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Proton spin‐lock ratio imaging for quantitation of glycosaminoglycans in articular cartilage
Author(s) -
Regatte Ravinder Reddy,
Akella Sarma V.S.,
Borthakur Arijitt,
Reddy Ravinder
Publication year - 2003
Publication title -
journal of magnetic resonance imaging
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.563
H-Index - 160
eISSN - 1522-2586
pISSN - 1053-1807
DOI - 10.1002/jmri.10228
Subject(s) - nuclear magnetic resonance , cartilage , materials science , pulse sequence , magnetic resonance imaging , glycosaminoglycan , proton , chemistry , analytical chemistry (journal) , optics , physics , anatomy , chromatography , medicine , biochemistry , quantum mechanics , radiology
Purpose To quantify glycosaminoglycans (GAG) in intact bovine patellar cartilage using the proton spin‐lock ratio imaging method. This approach exploits spin‐lattice relaxation time in the rotating frame (T 1ρ ) imaging and T 1ρ relaxivity (R 1ρ ). Materials and Methods All the magnetic resonance imaging (MRI) experiments were performed on a 4‐T whole‐body GE Signa scanner (GEMS, Milwaukee, WI), and spectroscopy experiments of chondroitin sulfate (CS) phantoms were done on a 2‐T custom‐built spectrometer. A custom‐built 11‐cm‐diameter transmit‐receive birdcage coil, which was tuned to a proton frequency of 170 MHz, was employed for the imaging experiments. T 1ρ measurements were made using a fast spin echo (FSE) sequence pre‐encoded with a three‐pulse cluster consisting of two 90° hard pulses separated by a low‐power rectangle pulse for spin‐locking. Results The methodology is first validated on CS phantoms and then used to quantify GAG content in intact bovine cartilage ( N = 5). There is a good agreement between the GAG map calculated from the T 1ρ ratio imaging method (71 ± 4%) and GAG measured from spectrophotometric assay (75 ± 5%) in intact bovine tissue. Conclusion We have demonstrated a proton spin‐lock ratio imaging method to quantify absolute GAG distribution in the cartilage in a noninvasive and nondestructive manner. J. Magn. Reson. Imaging 2003;17:114–121. © 2002 Wiley‐Liss, Inc.