Image Updating for Brain Shift Compensation During Resection

Abstract

Background: In open-cranial neurosurgery, preoperative magnetic resonance (pMR) images are typically coregistered for intraoperative guidance. Their accuracy can be significantly degraded by intraoperative brain deformation, especially when resection is involved.

Objective: To produce model updated MR (uMR) images to compensate for brain shift that occurred during resection, and evaluate the performance of the image-updating process in terms of accuracy and computational efficiency.

Methods: In 14 resection cases, intraoperative stereovision image pairs were acquired after dural opening and during resection to generate displacement maps of the surgical field. These data were assimilated by a biomechanical model to create uMR volumes of the evolving surgical field. A tracked stylus provided independent measurements of feature locations to quantify target registration errors (TREs) in the original coregistered pMR and uMR as surgery progressed.

Results: Updated MR TREs were 1.66 ± 0.27 and 1.92 ± 0.49 mm in the 14 cases after dural opening and after partial resection, respectively, compared to 8.48 ± 3.74 and 8.77 ± 4.61 mm for pMR, respectively. The overall computational time for generating uMRs after partial resection was less than 10 min.

Conclusion: We have developed an image-updating system to compensate for brain deformation during resection using a computational model with data assimilation of displacements measured with intraoperative stereovision imaging that maintains TREs less than 2 mm on average.

FIGURE 1.

The iSV system (red box). Two CCD cameras (yellow arrow) were connected to an adapter that was attached to one of the optical ports on the microscope head.

FIGURE 2.

Flowchart of the MR image-updating process.

FIGURE 3.

Comparison of pMR and uMRs with iSV surfaces from case 1. pMR = preoperative MR images; uMR = updated MR images; iSV = intraoperative stereovision. A, Representative 2-D view of pMR overlaid with iSV₁ and iSV₂ (yellow and red lines, respectively). B, Three-dimensional view of pMR overlaid with iSV₁, white arrow points to feature misaligned. C, Two-dimensional view of uMR₁ at the same coronal slice location, overlaid with iSV₁ and iSV₂ (yellow and red lines, respectively). D, Three-dimensional view of uMR₁ overlaid with iSV₁, white arrow points to feature accurately aligned. E, Two-dimensional view of uMR₂ at the same coronal slice location, overlaid with iSV₂ (red line). F, Three-dimensional view of uMR₂ overlaid with iSV₂, white arrow points to feature accurately aligned.

FIGURE 4.

Comparison of pMR and uMRs with iSV surfaces from case 10. pMR = preoperative MR images; uMR = updated MR images; iSV = intraoperative stereovision. A, Representative 2-D view of pMR overlaid with iSV₁ and iSV₂ (yellow and red lines, respectively). B, Three-dimensional view of pMR overlaid with iSV₁, white arrow points to feature misaligned. C, Two-dimensional view of uMR₁ at the same coronal slice location, overlaid with iSV₁ and iSV₂ (yellow and red lines, respectively). D, Three-dimensional view of uMR₁ overlaid with iSV₁, white arrow points to feature accurately aligned. E, Two-dimensional view of uMR₂ at the same coronal slice location, overlaid with iSV₂ (red line). F, Three-dimensional view of uMR₂ overlaid with iSV₂, white arrow points to feature accurately aligned.

FIGURE 5.

Comparison of pMR and uMRs with iSV surfaces from case 14. pMR = preoperative MR images; uMR = updated MR images; iSV = intraoperative stereovision. A, Representative 2-D view of pMR overlaid with iSV₁ and iSV₂ (yellow and red lines, respectively). B, Three-dimensional view of pMR overlaid with iSV₁, white arrow points to feature misaligned. C, Two-dimensional view of uMR₁ at the same coronal slice location, overlaid with iSV₁ and iSV₂ (yellow and red lines, respectively). D, Three-dimensional view of uMR₁ overlaid with iSV₁, white arrow points to feature accurately aligned. E, Two-dimensional view of uMR₂ at the same coronal slice location, overlaid with iSV₂ (red line). F, Three-dimensional view of uMR₂ overlaid with iSV₂, white arrow points to feature accurately aligned.

FIGURE 6.

Comparison of pMR and uMRs with iSV surfaces from case 11. pMR = preoperative MR images; uMR = updated MR images; iSV = intraoperative stereovision. A, Representative 2-D view of pMR overlaid with iSV₁, iSV₂ and iSV₃ (yellow, red and green lines, respectively). B, Three-dimensional view of pMR overlaid with iSV₁, white arrows point to features misaligned. C, Two-dimensional view of uMR₁ at the same coronal slice location, overlaid with iSV₁, iSV₂ and iSV₃ (yellow, red, and green lines, respectively). D, Three-dimensional view of uMR₁ overlaid with iSV₁, white arrows point to features accurately aligned. E, Two-dimensional view of uMR₂ at the same coronal slice location, overlaid with iSV₂ (red line). F, Three-dimensional view of uMR₂ overlaid with iSV₂, white arrows point to features accurately aligned. G, Two-dimensional view of uMR₃ at the same coronal slice location, overlaid with iSV₃ (red line). H, Three-dimensional view of uMR₃ overlaid with iSV₂, white arrow points to feature accurately aligned.