Characterization of normal and malignant mouse tissue by NMR lineshape-relaxation correlations in the rotation frame.

With the NMR lineshape-relaxation correlation technique the relaxation times and the relative magnitudes of the proton spin groups characterized by these respective relaxation times are obtained. In most tissues the spin-lattice relaxation in the rotating frame is nonexponential. The magnetization evolution can be represented as the sum of three exponential decays characterized by three T1rho relaxation times. The short T1rho component, corresponding to the rigid network protons, gives the most interesting information on the tissue. Results at 38 MHz are given for muscle, spleen, lung, and tumor EMT6 fibrosarcoma grown in the dorsal subcutaneous tissue of BALB/c mice. The absence of the magnetization component with short T1rho and short T2 in spleen tissue of tumorous mice demonstrates that the spleen is swollen to at least 5 times its original size so that the relative magnitude of the magnetization corresponding to collagen network is proportionally reduced. The NMR correlation technique is thus shown to be appropriate for such quantitative analysis.