Model-updated image guidance: initial clinical experiences with gravity-induced brain deformation

Abstract

Image-guided neurosurgery relies on accurate registration of the patient, the preoperative image series, and the surgical instruments in the same coordinate space. Recent clinical reports have documented the magnitude of gravity-induced brain deformation in the operating room and suggest these levels of tissue motion may compromise the integrity of such systems. We are investigating a model-based strategy which exploits the wealth of readily-available preoperative information in conjunction with intraoperatively acquired data to construct and drive a three dimensional (3-D) computational model which estimates volumetric displacements in order to update the neuronavigational image set. Using model calculations, the preoperative image database can be deformed to generate a more accurate representation of the surgical focus during an operation. In this paper, we present a preliminary study of four patients that experienced substantial brain deformation from gravity and correlate cortical shift measurements with model predictions. Additionally, we illustrate our image deforming algorithm and demonstrate that preoperative image resolution is maintained. Results over the four cases show that the brain shifted, on average, 5.7 mm in the direction of gravity and that model predictions could reduce this misregistration error to an average of 1.2 mm.

Strategies for brain shift evaluation

“…Furthermore, experience is reported in literature (Audette et al, 1999) which is based on optically scanning the operation field in order to measure the difference of the pre-and intraoperative situation. However, there is a promising strategy evolving more recently which tries to simulate the brain shift based on an underlying mathematical model (Skrinjar and Duncan, 1999;Miga et al, 1999;Hata et al, 2000;Kyriacou et al, 2000;Ferrant et al, 2001;Skrinjar et al, 2002;Miga et al, 2000c;Miga et al, 2000a).…”

“…Adjacent systems are coupled through their common boundary. Another simulation approach based on a 3D FE model Miga et al, 1999) applies parameters of the involved tissues which were experimentally obtained from animals (Miga et al, 2000a,b,c). In order to constrain the model, sparse surface information (Skrinjar and Duncan, 1999;Roberts et al, 1999;Skrinjar et al, 2002) is intraoperatively taken from different sources.…”

Estimating Brain Deformation During Surgery Using Finite Element Method: Optimization and Comparison of Two Linear Models

“…The important body forces that affect the brain deformation are gravity (ρ t g), where ρ t is the brain density, the buoyancy of the surrounding fluid (ρ f g), where ρ f is the density of the surrounding fluid, and the pressure gradient of the exteracellular fluid (▽p). Based on these assumptions, the model can be written as [15]:…”

Intensity and region-of-interest-based finite-element modeling of brain deformation

“…One of the important factors in MIS is how to quantify the deformation induced by surgical tools. The finite-element method (FEM) has been used in MIS of brain [1][2][3][4][5][6][7][8][9][10][11] and liver [12]. Traditionally, the FEM is applied over the entire volume, despite the fact that the surgical tool (e.g., the endoscope in minimally invasive brain surgery) is applied only over a small and well-specified region of the brain.…”