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Assessing Region of Interest Schemes for the Corticospinal Tract in Patients With Brain Tumors

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ABSTRACT

Diffusion tensor imaging (DTI) and diffusion tensor tractography (DTT) techniques are widely used for identifying the corticospinal tract (CST) white matter pathways as part of presurgical planning. However, mass effects in patients with brain tumors tend to cause anatomical distortions and compensatory functional reorganization of the cortex, which may lead to inaccurate mapping of white matter tracts. To overcome these problems, we compared different region-of-interest (ROI) selection schemes to track CST fibers in patients with brain tumors. Our study investigated the CSTs of 16 patients with intracranial tumors. The patients were classified into 3 subgroups according to the spatial relationships of the lesion and the primary motor cortex (PMC)/internal capsule. Specifically, we investigated the key factors that cause distorted tractography in patients with tumors. We compared 3 CST tractography methods that used different ROI selection schemes. The results indicate that CST fiber tracking methods based only on anatomical ROIs could possibly lead to distortions near the PMC region and may be unable to effectively localize the PMC. In contrast, the dual ROI method, which uses ROIs that have been selected from both blood oxygen level-dependent functional MRI (BOLD-fMRI) activation and anatomical landmarks, enabled the tracking of fibers to the motor cortex. The results demonstrate that the dual ROI method can localize the entire CST fiber pathway and can accurately describe the spatial relationships of CST fibers relative to the tumor. These results illustrate the reliability of using fMRI-guided DTT in patients with tumors. The combination of fMRI and anatomical information enhances the identification of tracts of interest in brains with anatomical deformations, which provides neurosurgeons with a more accurate approach for visualizing and localizing white matter fiber tracts in patients with brain tumors. This approach enhances surgical performance and perserves brain function.

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The CST fiber tracking results for patient 12, who was diagnosed with a grade II astrocytoma in the left frontal lobe, which affected the motor cortex and the left internal capsule. (A) The lesion and motor-activated area displayed on a T1-weighted image. (B) The CST fiber tracking results based on different ROI definitions. Yellow, green, and purple represent the CST fiber tracking results obtained using ROI1, ROI2, and ROI1 + ROI2, respectively. The CST fiber tracking results based on an anatomical landmark were distorted near the PMC area. When using the fMRI activation area as a seed region, CST fiber tracking reliably reached the motor cortex, and the spatial relationship between the CST and the tumor can be clearly observed. (C) The 3D visualization of the CST fiber tracking results based on different ROI definitions. CST = corticospinal tract, fMRI = functional MRI, PMC = primary motor cortex, ROI = region-of-interest.
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Figure 3: The CST fiber tracking results for patient 12, who was diagnosed with a grade II astrocytoma in the left frontal lobe, which affected the motor cortex and the left internal capsule. (A) The lesion and motor-activated area displayed on a T1-weighted image. (B) The CST fiber tracking results based on different ROI definitions. Yellow, green, and purple represent the CST fiber tracking results obtained using ROI1, ROI2, and ROI1 + ROI2, respectively. The CST fiber tracking results based on an anatomical landmark were distorted near the PMC area. When using the fMRI activation area as a seed region, CST fiber tracking reliably reached the motor cortex, and the spatial relationship between the CST and the tumor can be clearly observed. (C) The 3D visualization of the CST fiber tracking results based on different ROI definitions. CST = corticospinal tract, fMRI = functional MRI, PMC = primary motor cortex, ROI = region-of-interest.

Mentions: Group II patients (patients 7, 12, 13, 15 and 16) had a lesion in the PMC that affected the internal capsule. In these patients, the PMC and the internal capsule showed different degrees of deformation depending on the tumor mass effect. Figure 3 shows the CST fiber tracking results for patient 12. Patient 12 had a confirmed pathological diagnosis of grade II oligodendroglioma in the left parietal-occipital lobe. In this case, the lesion was located in the left M1 cortex and affected the left internal capsule. Figure 3A shows the lesion and the motor-activated area displayed on a T1-weighted image. Figure 3B and Figure 3C show the CST fiber tracking results based on different ROIs; yellow, green, and purple represent the CST fiber tracking results obtained by using ROI1, ROI2, and ROI1 + ROI2, respectively. Supplementary Figure S2 shows all of the CST results for Group II patients (patients 7, 12, 13, 15, and 16), all of whom had a tumor in the PMC that affected the internal capsule.


Assessing Region of Interest Schemes for the Corticospinal Tract in Patients With Brain Tumors
The CST fiber tracking results for patient 12, who was diagnosed with a grade II astrocytoma in the left frontal lobe, which affected the motor cortex and the left internal capsule. (A) The lesion and motor-activated area displayed on a T1-weighted image. (B) The CST fiber tracking results based on different ROI definitions. Yellow, green, and purple represent the CST fiber tracking results obtained using ROI1, ROI2, and ROI1 + ROI2, respectively. The CST fiber tracking results based on an anatomical landmark were distorted near the PMC area. When using the fMRI activation area as a seed region, CST fiber tracking reliably reached the motor cortex, and the spatial relationship between the CST and the tumor can be clearly observed. (C) The 3D visualization of the CST fiber tracking results based on different ROI definitions. CST = corticospinal tract, fMRI = functional MRI, PMC = primary motor cortex, ROI = region-of-interest.
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Related In: Results  -  Collection

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Figure 3: The CST fiber tracking results for patient 12, who was diagnosed with a grade II astrocytoma in the left frontal lobe, which affected the motor cortex and the left internal capsule. (A) The lesion and motor-activated area displayed on a T1-weighted image. (B) The CST fiber tracking results based on different ROI definitions. Yellow, green, and purple represent the CST fiber tracking results obtained using ROI1, ROI2, and ROI1 + ROI2, respectively. The CST fiber tracking results based on an anatomical landmark were distorted near the PMC area. When using the fMRI activation area as a seed region, CST fiber tracking reliably reached the motor cortex, and the spatial relationship between the CST and the tumor can be clearly observed. (C) The 3D visualization of the CST fiber tracking results based on different ROI definitions. CST = corticospinal tract, fMRI = functional MRI, PMC = primary motor cortex, ROI = region-of-interest.
Mentions: Group II patients (patients 7, 12, 13, 15 and 16) had a lesion in the PMC that affected the internal capsule. In these patients, the PMC and the internal capsule showed different degrees of deformation depending on the tumor mass effect. Figure 3 shows the CST fiber tracking results for patient 12. Patient 12 had a confirmed pathological diagnosis of grade II oligodendroglioma in the left parietal-occipital lobe. In this case, the lesion was located in the left M1 cortex and affected the left internal capsule. Figure 3A shows the lesion and the motor-activated area displayed on a T1-weighted image. Figure 3B and Figure 3C show the CST fiber tracking results based on different ROIs; yellow, green, and purple represent the CST fiber tracking results obtained by using ROI1, ROI2, and ROI1 + ROI2, respectively. Supplementary Figure S2 shows all of the CST results for Group II patients (patients 7, 12, 13, 15, and 16), all of whom had a tumor in the PMC that affected the internal capsule.

View Article: PubMed Central - PubMed

ABSTRACT

Diffusion tensor imaging (DTI) and diffusion tensor tractography (DTT) techniques are widely used for identifying the corticospinal tract (CST) white matter pathways as part of presurgical planning. However, mass effects in patients with brain tumors tend to cause anatomical distortions and compensatory functional reorganization of the cortex, which may lead to inaccurate mapping of white matter tracts. To overcome these problems, we compared different region-of-interest (ROI) selection schemes to track CST fibers in patients with brain tumors. Our study investigated the CSTs of 16 patients with intracranial tumors. The patients were classified into 3 subgroups according to the spatial relationships of the lesion and the primary motor cortex (PMC)/internal capsule. Specifically, we investigated the key factors that cause distorted tractography in patients with tumors. We compared 3 CST tractography methods that used different ROI selection schemes. The results indicate that CST fiber tracking methods based only on anatomical ROIs could possibly lead to distortions near the PMC region and may be unable to effectively localize the PMC. In contrast, the dual ROI method, which uses ROIs that have been selected from both blood oxygen level-dependent functional MRI (BOLD-fMRI) activation and anatomical landmarks, enabled the tracking of fibers to the motor cortex. The results demonstrate that the dual ROI method can localize the entire CST fiber pathway and can accurately describe the spatial relationships of CST fibers relative to the tumor. These results illustrate the reliability of using fMRI-guided DTT in patients with tumors. The combination of fMRI and anatomical information enhances the identification of tracts of interest in brains with anatomical deformations, which provides neurosurgeons with a more accurate approach for visualizing and localizing white matter fiber tracts in patients with brain tumors. This approach enhances surgical performance and perserves brain function.

No MeSH data available.


Related in: MedlinePlus