- Category: Press Releases
- 27 September 2011
CHICAGO, IL – Abdominal cancers may be detected sooner, with more specificity, and without exposing patients to ionizing radiation using a simple “contrast-enhanced ultrasound” (CEUS) scan, according to preliminary results of a new Canadian study.
“This readily available ultrasound tool can replace some CT scans, allowing us to accurately diagnose these cancers without radiation and at a significantly lower cost,” according to Dr. Stephanie Wilson, Professor of Radiology at the University of Calgary and a practicing radiologist at Foothills Medical Center in Calgary. Wilson described her work at the 26th annual Advances in Contrast Ultrasound conference in Chicago.
By comparison, expensive “big box” imaging tools like CT, PET and SPECT (nuclear) imaging all expose patients to ionizing radiation, which can increase an individual’s lifetime risk of cancer, according to Wilson.
One patient in the Canadian study was a 42-year-old man with acute flank pain and a high creatinine, according to Wilson. The patient could not tolerate a CT contrast agent, and a non- enhanced CT showed a mass suggesting a spontaneous retroperitoneal hematoma. A subsequent CEUS scan showed aggressive infiltrative kidney cancer.
“He should have had CEUS from the beginning,” Wilson said.
Another patient was a 32-year-old man who had pain after jogging. CEUS found a mass in his bladder and allowed physicians to characterize it as transitional cell carcinoma, which was missed on an earlier non-enhanced CT scan performed under a protocol specifically aimed at finding stones in the kidneys, ureters or bladder.
“Fortunately, because of CEUS, this young man’s cancer was promptly treated,” Wilson said.
Wilson said that CEUS is an “excellent tool” for detecting cancers of the kidney, liver, bladder, spleen, bowel and gall bladder, and for helping physicians differentiate between malignant and benign tumors.
CEUS uses a special ultrasound contrast agent to improve the clarity and accuracy of a standard ultrasound image. The ultrasound contrast agent is injected into the patient’s arm vein during the ultrasound exam and is metabolised and expelled from the body within minutes, according to Wilson. No ionizing radiation is used in standard ultrasound or CEUS, and ultrasound contrast agents do not contain the type of dye that can damage kidneys or other organs, she said.
CT scans generally are performed with the use of intravenously-injected CT contrast agents -- substances that, unlike ultrasound contrast agents, may damage kidneys. Therefore, in patients with compromised kidney function or prior allergy, CT scans are performed “dry” -- that is, without the benefit of these agents.
“This produces an inferior CT scan that does not detect many tumors, especially those that may be growing in the abdominal solid organs such as the kidney or liver,” according to Wilson. “And if a non-enhanced CT scan does detect a tumor, it will not permit a definitive diagnosis. For this reason, CEUS may make a significant contribution to patient management.”
Wilson said her team compared CEUS to non-enhanced CT because many patients cannot tolerate CT contrast agents. However, she said that based on her experience, CEUS also may be superior to contrast-enhanced CT because of CEUS’ diagnostic accuracy, lack of ionizing radiation, and significantly lower cost.
According to preliminary results of the study, based on results in 117 patients to date:
- In 72 patients with liver masses, CEUS allowed physicians to confidently identify and characterize all of the masses while non-enhanced CT missed part or all of the mass (32), or failed to allow physicians to confidently characterize the mass (40).
- In 35 patients with kidney masses, CEUS showed the masses to be either vascular or avascular (indicating the presence of cancer). Non-enhanced CT showed 30 of those masses but did not permit confident characterization of any of them.
- CT was marginally superior in imaging the retroperitoneum and was superior in the bones, where ultrasound is not useful.
Wilson recommended CEUS as an alternative to non-enhanced CT unless the patient has a high likelihood of bone disease or retroperitoneal disease.
According to Wilson, “CEUS may be an ideal imaging tool that can provide a safe and cost- effective alternative to CT, MRI, PET and SPECT (nuclear) scans. While these imaging tools are sometimes useful, CEUS is much less expensive and often provides equivalent if not superior diagnostic accuracy without any ionizing radiation whatsoever, and without risk of damaging kidneys or other organ systems.”
CEUS imaging is FDA-approved in the United States for certain types of cardiac imaging, but CEUS is approved and routinely used in Europe, Canada, Asia and Brazil for pinpointing disease and tumors in other parts of the body as well. Ultrasound contrast agents may be used for unapproved indications with patient consent, according to Wilson.
"Since ultrasound contrast agents circulate throughout the bloodstream, you can really image almost any part of the body -- depending on where you place the transducer," according to Dr. Steven Feinstein, a cardiologist at Rush University Medical Center in Chicago. Feinstein is director of the annual CEUS conference in Chicago and is Co-president of the International Contrast Ultrasound Society (ICUS), the only international and inter-disciplinary medical society exclusively devoted to CEUS imaging. ICUS has members in 58 countries, including cardiologists, radiologists, gastroenterologists, vascular medicine specialists, and other medical imaging professionals and scientists.
Feinstein uses CEUS to evaluate heart disease and, with patient consent, to detect plaque in neck arteries that may place patients at risk of stroke.
“The United States is actually behind the rest of the world when it comes to using CEUS,” according to Dr. Barry Goldberg, Co-president of ICUS and director of the Division of Diagnostic Ultrasound at Thomas Jefferson University Hospital in Philadelphia. Goldberg also is past president of national and international radiology societies.
“CEUS is cheaper, better, safer, and can avoid riskier and more expensive downstream tests,” according to Feinstein. “Also, since ultrasound equipment can be moved to the patient, CEUS offers immediate, real time diagnoses right at the bedside, which can be crucial when caring for critically ill patients who cannot be moved to an MRI or CT machine and cannot wait for a diagnosis.”
“Contrast-enhanced ultrasound is clearly a bargain compared to CT and MR,” according to Wilson, who said that the cost impact of imaging procedures has “never been more important than it is today.”
Nevertheless, according to Wilson, “reimbursement of CEUS is not yet competitive with CT and MRI, so the financial incentives have not caught up with all of the science that now shows very clearly the incredible benefits to patients and the safety of this very important diagnostic tool.”
Earlier work by Wilson showed that CEUS can be useful in assessing chronic gastro-intestinal disorders such as inflammatory bowel disease (IBD), which often afflicts young people and can require monitoring throughout life. CEUS may avoid the need for repeat CT scans, thereby reducing exposure to ionizing radiation over these young patients’ lifetimes.
The FDA-approved cardiac agents are Definity (sold by Lantheus Medical Imaging) and Optison (sold by GE Healthcare). They and two additional ultrasound contrast agents -- Sonovue (sold by Bracco) and Sonozoid (sold by GE Healthcare) -- are approved outside the United States for a variety of imaging applications.