Temperature Measurements by Nuclear Magnetic Resonance and Its Possible Use as a Means of In Vivo Noninvasive Temperature Measurement and for Hyperthermia Treatment Assessment

Abstract

It is well known that the control of hyperthermia treatment for deep-seated tumors is exceptionally difficult. At present, the increase in temperature produced by irradiation is monitored by the introduction of temperature sensors at specific points in the body. With this technique, the stress the patient inevitably has to endure is considerable. Furthermore, the possibility of the introduction of the temperature sensors causing a metastasis cannot be excluded. Temperature is the first parameter which suggests itself as a means to monitor hyperthermia treatment. Therefore it would seem worthwhile to look for alternative, noninvasive temperature measurement methods. Additionally, metabolic parameters which change upon irradiation may be suitable indicators of the success of hyperthermia treatment. It is, for example, known that hyperthermia treatment influences metabolic parameters as well as blood flow and pH values. Those effects which may occur during hyperthermia achieved by irradiation are: (1) temperature increase, (2) changes in metabolite concentrations, (3) changes in metabolic process rates, and (4) production of radicals. All the quantities listed here are, theoretically at least measurable by nuclear magnetic resonance (NMR). In order to indicate the potential of this technique, some of the more commonly occurring terms used in NMR will now be explained.