**6. Doppler studies**

The application of Doppler principles in ultrasound imaging has a long history. Its use in the demonstration of blood vessels and patterns of flow have been copiously reported. Consequently, Doppler studies finds extensive clinical use in assessment of pregnancies, gynecology, cardio-vascular system, neonatalogy, surgery and small parts. The question of whether flow exists or not in a lesion is an important tool in resolving Dilemmas and recognizing or characterizing disease processes. It must be recognized that the increased use of ultrasound in musculo-skeletal imaging relate to the capability and ease of using real-time Doppler US [15]. The amount of flow in the tissue under investigation can be compared with the normal to make diagnosis easy. Doppler is particularly useful when evaluating tumor masses, inflammatory changes related to the joints, tendinopathies and some forms of neuropathies. It is also important when differentiating a ganglionic lesion from sarcoma, and in synovitis [15, 16]. The need to differentiate between acute synovitis (pannus) and chronic fibrotic synovium, is made possible by the demonstration of increased blood flow in the former. In fact, the presence of increased blood flow which is present in proliferating pannus fairly correlates with active joint destruction and symptom development. Consequently, ultrasound can make valuable judgment about the prognosis of active sinovitis and pathological sequel of aggressive and destructive changes in the joint. The deployment of Superb Microvascular Imaging in current studies has improved the resolution and sensitivity compared to conventional methods such as Power Doppler. It is known that superb microvascular Doppler technology allows the operator to detect low-grade inflammation, which was hitherto impossible with Power Doppler. The consequence of early detection of active inflammation, is the prospect of early intervention and impact on treatment outcomes [17].
