Stroke 2021 12 ) , which include a rehabilitative regimen. To account for potential confounds arising from variations in pre-stroke health status and lesion sites, our sample was limited to first-ever stroke patients with unilateral supratentorial lesions who were functionally independent in activities of daily living (ADLs) before the stroke 8 , 9 , 10 , 11 ) . We also excluded patients who subsequently showed a deterioration in neurological manifestations and other medical conditions during acute care.…”

“…As in our previous studies 8 , 9 , 10 , 11 ) , DTI scans were typically conducted in the second week after admission to our acute care service. The scans were obtained using a 3.0-Tesla scanner (MAGNETOM Trio; Siemens AG, Erlangen, Germany) equipped with a 32-channel head coil.…”

“…The imaging process used has been described in detail elsewhere 8 , 9 , 10 , 11 ) . In brief, the initial steps included the elimination of the Gibbs ringing artifact, correction of distortions induced by eddy currents and echo-planar imaging, and application of bias field corrections by using MRtrix software 13 ) and the FMRIB Software Library (FSL) 14 ) .…”

“…This facilitated the generation of tractography data for 42 predefined sets of neural bundles. Parameter estimates including FA values were extracted using a threshold set at 0.01, in line with our previous studies 8 , 9 , 10 , 11 ) . For clarity, we concentrated on the neural tracts that are frequently impaired by stroke lesions 15 , 16 , 17 ) : the corticospinal tract (CST), the superior longitudinal fasciculus parts 1, 2, and 3 (SLF1–3), the frontal aslant (FAS), the anterior thalamic radiation (ATR), the inferior fronto-occipital fasciculus (IFOF), the inferior longitudinal fasciculus (ILF), and the uncinate fasciculus (UNF).…”

“…Of various parameters derived from tractography, fractional anisotropy (FA) is commonly used as an indicator of neural integrity within the brain, particularly as a marker of Wallerian degeneration 7 ) . In our previous studies, we successfully demonstrated the clinical applicability of this newly developed automated tractography approach in relation to hemiparesis and aphasia due to stroke 8 , 9 , 10 , 11 ) . To further expand the ability of this new method to assess the neural tracts within the brain, we conducted the present study to provide reference FA values for the neural tracts that are commonly involved in stroke pathology.…”