Proton spin-lattice relaxation studies of tissue response to radiotherapy in mice

Abstract

Proton spin-lattice relaxation times were measured with pulsed NMR spectroscopy at 60 MHz for a range of tissues from healthy and tumour-bearing mice. T₁ appeared to be significantly longer in the tumour than in any other tissue. Clearly distinct values of T₁ were found for the vital and necrotic parts of the tumour. Non-involved tissues of tumour-bearing mice, viz. spleen, muscle, and salivary gland tissue, showed an increase in T₁ relative to normal values. Irradiation of healthy mice with 6 MeV X-rays to a total-body dose of 15 Gy induced a shortening of T₁ in the spleen. Similar experiments on tumour-bearing mice showed a decrease of T₁ in the tumour, the spleen, the kidneys, and the liver. Attempts were made to interpret the results in terms of tissue hydration.