Transcranioplasty Ultrasound Through a Sonolucent Cranial Implant Made of Polymethyl Methacrylate: Phantom Study Comparing Ultrasound, Computed Tomography, and Magnetic Resonance Imaging Background: Current methods of transcranial diagnostic ultrasound imaging are limited by the skull's acoustic properties. Craniotomy, craniectomy, and cranioplasty procedures present opportunities to circumvent these limitations by substituting autologous bone with synthetic cranial implants composed of sonolucent biomaterials. Objective: This study examined the potential to image the brain using transcranioplasty ultrasound (TCU) through a sonolucent cranial implant. Materials and Methods: A validated adult brain phantom was imaged using computed tomography (CT), magnetic resonance imaging (MRI), and ultrasound without an implant. Next, for experimental comparison, TCU was performed through a sonolucent implant composed of clear polymethyl methacrylate. Results: All imaging modalities successfully revealed elements of the brain phantom, including the bilateral ventricular system, the falx cerebri, and a deep hyperdense mass representing a brain tumor or hematoma. In addition, ultrasound images were captured which closely resembled axial images obtained with both CT and MRI. Conclusion: The results obtained in this first-ever, preclinical, phantom study suggest TCU is now a viable immediate and long-term diagnostic imaging modality deserving of further clinical investigation. Address correspondence and reprint requests to Chad Gordon, DO, FACS, Division of Neuroplastic and Reconstructive Surgery, Department of Plastic and Reconstructive Surgery, Johns Hopkins University School of Medicine, JHOC, 8th Floor, 601N. Caroline St., Baltimore, MD 21287; E-mail: cgordon@jhmi.edu Received 11 February, 2019 Accepted 24 April, 2019 There was no external funding used for this study. CG is a consultant for Stryker and Longeviti Neuro Solutions. JH and CG are stockholders of Longeviti Neuro Solutions. None of the other authors have any conflicts to report. © 2019 by Mutaz B. Habal, MD.