Abstract Background: The application of transcranial focused ultrasound (FUS) for brain tissue ablation is limited by the significant challenges in ultrasound energy transmission through the skull. Objectives: The current study utilizes an anatomically accurate gel-filled skull phantom to investigate FUS transmission through three-dimensional (3D)-printed uniformly thin skull inserts, exploring the potential of a new therapeutic approach. Methods: The skull model was 3D printed using resin material, featuring a circular aperture for securing various skull inserts, and filled with an agar-silica gel mixture. Skull inserts of uniform thicknesses (1, 2, and 3 mm) and an anatomically accurate model featuring variable thickness, were tested. The impact of introducing each skull insert into the beam path during high-intensity FUS in the phantom was evaluated in terms of focal temperature elevation and lesion formation. These parameters were monitored through high-resolution imaging and thermometry within a 3T magnetic resonance imaging scanner. The results of sonication without skull interference served as reference. Results: FUS transmission was significantly distorted by the presence of skull inserts, with increasing thickness leading to a gradual reduction in the focal temperature. A large hyperintense lesion on T2-weighted turbo spin-echo images without skull interference diminished to a very small lesion with the 1-mm insert, while only a faint indication was observed with the 2-mm insert. However, temperature changes sufficient to cause tissue ablation were achieved using the 1-mm insert. Conclusion: The superior performance of the 1-mm resin insert suggests potential for new therapeutic applications using thin skull implants to enable FUS brain tumor ablation, pending further validation.
Antoniou et al. (Thu,) studied this question.