Development and Testing of an MRI-Compatible Immobilization Device for Head and Neck Imaging

MRI imaging with long acquisition times is prone to motion artifacts that can compromise image quality and lead to misinterpretation. Aiming to address this challenge at the sub-millimeter level, we developed and evaluated a maxilla immobilization approach, which is known to have better performance than other non-invasive techniques, using a personalized mouthpiece connected to an external MRI-compatible frame. The effectiveness of the device was evaluated by analyzing MRI imagery obtained in different immobilization conditions on a human volunteer. The SURF and Block Matching algorithms were assessed, supplemented by custom software. Compared with simple cushioning, the immobilizer reduced the amplitudes of involuntary slow-drift movements of the head by more than a factor two in the axial plane, with final values of 0.25 mm and 0.060°. Faster involuntary motions, including those caused by breathing (which were identifiable), were also suppressed, with final standard deviation values below 0.045 mm and 0.025°. It was also observed a strong restriction of intentional movements, translationally and angularly, by factors from 7.8 to 4.6, with final values of 0.5 mm and 0.2° for moderate forcing.