The Evolution of Ultrasound Technologies; from Anatomic to Physiologic, Histologic, and Molecular Imaging

Ultrasound imaging has long since been used for visualization of anatomic structures for disease diagnosis and guidance during therapeutic procedures. Benefits of Ultrasound include a lack of ionizing radiation and real-time dynamic imaging. It is also the least expensive, most widely available imaging technology. In gray scale ultrasonic imaging, the signals which form the image result from reflection and scattering of soundwaves where there are differences in the characteristic tissue impedances. Ultrasonography has changed little since the 1970s. Only basic anatomic information is obtained with the modality such as: organ length, cortical thickness, collecting system or ductal dilatation are assessed. Doppler Ultrasound allows assessment of vascular physiology including blood flow velocity, which in addition to anatomic images can be used to determine the hemodynamic physiologic significance of stenosis. Resistive Index (peak systolic velocity end diastolic velocity)/peak systolic velocity) a quantitative measure of blood flow, vascular resistance/compliance, is commonly used in the diagnosis of renal dysfunction [1].