Patient-Specific Stereotactic Frame for Transcranial Ultrasound Therapy

We designed, fabricated, and characterized a patient-specific, 3D-printed, stereotactic frame for repeated transcranial focused ultrasound (FUS) neuromodulation. The frame is compact, with minimal footprint, and can be removed and re-secured between treatments. The use of small skull anchor screws allows for the precise and repeatable transcranial FUS treatment without the need for MR-guidance following the initial calibration scan. Focus localization and repeatability were assessed via MR-thermometry on a macaque skull-phantom model. Focal localization, registration, steering, and re-steering was accomplished during the initial MRI calibration scan session. Keeping the steering coordinate constant in subsequent therapy and imaging sessions, we found good agreement between the steered foci and intended target, with target registration error of 0. 7 ± 0.3 and 0.7 ± 0.6mm (n = 4) in lateral and axial dimension, respectively. Focus position (steered and non-steered) was consistent, with sub-mm variation in each dimension between studies. Our preliminary studies show that our 3D printed, patient-specific stereotactic frame can reliably position and orient the ultrasound transducer for repeated targeting of brain regions without the need for MR-guidance. This compact frame will make continued transcranial FUS treatments financially and logistically more accessible to patients.