Evaluating Renal Artery Stenosis using MRI Techniques

The following article was written by Z. Jane Wang, M.D., Assistant Professor in Residence in the Department of Radiology and Biomedical Imaging at UCSF.

Narrowing of the arteries supplying the kidneys, known as renal artery stenosis, is the most common potentially reversible cause of high blood pressure and kidney failure in the United States. Early diagnosis of renal artery stenosis is critical to prevent permanent and irreversible kidney damage. Traditionally, blood tests are used to measure kidney function, but this method often diagnoses problems, such as from renal artery stenosis, when it’s too late to correct or reverse damage to the kidney tissue. Imaging plays an essential role in the prompt and accurate detection of renal artery stenosis.

Imaging studies used to diagnose renal artery stenosis include ultrasoundcomputed tomography (CT), and magnetic resonance imaging (MRI). While ultrasound is an effective screening tool for many patients, visualization of the renal artery in its entirety can be difficult. CT and MRI following intravenous injection of contrast material can provide exquisite details of the renal arterial anatomy, and are highly accurate for the diagnosis of renal artery stenosis. However, the use of iodinated contrast for CT or the gadolinium-based contrast for MRI may be problematic for patients already with renal dysfunction. In these patients, the iodinated CT contrast may potentially cause further kidney injury, and the gadolinium-based contrast can lead to a condition called nephrogenic systemic fibrosis (a serious condition that involves fibrosis of the skin, joints, and internal organs.)

The Department of Radiology and Biomedical Imaging at UCSF now offers a new MRI technique called Inhance, which can be used to evaluate arteries, including those supplying the kidneys, without the need for contrast injections. A recently published study compared the performance of this new technique to traditional MRI with contrast injection, and showed that there was good agreement between the two methods for the detection of significant (>50%) renal artery stenosis. The new non-contrast MR technique therefore should prove valuable for evaluating patients with suspected renal artery stenosis who are unable to undergo traditional contrast enhanced MRI.

For more information on Abdominal Imaging at UCSF, please see here.