FREQUENCY-DEPENDENCE OF T1 AND T2 RELAXATION-TIMES OF WATER IN NORMAL AND TUMORAL LUNG TISSUES - T2 RELAXATION-TIME EVIDENCE OF WATER DIFFERENT CHEMICAL-SHIFTS AND EXCHANGE-RATES

Water H-1 relaxation times, T1 and T2, have been measured at different magnetic fields for a total of 22 samples of normal and tumoral lung tissues taken away just after surgery. Results indicate that the average T1 values increase continuously with the inverse of the square root of the resonance frequency. The opposite trend is manifested for the average T2 values, which decrease continuously with the square of the frequency. We interpret the anomalous frequency, dependence of T2 by introducing in the relationship a field dependent term. This term is indicative of the presence of a minimum of two kinds of water molecular surroundings in both normal and neoplastic lung tissues. The upper limits of the exchange rates are derived in this way. The values of these exchange rates are different for normal and neoplastic tissue.