The Experts below are selected from a list of 36102 Experts worldwide ranked by ideXlab platform
Thomas Picht - One of the best experts on this subject based on the ideXlab platform.
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A new approach for corticospinal tract reconstruction based on navigated transcranial stimulation and standardized Fractional Anisotropy values
NeuroImage, 2012Co-Authors: Dietmar Frey, Valerie Strack, Edzard Wiener, Daniel Jussen, Peter Vajkoczy, Thomas PichtAbstract:Abstract Purpose To establish a novel approach for fiber tracking based on navigated transcranial magnetic stimulation (nTMS) mapping of the primary motor cortex and to propose a new algorithm for determination of an individualized Fractional Anisotropy value for reliable and objective fiber tracking. Methods 50 patients (22 females, 28 males, median age 58 years (20–80)) with brain tumors compromising the primary motor cortex and the corticospinal tract underwent preoperative MR imaging and nTMS mapping. Stimulation spots evoking muscle potentials (MEP) closest to the tumor were imported into the fiber tracking software and set as seed points for tractography. Next the individual FA threshold, i.e. the highest FA value leading to visualization of tracts at a predefined minimum fiber length of 110 mm, was determined. Fiber tracking was then performed at a Fractional Anisotropy value of 75% and 50% of the individual FA threshold. In addition, fiber tracking according to the conventional knowledge-based approach was performed. Results of tractography of either method were presented to the surgeon for preoperative planning and integrated into the navigation system and its impact was rated using a questionnaire. Results Mapping of the motor cortex was successful in all patients. A Fractional Anisotropy threshold for corticospinal tract reconstruction could be obtained in every case. TMS-based results changed or modified surgical strategy in 23 of 50 patients (46%), whereas knowledge-based results would have changed surgical strategy in 11 of 50 patients (22%). Tractography results facilitated intraoperative orientation and electrical stimulation in 28 of 50 (56%) patients. Tracking at 75% of the individual FA thresholds was considered most beneficial by the respective surgeons. Conclusions Fiber tracking based on nTMS by the proposed standardized algorithm represents an objective visualization method based on functional data and provides a valuable instrument for preoperative planning and intraoperative orientation and monitoring.
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A new approach for corticospinal tract reconstruction based on navigated transcranial stimulation and standardized Fractional Anisotropy values
NeuroImage, 2012Co-Authors: Dietmar Frey, Valerie Strack, Edzard Wiener, Daniel Jussen, Peter Vajkoczy, Thomas PichtAbstract:Abstract Purpose To establish a novel approach for fiber tracking based on navigated transcranial magnetic stimulation (nTMS) mapping of the primary motor cortex and to propose a new algorithm for determination of an individualized Fractional Anisotropy value for reliable and objective fiber tracking. Methods 50 patients (22 females, 28 males, median age 58 years (20–80)) with brain tumors compromising the primary motor cortex and the corticospinal tract underwent preoperative MR imaging and nTMS mapping. Stimulation spots evoking muscle potentials (MEP) closest to the tumor were imported into the fiber tracking software and set as seed points for tractography. Next the individual FA threshold, i.e. the highest FA value leading to visualization of tracts at a predefined minimum fiber length of 110 mm, was determined. Fiber tracking was then performed at a Fractional Anisotropy value of 75% and 50% of the individual FA threshold. In addition, fiber tracking according to the conventional knowledge-based approach was performed. Results of tractography of either method were presented to the surgeon for preoperative planning and integrated into the navigation system and its impact was rated using a questionnaire. Results Mapping of the motor cortex was successful in all patients. A Fractional Anisotropy threshold for corticospinal tract reconstruction could be obtained in every case. TMS-based results changed or modified surgical strategy in 23 of 50 patients (46%), whereas knowledge-based results would have changed surgical strategy in 11 of 50 patients (22%). Tractography results facilitated intraoperative orientation and electrical stimulation in 28 of 50 (56%) patients. Tracking at 75% of the individual FA thresholds was considered most beneficial by the respective surgeons. Conclusions Fiber tracking based on nTMS by the proposed standardized algorithm represents an objective visualization method based on functional data and provides a valuable instrument for preoperative planning and intraoperative orientation and monitoring.
David M. Greer - One of the best experts on this subject based on the ideXlab platform.
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Longitudinal Diffusion Tensor Imaging Detects Recovery of Fractional Anisotropy Within Traumatic Axonal Injury Lesions
Neurocritical Care, 2016Co-Authors: Brian L. Edlow, William A. Copen, Saef Izzy, Andre Kouwe, Mel B. Glenn, Steven M. Greenberg, David M. GreerAbstract:Background Traumatic axonal injury (TAI) may be reversible, yet there are currently no clinical imaging tools to detect axonal recovery in patients with traumatic brain injury (TBI). We used diffusion tensor imaging (DTI) to characterize serial changes in Fractional Anisotropy (FA) within TAI lesions of the corpus callosum (CC). We hypothesized that recovery of FA within a TAI lesion correlates with better functional outcome. Methods Patients who underwent both an acute DTI scan (≤day 7) and a subacute DTI scan (day 14 to inpatient rehabilitation discharge) at a single institution were retrospectively analyzed. TAI lesions were manually traced on the acute diffusion-weighted images. Fractional Anisotropy (FA), apparent diffusion coefficient (ADC), axial diffusivity (AD), and radial diffusivity (RD) were measured within the TAI lesions at each time point. FA recovery was defined by a longitudinal increase in CC FA that exceeded the coefficient of variation for FA based on values from healthy controls. Acute FA, ADC, AD, and RD were compared in lesions with and without FA recovery, and correlations were tested between lesional FA recovery and functional recovery, as determined by disability rating scale score at discharge from inpatient rehabilitation. Results Eleven TAI lesions were identified in 7 patients. DTI detected FA recovery within 2 of 11 TAI lesions. Acute FA, ADC, AD, and RD did not differ between lesions with and without FA recovery. Lesional FA recovery did not correlate with disability rating scale scores. Conclusions In this retrospective longitudinal study, we provide initial evidence that FA can recover within TAI lesions. However, FA recovery did not correlate with improved functional outcomes. Prospective histopathological and clinical studies are needed to further elucidate whether lesional FA recovery indicates axonal healing and has prognostic significance.
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longitudinal diffusion tensor imaging detects recovery of Fractional Anisotropy within traumatic axonal injury lesions
Neurocritical Care, 2016Co-Authors: Brian L. Edlow, William A. Copen, Saef Izzy, Mel B. Glenn, Steven M. Greenberg, Andre Van Der Kouwe, David M. GreerAbstract:Background Traumatic axonal injury (TAI) may be reversible, yet there are currently no clinical imaging tools to detect axonal recovery in patients with traumatic brain injury (TBI). We used diffusion tensor imaging (DTI) to characterize serial changes in Fractional Anisotropy (FA) within TAI lesions of the corpus callosum (CC). We hypothesized that recovery of FA within a TAI lesion correlates with better functional outcome.
Joaquín Serena - One of the best experts on this subject based on the ideXlab platform.
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decreased corticospinal tract Fractional Anisotropy predicts long term motor outcome after stroke
Stroke, 2013Co-Authors: Josep Puig, Gerard Blasco, Götz Thomalla, Mar Castellanos, Jaume Figueras, Sebastian Remollo, Cecile Van Eendenburg, Josep Daunisiestadella, Javier Sanchezgonzalez, Joaquín SerenaAbstract:Background and Purpose—Nearly 50% of patients have residual motor deficits after stroke, and long-term motor outcome is difficult to predict. We assessed the predictive value of axonal damage to the corticospinal tract indexed by diffusion tensor imaging Fractional Anisotropy for long-term motor outcome. Methods—Consecutive patients with middle cerebral artery stroke underwent multimodal MRI, including diffusion tensor imaging ≤12 hours, 3 days, and 30 days after onset. Clinical severity, infarct volume, location of corticospinal tract damage on diffusion tensor tractography, and ratios of Fractional Anisotropy (rFA) between affected and unaffected sides of the corticospinal tract at the pons were evaluated. Severity of motor deficit at 2 years was categorized using the Motricity Index as no deficit (Motricity Index, 100), slight-moderate deficit (Motricity Index, 99–50), or severe deficit (Motricity Index, <50). Results—We evaluated 70 patients (28 women; 72±12 years). rFA values at day 30 correlated wit...
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Decreased Corticospinal Tract Fractional Anisotropy Predicts Long-term Motor Outcome After Stroke
Stroke, 2013Co-Authors: Josep Puig, Gerard Blasco, Josep Daunis-i-estadella, Götz Thomalla, Mar Castellanos, Jaume Figueras, Sebastian Remollo, Cecile Van Eendenburg, Javier Sánchez-gonzález, Joaquín SerenaAbstract:Background and Purpose—Nearly 50% of patients have residual motor deficits after stroke, and long-term motor outcome is difficult to predict. We assessed the predictive value of axonal damage to the corticospinal tract indexed by diffusion tensor imaging Fractional Anisotropy for long-term motor outcome. Methods—Consecutive patients with middle cerebral artery stroke underwent multimodal MRI, including diffusion tensor imaging ≤12 hours, 3 days, and 30 days after onset. Clinical severity, infarct volume, location of corticospinal tract damage on diffusion tensor tractography, and ratios of Fractional Anisotropy (rFA) between affected and unaffected sides of the corticospinal tract at the pons were evaluated. Severity of motor deficit at 2 years was categorized using the Motricity Index as no deficit (Motricity Index, 100), slight-moderate deficit (Motricity Index, 99–50), or severe deficit (Motricity Index,
Dietmar Frey - One of the best experts on this subject based on the ideXlab platform.
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A new approach for corticospinal tract reconstruction based on navigated transcranial stimulation and standardized Fractional Anisotropy values
NeuroImage, 2012Co-Authors: Dietmar Frey, Valerie Strack, Edzard Wiener, Daniel Jussen, Peter Vajkoczy, Thomas PichtAbstract:Abstract Purpose To establish a novel approach for fiber tracking based on navigated transcranial magnetic stimulation (nTMS) mapping of the primary motor cortex and to propose a new algorithm for determination of an individualized Fractional Anisotropy value for reliable and objective fiber tracking. Methods 50 patients (22 females, 28 males, median age 58 years (20–80)) with brain tumors compromising the primary motor cortex and the corticospinal tract underwent preoperative MR imaging and nTMS mapping. Stimulation spots evoking muscle potentials (MEP) closest to the tumor were imported into the fiber tracking software and set as seed points for tractography. Next the individual FA threshold, i.e. the highest FA value leading to visualization of tracts at a predefined minimum fiber length of 110 mm, was determined. Fiber tracking was then performed at a Fractional Anisotropy value of 75% and 50% of the individual FA threshold. In addition, fiber tracking according to the conventional knowledge-based approach was performed. Results of tractography of either method were presented to the surgeon for preoperative planning and integrated into the navigation system and its impact was rated using a questionnaire. Results Mapping of the motor cortex was successful in all patients. A Fractional Anisotropy threshold for corticospinal tract reconstruction could be obtained in every case. TMS-based results changed or modified surgical strategy in 23 of 50 patients (46%), whereas knowledge-based results would have changed surgical strategy in 11 of 50 patients (22%). Tractography results facilitated intraoperative orientation and electrical stimulation in 28 of 50 (56%) patients. Tracking at 75% of the individual FA thresholds was considered most beneficial by the respective surgeons. Conclusions Fiber tracking based on nTMS by the proposed standardized algorithm represents an objective visualization method based on functional data and provides a valuable instrument for preoperative planning and intraoperative orientation and monitoring.
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A new approach for corticospinal tract reconstruction based on navigated transcranial stimulation and standardized Fractional Anisotropy values
NeuroImage, 2012Co-Authors: Dietmar Frey, Valerie Strack, Edzard Wiener, Daniel Jussen, Peter Vajkoczy, Thomas PichtAbstract:Abstract Purpose To establish a novel approach for fiber tracking based on navigated transcranial magnetic stimulation (nTMS) mapping of the primary motor cortex and to propose a new algorithm for determination of an individualized Fractional Anisotropy value for reliable and objective fiber tracking. Methods 50 patients (22 females, 28 males, median age 58 years (20–80)) with brain tumors compromising the primary motor cortex and the corticospinal tract underwent preoperative MR imaging and nTMS mapping. Stimulation spots evoking muscle potentials (MEP) closest to the tumor were imported into the fiber tracking software and set as seed points for tractography. Next the individual FA threshold, i.e. the highest FA value leading to visualization of tracts at a predefined minimum fiber length of 110 mm, was determined. Fiber tracking was then performed at a Fractional Anisotropy value of 75% and 50% of the individual FA threshold. In addition, fiber tracking according to the conventional knowledge-based approach was performed. Results of tractography of either method were presented to the surgeon for preoperative planning and integrated into the navigation system and its impact was rated using a questionnaire. Results Mapping of the motor cortex was successful in all patients. A Fractional Anisotropy threshold for corticospinal tract reconstruction could be obtained in every case. TMS-based results changed or modified surgical strategy in 23 of 50 patients (46%), whereas knowledge-based results would have changed surgical strategy in 11 of 50 patients (22%). Tractography results facilitated intraoperative orientation and electrical stimulation in 28 of 50 (56%) patients. Tracking at 75% of the individual FA thresholds was considered most beneficial by the respective surgeons. Conclusions Fiber tracking based on nTMS by the proposed standardized algorithm represents an objective visualization method based on functional data and provides a valuable instrument for preoperative planning and intraoperative orientation and monitoring.
Brian L. Edlow - One of the best experts on this subject based on the ideXlab platform.
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Longitudinal Diffusion Tensor Imaging Detects Recovery of Fractional Anisotropy Within Traumatic Axonal Injury Lesions
Neurocritical Care, 2016Co-Authors: Brian L. Edlow, William A. Copen, Saef Izzy, Andre Kouwe, Mel B. Glenn, Steven M. Greenberg, David M. GreerAbstract:Background Traumatic axonal injury (TAI) may be reversible, yet there are currently no clinical imaging tools to detect axonal recovery in patients with traumatic brain injury (TBI). We used diffusion tensor imaging (DTI) to characterize serial changes in Fractional Anisotropy (FA) within TAI lesions of the corpus callosum (CC). We hypothesized that recovery of FA within a TAI lesion correlates with better functional outcome. Methods Patients who underwent both an acute DTI scan (≤day 7) and a subacute DTI scan (day 14 to inpatient rehabilitation discharge) at a single institution were retrospectively analyzed. TAI lesions were manually traced on the acute diffusion-weighted images. Fractional Anisotropy (FA), apparent diffusion coefficient (ADC), axial diffusivity (AD), and radial diffusivity (RD) were measured within the TAI lesions at each time point. FA recovery was defined by a longitudinal increase in CC FA that exceeded the coefficient of variation for FA based on values from healthy controls. Acute FA, ADC, AD, and RD were compared in lesions with and without FA recovery, and correlations were tested between lesional FA recovery and functional recovery, as determined by disability rating scale score at discharge from inpatient rehabilitation. Results Eleven TAI lesions were identified in 7 patients. DTI detected FA recovery within 2 of 11 TAI lesions. Acute FA, ADC, AD, and RD did not differ between lesions with and without FA recovery. Lesional FA recovery did not correlate with disability rating scale scores. Conclusions In this retrospective longitudinal study, we provide initial evidence that FA can recover within TAI lesions. However, FA recovery did not correlate with improved functional outcomes. Prospective histopathological and clinical studies are needed to further elucidate whether lesional FA recovery indicates axonal healing and has prognostic significance.
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longitudinal diffusion tensor imaging detects recovery of Fractional Anisotropy within traumatic axonal injury lesions
Neurocritical Care, 2016Co-Authors: Brian L. Edlow, William A. Copen, Saef Izzy, Mel B. Glenn, Steven M. Greenberg, Andre Van Der Kouwe, David M. GreerAbstract:Background Traumatic axonal injury (TAI) may be reversible, yet there are currently no clinical imaging tools to detect axonal recovery in patients with traumatic brain injury (TBI). We used diffusion tensor imaging (DTI) to characterize serial changes in Fractional Anisotropy (FA) within TAI lesions of the corpus callosum (CC). We hypothesized that recovery of FA within a TAI lesion correlates with better functional outcome.
