Tractometry‐Based Estimation of Corticospinal Tract Injury to Assess Initial Impairment and Predict Functional Outcomes in Ischemic Stroke Patients

Abstract

Background: Corticospinal tract (CST) injury has been shown to exert a major influence on functional recovery after ischemic stroke. Purpose: To evaluate the prognostic value of CST injury estimated using a recent developed tractometry-based method. Study Type: Prospective. Population: Forty-eight patients with CST damage induced by stroke lesion who underwent brain magnetic resonance imaging within 7 days from onset. Sequence: Diffusion-weighted imaging (b = 1000 seconds/mm 2 ) and diffusion kurtosis imaging (DKI) spin-echo echoplanar sequence with three b-values (0, 1250, and 2500 seconds/mm 2 ) at 3.0 T. Assessment: A recently developed approach that combines tract segmentation and orientation mapping was used for CST-specific tractography and tractometry. CST injury was estimated using the proposed method with diffusion metrics extracted from DKI sequence and with the first principal component (PC1) of the metrics. We also calculated the weighted lesion load (wLL) for comparison. Clinical evaluation included the National Institutes of Health Stroke Score in the acute phase and the modified Rankin scale at 3 months post-stroke. The correlations between CST injury and initial motor impairment, as well as the prognostic values of CST injury for functional outcomes were evaluated. Statistical Tests: Pearson correlation and logistic regression. Area under the receiver operating characteristic curve. P < 0.05 was considered statistically significant. Results: CST injury calculated with diffusion metrics except fractional anisotropy all showed significant correlations with initial motor impairment. PC1 achieved the largest correlation coefficient (R = 0.65) compared with wLL and other diffusion metrics. In addition to wLL, DKI_AK, AFD_total, and PC1 maximum all showed predictive values for functional outcomes. Data Conclusion: Structural injury to CST is important for the assessment of the extent of injury and the prediction of functional outcome. The method proposed in our study could provide an imaging indicator to quantify the CST injury after ischemic stroke. Level of Evidence: 2 Technical Efficacy: Stage 1

Performance Comparison of Different Neuroimaging Methods for Predicting Upper Limb Motor Outcomes in Patients after Stroke

“…Doughty et al [ 30 ] suggested that CST lesion load in the acute phase predicts 3-month outcomes better than the FAA of regions of interests (ROIs) distal to the lesion. A recent study estimating CST injury by the proposed method with diffusion metrics extracted from the diffusional kurtosis imaging (DKI) sequence and with the first principal component (PC1) of the metrics found that DKI_AK, AFD_total, and PC1 showed similar predictive values to those of wLL for functional outcomes [ 31 ]. Although previous studies have confirmed that FA is a good predictor of 3-month functional outcomes, our results suggested that the AUCs for CST-wLL in the subacute phase were similar to those of the FAAI.…”

Association between superior longitudinal fasciculus, motor recovery, and motor outcome after stroke: a cohort study

“…One important source of discrepancy is the methodology used to assess the CST white matter integrity (i.e., which diffusion tensor imaging metrics and which methods to use for CST tract reconstruction) (18). Li et al (21) reported, in a tractometry-based study, that, if mean diffusivity, axial diffusivity, and radial diffusivity correlated with the modified Rankin scale at 3 months, FA failed to reach statistical significance.…”

Assessment of corticospinal tract remodeling based on diffusion tensor imaging in the treatment of motor dysfunction after ischemic stroke by acupuncture: A meta-analysis

“…[9,10] Therefore, an adequate grasp of the infarct size and CST damage in the clinic can help to make an effective judgment of the degree of motor function impairment in patients. [11] MRI is an important basis for confirming the diagnosis and localization of IS in clinical practice. Among them, Diffusion Tensor Imaging (DTI) can show the morphological changes of the corticospinal tracts by processing visualization, and can accurately quantify the damage of the white matter fiber tracts by fractional anisotropy (FA), average diffusion coefficient (ADC), etc., which can objectively reflect the degree of CST nerve damage in IS patients.…”