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Detection of changes in articular cartilage proteoglycan by T 1ρ magnetic resonance imaging
Author(s) -
Wheaton Andrew J.,
Dodge George R.,
Borthakur Arijitt,
Kneeland J. Bruce,
Schumacher H. Ralph,
Reddy Ravinder
Publication year - 2005
Publication title -
journal of orthopaedic research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.041
H-Index - 155
eISSN - 1554-527X
pISSN - 0736-0266
DOI - 10.1016/j.orthres.2004.06.015
Subject(s) - cartilage , magnetic resonance imaging , osteoarthritis , proteoglycan , ex vivo , chemistry , in vivo , nuclear magnetic resonance , biomedical engineering , nuclear medicine , medicine , anatomy , pathology , biology , radiology , physics , alternative medicine , microbiology and biotechnology
The purpose of this work is to demonstrate the feasibility of T 1ρ ‐weighted magnetic resonance imaging (MRI) to quantitatively measure changes in proteoglycan content in cartilage. The T 1ρ MRI technique was implemented in an in vivo porcine animal model with rapidly induced cytokine‐mediated cartilage degeneration. Six pigs were given an intra‐articular injection of recombinant porcine interleukin‐1β (IL‐1β) into the knee joint before imaging to induce changes in cartilage via matrix metalloproteinase (MMP) induction. The induction of MMPs by IL‐1 was used since it has been extensively studied in many systems and is known to create conditions that mimic in part characteristics similar to those of osteoarthritis. The contralateral knee joint was given a saline injection to serve as an internal control. T 1ρ ‐weighted MRI was performed on a 4 T whole‐body clinical scanner employing a 2D fast spin‐echo‐based T 1ρ imaging sequence. T 1ρ relaxation parameter maps were computed from the T 1ρ ‐weighted image series. The average T 1ρ relaxation rate, R 1ρ (1/ T 1ρ ) of the IL‐1β‐treated patellae was measured to be on average 25% lower than that of saline‐injected patellae indicating a loss of proteoglycan. There was an average reduction of 49% in fixed charge density, measured via sodium MRI, of the IL‐1β‐treated patellae relative to control corroborating the loss of proteoglycan. The effects of IL‐1β, primarily loss of PG, were confirmed by histological and immunochemical findings. The results from this study demonstrate that R 1ρ is able to track proteoglycan content in vivo. © 2004 Orthopaedic Research Society. Published by Elsevier Ltd. All rights reserved.