Novel MRI Phantoms for Investigating Skull-Brain Mechanics

Authors

• S SAHA
• C MENG
• S WANG
• H CAI
• G CUI

Abstract

Traumatic brain injury (TBI) is a serious health condition that affects both military and civilian populations. However, the mechanisms linking mechanical insult and neurological injury, more specifically how skull motion is transmitted to brain motion during TBI, are not well understood. Here, we developed two skull-brain phantom (SBP) models to evaluate MRI investigations of skull-brain mechanics. The SBP models were developed using two identical cylindrical molds with attached boundary (SBPa) and unattached boundary (SBPu). The inside of the mold represents the brain region whereas the cavities inside the wall represent marrow within the skull. Polyacrylamide gel is used as a brain tissue simulant. We performed neck rotation (32° rotation within the axial plane) experiment using a custom MRI-compatible device. The tagged MRI study was performed using a 1.5 T Siemens Aera MR scanner. Data was acquired using a 1–1 SPAMM tagging pulse followed by 2D cine gradient echo acquisition using two axial acquisitions with orthogonal tag directions and the following acquisition parameters: FOV = 240×240 mm, matrix = 24×160, slice thickness = 8 mm, TR/TE = 3.18/1.68 ms, tag spacing = 8 mm. Harmonic phase (HARP) analysis was performed to measure the displacement vectors and calculate maximum principal strain (MPS, largest eigenvalue of strain tensor). The results suggest that at the point of impact, the MPS is larger with a fixed boundary (SBPa: 0.014 vs SBPu: 0.010). However, after impact, strains were increased in SBPu model due to torsional wave. These models can be developed further by incorporating fat-water emulsion.

Scientific Focus Area: Biomedical Engineering and Biophysics

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