FOLLOW-UP AND DIAGNOSIS OF RECURRENCES AF TER RADIOCHEMOTHERAPY OF MALIGNANT HEAD AND NECK TUMORS

339 CT and 95 MRT examinations in 210 patients were evaluated retrospe ctively to determine the value of CT and MRT for follow-up of head and neck tumors and for diagnosing recurrences. Semi-quantitative evaluat ion of tumor extent during and after radiotherapy showed advantages fo r MRT since changes induced by treatment, particularly oedema, produce d less contrast loss in the images. CT had a sensitivity of 81% for th e recognition of recurrences; this was 92% for MRT Specificity for CT was 76% and for MRT 86%. Concerning the reliability of individual diag nostic criteria, space occupying lesions were the most valuable in CT diagnosis. For MRT, space occupying lesions and infiltration into neig hbouring structures were of equal value. Because of differences in the nature of the signals, MRT proved better than CT in characterising re current masses and this improved the differentiation between scarring and local tumour recurrence.