Fabrication of a positional brain shift phantom through the utilization of the frozen intermediate hydrogel state

Synthetic models (phantoms) of the brain-skull system are useful tools for the study of surgical events that are otherwise difficult to study directly in humans. To date, very few studies can be found which replicate the full anatomical brain-skull system. Such models are required to study the more global mechanical events that can occur in neurosurgery, such as positional brain shift. Presented in this work is a novel workflow for the fabrication of a biofidelic brain-skull phantom which features a full hydrogel brain with fluid-filled ventricle/fissure spaces, elastomer dural septa and fluid-filled skull. Central to this workflow is the utilization of the frozen intermediate curing state of an established brain tissue surrogate, which allows for a novel moulding and skull installation approach that permits a much fuller recreation of the anatomy. The mechanical realism of the phantom was validated through indentation testing of the phantom's brain and simulation of the supine to prone brain shift event, while the geometric realism was validated through magnetic resonance imaging. The developed phantom captured a novel measurement of the supine to prone brain shift event with a magnitude that accurately reproduces that seen in the literature

An Anthropomorphic Polyvinyl Alcohol Triple-Modality Brain Phantom based on Colin27

International audienceWe propose a method for the creation of an anatomically and mechanically realistic brain phantom from polyvinyl alcohol cryogel (PVA-C) for validation of image processing methods for segmentation, re- construction, registration, and denoising. PVA-C is material widely used in medical imaging phantoms for its mechanical similarities to soft tis- sues. The phantom was cast in a mold designed using the left hemiphere of the Colin27 brain dataset [1] and contains deep sulci, a complete in- sular region, and an anatomically accurate left ventricle. Marker spheres and inflatable catheters were also implanted to enable good registration and simulate tissue deformation, respectively. The phantom was designed for triple modality imaging, giving good contrast images in computed tomography, ultrasound, and magnetic resonance imaging. Multimodal data acquired from this phantom are made freely available to the image processing community (http://pvabrain.inria.fr) and will aid in the validation and further development of medical image processing tech- niques

MICCAI 2010 Poster : An Anthropomorphic Polyvinyl Alcohol Triple-Modality Brain Phantom based on Colin27

<p>We propose a method for the creation of an anatomically and mechanically realistic brain phantom from polyvinyl alcohol cryogel (PVA-C) for validation of image processing methods for segmentation, reconstruction, registration, and denoising. PVA-C is material widely used in medical imaging phantoms for its mechanical similarities to soft tissues. The phantom was cast in a mold designed using the left hemiphere of the Colin27 brain dataset [Holmes et al. 1998] and contains deep sulci, a complete insular region, and an anatomically accurate left ventricle. Marker spheres and inflatable catheters were also implanted to enable good registration and simulate tissue deformation, respectively. The phantom was designed for triple modality imaging, giving good contrast images in computed tomography, ultrasound, and magnetic resonance imaging. Multimodal data acquired from this phantom are made freely available to the image processing community (http://pvabrain.inria.fr) and will aid in the validation and further development of medical image processing techniques.</p

A phantom for the study of positional brain shift

Positional brain shift (PBS) is the term given to the displacement of the brain which occurs upon surgical reorientation of the head and presents as one of the many sources of targeting error in high precision neurosurgery. Due to the impracticality of imaging humans in non-standard positions, however, there is currently insufficient information for surgeons to utilize in order to mitigate against PBS in surgical planning. To better characterise PBS, a novel synthetic model (phantom) of the brain-skull system was developed, comprising hydrogel brain (inc. imaging beads) with water filled ventricle cavity, elastomer dural septa, water filled subarachnoid space, and plastic skull. This phantom was validated by simulating the supine to prone PBS event and mechanically tuning the phantom’s hydrogel brain such that the general magnitude of shift (measured through CT imaging) matched that reported in human MRI studies. Using this phantom, brain shift characterisation was performed for a discrete representation of the continuous spectrum of possible positional transitions in neurosurgery. Here, brain shift was measured across eight positional transitions at 44 locations within the brain. Eight novel PBS maps were produced as a result of this study, with mean brain shift ranging between 0.39 and 0.94 mm and the standard deviation of shift within each PBS map ranging between 0.12 and 0.44 mm. The greatest shift was found upon transition from the supine to elevated right decubitus position, with a shift of 2 mm being measured in the left parietal lobe. Importantly, it was found that, a) clinically significant brain shift took place across all transitions and, b) clinically significant variability took place between the brain shift patterns of individual transitions at the local level. Together these findings further highlight the need for the consideration of PBS in surgical planning and strongly suggest that versatile parametric software are likely needed to account for the variable shifting of neurosurgical targets. The developed phantom has allowed for novel insights into an event otherwise difficult to study in humans. With further developments, it is believed that the phantom can be used to study other similarly problematic events, such as trauma