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Signal Normalization Strategies Towa...

Lau, Justin Yat Cheong.

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Signal Normalization Strategies Towards Robust Carbon-13 Imaging for Clinical Translation.

Record Type:	Electronic resources : Monograph/item
Title/Author:	Signal Normalization Strategies Towards Robust Carbon-13 Imaging for Clinical Translation./
Author:	Lau, Justin Yat Cheong.
Published:	Ann Arbor : ProQuest Dissertations & Theses, : 2018,
Description:	149 p.
Notes:	Source: Dissertations Abstracts International, Volume: 80-02, Section: B.
Contained By:	Dissertations Abstracts International80-02B.
Subject:	Medical imaging. -
Online resource:	http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=10687939
ISBN:	9780438186606

Signal Normalization Strategies Towards Robust Carbon-13 Imaging for Clinical Translation.
Lau, Justin Yat Cheong.

Signal Normalization Strategies Towards Robust Carbon-13 Imaging for Clinical Translation. - Ann Arbor : ProQuest Dissertations & Theses, 2018 - 149 p.

Source: Dissertations Abstracts International, Volume: 80-02, Section: B.

Thesis (Ph.D.)--University of Toronto (Canada), 2018.

This item must not be sold to any third party vendors.

Prostate cancer is a heterogeneous disease. Some patients present with rapid progression, while many others never exhibit clinical symptoms. Difficulties in assessing risk of disease progression with currently available medical imaging modalities lead to treatment of both groups. However, inappropriate treatment of an indolent disease can have potential side effects with little benefit to the patient. Hyperpolarized ¹³C magnetic resonance imaging is presented as a modality that can detect increased lactate production associated with transformation to metastatic disease. An increased ¹³C lactate signal may be a valuable early indication of disease progression for patients under active surveillance. There is currently no consensus on how to interpret the observed lactate signal. In this dissertation, three signal normalization techniques are presented to prospectively account for the experimental factors of spin polarization, substrate delivery, and off-resonance. Dynamic nuclear polarization confers a temporary signal enhancement resulting from a non-equilibrium spin polarization. The polarization decreases with time due to longitudinal relaxation. For pyruvate, a spectral feature known as asymmetry can be correlated with the spin polarization. Calibration data were acquired as an empirical relationship between asymmetry and spin polarization. By prospectively accounting for the spin polarization, the normalized signal better reflects the metabolic activity in the tissue. Low ¹³C lactate signal could be attributed to slow metabolic activity or poor substrate delivery. Normalization of ¹³C lactate by the signal intensity of a co-polarized perfusion agent is proposed as an approach to account for substrate delivery. Spectrally-selective signal excitation schemes can greatly simplify signal encoding requirements, but the frequency sensitivity can also lead to incomplete excitation and imaging artifacts if the prescribed excitation frequency does not match the resonance frequency of the signal of interest. A modified pulse sequence with wider spectral passbands and multi-echo acquisition is proposed as a prospective flip angle normalization strategy. The dissertation concludes with a presentation of the current state of clinical translation of hyperpolarized ¹³C imaging technology in Toronto. The first ¹³C image of the human heart is shown along with preliminary data from the prostate cancer clinical trial.

ISBN: 9780438186606Subjects--Topical Terms:

3172799
Medical imaging.

Signal Normalization Strategies Towards Robust Carbon-13 Imaging for Clinical Translation.
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500 $a Publisher info.: Dissertation/Thesis.
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520 $a Prostate cancer is a heterogeneous disease. Some patients present with rapid progression, while many others never exhibit clinical symptoms. Difficulties in assessing risk of disease progression with currently available medical imaging modalities lead to treatment of both groups. However, inappropriate treatment of an indolent disease can have potential side effects with little benefit to the patient. Hyperpolarized ¹³C magnetic resonance imaging is presented as a modality that can detect increased lactate production associated with transformation to metastatic disease. An increased ¹³C lactate signal may be a valuable early indication of disease progression for patients under active surveillance. There is currently no consensus on how to interpret the observed lactate signal. In this dissertation, three signal normalization techniques are presented to prospectively account for the experimental factors of spin polarization, substrate delivery, and off-resonance. Dynamic nuclear polarization confers a temporary signal enhancement resulting from a non-equilibrium spin polarization. The polarization decreases with time due to longitudinal relaxation. For pyruvate, a spectral feature known as asymmetry can be correlated with the spin polarization. Calibration data were acquired as an empirical relationship between asymmetry and spin polarization. By prospectively accounting for the spin polarization, the normalized signal better reflects the metabolic activity in the tissue. Low ¹³C lactate signal could be attributed to slow metabolic activity or poor substrate delivery. Normalization of ¹³C lactate by the signal intensity of a co-polarized perfusion agent is proposed as an approach to account for substrate delivery. Spectrally-selective signal excitation schemes can greatly simplify signal encoding requirements, but the frequency sensitivity can also lead to incomplete excitation and imaging artifacts if the prescribed excitation frequency does not match the resonance frequency of the signal of interest. A modified pulse sequence with wider spectral passbands and multi-echo acquisition is proposed as a prospective flip angle normalization strategy. The dissertation concludes with a presentation of the current state of clinical translation of hyperpolarized ¹³C imaging technology in Toronto. The first ¹³C image of the human heart is shown along with preliminary data from the prostate cancer clinical trial.
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