[In vivo nuclear magnetic resonance tomography measurement of vocal cord temperature during phonation].

In the glottal area, a series of transversal sections was recorded by means of a nuclear magnetic resonance tomograph using the technique of fast FLASH recording. During the record, the subject uttered the vowel [a:] with 180 Hz and 80 dB(A). The flip angle (35 degrees C) was chosen so as to get maximum contrast in the tissue tomogram due to a temperature shift. The tissue temperature was evaluated by the measurement of the dependence of the relaxation time on the temperature in a gelatinized and doped test solution which was similar in relaxation times to the tissue. In the vocal folds, the temperature increased by about 4 degrees C after prolonged phonation (20 x 20 s). The importance of this technique and the result is discussed with reference to the phonatory function of the larynx.