A quantitative MRI protocol for assessing matrix and mineral densities and degree of mineralization of human cortical bone / Alan C. Seifert.

Format:

Book

Manuscript

Thesis/Dissertation

Author/Creator:

Seifert, Alan C., author.

Contributor:

Wehrli, F. W., degree supervisor.

Gee, James C., 1964- degree committee member.

Delikatny, Edward James, 1957- degree committee member.

Reddy, Ravinder, degree committee member.

Leonard, Mary B., degree committee member.

University of Pennsylvania. Department of Bioengineering, degree granting institution.

Language:

English

Subjects (All):

Penn dissertations--Bioengineering.

Bioengineering--Penn dissertations.

Local Subjects:

Penn dissertations--Bioengineering.

Bioengineering--Penn dissertations.

Physical Description:

xx, 144 leaves : illustrations (some color) ; 29 cm

Production:

[Philadelphia, Pennsylvania] : University of Pennsylvania, 2015.

Summary:

Two categories of bone disease, osteoporosis and osteomalacia, affect bone in different ways: bone mineral and matrix are lost in roughly equal proportions in osteoporosis, while only mineral is depleted in osteomalacia. The difference between these disorders is in bone mineralization: the mass of mineral per volume of bone matrix, excluding pore spaces. Standard clinical examinations measure x-ray attenuation to infer mineral density. However, bone mineral density alone cannot fully describe bone health. Advances in solid-state 31 P and 1 H magnetic resonance imaging (MRI) have enabled quantification of the densities of extremely short-lived bone mineral 31 P and matrix-bound water 1 H signals as surrogates for bone mineral and matrix densities. The ratio of these two measurements provides the degree of mineralization of bone (DMB). In this dissertation, the relaxation properties of bone mineral 31 P and water 1 H were analyzed, the surrogacy of bound water concentration for bone matrix density was established, and measurements of bone mineral 31 P and matrix-associated water 1 H densities in human bone specimens were designed and implemented on clinical scanners. Although bone mineral 31 P longitudinal relaxation time (T1 ) increased and effective transverse relaxation time (T 2*) decreased with increasing field strength, the predicted signal-to-noise ratio (SNR) increased slightly. Also, the short-T2* fraction of bone water calculated by 1 H bi-component fitting was correlated with porosity and matrix density at 1.5 T, but these associations weakened as field strength increased. In contrast, short-transverse relaxation time (T2 ) fraction was highly correlated with gold-standard measurements, suggesting the superiority of T2 -based methods for separation of bound and pore water fractions. Additionally, single adiabatic inversion-recovery zero echo time (SIR-ZTE) 1 H density was correlated negatively with porosity and positively with matrix and mineral densities, suggesting that this MRI method provides a surrogate measure of bone matrix density. Finally, both bone mineral 31 P and matrix-associated 1 H densities in human cortical bone specimens were correlated negatively with porosity and age, and positively with peripheral quantitative computed tomography (pQCT) density. As expected, DMB was uncorrelated with porosity, age, or pQCT density. This work established the feasibility of image-based quantification of bone mineral and bound water densities using clinical hardware.

Notes:

Ph. D. University of Pennsylvania 2015.

Department: Bioengineering.

Supervisor: Felix W. Wehrli.

Includes bibliographical references.

OCLC:

948335500