Comparison of Duplex sonography and color Doppler imaging in renal allograft evaluation: a prospective study

A prospective study compared the diagnostic capability of quantitative Duplex sonography (DS) and color Doppler imaging (CDI) in 49 consecutive patients with 50 renal allografts. Sixty five DS examinations and 65 CDI examinations were performed by two independent investigators on two different machines on the same day. The resistive index (RI) was calculated and the color flow of renal arteries was observed up to the arcuate arteries. There was good correlation of RI values obtained by DS and CDI at all vascular sites. Thirty one allografts were functioning stably and 19 were in a state of dysfunction, defined by histology (n = 17). Forty allografts presented with a RI < 0.9 and normal color flow. All five allografts with a pathologic RI 0.9 showed abnormal color flow (missing flow in arcuate and/or interlobar arteries). Five allografts had a RI < 0.9 but abnormal color flow, possibly due to atrial fibrillation, hypertension, heart failure or a combination of these. A normal color flow pattern excludes severe vascular compromise to the allograft. In addition, CDI revealed three biopsy-related vascular lesions; two of them had been missed by DS.