Predicting the transmission of ultrasound through the skull : estimation of the acoustic properties of bone using computed tomography and magnetic resonance imaging
Abstract/Contents
- Abstract
- Interest in transcranial magnetic resonance guided focused ultrasound (tcMRgFUS) is being driven by an ever increasing number of applications. tcMRgFUS uses ultrasound transmitted through the intact skull to achieve a therapeutic outcome. Therapies under investigation include ablation as an alternative to surgery, targeted drug delivery through the temporary opening of the blood brain barrier, or the modulation of neurons. All of these applications rely on simulations of the propagation of ultrasound through the skull in order to compute the patient specific corrections necessary to efficiently transfer acoustic energy into the brain. In turn, these simulations rely on patient specific estimates of acoustic properties such as velocity and attenuation. These estimates are usually made using CT images of the patient. In this thesis I examine current models of predicting acoustic velocity and attenuation and propose modifications to these models. My analysis relies on experiments performed using 100 samples taken from two ex-vivo skulls. Each fragment is imaged using clinical CT, micro CT, and MRI and the acoustic velocity and attenuation of each fragment are measured. The velocity data are used to show that variations in the x-ray energy and reconstruction algorithm used to acquire a CT scan have a significant impact on the relationship between Hounsfield units (HU) and velocity that is not adequately accounted for in existing transformations of HU to velocity. Further, HU provide an incomplete estimate of velocity because they do not provide information about the pore structure in the skull. My results show that MR has the potential to provide this missing information. The attenuation results show that attenuation monotonically decreases with HU and that both CT and MR can predict acoustic attenuation in the human skull.
Description
| Type of resource | text |
|---|---|
| Form | electronic resource; remote; computer; online resource |
| Extent | 1 online resource. |
| Place | California |
| Place | [Stanford, California] |
| Publisher | [Stanford University] |
| Copyright date | 2018; ©2018 |
| Publication date | 2018; 2018 |
| Issuance | monographic |
| Language | English |
Creators/Contributors
| Author | Webb, Taylor D |
|---|---|
| Degree supervisor | Pauly, Kim Butts (Kim Rosemary Butts) |
| Thesis advisor | Pauly, Kim Butts (Kim Rosemary Butts) |
| Thesis advisor | Dahl, Jeremy J, 1976- |
| Thesis advisor | Ghanouni, Pejman |
| Thesis advisor | Khuri-Yakub, Butrus T, 1948- |
| Degree committee member | Dahl, Jeremy J, 1976- |
| Degree committee member | Ghanouni, Pejman |
| Degree committee member | Khuri-Yakub, Butrus T, 1948- |
| Associated with | Stanford University, Department of Electrical Engineering. |
Subjects
| Genre | Theses |
|---|---|
| Genre | Text |
Bibliographic information
| Statement of responsibility | Taylor D. Webb. |
|---|---|
| Note | Submitted to the Department of Electrical Engineering. |
| Thesis | Thesis Ph.D. Stanford University 2018. |
| Location | electronic resource |
Access conditions
- Copyright
- © 2018 by Taylor D Webb
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