Harvard Catalyst Profiles

The transmission of ultrasound (US) through the skull bone has been investigated for therapeutic and imaging applications. One of the primary obstacles to the effective application of transcranial US is bone-induced phase aberration due to geometric variations both within a subject and between subjects. The predictability of the transmitted US wavefield within the cranial vault is paramount to the development of clinically useful US-based procedures ranging from intracranial tumor ablation and drug delivery to intraoperative monitoring and hemorrhage detection. The present gold standard for assessing skull thickness for US phase aberration correction is x-ray computed tomography (CT). Because CT has several inherent limitations as compared to US (e.g., safety, cost, and convenience), there is an interest in US-based methods for skull thickness prediction.

The proposed study will investigate the potential for using US-derived data to perform aberration correction for the transcranial propagation of US. Specific details pertaining to human skull geometry will be statistically analyzed to formulate a framework by which US-based measurements will yield comparable aberration correction as CT measurements.

This study will involve benchtop experimentation with US transducers and specialized instrumentation; computer-based image processing (US and CT); and the use of human ex vivo calvarium specimens.

Rapid developments in brain imaging within the past few decades have yielded numerous modalities and tools for enhancing our understanding of normal and pathological brain anatomy. Some of these modalities include x-ray computed tomography (CT), magnetic resonance imaging (MRI), and ultrasound (US). As these tools have become more readily available for clinicians and researchers, it has been suggested that the combined use of multiple radiological modalities, whether in situ or synergized post-procedurally, can yield tremendous benefits in both research and clinical settings.

The development of radiological tools requires the use of phantom materials that mimic the behavior of human tissues in response to the specific radiological modality being studied. Our lab, as a highly interdisciplinary research environment, incorporates numerous imaging modalities into our investigations and as such, is interested in the development of an anatomically-accurate human brain phantom that can respond in a brain tissue-like fashion to x-ray irradiation, MRI imaging, and ultrasound. In addition, as part of a larger study to investigate the use of ultrasound for thermal ablation of intracranial tumors, the multiple-modality brain phantom should also absorb and dissipate thermal energy in a fashion similar to the human brain.

This study will involve benchtop experimentation (including measurements with CT scanners, MRI scanners, US transducers, and other specialized instrumentation) and computer-based image processing (CT, MRI, and US).