Multi-exponential water proton spin-lattice relaxation in biological tissues and its implications for quantitative NMR imaging

• Published in: Physics in medicine & biology Vol. 29; no. 5; p. 509
• Main Authors: Bakker, C J, Vriend, J
• Format: Journal Article
• Language: English
• Published: England 01-05-1984
• Subjects: Adenocarcinoma; Animals; Magnetic Resonance Spectroscopy; Male; Mammary Neoplasms, Experimental; Mice; Mice, Inbred C57BL; Neoplasm Transplantation; Protons; Water
• ISSN: 0031-9155
• DOI: 10.1088/0031-9155/29/5/003

This in vitro study was undertaken to examine whether water proton spin-lattice relaxation in biological tissues is adequately described by a single time constant T1, to define under what circumstances a multi-exponential approach is indicated, and to study the implications of multi- exponentiality for quantitative NMR imaging. Water proton relaxation curves were measured with the 180-tau-90 method at 60 MHz. Uni- and bi-exponential curves were fitted to the empirical curves using chi 2 as a criterion for the goodness of fit. An F-test was applied to test the validity of each exponential term as it was added to the fitting function. Taking into account experimental accuracy, the uni-exponential model appeared to be an adequate description of the relaxation data for necrotic tissue. Eyelens and fat showed distinct bi- exponentiality , while liver, spleen, salivary gland, tumour, and muscle presented intermediate cases. The bi-exponential analysis generally yields a minor component with a fast relaxation time, T11 less than 20 ms, and a slow relaxation major component with T12 greater than 300 ms. A simplified bi-exponential model is proposed for implementation in quantitative NMR imaging. The results seem to be consistent with current views about water proton spin-lattice relaxation in biological tissues.