A method of measuring a tissue parameter such as proteoglycan content and other relevant tissue parameters, e.g. tissue pH, in a tissue or an organ of a subject includes generating first and second frequency magnetic resonance data using T1ρ scans at different frequencies, wherein the frequencies are symmetric. The method also includes combining the first frequency magnetic resonance data and the second frequency magnetic resonance data to remove a number of contributions from a number of relaxation mechanisms other than chemical exchange, thereby obtaining chemical exchange-specific magnetic resonance data indicative of the tissue parameter in the tissue or the organ. The chemical exchange-specific magnetic resonance data may be used to measure the proteoglycan content in the tissue or organ.
