The Evaluation of Renal Hemodynamics with Doppler Ultrasonography

Gray-scale renal ultrasonography (US) is still performed as a matter of course during the initial evaluation of both native and transplant renal dysfunction. The results, however, often fail to impact on the differential diagnosis or management of renal diseases. Despite major technological advances, gray-scale renal US has remained largely unchanged since the 1970s. It provides only basic anatomical data, such as renal length, cortical thickness, and collecting system dilatation grades. While these may assist in the analysis of disease chronicity, ultrasonographic findings are often normal in spite of the presence of severe renal dysfunction. Clinicians and radiologists are agreed that even the increased renal echogenicity accompanied by renal failure (medical renal disease) requires greater specificity and sensitivity to make it clinically relevant. Collecting system dilatation detection is reliable, though it is not always possible to distinguish between obstructive and non-obstructive pelvicaliectasis on the basis of gray-scale US alone. This purely anatomic approach to renal US, combined with other improved and more economical modalities, has led to nephrologists, internists, and urologists becoming more involved in the field of radiology (Tublin et al., 2003).