We developed a new quantitative concept in dynamic renal transplant imaging, the Trend Distribution Ratio, and tested its diagnostic usefulness in 137 examinations. This ratio is an expression of the distribution of blood flow velocity in different areas of the kidney. With regard to the differential diagnosis between acute tubular necrosis and the various forms of rejection we arrived at a sensitivity of 0.83 and a specificity of 0.54. A differentiation between the various histological types of rejection has not yet been possible.