In 21 recipients of renal transplants suspected of allograft necrosis, the authors correlated the results of imaging to pathologic and histologic data in order to describe the magnetic resonance (MR) imaging and color Doppler ultrasonographic (US) characteristics of infarction. All patients underwent MR imaging performed with and without gadolinium tetraazacyclododecanetetraacetic acid (DOTA) and color Doppler US. Nonenhanced T1-weighted images showed no obvious changes, whereas nonenhanced T2-weighted images demonstrated a slight increase in signal intensity in areas of ischemic necrosis and low or heterogeneous signal intensity in areas of hemorrhagic necrosis. Gd-DOTA-enhanced MR images showed no contrast material uptake in infarcted areas. Color Doppler US characteristics of infarction included absence of Doppler signal and alteration of the cortical echogenic structure, particularly in cases of ischemic necrosis. Color Doppler US allows measurement of vascular resistance and assessment of intrarenal vasculature and the renal pedicle. Gd-DOTA-enhanced MR imaging is useful in confirming the diagnosis of infarction and provides an accurate evaluation of the extent of the infarct.

We report the results of a prospective study about the detection of tumoral neovascularization, the renal vein involvement and the characterization of renal tumors by color and pulsed doppler. Twenty-six renal tumors including 19 renal carcinomas and 7 benign tumors (2 angiomyolipomas, 2 oncocytomas, 2 complex cysts and one adenoma) were prospectively explored. Benign cysts were excluded from the study. The results were correlated to pathologic (24/26) and angiographic datas (24/26). Doppler ultrasonography seems to be an accurate method for the detection of a neovascularization (19 true-positives/19 vascularised tumors, no false-positive) but pulsed doppler (no false-negative) is more sensitive than color doppler imaging (3 false-negatives), the results of color doppler were improved by using a new software for the color detection of very low flow. Spectral analysis found 3 different types of doppler curves inside the masses, but all of them were observed in benign and malignant tumors. We did not find any correlation between the size of the tumor and the peak systolic velocity. The specificity of Doppler regarding the renal vein and inferior vena cava involvement seems to be good (no false-positive). But as, in our series, we do not have any case of main renal vein involvement, the sensitivity of this technique cannot be assessed.