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Can fully automated detection of corticospinal tract damage be used in stroke patients?

ABSTRACT: OBJECTIVE:We compared manual infarct definition, which is time-consuming and open to bias, with an automated abnormal tissue detection method in measuring corticospinal tract-infarct overlap volumes in chronic stroke patients to help predict motor outcome. METHODS:Using diffusion tensor imaging and probabilistic tractography, 4 corticospinal tracts from the primary motor cortex, dorsal and ventral premotor cortices, and supplementary motor area to the ipsilateral lower pons were reconstructed in 23 healthy controls. Tract-infarct overlap volume of each of the 4 corticospinal tracts was determined by overlapping the patients' lesions onto the control tract templates, using both manually and automatically defined infarcts in 51 patients. Correlations with upper limb motor impairment were assessed and both methods were directly compared using intraclass correlations (ICC). RESULTS:Greater impairment was seen in patients with greater corticospinal tract-infarct overlap with either method (rmanual range = 0.32-0.46; rautomated range = 0.42-0.57). Consistency between manual and automated methods was good to excellent for all 4 corticospinal tracts (ICC range = 0.71-0.80). CONCLUSIONS:Our results demonstrate that automated infarct identification performs equally as well as a manual method in quantifying corticospinal tract-infarct overlap following stroke.

SUBMITTER: Kou N

PROVIDER: S-EPMC3721100 | biostudies-literature | 2013 Jun

REPOSITORIES: biostudies-literature

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Can fully automated detection of corticospinal tract damage be used in stroke patients?

Kou Nancy N Park Chang-hyun CH Seghier Mohamed L ML Leff Alexander P AP Ward Nick S NS

Neurology 20130508 24

<h4>Objective</h4>We compared manual infarct definition, which is time-consuming and open to bias, with an automated abnormal tissue detection method in measuring corticospinal tract-infarct overlap volumes in chronic stroke patients to help predict motor outcome.<h4>Methods</h4>Using diffusion tensor imaging and probabilistic tractography, 4 corticospinal tracts from the primary motor cortex, dorsal and ventral premotor cortices, and supplementary motor area to the ipsilateral lower pons were r ...[more]

PMID: 23658388

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Project description:ObjectiveStudies on upper limb recovery following stroke have highlighted the importance of the structural and functional integrity of the corticospinal tract (CST) in determining clinical outcomes. However, such relationships have not been fully explored for the lower limb. We aimed to test whether variation in walking impairment was associated with variation in the structural or functional integrity of the CST.MethodsTranscranial magnetic stimulation was used to stimulate each motor cortex while EMG recordings were taken from the vastus lateralis (VL) bilaterally; these EMG measures were used to calculate both ipsilateral and contralateral recruitment curves for each lower limb. The slope of these recruitment curves was used to examine the strength of functional connectivity from the motor cortex in each hemisphere to the lower limbs in chronic stroke patients and to calculate a ratio between ipsilateral and contralateral outputs referred to as the functional connectivity ratio (FCR). The structural integrity of the CST was assessed using diffusion tensor MRI to measure the asymmetry in fractional anisotropy (FA) of the internal capsule. Lower limb impairment and walking speed were also measured.ResultsThe FCR for the paretic leg correlated with walking impairment, such that greater relative ipsilateral connectivity was associated with slower walking speeds. Asymmetrical FA values, reflecting reduced structural integrity of the lesioned CST, were associated with greater walking impairment. FCR and FA asymmetry were strongly positively correlated with each other.ConclusionsPatients with relatively greater ipsilateral connectivity between the contralesional motor cortex and the paretic lower limb were more behaviorally impaired and had more structural damage to their ipsilesional hemisphere CST.SignificanceMeasures of structural and functional damage may be useful in the selection of therapeutic strategies, allowing for more tailored and potentially more beneficial treatments.

Project description:BackgroundMotor outcome after stroke is associated with reorganisation of cortical networks and corticospinal tract (CST) integrity. However, the relationships between motor severity, CST damage, and functional brain connectivity are not well understood. Here, the main objective was to study the effect of CST damage on the relationship between functional motor network connectivity and hand motor function in two groups of stroke patients: the severely (n=8) and the mildly impaired (n=14).MethodsTwenty-two carotid stroke patients with motor deficits were studied with magnetic resonance imaging (MRI) at 3 weeks, at 3 and 6 months. Healthy subjects (n=28) were scanned once. The CST injury was assessed by fractional anisotropy values. Functional connectivity was studied from a whole-hand grip task fMRI in a cortical and cerebellar motor network. Functional connectivity indexes were computed between these regions at each time point. The relationship between hand motor strength, ipsilesional CST damage and functional connectivity from the primary motor cortex (M1) was investigated using global and partial correlations.FindingsIn mildly impaired patients, cortico-cortical connectivity was disturbed at three weeks but returned to a normal pattern after 3 months. Cortico-cerebellar connectivity was still decreased at 6 months. In severely impaired patients, the cortico-cortical connectivity tended to return to a normal pattern, but the cortico-cerebellar connectivity was totally abolished during the follow-up. In the entire group of patients, the hand motor strength was correlated to the ipsilesional functional connectivity from M1. Partial correlations revealed that these associations were not anymore significant when the impact of CST damage was removed, except for the ipsilesional M1-contralateral cerebellum connectivity.ConclusionFunctional brain connectivity changes can be observed, even in severely impaired patients with no recovery. Upper limb function is mainly explained by the CST damage and by the ipsilesional cortico-cerebellar connectivity.

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Can fully automated detection of corticospinal tract damage be used in stroke patients?

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Can fully automated detection of corticospinal tract damage be used in stroke patients?

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