In-vitro validation, with histology, of intravascular ultrasound in renal arteries

Objective To investigate the feasibility of using intravascular ultrasound to characterize normal and diseased renal arteries. Materials and methods Forty-four renal artery specimens from 21 humans, rem oved at autopsy, were studied with intravascular ultrasound in vitro. From each vascular specimen, two to four sets of corresponding intravascular ult rasound images and histologic sections were subjected to qualitative analys is. The renal arterial wall was considered normal by intravascular ultrasou nd when the wall thickness (intima and media) was 0.5 mm or less. On intrav ascular ultrasound imaging, a distinction was made between bright lesions w ith or without peripheral shadowing (i.e. calcification). Histological sect ions were examined and fibromuscular lesions were scored with or without ca lcifications. Quantitative analysis of a multitude of intravascular ultraso und cross-sections (interval 5 mm) included assessment of the lumen area, v essel area, plaque area and percentage area obstructed. The target site (sm allest lumen area) was compared with a reference site (largest lumen area b efore the first major side branch). Results Of the 130 corresponding intravascular ultrasound images and histol ogic sections analysed, 55 were normal and 75 presented a bright lesion on ultrasound; in 31 lesions, peripheral shadowing was involved. The sensitivi ty of the intravascular ultrasound in detecting calcifications was 87%, and the specificity was 89%. Lumen area reduction at the target site was assoc iated with vessel and plaque area enlargement in eight specimens, with plaq ue area enlargement in 12 specimens and with a vessel area reduction in 21 specimens. Conclusions Intravascular ultrasound is a reliable technique for distinguis hing renal arteries with or without a lesion. Both plaque development and l ocal vessel narrowing may result in renal artery stenosis. (C) Lippincott W illiams & Wilkins.