This proposal is driven by a specific clinical scenario- the patient with orthodontic appliances (braces) undergoing MRI of the brain in whom the ferromagnetic braces result in significant degradation in B0 homogeneity and cause significant signal loss in regions immediately adjacent to the oral cavity (e.g. facial structures and orbits) as well as image distortion over variable portions of the brain. These image distortions are most pronounced at the base of the brain, the brainstem, and the blood vessels that perfuse the brain. The artifacts are most severe for diffusion weighted imaging (DWI), gradient echo (GRE) imaging, MR angiography (MRA), susceptibility weighted imaging (SWI), and MR spectroscopy (MRS). Although the typical inversion recovery and fast spin echo sequences used to diagnosis structural abnormalities of the brain are usually of diagnostic quality in patients with orthodontic appliances, DWI, MRA, SWI, functional MRI (fMRI), MRS, and volumetric imaging sequences are often non-diagnostic. Newly developed MRI techniques such as CEST (chemical exchange saturation transfer)
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These devices will minimize artifacts from a wide range of induced magnetic moments in orthodontic appliances. The devices will accommodate different maxillary/mandibular arch sizes and shapes.
Aim 2: Safety testing of the intraoral device. The device will endure 15 cycles of sterilization and experiencing forces and torques inside the MRI scanner.
Aim 3: Testing the device on head phantom using dental model of three different sizes. B0 inhomogeneity and geometric distortion on DWI (the technique with most severe geometric distortions) will be quantified.
Aim 4: To test the effectiveness of this field inhomogeneity correction technique with a variety of MRI pulse sequences in a group subjects. Type 1 and Type 2 devices will each be tested on 15 subjects (total 30
These devices will minimize artifacts from a wide range of induced magnetic moments in orthodontic appliances. The devices will accommodate different maxillary/mandibular arch sizes and shapes.
Aim 2: Safety testing of the intraoral device. The device will endure 15 cycles of sterilization and experiencing forces and torques inside the MRI scanner.
Aim 3: Testing the device on head phantom using dental model of three different sizes. B0 inhomogeneity and geometric distortion on DWI (the technique with most severe geometric distortions) will be quantified.
Aim 4: To test the effectiveness of this field inhomogeneity correction technique with a variety of MRI pulse sequences in a group subjects. Type 1 and Type 2 devices will each be tested on 15 subjects (total 30