[Ultrasound evaluation of characteristics of cervical lymph nodes with special reference to color Doppler ultrasound. A contribution to differentiating reactive from metastatic lymph node involvement in the neck].

BACKGROUND: Cervical mass due to lymphadenopathy is a common cause for consultation of an ENT specialist by patients. In many cases exact differentiation without biopsy between reactive and metastatic lymphnodes is difficult but crucial and necessary for each patient. Ultrasound is the imaging system with the highest sensitivity for the evaluation of pathological lymph nodes. However, differentiating benign and malignant lesions remains a problem.

PATIENTS: In a prospective study, 138 cervical lymph nodes of 62 patients were evaluated according to conventional ultrasound criteria such as size, shape, brightness, demarcation, etc., and according to parameters of color doppler sonography such as intensity and localization of perfusion. The so called Pourcelot or resistance index, an objective parameter, was measured in order to examine a possible improvement of specificity in differential diagnosis of both entities. All lymph nodes were surgically removed and histologically examined after ultrasonography.

RESULTS: 133 lymph nodes were evaluated in the study. Lymphadenitis was demonstrated in 72 cases, whereas 61 of the lumps showed metastases of squamous cell carcinoma of the head and neck region. Three patients with primary malignant lymphoma were excluded from the study. The conventional ultrasound parameters such as size, homogenity, shape and brightness did not reveal any substantial difference between the two groups. However, lymph node metastases significantly showed higher Doppler signals than the reactive ones. Most of the metastases were perfused in the periphery or had a diffuse spread of blood flow. The most valuable parameter from the prognostical point of view proved to be the Pourcelot Index with a threshold value less than 0.6 for metastases, which increased the specificity to 92% with a probability of p = 0.001.

CONCLUSIONS: The results of this study demonstrate an increase of the ultrasound specificity in differentiation of pathological cervical lymph nodes using color flow imaging. Unfortunately, this method does not enable the physician to correctly diagnose the findings in all patients. Therefore histological evaluation is mandatory in all doubtful cases.