White matter tractography by diffusion tensor imaging plays an important role in prognosis estimation of acute lacunar infarctions

Lesion Indexes Predict Early Neurologic Deterioration in Lenticulostriate Single Small Subcortical Infarction

BACKGROUND AND PURPOSE

Early neurologic deterioration (END) often occurs during hospitalization in single small subcortical infarction (SSSI). The objective was to identify imaging predictors of END.

MATERIALS AND METHODS

SSSIs in the lenticulostriate artery within 72 hours of stroke onset from January 2015 to June 2021 were consecutively enrolled. The posteriority and laterality indexes were assessed on the second section from the top of the corona radiata section showing the lateral ventricle on DWI. A multivariate logistic analysis was used to explore the predictors of END.

RESULTS

A total of 402 patients were included in this study, among whom 93 (23.1%) experienced END. The optimal cutoff points of the posteriority and laterality indexes for predicting END were given by a receiver operating characteristic curve. A multivariate logistic analysis showed that the posteriority index of ≥0.669 (OR: 2.53; 95% CI: 1.41-4.56; P = .002) and the laterality index of ≥0.950 (OR: 2.03; 95% CI: 1.03-4.00; P = .042) were independently associated with the risk of END. Accordingly, the SSSIs were further divided into 4 types: anterior lateral type (AL-type), anterior medial type (AM-type), posterior lateral type (PL-type), and posterior medial type (PM-type). After the multivariate analysis, in comparison with the AL-type, the AM-type (OR: 3.26; 95% CI: 1.10-9.65), PL-type (OR: 4.68; 95% CI: 1.41-15.56), and PM-type (OR: 6.77; 95% CI: 2.53-18.04) carried significantly elevated risks of END. The PM-type was associated with the highest risk of END.

CONCLUSIONS

The PM-type was found to be associated with the highest risk of END.

Elucidating the mechanisms of post-stroke motor recovery mediated by electroacupuncture using diffusion tensor tractography

Acupuncture has been commonly used for post-stroke patients, and electroacupuncture allows simultaneous application of acupuncture and electrical stimulation. We aimed to elucidate the mechanism of electroacupuncture on post-stroke motor recovery using diffusion tensor tractography. A total of 33 subacute stroke patients were recruited. The control group was subjected to conventional rehabilitation therapy. In contrast, the patients in the experimental group received electroacupuncture treatment for 30 min per session for 4 weeks in addition to the rehabilitation therapy. Fugl-Meyer assessment of the lower extremity (FMA_L), functional ambulation categories (FAC), and the Korean version of modified Barthel index (K-MBI) were used to compare behavioral outcomes between groups. The corticospinal tract (CST) was examined before and after the intervention via diffusion tensor tractography (DTT) to determine the motor recovery mechanism mediated by electroacupuncture. After 4 weeks of intervention, both the control and experimental groups showed a significant improvement with respect to FMA_L, FAC, and K-MBI. The level of improvement in FMA_L, FAC, and K-MBI did not vary significantly between the two groups. However, DTT results showed that the CST fractional anisotropy of the affected side (control: from 0.456 to 0.464, experimental: from 0.459 to 0.512) and its ratio (control: from 89.8 to 90.3, experimental: from 90.2 to 93.3) were significantly different between the two groups (p = 0.032 and p = 0.018). In addition, there were significant differences in the CST axial diffusivity of affected side (control: from 0.783 to 0.877, experimental: from 0.840 to 0.897) and its ratio variation (control: from 87.9 to 100.0, experimental: from 95.7 to 100.7) between the groups (p = 0.003 and p = 0.001). Electroacupuncture played a role in promoting brain plasticity and delaying neural degeneration in subacute period after stroke. Thus, electroacupuncture could be an effective adjuvant therapy in addition to conventional rehabilitation for motor recovery after stroke in a long-term perspective.

Infarct site and prognosis in small subcortical infarction: Role of the corticospinal tract and lentiform

OBJECTIVE

To determine the impact of infarct site combinations on prognosis of small subcortical infarction (SSI) by classifying the infarcted perforator area in relation to the anatomical structures that surround and/or involve the corticospinal tract.

METHODS

Consecutive patients with SSI ≤24 h from onset to initial magnetic resonance imaging (MRI) and ≤ 14 days from onset to second MRI were included. Infarct sites were defined as follows: caudate head, lentiform (L), corona radiata (CR), posterior limb and genu of the internal capsule (IC), thalamus, and brainstem with or without involvement of the corticospinal tract. An unfavorable outcome was defined as a modified Rankin Scale score of 2 to 6 at 3 months from onset. Infarct site combinations related to an unfavorable outcome were evaluated.

RESULTS

We screened 1558 consecutive patients with ischemic strokes, including 128 with SSI (99 [77%] male, median age 64 years). Of all, 29 (23%) had unfavorable outcomes. Factors associated with unfavorable outcomes were age (odds ratio (OR) 2.057, 95% confidence interval (CI) 1.230-3.493, p = 0.006), maximum infarct area (OR 1.094, 95% CI 1.030-1.163, p = 0.004), and infarct simultaneously involving the CR, IC, and L (OR 9.403, 95% CI 1.506-58.710, p = 0.016). Patients with simultaneous involvement of the CR, IC, and L were likely to have a higher subscore in the National Institutes of Health Stroke Scale item of arm motor impairment at discharge (OR 2.947, 95% CI 1.098-7.910, p = 0.032).

CONCLUSIONS

Infarcts involving the CR, IC, and L predict unfavorable outcomes in SSI.

Can diffusion tensor imaging lesion patterns predict the outcome of ischemic stroke?

Background

Stroke can affect any portion of the central nervous system leading to a wide variety of symptoms depending on the part that is involved. Diffusion tensor imaging (DTI) is an emerging neuroimaging technique that allows measuring the integrity of white matter tracts.

Objectives

The objective of this study is to find out if the diffusion tensor tractography technique can provide prognostic information regarding clinical outcome following ischemic stroke.

Subjects and methods

Forty patients with acute ischemic stroke were studied with DTI. Size of infraction, degree of reduction of fractional anisotropy (FA), and pattern of corticospinal tract (CST) affection were identified. We assessed our patients according to the National Institute of Health Stroke Scale (NIHSS) and Medical Research Council (MRC) scale at onset of stroke and 3 months later.

Results

FA reduction was correlated with MRC and NIHSS on admission (P < 0.001, 0.004 respectively) and after 3 months (P < 0.001, 0.013 respectively). The pattern of CST affection was associated with NIHSS and MRC after 3 months (P = 0.035, 0.001 respectively).

Conclusion

DTI may be an indirect indicator of the ischemic stroke outcome.

Can the integrity of the corticospinal tract predict the long-term motor outcome in poststroke hemiplegic patients?

This study aimed to investigate the long-term motor outcome according to early diffusion tensor tractography findings for the affected corticospinal tract (CST) in poststroke hemiplegic patients. A total of 48 supratentorial subacute patients after stroke were enrolled, who had a brain MRI scan within 6 weeks from onset, and no stroke recurrence reported within the 2-year follow-up period. Diffusion tensor images were obtained and CSTs were reconstructed. The participants were classified into three groups: type A, the CST originating from the primary motor cortex was preserved around the lesion area; type B, the CST was similar to type A, except that the fiber originated from the area adjacent to the primary motor cortex; and type C, the CST was interrupted or not shown. Motor functions using Fugl-Meyer Motor Assessment (FMA), the Box and Block Test (BBT), and Functional Ambulation Category, and cognitive function using Mini-Mental Status Examination (MMSE) were measured at baseline and at 2 years from stroke onset. Changes in FMA and BBT were significantly different according to diffusion tensor tractography type at follow-up (P<0.05), but Functional Ambulation Category and Mini-Mental Status Examination were not. In post-hoc analysis, groups A and B showed greater significant improvements on the BBT and on the upper FMA subscale (shoulder/elbow, wrist, and hand) compared with group C (corrected P<0.05), but did not on lower FMA. This study showed the importance of CST integrity for stoke motor recovery. The early integrity of the CST may be useful in predicting long-term motor outcomes, specifically with motor recovery of the upper extremity and hand function.

Can Neurological Biomarkers of Brain Impairment Be Used to Predict Poststroke Motor Recovery? A Systematic Review

Background There is growing interest to establish recovery biomarkers, especially neurological biomarkers, in order to develop new therapies and prediction models for the promotion of stroke rehabilitation and recovery. However, there is no consensus among the neurorehabilitation community about which biomarker(s) have the highest predictive value for motor recovery. Objective To review the evidence and determine which neurological biomarker(s) meet the high evidence quality criteria for use in predicting motor recovery. Methods We searched databases for prognostic neuroimaging/neurophysiological studies. Methodological quality of each study was assessed using a previously employed comprehensive 15-item rating system. Furthermore, we used the GRADE approach and ranked the overall evidence quality for each category of neurologic biomarker. Results Seventy-one articles met our inclusion criteria; 5 categories of neurologic biomarkers were identified: diffusion tensor imaging (DTI), transcranial magnetic stimulation (TMS), functional magnetic resonance imaging (fMRI), conventional structural MRI (sMRI), and a combination of these biomarkers. Most studies were conducted with individuals after ischemic stroke in the acute and/or subacute stage (~70%). Less than one-third of the studies (21/71) were assessed with satisfactory methodological quality (80% or more of total quality score). Conventional structural MRI and the combination biomarker categories ranked "high" in overall evidence quality. Conclusions There were 3 prevalent methodological limitations: (a) lack of cross-validation, (b) lack of minimal clinically important difference (MCID) for motor outcomes, and (c) small sample size. More high-quality studies are needed to establish which neurological biomarkers are the best predictors of motor recovery after stroke. Finally, the quarter-century old methodological quality tool used here should be updated by inclusion of more contemporary methods and statistical approaches.

Correlation between ambulatory function and clinical factors in hemiplegic patients with intact single lateral corticospinal tract: A pilot study

To define the relationship between the complete destruction of 1 lateral corticospinal tract (CST), as demonstrated by diffusion tensor imaging (DTI) tractography, and ambulatory function 6 months following stroke.Twenty-six adults (17 male, 9 female) with poststroke hemiplegia who were transferred to the physical medicine and rehabilitation department. Participants underwent DTI tractography, which showed that 1 lateral CST had been clearly destroyed.Functional ambulation classification (FAC) scores at admission, discharge, and 6 months after discharge were used to evaluate the patients' ability to walk. The National Institutes of Health Stroke Scale (NIHSS) and the Korean version of the modified Barthel index (K-MBI) at admission, discharge, and 6 months after discharge were used to evaluate the degree of functional recovery.Of the 26 patients, 18 were nonambulatory (FAC level 1-3), and 8 were able to walk without support (FAC level 4-6). The type of stroke (infarction or hemorrhage), site of the lesion, spasticity of lower extremities, cranioplasty, and the time taken from onset to MRI were not statistically significantly correlated with the ability to walk. However, statistically significant correlations were found in relation to age, K-MBI scores, and initial NIHSS scores.Despite the complete damage to the lesion site and the preservation of 1 unilateral CST, as shown by DTI, good outcomes can be predicted on the basis of younger age, low NIHSS scores, and high MBI scores at onset.

Transcranial Magnetic Stimulation and Diffusion Tensor Tractography for Evaluating Ambulation after Stroke

BACKGROUND AND PURPOSE

We aimed to investigate the usefulness of combining transcranial magnetic stimulation (TMS) and diffusion tensor tractography (DTT) to evaluate corticospinal tract (CST) integrity and subsequently predict ambulatory function after middle cerebral artery (MCA) stroke.

METHODS

Forty-three patients with first MCA stroke underwent TMS and DTT to evaluate CST integrity. Patients were classified into four groups according to the presence of motor-evoked potentials (MEPs) obtained from the tibialis anterior muscle and CST integrity. Motor impairment and functional status were assessed using the Fugl-Meyer Assessment, Functional Ambulation Category, and Korean modified Barthel Index, both at the time of admission and after 4 weeks of rehabilitation.

RESULTS

Patients with the presence of both measurable MEPs and a preserved CST showed better motor recovery and ambulatory function than other groups at the 4-week follow-up. Intact CSTs were not visualized in patients without detectable MEPs. Among the patients displaying MEPs, those with preserved CSTs showed better recovery of paretic lower extremities.

CONCLUSIONS

Combined assessment using TMS and DTT to evaluate CST integrity confers advantages in predicting motor and ambulation recovery in patients with MCA stroke.

Prediction of Upper Limb Motor Recovery after Subacute Ischemic Stroke Using Diffusion Tensor Imaging: A Systematic Review and Meta-Analysis

Early evaluation of the pyramidal tract using Diffusion Tensor Imaging (DTI) is a prerequisite to decide the optimal treatment or to assess appropriate rehabilitation. The early predictive value of DTI for assessing motor and functional recovery in ischemic stroke (IS) has yielded contradictory results. The purpose is to systematically review and summarize the current available literature on the value of Fractional Anisotropy (FA) parameter of the DTI in predicting upper limb motor recovery after sub-acute IS. MEDLINE, PubMed, EMBASE, Google Scholar and Cochrane CENTRAL searches were conducted from January 1, 1950, to July 31, 2015, which was supplemented with relevant articles identified in the references. Correlation between FA and upper limb motor recovery measure was done. Heterogeneity was examined using Higgins I-squared, Tau-squared. Summary of correlation coefficient was determined using Random Effects model. Out of 166 citations, only eleven studies met the criteria for inclusion in the systematic review and six studies were included in the meta-analysis. A random effects model revealed that DTI parameter FA is a significant predictor for upper limb motor recovery after sub-acute IS [Correlation Coefficient=0.82; 95% Confidence Interval-0.66 to 0.90, P value<0.001]. Moderate heterogeneity was observed (Tau-squared=0.12, I-squared=62.14). The studies reported so far on correlation between DTI and upper limb motor recovery are few with small sample sizes. This meta-analysis suggests strong correlation between DTI parameter FA and upper limb motor recovery. Well-designed prospective trials embedded with larger sample size are required to establish these findings.

Prediction of Motor Recovery Using Diffusion Tensor Tractography in Supratentorial Stroke Patients With Severe Motor Involvement

OBJECTIVE

To investigate whether early stage diffusion tensor tractography (DTT) values predict motor function at 3 months after onset in supratentorial stroke patients with severe motor involvement.

METHODS

A retrospective study design was used to analyze medical records and neuroimaging data of 49 supratentorial stroke patients with severe motor involvement. Diffusion tensor imaging was assessed within 3 weeks after stroke in all patients. Three-dimensional tractography of the ipsilateral corticospinal tract (CST) was performed using the fiber assignment of the continuous tracking algorithm. The two-step DTT analysis was used. The first step was classification according to ipsilateral CST visualization. The second step was a quantitative analysis of the visible-CST group parameters. Motor function was assessed at 2 weeks and at 3 months after stroke. Comparative and correlation analyses were performed between DTT-derived measures and motor assessment scores.

RESULTS

Motor function of the upper extremity at 3 months after stroke was significantly higher in the visible-CST group than that in the nonvisible-CST group (p<0.05). Early stage fractional anisotropy was of DTT correlated significantly with upper extremity motor function at 3 months after stroke in the visible-CST group (p<0.05).

CONCLUSION

These results demonstrate that early DTT-derived measures predict motor recovery in the upper extremity at 3 months after onset in supratentorial stroke patients with severe motor involvement.

Diffusion tensor imaging change in crus cerebri in striatocapsular infarction and correlation with upper extremity motor dysfunction

PURPOSE

There is limited information about the secondary changes in the pyramidal tract after some specific types of deep brain infarction including striatocapsular infarction. The aims of the current study were to investigate diffusion changes in the crus cerebri in patients with striatocapsular infarction using diffusion tensor imaging (DTI), and analyze the relationship between such changes and upper extremity motor dysfunction.

MATERIALS AND METHODS

Fifteen patients with acute onset of striatocapsular infarction and unilateral upper extremity motor dysfunction for the first time were studied prospectively. DTI was performed 2 weeks after disease onset, fractional anisotropy and mean diffusivity values of the bilateral crus cerebri were measured, the asymmetry indices of bilateral fractional anisotropy were calculated, and the relationship between the asymmetry index value and the Fugl-Meyer assessment score for the affected upper extremity function was evaluated.

RESULTS

Two weeks after disease onset, the fractional anisotropy value of the affected crus cerebri was reduced significantly compared with that of the unaffected crus cerebri (0.69 vs. 0.77; p < 0.001); there was no significant difference between bilateral mean diffusivity values. After correction for infarct size (448.93 ± 227.67 mm(2)) there was a negative correlation between the asymmetry index value and the Fugl-Meyer assessment score of the affected upper extremity (r = -0.78, p = 0.001).

CONCLUSIONS

DTI can detect the diffusion change in the crus cerebri in patients with striatocapsular infarction during the early stage of the disease and the integrity of the pyramidal tract in the crus cerebri is closely related to the motor function of the affected upper extremity.

Hemodynamic factors may play a critical role in neurological deterioration occurring within 72 hrs after lacunar stroke

Background

Whether a perfusion defect exists in lacunar infarct and whether it is related to early neurological deterioration (END) is still under debate. The aim of this study was to evaluate whether END in lacunar infarct is related to a perfusion defect using diffusion-weighted imaging (DWI), diffusion tensor imaging (DTI) and perfusion MR imaging.

Methods

One hundred and forty-one consecutive patients had an MRI scan within 30 hours after onset of symptoms and 43 patients with acute lacunar infarct and classic lacunar syndrome were recruited. The MRI sequences included DWI, DTI and cerebral blood flow (CBF) maps to respectively represent the topographic locations of acute infarcts, the corticospinal tract and perfusion defects. The END was defined in reference to the National Institute of Health Stroke Scale (NIHSS) as an increase ≧2 within 72 hours. Cohen's Kappa coefficient was used to examine the reliability between the 2 image readers. A multivariate logistic regression model was constructed adjusting for baseline variables.

Results

Ten out of the 43 patients had END. Patients having END was significantly associated with lower chances of favorable and good outcomes at 3 months (p = 0.01 and p = 0.002, respectively). END was predicted when the non-core hypoperfused area overlapped on the corticospinal tract, which is defined as the expected END profile. Cohen's Kappa coefficient between the 2 image readers to define images of expected END profiles was 0.74. In 15 patients with expected END profile, 9 had END clinically, whereas 28 patients had no expected END profile, and only 1 patient had END (p<0.0001). After adjusting for sex, the expected END profile was still associated with END (odds ratio, 42.2; p = 0.002).

Conclusion

Our study demonstrated that the END in acute lacunar stroke is likely related to the transformation of non-core hypoperfused area into infarction in the anatomy of corticospinal tracts.

Corticospinal tract diffusion abnormalities early after stroke predict motor outcome

BACKGROUND

Prognosis of long-term motor outcome of acute stroke patients with severe motor impairment is difficult to determine.

OBJECTIVE

Our primary goal was to evaluate the prognostic value of corticospinal tract (CST) injury on motor outcome of the upper limb compared with motor impairment level and lesion volume.

METHODS

In all, 10 acute stroke patients with moderately severe to severe motor impairment of the upper limb underwent diffusion tensor imaging (DTI) and testing of upper limb strength and dexterity at acute, subacute, and chronic poststroke time points. A density-weighted CST atlas was constructed using DTI tractography data from normal participants. This CST atlas was applied, using a largely automated process, to DTI data from patients to quantify CST injury at each time point. Differences in axial diffusivity (AD), radial diffusivity (RD), and fractional anisotropy (FA) of the ipsilesional CST relative to the contralesional CST were measured.

RESULTS

Acute loss in CST AD correlated most strongly and significantly with subacute and chronic strength and dexterity and remained significant after adjusting for acute motor impairment or lesion volume. Subacute loss in CST FA correlated most strongly with chronic dexterity, whereas subacute behavioral measures of limb strength correlated most strongly with chronic strength measures.

CONCLUSIONS

Loss in acute CST AD and subacute CST FA are strong prognostic indicators of future motor functions of the upper limb for stroke patients with substantial initial motor impairment. DTI-derived measure of CST injury early after stroke may have utility in health care planning and in design of acute stroke clinical trials.

Corticospinal tract change during motor recovery in patients with medulla infarct: a diffusion tensor imaging study

Diffusion tensor imaging (DTI) and tractography (DTT) provide a powerful vehicle for investigating motor recovery mechanisms. However, little is known about these mechanisms in patients with medullary lesions. We used DTI and DTT to evaluate three patients presenting with motor deficits following unilateral medulla infarct. Patients were scanned three times during 1 month (within 7, 14, and 30 days after stroke onset). Fractional anisotropy (FA) values were measured in the medulla, cerebral peduncle, and internal capsule. The three-dimensional corticospinal tract (CST) was reconstructed using DTT. Patients 1 and 2 showed good motor recovery after 14 days, and the FA values of their affected CST were slightly decreased. DTTs demonstrated that the affected CST passed along periinfarct areas and that tract integrity was preserved in the medulla. Patient 3 had the most obvious decrease in FA values along the affected CST, with motor deficits of the right upper extremity after 30 days. The affected CST passed through the infarct and was disrupted in the medulla. In conclusion, DTI can detect the involvement and changes of the CST in patients with medulla infarct during motor recovery. The degree of degeneration and spared periinfarct CST compensation may be an important motor recovery mechanism.

Diffusion tensor imaging study of the response to constraint-induced movement therapy of children with hemiparetic cerebral palsy and adults with chronic stroke

OBJECTIVE

To investigate the relationship of white matter integrity and path of the corticospinal tract (CST) on arm function before and after constraint-induced (CI) movement therapy in children with hemiparetic cerebral palsy (CP) and adults with chronic stroke.

DESIGN

Study 1 used a multiple-baseline pre-post design. Study 2 was a randomized controlled trial.

SETTING

Outpatient rehabilitation laboratory.

PARTICIPANTS

Study 1 included children with hemiparetic CP (n=10; mean age ± SD, 3.2±1.7y). Study 2 included adults with chronic stroke (n=26; mean age ± SD, 65.4±13.6y) who received either CI therapy or a comparison therapy.

INTERVENTIONS

Children in study 1 received CI therapy for 3.5h/d for 15 consecutive weekdays. Adults in study 2 received either CI therapy or a comparison therapy for 3.5h/d for 10 consecutive weekdays.

MAIN OUTCOME MEASURES

Diffusion tensor imaging was performed to quantify white matter integrity. Motor ability was assessed in children using the Pediatric Motor Activity Log-Revised and Pediatric Arm Function Test, and in adults with the Motor Activity Log and Wolf Motor Function Test.

RESULTS

Participants in both studies improved in real-world arm function and motor capacity. Children and adults with disrupted/displaced CSTs and children with reduced fractional anisotropy values were worse on pretreatment tests of motor function than participants with unaltered CSTs. However, neither integrity (fractional anisotropy) nor distorted or disrupted path of the CST affected motor improvement after treatment.

CONCLUSIONS

Participants who had reduced integrity, displacement, or interruption of their CST performed worse on pretreatment motor testing. However, this had no effect on their ability to benefit from CI therapy. The results for children and adults are consistent with one another.

Diffusion Tensor Imaging for Predicting Hand Motor Outcome in Chronic Stroke Patients

OBJECTIVE: Previous studies have indicated that diffusion tensor imaging (DTI) values are related to clinical outcome in stroke patients. This prospective study explored whether DTI values were predictive for hand function outcome in chronic stroke patients. METHODS: The DTI parameters (rλ1, rλ23, fractional anisotropy [rFA] and mean diffusivity [rMD]) were investigated in patients with completely paralysed hands (CPH; n = 10) or partially paralysed hands (PPH; n = 10), by two methods of analysis: segment of the corticospinal tract [sCST] analysis; pure region of interest [ROI] analysis. Spearman's correlation coefficient was used to assess the correlation between the DTI parameters and the following clinical measures: Fugl—Meyer Assessment [FMA]; National Institutes of Health Stroke Scale [NIHSS]. RESULTS: Significant differences were found between CPH and PPH for rFA and rλ23 (sCST analysis) and for rMD and rλ23 (ROI analysis). The rλ23 (sCST analysis) correlated with the NIHSS; the rMD (sCST analysis) correlated with the FMA (hand). CONCLUSION: The three parameters, rFA, rλ23 and rMD may have predictive value for evaluating hand function outcome in chronic stroke patients.

Acute damage to the posterior limb of the internal capsule on diffusion tensor tractography as an early imaging predictor of motor outcome after stroke

BACKGROUND AND PURPOSE

Early prediction of motor outcome is of interest in stroke management. We aimed to determine whether lesion location at DTT is predictive of motor outcome after acute stroke and whether this information improves the predictive accuracy of the clinical scores.

MATERIALS AND METHODS

We evaluated 60 consecutive patients within 12 hours of middle cerebral artery stroke onset. We used DTT to evaluate CST involvement in the motor cortex and premotor cortex, centrum semiovale, corona radiata, and PLIC and in combinations of these regions at admission, at day 3, and at day 30. Severity of limb weakness was assessed by using the motor subindex scores of the National Institutes of Health Stroke Scale (5a, 5b, 6a, 6b). We calculated volumes of infarct and fractional anisotropy values in the CST of the pons.

RESULTS

Acute damage to the PLIC was the best predictor associated with poor motor outcome, axonal damage, and clinical severity at admission (P < .001). There was no significant correlation between acute infarct volume and motor outcome at day 90 (P = .176, r = 0.485). The sensitivity, specificity, and positive and negative predictive values of acute CST involvement at the level of the PLIC for motor outcome at day 90 were 73.7%, 100%, 100%, and 89.1%, respectively. In the acute stage, DTT predicted motor outcome at day 90 better than the clinical scores (R(2) = 75.50, F = 80.09, P < .001).

CONCLUSIONS

In the acute setting, DTT is promising for stroke mapping to predict motor outcome. Acute CST damage at the level of the PLIC is a significant predictor of unfavorable motor outcome.

Quantitative diffusion tensor imaging for evaluation of motor function in patients with brain infarcts

OBJECTIVE

To evaluate the quantitative diffusion value in ipsilateral cerebral peduncle of patients with differing motor function abilities and analyse the thresholds discriminating the poor motor function disability.

METHOD

Twenty-nine patients who previously suffered stroke underwent diffusion tensor imaging examinations. Motor function was evaluated 8 months after the event. The ipsilateral apparent diffusion coefficient (ADC) and fractional anisotropy (FA) of cerebral peduncle and ADC ratio and FA ratio of patients with different motor function scales were analysed.

RESULTS

The ipsilateral FA value and FA ratio were distinctly different in patients with different motor function scales, and significantly correlated with the motor function scales. There was no significant difference of ipsilateral ADC and ADC ratio, and neither had correlation with motor function scale. The patients with poor motor function scale could be discriminated by the cutoff value of ipsilateral FA of 0.453 and FA ratio of 0.623 with sensitivity of 90%, 75% and specificity of 88.9%, 88.9% respectively.

CONCLUSIONS

The ipsilateral FA value and FA ratio were feasible and better imaging indices in discriminating patients with poor motor function ability.

Tract-specific and region of interest analysis of corticospinal tract integrity in subcortical ischemic stroke: reliability and correlation with motor function of affected lower extremity

BACKGROUND AND PURPOSE

TS analysis has been suggested as a useful method to evaluate the fiber integrity of white matter tracts. This study investigated the intrarater and interrater reliability and validity of a TS analysis for the CST and compared the results with those of a ROI-based analysis.

MATERIALS AND METHODS

Diffusion spectrum imaging was performed on 7 patients with subcortical ischemic stroke on a 3T MR imaging system. For the TS analysis, seed regions were placed at the cerebral peduncle and the medial portion of the primary motor cortex to reconstruct the tracts of the CST for motor control of the lower extremity. The mean GFA was measured at the PLIC by calculating the weighted sum of the GFAs sampled by the CST tracts at this segment. For the ROI-based analysis, the posterior two-thirds of the PLIC were enclosed on the GFA maps, and the mean GFA in this ROI was calculated.

RESULTS

The results showed good-to-excellent intrarater and interrater reliability on the seed region/ROI placement (mean kappa values >0.80) and mean GFA values (ICCs >0.90) for both the TS and ROI-based analyses. Both the GFA(PLIC-TS) and GFA(PLIC-ROI) values were highly correlated with the motor function of the affected lower extremity (r = 0.76 and 0.80, respectively; P < .05).

CONCLUSIONS

We demonstrated good reliability and validity of the TS and ROI-based analyses of the CST corresponding to lower extremity motor control in patients with subcortical ischemic stroke.

Motor outcome prediction using diffusion tensor tractography in pontine infarct

We investigated whether the integrity of the corticospinal tract classified by diffusion tensor tractography (DTT) can predict the motor outcome in 25 patients with pontine infarct. DTTs were obtained in the early stage of stroke (5-30 days) and were classified into two groups (type A: the integrity of corticospinal tract was preserved around the infarct; type B: corticospinal tract was interrupted). DTT type A patients showed better motor function than the type B patients at 6 months after onset. DTT obtained at the early stage of pontine infarct appears to have predictive value for motor outcome in patients with pontine infarct.

Cell-based therapy in ischemic stroke

Cell-based therapy for stroke represents a third wave of therapeutics for stroke and one focused on restorative processes with a longer time window of opportunity than neuroprotective therapies. An early time window, within the first week after stroke, is an opportunity for intravenously delivered bone marrow and perinatally derived cells that can home to areas of tissue injury and target brain remodeling. Allogeneic cells will likely be the most scalable and commercially viable product. Later time windows, months after stroke, may be opportunities for intracerebral transplantation of neuronally differentiated cell types. An integrated approach of cell-based therapy with early-phase clinical trials and continued preclinical work with focus on mechanisms of action is needed.