Associations of Diffusion-Tensor Fractional Anisotropy and FIM Outcome Assessments After Intracerebral Hemorrhage

Hypothermia protects the integrity of corticospinal tracts and alleviates mitochondria injury after intracerebral hemorrhage in mice

Disruption of corticospinal tracts (CST) is a leading factor for motor impairments following intracerebral hemorrhage (ICH) in the striatum. Previous studies have shown that therapeutic hypothermia (HT) improves outcomes of ICH patients. However, whether HT has a direct protection effect on the CST integrity and the underlying mechanisms remain largely unknown. In this study, we employed a chemogenetics approach to selectively activate bilateral warm-sensitive neurons in the preoptic areas to induce a hypothermia-like state. We then assessed effects of HT treatment on the integrity of CST and motor functional recovery after ICH. Our results showed that HT treatment significantly alleviated axonal degeneration around the hematoma and the CST axons at remote midbrain region, ultimately promoted skilled motor function recovery. Anterograde and retrograde tracing revealed that HT treatment protected the integrity of the CST over an extended period. Mechanistically, HT treatment prevented mitochondrial swelling in degenerated axons around the hematoma, alleviated mitochondrial impairment by reducing mitochondrial ROS accumulation and improving mitochondrial membrane potential in primarily cultured cortical neurons with oxyhemoglobin treatment. Serving as a proof of principle, our study provided novel insights into the application of HT to improve functional recovery after ICH.

White matter fiber integrity and structural brain network topology: implications for balance function in postischemic stroke patients

Previous studies have suggested that ischemic stroke can result in white matter fiber injury and modifications in the structural brain network. However, the relationship with balance function scores remains insufficiently explored. Therefore, this study aims to explore the alterations in the microstructural properties of brain white matter and the topological characteristics of the structural brain network in postischemic stroke patients and their potential correlations with balance function. We enrolled 21 postischemic stroke patients and 21 age, sex, and education-matched healthy controls (HC). All participants underwent balance function assessment and brain diffusion tensor imaging. Tract-based spatial statistics (TBSS) were used to compare the fractional anisotropy, mean diffusivity, axial diffusivity, and radial diffusivity of white matter fibers between the two groups. The white matter structural brain network was constructed based on the automated anatomical labeling atlas, and we conducted a graph theory-based analysis of its topological properties, including global network properties and local node properties. Additionally, the correlation between the significant structural differences and balance function score was analyzed. The TBSS results showed that in comparison to the HC, postischemic stroke patients exhibited extensive damage to their whole-brain white matter fiber tracts (P < 0.05). Graph theory analysis showed that in comparison to the HC, postischemic stroke patients exhibited statistically significant reductions in the values of global efficiency, local efficiency, and clustering coefficient, as well as an increase in characteristic path length (P < 0.05). In addition, the degree centrality and nodal efficiency of some nodes in postischemic stroke patients were significantly reduced (P < 0.05). The white matter fibers of the entire brain in postischemic stroke patients are extensively damaged, and the topological properties of the structural brain network are altered, which are closely related to balance function. This study is helpful in further understanding the neural mechanism of balance function after ischemic stroke from the white matter fiber and structural brain network topological properties.

Outcome Prediction by Combining Corticospinal Tract Lesion Load with Diffusion-tensor Fractional Anisotropy in Patients after Hemorrhagic Stroke

Objectives

The objective of this study was to evaluate the predictive precision of combining the corticospinal tract lesion load (CST-LL) with the diffusion-tensor fractional anisotropy of the corticospinal tract (CST-FA) in the lesioned hemispheres regarding motor outcomes.

Methods

Patients with putaminal and/or thalamic hemorrhage who had undergone computed tomography (CT) soon after onset in our hospital were retrospectively enrolled. The CST-LL was calculated after registration of the CT images to a standard brain. Diffusion-tensor imaging was performed during the second week after onset. Standardized automated tractography was employed to calculate the CST-FA. Outcomes were assessed at discharge from our affiliated rehabilitation facility using total scores of the motor component of the Stroke Impairment Assessment Set (SIAS-motor total; null to full, 0 to 25). Multivariate regression analysis was performed with CST-LL and CST-FA as explanatory variables and SIAS-motor total as a target value.

Results

Twenty-five patients participated in this study. SIAS-motor total ranged from 0 to 25 (median, 17). CST-LL ranged from 0.298 to 7.595 (median, 2.522) mL, and the lesion-side CST-FA ranged from 0.211 to 0.530 (median, 0.409). Analysis revealed that both explanatory variables were detected as statistically significant contributory factors. The estimated t values indicated that the contributions of these two variables were almost equal. The obtained regression model accounted for 63.9% of the variability of the target value.

Conclusions

Incorporation of the CST-LL with the lesion-side CST-FA enhances the precision of the stroke outcome prediction model.

Applicability of fractional anisotropy from standardized automated tractography for outcome prediction of patients after stroke

[Purpose] Diffusion-tensor fractional anisotropy has been used for outcome prediction in stroke patients. We assessed the clinical applicability of the two major fractional anisotropy methodologies-fractional anisotropy derived from segmentation maps in the standard brain (region of interest) and fractional anisotropy derived from standardized automated tractography-in relation to outcomes. [Participants and Methods] The study design was a retrospective survey of medical records collected from October 2021 to September 2022. Diffusion-tensor imaging was conducted in the second week after stroke onset. Outcomes were assessed using the total score of the motor component of the Stroke Impairment Assessment Set (null to full, 0 to 25). Correlations between fractional anisotropy and the outcomes were then assessed. [Results] Fourteen patients with hemorrhagic stroke were sampled. The fractional anisotropy from standardized automated tractography of the corticospinal tract on the lesion side (mean ± standard deviation, 0.403 ± 0.070) was significantly and tightly correlated (r=0.813) with the outcomes (13.4 ± 9.2), whereas the fractional anisotropy from a region of interest set in the cerebral peduncle on the lesion side (0.548 ± 0.064) was not significantly correlated with the outcomes (r=0.507). [Conclusion] The findings suggest that fractional anisotropy derived from standardized automated tractography can be more applicable to outcome prediction than that derived from a region of interest defined in the standard brain.

Automated Tractography for the Assessment of Aphasia in Acute Care Stroke Rehabilitation: A Case Series

Background

Aphasia is a common disorder among stroke patients. Assessment of aphasia is essential for scheduling appropriate rehabilitative treatment. Although this is conventionally accomplished using neuropsychological test batteries, these tests are not always accessible because of attention and/or consciousness disturbances during acute care. To overcome this issue, we have introduced a newly developed automated tractography known as XTRACT.

Cases

Diffusion-tensor images were acquired from three patients on days 10-14. Brain images were processed by XTRACT, which automatically extracts neural tracts using standardized protocols. Fractional anisotropy (FA) values were then bilaterally evaluated in the following neural tracts associated with aphasia: arcuate fasciculus, inferior fronto-occipital fasciculus, middle longitudinal fasciculus, inferior longitudinal fasciculus, and uncinate fasciculus. Case 1 had word-finding difficulty on admission. FA values in the lesioned left hemisphere were not decreased in all tracts and this patient fully recovered during acute care. Case 2 had reduced spontaneous speech and a low FA value in the left arcuate fasciculus. Rehabilitative treatment was scheduled to improve the verbal output of sentences and word recall. Case 3 could not complete the conventional aphasia test battery because of attention disturbance. He had low FA values in all tracts in the left hemisphere. Rehabilitative treatment was designed to focus on both speaking and auditory comprehension.

Discussion

Automated tractography enables quantitative assessment of the neural damage associated with aphasia, even in patients with attention and/or consciousness disturbances. This modality can aid in the assessment of aphasia and allows the planning of appropriate rehabilitative treatment.

Application study of DTI combined with ASL in the crossed cerebellar diaschisis after subacute cerebral hemorrhage

PURPOSE

To study the value of 3.0T magnetic resonance imaging with diffusion tensor imaging (DTI) and 3D-arterial spin labeling (ASL) perfusion imaging in the diagnosis of the crossed cerebellar diaschisis (CCD) after the unilateral supratentorial subacute cerebral hemorrhage.

METHODS

Fifty-eight patients with the unilateral supratentorial subacute cerebral hemorrhage who underwent diffusion tensor imaging (DTI), 3D-arterial spin labeling (ASL), and conventional magnetic resonance imaging (MRI) scanning were enrolled. Cerebral blood flow (CBF) values of the perihematomal edema (PHE) and bilateral cerebellar hemisphere were measured on ASL mapping, and the fractional anisotropy (FA) and mean diffusivity (MD) values of the bilateral cortical, pontine, and middle cerebellar peduncle (MCP) were measured on DTI mapping.

RESULTS

In the CCD(+) group, FA values of the cerebral cortex and pontine ipsilateral to the lesion were statistically reduced compared to the contralateral side (P < 0.05), and the FA and MD values of the middle cerebellar peduncle (MCP) contralateral to the lesion were statistically reduced compared to the ipsilateral side (P < 0.05). Positive correlation was detected between the CBF values of the perihematomal edema (PHE) and the CBF values of cerebellar hemispheres (r = 0.642, P < 0.05), whereas the CBF values of PHE had a significantly high positive correlation with the FA in the contralateral MCP (r = 0.854, P < 0.05). CBF values in the contralateral cerebellar hemisphere correlated with FA (r = 0.466, P < 0.05) and MD values (r = 0.718, P < 0.05) in the contralateral MCP.

CONCLUSION

Hemodynamic alterations of PHE and cortical-ponts-cerebellum (CPC) fibrous pathway damage are associated with the development of CCD; DTI technique can assess the degree of CPC fiber pathway injury at an early stage.

Brain regions associated with Brunnstrom and functional independence measure scores in patients after a stroke: a tract-based spatial statistics study

[Purpose] We aimed to assess diffusion tensor fractional anisotropy to outline the brain regions associated with the long-term motor and cognitive functional outcomes of patients with stroke. [Participants and Methods] Eighty patients from our previous study were enrolled. Fractional anisotropy maps were acquired on days 14-21 after stroke onset, and tract-based spatial statistics were applied. Outcomes were scored using the Brunnstrom recovery stage and Functional Independence Measure motor and cognition components. Fractional anisotropy images were assessed in relation to outcome scores using the general linear model. [Results] For both the right (n=37) and left (n=43) hemisphere lesion groups, the corticospinal tract and the anterior thalamic radiation were most strongly associated with the Brunnstrom recovery stage. In contrast, the cognition component involved large regions encompassing the anterior thalamic radiation, superior longitudinal fasciculus, inferior longitudinal fasciculus, uncinate fasciculus, cingulum bundle, forceps major, and forceps minor. The results for the motor component were intermediate between those for the Brunnstrom recovery stage and those for the cognition component. [Conclusion] Motor-related outcomes were associated with fractional anisotropy decreases in the corticospinal tract, whereas cognitive outcomes were related to broad regions of association and commissural fibers. This knowledge will help scheduling appropriate rehabilitative treatments.

Applicability of automated tractography during acute care stroke rehabilitation

[Purpose] 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.

Outcome Prediction of Patients with Intracerebral Hemorrhage by Measurement of Lesion Volume in the Corticospinal Tract on Computed Tomography

Objective:

This study investigated the potential utility of computed tomography for outcome prediction in patients with intracerebral hemorrhage.

Methods:

Patients with putaminal and/or thalamic hemorrhage for whom computed tomography images were acquired in our hospital emergency room soon after onset were retrospectively enrolled. Outcome measurements were obtained at discharge from the convalescent rehabilitation ward of our affiliated hospital. Hemiparesis was evaluated using the total score of the motor component of the Stroke Impairment Assessment Set (SIAS-motor; null to full, 0 to 25), the motor component of the Functional Independence Measure (FIM-motor; null to full, 13 to 91), and the total length of hospital stay. After registration of the computed tomography images to the standard brain, the volumes of the hematoma lesions located in the corticospinal tract were calculated. The correlation between the corticospinal tract lesion volumes and the outcome measurements was assessed using Spearman’s rank correlation test.

Results:

Thirty patients were entered into the final analytical database. Corticospinal tract lesion volumes ranged from 0.002 to 4.302 ml (median, 1.478). SIAS-motor scores ranged from 0 to 25 (median, 20), FIM-motor scores ranged from 15 to 91 (median, 80.5), and the total length of hospital stay ranged from 31 to 194 days (median, 106.5). All correlation tests were statistically significant (P <0.01). The strongest correlation was for SIAS-motor total (R=–0.710), followed by FIM-motor (R=–0.604) and LOS (R=0.493).

Conclusions:

These findings suggest that conventional computed tomography images may be useful for outcome prediction in patients with intracerebral hemorrhage.

Outcome prediction in patients with putaminal hemorrhage at admission to a convalescent rehabilitation ward based on hemorrhage volume assessed with computed tomography during acute care

[Purpose] The aim of this study was to assess the usefulness of computed tomography for outcome prediction in patients with putaminal hemorrhage at admission to a convalescent rehabilitation ward. [Participants and Methods] Patients admitted to our convalescent rehabilitation ward after transfer from acute care hospitals were included in this study. Multiple regression analyses were performed using the score in the motor component of the Functional Independence Measure at discharge as the target value. Hemorrhage volume assessed with computed tomography during acute care and age were set as the explanatory variables. The motor component of the Functional Independence Measure score at admission and the time (days) from onset were also recorded. Correlation analyses between all the possible pairs of explanatory variables were then performed. [Results] Hemorrhage volume and age were both significant contributors to the motor component of the Functional Independence Measure score at discharge. However, the contribution of hemorrhage volume disappeared when the time from onset and motor component of the Functional Independence Measure score at admission were added. Hemorrhage volume significantly correlated with the time from onset and motor component of the Functional Independence Measure score at admission. [Conclusion] The present findings suggest that computed tomography may be useful for outcome prediction from the acute stage in stroke patients with putaminal hemorrhage. However, because of multicollinearity, its predictive power was reduced when the patients were transferred to a convalescent rehabilitation ward.

Integrity of The Hand Fibers of The Corticospinal Tract Shown by Diffusion Tensor Imaging Predicts Hand Function Recovery After Hemorrhagic Stroke

BACKGROUND

Hand motor function is often severely affected in patients with hemorrhagic stroke. The present study aimed to investigate the feasibility of predicting hand function recovery after hypertensive intracerebral hemorrhage using diffusion tensor imaging (DTI).

METHODS

A total of 75 patients with hypertensive intracerebral hemorrhage were prospectively included. DTI of the corticospinal tract (CST) connecting the hand knob area of the precentral gyrus and the cerebral peduncle was performed at around 3 weeks after stroke. Integrity of the CST was evaluated as no disruption, partial disruption, and complete disruption. Hand function was compared by the Brunnstrom recovery stage of hand (BRS-H) at post-stroke 3 weeks and 3 months.

RESULTS

Degrees of integrity of the corticospinal cord was negatively correlated with the BRS-H at both post-stroke 3 weeks (r = -0.77, p < 0.01) and 3 months (r = -0.75, p < 0.01). Patients with intact CST or completely disrupted CST shown by DTI did not show significant improvement in the BRS-H at post-stroke 3 months. However, those with partially disrupted CST showed significant improvement in the BRS-H at post-stroke 3 months compared to 3 weeks (3.79 ± 1.36 vs 2.53 ± 1.58, p = 0.012).

CONCLUSIONS

DTI can be used to visualize the damage to the hand fibers of the CST. Patients with partially disrupted CST may benefit most from rehabilitation therapy for hand function recovery after hypertensive intracerebral hemorrhage.

Evidence of motor injury due to damaged corticospinal tract following acute hemorrhage in the basal ganglia region

The integrity of the corticospinal tract (CST) is significantly affected following basal ganglia haemorrhage. We aimed to assess the local features of CST and to effectively predict motor function by diffusion characteristics of CST in patients with motor injury following acute haemorrhage in the acute basal ganglia region. We recruited 37 patients with paresis of the lateral limbs caused by acute basal ganglia haemorrhage. Based on the automated fiber quantification method to track CST, assessed the character of each CST segment between the affected and contralateral sides, and correlated these with the Fugl-Meyer (FM) and Barthel Index (BI) scores at 6 months after onset. The fractional anisotropy (FA) values of the injured side of CST showed a significantly lower FA than the contralateral side along the tract profiles (p < 0.05, corrections for multiple comparisons). The FA values of each site at the internal capsule, closed corona radiata were positively correlated with the FM and BI score at 6 months after onset (p < 0.001, respectively). Our findings assessed the character of CST vividly in detail and dementated the primary sites of CST can predict the long-term outcome of motor function. This study may facilitate future clinical and cognitive studies of acute haemorrhage.

Comparison of Fractional Anisotropy from Tract-Based Spatial Statistics with and without Lesion Masking in Patients with Intracerebral Hemorrhage: A Technical Note

BACKGROUND

Diffusion-tensor fractional anisotropy (FA) is an index of neural-fiber damage in patients following stroke. To better characterize FA, tract-based spatial statistics (TBSS) is frequently used, which involves spatial transformation into the standard brain space. Despite its utility, this technique is susceptible to space-occupying hematoma in patients with intracerebral hemorrhage. To correct this, "lesion making" has been proposed. Here, FA values from TBSS without lesion masking and TBSS with lesion masking were compared, and the clinical utility was evaluated.

METHODS

Forty patients from our previously published work were entered into the study. Diffusion-tensor imagings were acquired 14-21 days after onset and FA maps were generated. Lesion masks were produced in reference with nondiffusion (b = 0) brain images. Two types (with or without lesion masking) of TBSS were then performed. For both types, using individual data we extracted mean FA values within for the corticospinal tract (CST) and the superior longitudinal fasciculus (SLF). FA ratio (rFA) between the lesioned hemisphere and the unaffected hemisphere was then calculated. The two sets of the data were then compared by assessing residuals of mean root sum square error (RMSE).

RESULTS

Although rFA obtained from TBSS with lesion masking tended to be slightly smaller, the estimated RMSE was .025 for both the CST and the SLF.

CONCLUSIONS

The estimated FA differences between the two sets of TBSS were very small. Considering the time for manual labor for producing lesion masks, regular TBSS without lesion masking may be sufficient in terms of clinical utility.

Predicting Motor Outcome in Acute Intracerebral Hemorrhage

BACKGROUND AND PURPOSE

Predicting motor outcome following intracerebral hemorrhage is challenging. We tested whether the combination of clinical scores and DTI-based assessment of corticospinal tract damage within the first 12 hours of symptom onset after intracerebral hemorrhage predicts motor outcome at 3 months.

MATERIALS AND METHODS

We prospectively studied patients with motor deficits secondary to primary intracerebral hemorrhage within the first 12 hours of symptom onset. Patients underwent multimodal MR imaging including DTI. We assessed intracerebral hemorrhage and perihematomal edema location and volume, and corticospinal tract involvement. The corticospinal tract was considered affected when the tractogram passed through the intracerebral hemorrhage or/and the perihematomal edema. We also calculated affected corticospinal tract-to-unaffected corticospinal tract ratios for fractional anisotropy, mean diffusivity, and axial and radial diffusivities. Motor impairment was graded by the motor subindex scores of the modified NIHSS. Motor outcome at 3 months was classified as good (modified NIHSS 0-3) or poor (modified NIHSS 4-8).

RESULTS

Of 62 patients, 43 were included. At admission, the median NIHSS score was 13 (interquartile range = 8-17), and the median modified NIHSS score was 5 (interquartile range = 2-8). At 3 months, 13 (30.23%) had poor motor outcome. Significant independent predictors of motor outcome were NIHSS and modified NIHSS at admission, posterior limb of the internal capsule involvement by intracerebral hemorrhage at admission, intracerebral hemorrhage volume at admission, 72-hour NIHSS, and 72-hour modified NIHSS. The sensitivity, specificity, and positive and negative predictive values for poor motor outcome at 3 months by a combined modified NIHSS of >6 and posterior limb of the internal capsule involvement in the first 12 hours from symptom onset were 84%, 79%, 65%, and 92%, respectively (area under the curve = 0.89; 95% CI, 0.78-1).

CONCLUSIONS

Combined assessment of motor function and posterior limb of the internal capsule damage during acute intracerebral hemorrhage accurately predicts motor outcome.