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43 patients with malignant tumours of the larynx or hypopharynx were examined by MRT and CT to compare their accuracy for T-staging. There was histological confirmation in all cases. Histological studies showed an accuracy in T-staging of 90% for MRT and 82% for CT. Differentiation between stages T2/T3 and T3/T4 is possible in most cases by either method. A source of error is the difficulty of differentiating oedema or inflammatory changes from tumour. This led to occasional overinterpretation of the T4 stage. Demonstration of cartilage involvement was easier with MRT (88%) than with CT (84%). The use of Gd-DTPA with T1 weighted and proton weighted sequences allows earlier diagnosis of cartilage invasion. Early cartilage involvement may be missed by CT when it is seen on MRT. In addition, the ability to produce coronal and sagittal images by MRT makes this superior to CT in judging tumour extension.

In 64 patients with malignant lesions of the larynx, CT and microlaryngoscopy (ML) were evaluated in terms of T-staging. Histological information was present in all cases following operation. CT showed an accuracy of 90% in T-staging. ML showed an accuracy of only 71% of correct T-staging. CT is superior to ML particularly in distinguishing between stages T3 and T4 and T1 and T2. CT tends to overestimate tumour stage whereas ML tends to underestimate it. CT was also compared with palpation and sonography as regards N-staging. In this respect sonography has the highest accuracy (94%) followed by palpation (76%) and CT (74%).

The diagnosis of retrocochlear damage is supported by an increased latency difference between peak I and peak V. In case of high frequency hearing loss peak I is often hard to determine, and peak V latency may be shifted not only by neural delay, but also by missing basal hair cells. The amount of cochlear delay can be estimated by a procedure presented here. High frequency decay was simulated by steep high-pass noise masking. Peak V latency turned out to be established by the highest unaffected frequency components of the click stimulus. Thus, in case of a high frequency gap (with normalization towards higher frequencies) latency may be almost normal. In case of prolonged latency the amount ascribable to the cochlea may be rather precisely be estimated. If the whole lag is explained this way, unnecessary further diagnostics can be avoided.

The value of sonography for demonstrating cervical lymph node metastases has been studied, using longitudinal and transverse measurements as criteria for malignancy. A transverse/longitudinal quotient greater than 2 indicates the presence of metastases with a 96% assurance. Using only longitudinal measurements lymph node metastases can be excluded with only a 36% assurance. The sensitivity of both methods also differs (95% for the maximal transverse quotient as against 90% for longitudinal measurements). The use of the maximal transverse quotient increases specificity from 36 to 96%. This gives sonography an accuracy of 95%.

Palpation and CT are used before treatment, in addition to sonography, in patients with tumours in the head and neck for lymph node staging. The accuracy of CT in identifying lymph node metastases is 79% and in our clinical material is similar to the accuracy of palpation (81%). Sensitivity of CT (93%) is better than palpation (82%). Specificity of CT (65%) is less than that of palpation (82%). The high percentage of false positives from CT (35%) is due to enlargement of the lymph nodes resulting from sinus histiocytosis or follicular hyperplasia. CT is significantly superior to palpation in demonstrating the relationship of the lymph nodes to the surrounding tissues (vessels, muscles, bones).