Current status of power Doppler and color Doppler sonography in the differential diagnosis of lymph node lesions

The use of Power Doppler sonography in nodal diseases provides an improvement of early and noninvasive diagnosis of regional metastatic involvement. By using Power Doppler sonography it is possible to characterize lymph nodes as reactively enlarged, metastases, malignant lymphoma, tuberculosis and to study cervical cysts. The high diagnostic accuracy is based on perfusion–characteristics of these lymph nodes. Reactive lymph nodes show increased central perfusion of the hilum, whereas metastases tend to show increased peripheral perfusion. Affected lymph nodes in patients with by malignant lymphoma are highly perfused in the center but also peripheral. Power Doppler sonography is still not able to discriminate small (<8 mm) nonnecrotic metastasis or micrometastases from reactive lymph nodes. The purpose of this paper is to provide a summary of the current status of power Doppler and Doppler sonography in the differential diagnosis of lymph nodes.