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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 1. (A) The lesion and motor-activated area are 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 lesion is located in the left motor area, and it did not affect the left internal capsule. Fiber tracking approaches based on ROI2 and ROI1 + ROI2 reached the motor cortex, whereas the reliability of CST tracking solely based on the ROI1 approach was lower due to the tumor mass effect. (C) The 3D visualization of the CST fiber tracking results based on different ROI definitions. CST = corticospinal tract, ROI = region-of-interest.
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Figure 2: The CST fiber tracking results for patient 1. (A) The lesion and motor-activated area are 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 lesion is located in the left motor area, and it did not affect the left internal capsule. Fiber tracking approaches based on ROI2 and ROI1 + ROI2 reached the motor cortex, whereas the reliability of CST tracking solely based on the ROI1 approach was lower due to the tumor mass effect. (C) The 3D visualization of the CST fiber tracking results based on different ROI definitions. CST = corticospinal tract, ROI = region-of-interest.

Mentions: Group I patients (patients 1, 3, 4, 6, 10, and 11) had a tumor in the PMC that did not affect the internal capsule. Figure 2 shows patient 1's CST fiber tracking results using the 3 different ROI approaches. Patient 1 had a confirmed pathological diagnosis of microcystic meningioma in the left frontoparietal lobe. In this case, the patient's lesion was located in the left PMC and did not affect the left internal capsule. Figure 2A displays the lesion and the motor-activated area on a T1-weighted image. Figure 2B shows 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. Figure 2C shows the 3D visualization of the CST fiber tracking results based on different ROI definitions. These results indicate that the lesion in the left frontoparietal lobe had a significant mass effect on the CST. We were able to successfully track fiber related to hand movement when using the fMR I-based definition of the ROI (ROI2) or the dual ROI (ROI1 + ROI2) approach. However, CST fiber tracking that was solely based on the anatomical ROI (ROI1) showed significantly compromised integrity because of the mass effect of the lesion on the brain tissue. The validity of our approach can be observed in supplementary Figure S1, which shows all of the CST results for Group I patients (patients 1, 3, 4, 6, 10, and 11).


Assessing Region of Interest Schemes for the Corticospinal Tract in Patients With Brain Tumors
The CST fiber tracking results for patient 1. (A) The lesion and motor-activated area are 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 lesion is located in the left motor area, and it did not affect the left internal capsule. Fiber tracking approaches based on ROI2 and ROI1 + ROI2 reached the motor cortex, whereas the reliability of CST tracking solely based on the ROI1 approach was lower due to the tumor mass effect. (C) The 3D visualization of the CST fiber tracking results based on different ROI definitions. CST = corticospinal tract, ROI = region-of-interest.
© Copyright Policy - open-access
Related In: Results  -  Collection

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Show All Figures
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Figure 2: The CST fiber tracking results for patient 1. (A) The lesion and motor-activated area are 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 lesion is located in the left motor area, and it did not affect the left internal capsule. Fiber tracking approaches based on ROI2 and ROI1 + ROI2 reached the motor cortex, whereas the reliability of CST tracking solely based on the ROI1 approach was lower due to the tumor mass effect. (C) The 3D visualization of the CST fiber tracking results based on different ROI definitions. CST = corticospinal tract, ROI = region-of-interest.
Mentions: Group I patients (patients 1, 3, 4, 6, 10, and 11) had a tumor in the PMC that did not affect the internal capsule. Figure 2 shows patient 1's CST fiber tracking results using the 3 different ROI approaches. Patient 1 had a confirmed pathological diagnosis of microcystic meningioma in the left frontoparietal lobe. In this case, the patient's lesion was located in the left PMC and did not affect the left internal capsule. Figure 2A displays the lesion and the motor-activated area on a T1-weighted image. Figure 2B shows 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. Figure 2C shows the 3D visualization of the CST fiber tracking results based on different ROI definitions. These results indicate that the lesion in the left frontoparietal lobe had a significant mass effect on the CST. We were able to successfully track fiber related to hand movement when using the fMR I-based definition of the ROI (ROI2) or the dual ROI (ROI1 + ROI2) approach. However, CST fiber tracking that was solely based on the anatomical ROI (ROI1) showed significantly compromised integrity because of the mass effect of the lesion on the brain tissue. The validity of our approach can be observed in supplementary Figure S1, which shows all of the CST results for Group I patients (patients 1, 3, 4, 6, 10, and 11).

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