[Imaging of vascular complications of renal transplantation]

The accuracy of color Doppler US (CDUS) for the detection of main renal transplant artery stenoses is excellent (Se 92%; SP 99%). Whereas the sensitivity of CDUS is still unsatisfactory for the detection of arterial branch stenosis (Se 70%), it has become higher than previously reported because of the ability of color flow images to identify hemodynamic changes at the site of stenosis and focal downstream repercussions in the case of tight stenosis. Color Doppler US is a valuable method in the detection of segmental infarction or large areas of cortical necrosis. However, small superficial cortical perfusion defects are usually undetectable by color Doppler. Contrast-enhanced MRI appears to be more accurate than color Doppler US; it is useful in confirming the diagnosis of infarction and detecting small infarcts missed by color Doppler US, and provides an accurate evaluation of the extent of the infarct; Spectral features (reflux during the whole diastole) obtained from renal arteries in case of acute renal vein thrombosis are suggestive but not specific since they can be observed in the case of severe acute rejection with cortical necrosis. Such findings associated with a lack of venous Doppler signals in the whole kidney are highly suggestive of renal transplant vein thrombosis. Post-biopsy arteriovenous fistulas and false arterial aneurysms are accurately detected by color Doppler Imaging. Color Doppler appears to be the primary Imaging modality for early detection of renal allograft vascular complications.(ABSTRACT TRUNCATED AT 250 WORDS)