Proton magnetic resonance characterization of brain tumours.

A series of different human brain tumours have been characterized with respect to the proton spin-lattice relaxation time (T1) and the water content. In malignant tumour tissue the mean T1 values are significantly larger than in benign ones. The tumours of different histological types showed notable differences in the relationship between proton relaxation rate (1/T1) and the corresponding water content (r). Malignant tumours exhibited a large variation in the water content in the presence of relatively small changes in relaxation rates, whilst just the opposite was true of the benign tumours and normal tissue. Taking into consideration the fast exchange between the intracellular and extracellular fluid, the (1/T1)/r relationship observed in malignant tissue is explainable by the variation in water content in the extracellular fluid due to oedema, which is most pronounced in malignant tumours. The individual response of patients to the malignant growth seems to determine the tissue water content and hence the measured relaxation time, whilst it appears that the relaxation rate and the water content of the malignant cells of the same tumour type do not vary appreciably from one patient to another. On the other hand, benign and non-tumourous tissue cells from different patients show larger variations in T1, whilst the variations in the extracellular water content are obviously smaller than in malignant tissues.