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April 29, 2011

ARDMS Updates and Headlines in the News:

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Ultrasound Shows Promise in Wound Healing

Using Ultrasound First for Appendicitis Could Save over $1 Billion

Ultrasound May Offer Real-Time Ablation Results

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Ultrasound Shows Promise in Wound Healing

New ultrasound devices have shown promise in healing wounds, according to Dr. Jonathan Rosenblum, a podiatrist at Shaare Zedek Medical Center, Jerusalem.

"In the right hands, with the right modality, it could be a sonic boom," he said. He cautioned that "there is no good evidence yet for ultrasound for any aspect of wound care." But in his presentation at the Diabetic Foot Global Conference, he said that many encouraging cases have been reported, along with impressive laboratory research, and that he hopes to launch randomized, controlled trials soon.

Dr. Rosenblum first became interested in the technology when he tried it out on a painful venous ulcer and found that the treatment not only reduced pain but seemed to speed the healing. "With a simple saline dressing and no compression, within 10 days we went from a nasty, sloughy wound bed to a soft epithelial covering," he said at the conference. He has since tried it out on a wide variety of wounds with good success.

“Researchers have experimented with ultrasound therapy using longitudinal, shear, and acoustic waves,”he said. And they’ve tried high and low frequency, and high and low intensity.

Some high-frequency ultrasound devices are being used to treat pain in soft tissue, said Dr. Rosenblum. But they aren’t effective for wound care because the energy isn’t focused on the dermis, he said. "A lot of it is being wasted deeper than you need it, and you’re not getting the effect that you want."

To address that problem several years ago, inventors experimented with low-frequency devices, but these machines were too large to be commercially viable, said Dr. Rosenblum. "They took up whole rooms," he said. "These were 6-foot-tall devices."

More recently, smaller devices have been created using surface acoustic waves, a technology that is also used in some touch screens, he said. It is this technology that looks promising for wound care, said Dr. Rosenblum.

Experiments by John Loike, Ph.D., at Columbia University in New York have shown that the migration of neutrophils and epithelial cells can be significantly influenced by this type of ultrasound waves, said Dr. Rosenblum.  Other researchers have shown increased local uptake of systemic gentamicin in pseudomonas biofilms, increasing the kill rate of the antibiotic.

In addition to fighting pathogens, ultrasound may spur skin growth, said Dr. Rosenblum. "It has been shown effective in all types of collagen synthesis, including cartilage, tendon, [and] skin," he said. And it has shown capacity to reawaken senescent cells, he added.

So how can ultrasound cause these effects? One possibility is the heat generated by the energy from the waves, said Dr. Rosenblum, which could affect various aspects of healing. For example, collagenase is sensitive to temperature.

But heat itself is probably not the whole story, he said. One other possibility is that ultrasound may stimulate cells to produce nitrous oxide. In addition to being a powerful analgesic, ultrasound is a potent vasodilator.

"We came to the conclusion that ultrasound may be beneficial to wound healing," Dr. Rosenblum said . "I’d like to see a couple of good studies that could change that to ‘is beneficial to wound healing.’ "

View the article online

Article written by staff at skinandallergynews.com and adapted for the purposes of this newsletter.

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Using Ultrasound First For Appendicitis Could Save Over $1 Billion

Partially substituting ultrasound for CT in evaluating appendicitis could save the U.S. healthcare system more than $1 billion, according to research presented at the American Institute of Ultrasound in Medicine (AIUM) annual meeting.

Using data from a variety of sources, a Thomas Jefferson University team projected that utilizing ultrasound first for evaluating appendicitis in the U.S. could save $1.2 billion and prevent 174 cancer deaths each year by avoiding radiation exposure from CT scans. The group's proposed protocol would send patients directly to surgery if they have a positive ultrasound study; those with negative results would still receive a CT scan.

While ultrasound has high positive predictive value for appendicitis and provides low cost and no radiation exposure, the modality appears underutilized in this application, said Dr. Levon Nazarian. He presented the research findings on behalf of lead author Laurence Parker, PhD.

The researchers sought to estimate the cost and radiation exposure savings for their proposed appendicitis evaluation protocol. To determine the amount and costs of CT and ultrasound performed to evaluate appendicitis, the researchers used the U.S. Centers for Medicare and Medicaid Services (CMS) 5% Carrier, Inpatient, and Beneficiary files for 2007 and the Physician/Supplier Procedure Summary master files for 2007.

They estimated the national incidence of appendicitis and abdominal pain by examining hospital discharge summaries from the National Center for Health Statistics and the Agency for Healthcare Research and Quality.

The study team also performed a meta-analysis of 74 recent research studies to determine the positive predictive value of ultrasound and CT for evaluating appendicitis. To estimate radiation exposure from an average abdominal and pelvic CT, the authors reviewed 30 consecutive patients from their institution's RIS. They then extrapolated the Biological Effects of Ionizing Radiation (BEIR) VII model to estimate excess cancer deaths due to CT appendicitis evaluation.

From their meta-analysis, the authors estimated that ultrasound's sensitivity and specificity was 87.5% and 92.7%, compared with 93.4% and 95.3% for CT. Ultrasound had a positive predictive value of 91% for appendicitis, 1.5% less than CT's positive predictive value of 92.5%.

In estimating the savings from the proposed ultrasound protocol, the researchers assumed that virtually all of the appendicitis cases had presenting symptoms of right lower quadrant abdominal pain. From the 5% Medicare sample that included 1.8 million beneficiaries, the researchers found that 650 patients had appendicitis admissions, and five of these patients were double-coded, leading to 645 unique patients. These patients received 1,288 CT exams of the abdomen and pelvis.

"There was a ratio of one abdominal and one pelvic CT for every case of appendicitis diagnosed in this country," Nazarian said. "But only less than 4% receive an ultrasound. The cost differences between CT and a limited abdominal ultrasound average [$458.53]."

There were also 863 admissions for right lower quadrant abdominal pain. With 650 cases of appendicitis and 863 diagnoses of abdominal pain in the right lower quadrant, the protocol would result in 1,513 limited ultrasound scans being performed to avoid CT on 569 patients (the result of 650 cases multiplied by 87.5% ultrasound sensitivity).

Imaging cost savings in the 5% Medicare sample would total $177,318 and approximately $3.5 million if extrapolated to the Medicare population as a whole. Based on the estimated discharge survey estimates in the U.S. for appendicitis of 300,000 per year, savings would reach $82.5 million, Nazarian said.

More false positives

Noting, however, that the 1.5% differential in positive predictive value between ultrasound and CT would lead to more false positives and excess surgeries, the researchers also estimated those added costs.

With 300,000 cases, there would be 4,500 unnecessary surgeries each year. Considering an average appendectomy cost of $24,878, the total cost for these 4,500 surgeries would be $112 million.

On face value, that's $28.5 million more than the imaging cost savings from the proposed ultrasound protocol, Nazarian said. There would also be 5.4 excess deaths due to the 0.12% hospital surgery death rate.But radiation exposure savings tilt the advantage back to ultrasound.

From their survey of 30 CT abdominal/pelvic exams at their institution, the researchers estimated the radiation effective dose to be 12.4 ± 5.2 mSv. Based on BEIR VII health risk rates, the ultrasound protocol would eliminate exposure of 3.2 million mSv in the total U.S. population, preventing 174 excess cancer deaths (including the 5.4 added deaths from the excess surgeries).

With the U.S. Environmental Protection Agency's (EPA) estimated value of a human life at $7.4 million, total U.S. savings from preventing these deaths would reach $1.3 billion. Subtracting the added costs from the protocol would lead to a net savings of more than $1.2 billion per year, Nazarian said.

Nazarian acknowledged a number of limitations in their study, including the assumption that it's appropriate to develop estimates for the Medicare population and apply them to the total U.S. population and vice versa.

"I would argue, though, that since appendicitis is so common in younger individuals, you might have more years of life saved [by using ultrasound first] and more cancers that we would induce by doing CTs on the younger population," he said.

In addition, the study assumed that right lower quadrant abdominal pain is the major presenting diagnosis for appendicitis. Also, because excess cancer deaths prevented are not immediate, the researchers need to calculate more precisely the years of life saved, Nazarian said.

View the article online

Article written by staff at auntminnie.com and adapted for the purposes of this newsletter.

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Ultrasound May Offer Real-Time Ablation Results

Contrast-enhanced ultrasound clearly depicts ultrasound ablation of prostate cancer within minutes of the procedure, correlating strongly with biopsy findings and potentially offering interventional radiologists an intraoperative technique to determine whether repeat ablation is necessary, according to a study published in the May issue of Radiology.
 
Transrectal high-intensity focused ultrasound (HIFU) ablation is used to treat localized prostate cancer as an alternative to surgery as well as to treat recurrences following external beam radiotherapy. At present, however, physicians lack a reliable method for delineating devascularized ablated tissue from nonablated viable tissue, leaving physicians with incomplete information regarding responsiveness to treatment.

“We hypothesized that contrast-enhanced US [ultrasound] with use of the sulfur hexafluoride microbubble contrast agent could depict the volume and position of the treated zone as well as the parts of the gland that were not destroyed,” explained Olivier Rouvière, MD, PhD, and co-authors from Hôpital Edouard Herriot, Hospices Civils de Lyon, in Lyon, France.

Rouvière and colleagues sought to assess the use of contrast-enhanced ultrasound to evaluate the viability and devascularization of tissue following HIFU ablation for prostate cancer. The authors compared ultrasound findings, acquired immediately after ablation, one to three days after treatment and 30 to 45 days after treatment with biopsies taken between 30 and 45 days after ablation.

Twenty-eight patients (median Gleason score 6) underwent HIFU prostate ablation followed by ultrasound at one to three and 30 to 45 days after treatment, as well as biopsy. An additional six patients (median Gleason score 6.5) underwent ultrasound between 15 and 30 minutes after ablation as well as one day after ablation.

Contrast-enhanced ultrasound depicted a large devascularized zone with peripheral enhancing areas (indicating viable tissue) localized anteriorly in all 28 patients on one- to three-day and 30- to 45-day post-ablation ultrasound. Peripheral enhancing areas were also visualized at the apex in 20 patients, posteriorly in nine patients and laterally in five patients. Gadolinium-enhanced MRI agreed with these findings.

Sites to undergo biopsy were classified as S0 for no enhancement on ultrasound, S1 for mild and/or patchy enhancement or S2 for market enhancement. Biopsy revealed viable gland tissue in 6 percent of S0-scored sites, increasing to 34 percent for S1 sites and 60 percent for S2 sites.

Odds ratios for biopsying viable tissue at ultrasound-scored S1 and S2 sites, compared with S0 (unenhanced/devascularized) sites were 21 and 73, respectively. The authors reported similar findings for the 15- to 30-minute and one-day post ablation ultrasound results.

“In conclusion, contrast-enhanced US clearly depicts HIFU-induced prostate devascularization within minutes after the end of the treatment, and this capability remains unchanged for at least 30 to 45 days. The observed highly significant correlation between post-HIFU contrast-enhanced US and biopsy findings in the ablated prostate suggests that all tissues with enhancement at contrast-enhanced US should be considered to have a high probability of harboring viable tissue,” Rouvière and colleagues wrote.

“Contrast-enhanced US seems to be a promising method for assessing the extent of ablated (devascularized) and viable (enhancing) tissue immediately after HIFU treatment. In the future, this might enable immediate repeat treatment in cases of incomplete tissue destruction."

View the article online

Article written by staff at healthimaging.com and adapted for the purposes of this newsletter.

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