12 Intra-operative Measurement of Brain Deformation
309
neuronavigation system, registered to the patient, and used to guide the initial
surgical approach. During surgery, intra-operative imaging is used to measure brain
shift. Several different sources of intra-operative image data have been used to
measure brain shift, including iMRI [20, 52–54], iUS [25, 55–62], and 3D models
of the exposed cortical surface obtained using laser range scanning [63, 64] or
surface reconstruction from stereo image pairs [65]. Given these measurements
of brain shift, there are two standard methods for modelling brain deformation:
biomechanical modelling (reviewed in Chap. 6 of this book and in [10, 66]) and
nonrigid image registration (reviewed in [11]). The deformation model can then be
applied to pre-operative image data to map it to the true shape of the brain during
surgery.
12.3 Intra-operative Imaging Methods
Systems that compensate for brain shift require intra-operative measurement of
brain deformation. Ideally, measurements should be acquired at frequent intervals,
cause minimal disruption to surgery, and support accurate modelling of brain shift,
particularly near tumour margins (e.g. accurate to within 1–2 mm). The most
common methods that have been used to measure brain shift are iMRI, iUS, and
measurements of cortical surface displacements.
12.3.1 Intra-operative MRI and Computed Tomography
While the early vision of performing tumour resections in an open magnet has
not proven to be commercially viable, several systems have been developed that
combine an operating room with convenient access to MR imaging, either by
moving the patient or the scanner. To date, more than 200 such systems have been
installed. Figure 12.5 shows the Advanced Multimodality Image-Guided Operating
Suite (AMIGO) [67], an early system of this type, which was installed at Brigham
and Women’s Hospital in Boston, MA in 2011. This facility is used for both research
and for clinical procedures, including neurosurgery for tumour resection. AMIGO
includes a PET/CT room, operating room, and MR room. Video integration enables
visualisation of navigation and other video sources. The combined use of MRI and
CT with PET allows the clinicians to integrate anatomical, functional, and metabolic
information that helps in decision-making during tumour resections.
AMIGO and similar systems provide iMRI that can be used to measure brain
shift. However, frequent image updates in these systems are impractical because
they require moving either the magnet or the patient between adjoining rooms.
In AMIGO, iMRI is typically performed only once per procedure during brain
tumour resections. While this limitation, coupled with the complex progression
309
neuronavigation system, registered to the patient, and used to guide the initial
surgical approach. During surgery, intra-operative imaging is used to measure brain
shift. Several different sources of intra-operative image data have been used to
measure brain shift, including iMRI [20, 52–54], iUS [25, 55–62], and 3D models
of the exposed cortical surface obtained using laser range scanning [63, 64] or
surface reconstruction from stereo image pairs [65]. Given these measurements
of brain shift, there are two standard methods for modelling brain deformation:
biomechanical modelling (reviewed in Chap. 6 of this book and in [10, 66]) and
nonrigid image registration (reviewed in [11]). The deformation model can then be
applied to pre-operative image data to map it to the true shape of the brain during
surgery.
12.3 Intra-operative Imaging Methods
Systems that compensate for brain shift require intra-operative measurement of
brain deformation. Ideally, measurements should be acquired at frequent intervals,
cause minimal disruption to surgery, and support accurate modelling of brain shift,
particularly near tumour margins (e.g. accurate to within 1–2 mm). The most
common methods that have been used to measure brain shift are iMRI, iUS, and
measurements of cortical surface displacements.
12.3.1 Intra-operative MRI and Computed Tomography
While the early vision of performing tumour resections in an open magnet has
not proven to be commercially viable, several systems have been developed that
combine an operating room with convenient access to MR imaging, either by
moving the patient or the scanner. To date, more than 200 such systems have been
installed. Figure 12.5 shows the Advanced Multimodality Image-Guided Operating
Suite (AMIGO) [67], an early system of this type, which was installed at Brigham
and Women’s Hospital in Boston, MA in 2011. This facility is used for both research
and for clinical procedures, including neurosurgery for tumour resection. AMIGO
includes a PET/CT room, operating room, and MR room. Video integration enables
visualisation of navigation and other video sources. The combined use of MRI and
CT with PET allows the clinicians to integrate anatomical, functional, and metabolic
information that helps in decision-making during tumour resections.
AMIGO and similar systems provide iMRI that can be used to measure brain
shift. However, frequent image updates in these systems are impractical because
they require moving either the magnet or the patient between adjoining rooms.
In AMIGO, iMRI is typically performed only once per procedure during brain
tumour resections. While this limitation, coupled with the complex progression