Intravascular ultrasound assessment of the renal artery

Objective: To determine the feasibility and diagnostic value of catheter-based intravascular ultrasound imaging compared with angiography for visualizing renal artery structure. Design: Renal artery images were obtained in patients with renal artery stenosis having percutaneous balloon angioplasty and in normal subjects by digital angiography and by a 20-MHz, mechanically driven, catheter-based, intravascular ultrasound imaging system. Setting: A referral-based university hospital. Patients: Four randomly selected normal subjects without known renal disease and four consecutive patients with known renal artery stenosis referred for percutaneous balloon angioplasty. Interventions: Digital angiograms and intravascular ultrasound images of nine renal artery segments were obtained. In patients with renal artery stenosis, imaging was done before and after balloon angioplasty. Main Results: Digital angiography and ultrasonography correlated closely in the determination of arterial lumen diameter (r = 0.81) and cross-sectional area (r = 0.83). However, ultrasonography provided structural information not shown by angiography. All normal arteries showed discrete intimai, medial, and adventitial wall layers by ultrasonography. In the five stenotic segments, angiography identified the cause of stenosis to be atherosclerosis in four patients and fibromuscular dysplasia in one patient. Ultrasound imaging, however, identified the disease process as atherosclerosis in three patients and as fibromuscular dysplasia in two patients. After renal angioplasty, ultrasonography identified three arterial dissections, only one of which was shown by angiography. Conclusions: These preliminary data indicate that catheter-based intravascular ultrasound imaging of the renal artery is feasible and correlates well with angiography in assessing renal artery size and also provides potentially important additional structural information that permits a better characterization of arterial pathology.