Contrast-enhanced ultrasound aids diagnosis of kidney cancer

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An enhanced ultrasound scan of the kidney is more accurate than computed tomography and magnetic resonance imaging in predicting cancer.

A 10-year study presented at an international medical conference in Chicago this week contends that such simpler imaging procedures can thus eliminate the need for unnecessary biopsies and surgeries.

The study examined the potential for contrast-enhanced ultrasound, which applies contrast medium to traditional medical sonography. The contrast agents rely on the different ways in which sound waves are reflected from interfaces between substances. Contrast-enhanced ultrasound uses liquid suspensions of biocompatible microbubbles that are injected into a patient's arm vein during an ultrasound scan. The microbubbles reflect ultrasound waves as they flow through the body's microvasculature with red blood cells, and are expelled from the body within minutes.

"Contrast-enhanced ultrasound is a very robust technique with an extremely high predictive value," says Richard Barr, MD, who presented the findings to members of the International Contrast Ultrasound Society. Barr is a professor of radiology at Northeast Ohio Medical University and is a member of the board of directors of the organization, which seeks to advance the appropriate use of contrast-enhanced ultrasound.

In a subgroup of patients initially believed to have a high probability of malignancy, contrast-enhanced ultrasound found that 78 percent of the tumors were actually not malignant, according to Barr. As a result, those patients were spared invasive biopsies or surgery to remove the tumor.

In addition, in another subgroup of patients believed to have a 100 percent chance of malignancy, 38.7 percent of the kidney masses were found to be nonmalignant, and those patients also avoided surgery.

Results were more accurate than either CT or MRI scans, and also ultrasound is less expensive than the other imaging modalities, the researchers indicated.

Barr says contrast-enhanced ultrasound also does not expose patients to ionizing radiation, and the microbubbles present no risk of kidney or liver damage. He also noted that the procedure offers real-time imaging and the opportunity for an immediate assessment of a tumor's blood flow - which in turn indicates whether the tumor is malignant.

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