Title

Chemical exchange in knee cartilage assessed by R1ρ (1/T1ρ) dispersion at 3T.

Document Type

Article

Abstract

PURPOSE: To quantify the characteristics of proton chemical exchange in knee cartilage in vivo by R1ρ dispersion analysis.

MATERIALS AND METHODS: Six healthy subjects (one female and five males, age range 24 to 71 y) underwent T1ρ imaging of knee cartilage on a 3T MRI scanner. Quantitative estimates of R1ρ (=1/T1ρ) were made using 5 different spin-lock durations for each of 12 different spin-lock amplitudes over the range 0 to 550Hz. When the variations of R1ρ with spin-locking strength (the R1ρ dispersion) are dominated by chemical exchange contributions, R1ρ dispersion curves can be analyzed to derive quantitative characteristics of the exchange and provide information on tissue composition. In this work, in vivo R1ρ dispersion of human knee articular cartilage at 3T was analyzed, and the exchange rates of protons between water and macromolecular hydroxyls (mainly in glycosaminoglycans) were estimated based on a theoretical model.

RESULTS: R1ρ values showed marked dispersion in articular cartilage and varied by approximately 50% between low and high values of the locking field, a change much greater than in surrounding tissues, consistent with greater contributions from chemical exchange. From the theoretical model, the exchange rates in cartilage were estimated to be in the range of 1.0-3.0kHz, and varied within the tissue. Variations within a single knee appear to be larger with increasing age.

CONCLUSION: R1ρ dispersion analysis may provide more specific information for studying cartilage biochemical composition and form the basis for quantitative evaluation of cartilage disorders.

Keywords

Adult, Aged, Cartilage, Articular, Female, Glycosaminoglycans, Healthy Volunteers, Humans, Image Processing, Computer-Assisted, Knee, Magnetic Resonance Imaging, Male, Middle Aged, Models, Theoretical, Water

Medical Subject Headings

Adult; Aged; Cartilage, Articular; Female; Glycosaminoglycans; Healthy Volunteers; Humans; Image Processing, Computer-Assisted; Knee; Magnetic Resonance Imaging; Male; Middle Aged; Models, Theoretical; Water

Publication Date

1-1-2015

Publication Title

Magnetic resonance imaging

ISSN

1873-5894

Volume

33

Issue

1

First Page

38

Last Page

42

PubMed ID

25093631

Digital Object Identifier (DOI)

10.1016/j.mri.2014.07.008

This document is currently not available here.

Share

COinS