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April 1, 2011

ARDMS Updates and Headlines in the News:

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New Ultrasound Technique for Imaging Defects in Babies' Hearts

Elastography Aids in Assessing Axillary Lymph Nodes

Calcium Screening Prompts Patients to Take Action

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New Ultrasound Technique for Imaging Defects in Babies' Hearts

The medical imaging laboratory in Trondheim, Norway, has developed a new ultrasound technique that gives an enhanced ability to discover heart defects in newborns.

Color Doppler imaging has been the standard in ultrasound since the late 1980s. MI Lab’s new ultrasound method, called blood flow imaging (BFI), provides two-dimensional blood flow information by visualizing blood speckle movement superimposed on color Doppler images.

The resulting pattern displays blood flow regardless of the ultrasound beam orientation — providing greater information about flow direction as well as a more intuitive visualization. Blood flow rate can also be measured, and doctors will soon be able to determine the actual volume of blood flowing through normal and pathological openings.

“Making the correct diagnosis is the greatest challenge facing pediatric cardiologists,” explained Siri-Ann Nyrnes, Consultant at the Pediatric Department of St Olav’s Hospital. “The organs are so small, and current ultrasound imaging can only provide limited information. A cardiologist needs many years of experience to be able to make a diagnosis with any certainty.”

In a pilot study, researchers examined 13 children with ventricular septal defect (a hole in the wall between the right and left ventricles of the heart, the most common heart defect in newborns). Using both new and conventional blood flow imaging methods, the researchers concluded that compared to the color Doppler, the new method provides a significantly more detailed image of blood flow.

“The images in this study were created by the physician and technician working together, so the latter could see first-hand what we physicians are contending with, and what we need in order to improve our diagnostics,” said Dr Nyrnes. “The method is being refined with each patient.”

Now MI Lab is taking the method a step further by using plane wave imaging, which can generate an image more quickly. A pilot study of five newborns indicated that plane wave imaging yielded 5-10 times more images per second, with a substantially higher image quality.

“Quantifying the blood flow is our next objective,” said engineer and research fellow Lasse Løvstakken. “Ultimately we want to develop this method to provide blood flow information in 3D.”

View the article online

Article written by staff at mtbeurope.info and adapted for the purposes of this newsletter.

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Elastography Aids in Assessing Axillary Lymph Nodes

Ultrasound elastography can be a valuable adjunct to conventional ultrasound in preoperative assessment of axillary lymph nodes, according to research from the Cambridge Breast Unit in Cambridge, U.K.

In a 50-patient study, the study team found that elastography could reliably demonstrate axillary lymph nodes and differentiate between benign and malignant nodes. When used in conjunction with conventional ultrasound, elastography could also increase sensitivity for identifying abnormal lymph nodes for biopsy, said presenter Kathryn Taylor.

In women with suspected breast cancer, axillary lymph nodes are typically examined using ultrasound with or without core biopsy. But this routine practice carries a significant false-negative rate, Taylor said.

"Up to 30% of nodes appearing as normal node morphology are actually metastatic," Taylor said.

As a result, the researchers sought to compare the use of elastography with conventional ultrasound in the axilla. They aimed to determine if the technique could demonstrate axillary lymph nodes at all, whether it could differentiate benign from malignant nodes, and whether it could -- in conjunction with conventional ultrasound -- increase sensitivity for identifying abnormal lymph nodes.

In the pilot patient cohort, 50 women with sonographically suspicious (BI-RADS category 4 or 5) solid breast lesions received elastography of the ipsilateral axilla at the same time as their conventional ultrasound. Scans were performed using a Sonix SP scanner (Ultrasonix Medical) with an 8- to 16-MHz transducer and a frame rate of more than 10 frames per second. The patients had an age range of 27 to 88 years, with a mean age of 57.

The researchers utilized Cambridge University's own Stradwin software, which displays elastograms in grayscale alongside the conventional ultrasound studies. A black color display denotes stiff tissue, while white represents soft tissue.

Conventional ultrasound studies were scored using standard criteria, while the elastography studies were visually scored in retrospective fashion as 1 (normal), 2 (benign), 3 (suspicious), or 4 (malignant). A score of 1 indicated that the node tissue was indistinguishable from surrounding tissue, while a score of 2 indicated there was an incomplete or complete rim on the outside of the node.

A score of 3 was given if more than 50% of the node was displayed as black (or stiff) on the software, and a score of 4 meant that the tissue was shown as completely black. The researchers set a theoretical cut-point for biopsy between scores 2 and 3.

The researchers then compared the elastography results with the conventional ultrasound findings and the reference standard of surgical histology.

Of the 50 patients, 21 (42%) had metastatic axillary lymph nodes, while 29 (58%) had normal nodes.

In the 23 studies that were reviewed as positive on conventional ultrasound, 19 were also positive on elastography. Of the 19 that were also positive on elastography, 15 were ultimately confirmed positive on histology, Taylor said. An additional four positive results were found on elastography alone.

Four of the studies reported as positive on conventional ultrasound were negative on elastography. Three of these negative results were also negative on histology, while one negative was ultimately positive on histology.

On elastography, 23 patients had negative results that were ultimately confirmed to be negative on histology. One was a false negative, however.

"We need to remember in this scenario [that] unlike elastography of breast lesions where we are in principle more interested in specificity than sensitivity since we don't want to perform unnecessary benign biopsies, in the axilla, within reason, we are more interested in sensitivity," Taylor said.

At the expense of lower specificity, higher sensitivity could also be achieved if the elastography cut-point for biopsy was changed to be between BI-RADS score 1 and score 2, according to Taylor.

"In practical terms, [this] would make it a very easy decision whether or not to biopsy, because we would then be biopsying basically anything in the node area that looks stiff, “Taylor said. "That would actually give us sensitivity of 100% and specificity -- still acceptable -- of 66%."

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

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Calcium Screening Prompts Patients to Take Action

Patients who get their coronary calcium scores take steps to reduce their heart disease risk factors more often than those who don't get the scan, researchers say.

Scanned patients had significantly better improvements in several risk factors, including systolic blood pressure, LDL cholesterol, and waist circumference, Daniel Berman, MD, of Cedars-Sinai Medical Center in Los Angeles, and colleagues reported in the Journal of the American College of Cardiology.

"Patients who knew their coronary calcium scores improved their coronary heart disease risk compared with those with no scan, and those with high calcium scores were motivated to take even more aggressive steps to reduce their risk," Berman said in a statement.

In addition, these patients had no increased medical procedure costs during four years of follow-up compared with those who weren't scanned, although their drug costs did tend to be higher, the researchers said.

It's well-established that calcium screening predicts cardiac events, but its impact on subsequent medical management and coronary artery disease risk is not known.

So researchers at Cedars-Sinai conducted the Early Identification of Subclinical Atherosclerosis by Noninvasive Imaging Research (EISNER) trial in 2,137 patients with coronary artery disease risk factors but no history of heart disease. Of those, 1,424 had a coronary artery calcium scan, while the remaining 713 didn't get the scan.

All participants were followed for four years, and the primary endpoint was change in coronary artery disease risk factors and Framingham Risk Score at that time.

The researchers found that those who were scanned had significantly better improvements in systolic blood pressure (P=0.02), LDL cholesterol (P=0.04), and waist circumference among those with increased abdominal girth (P=0.01).

There was also a trend toward weight loss in overweight patients, although it wasn't significant.

There were no differences between the groups with respect to HDL cholesterol, triglycerides, glucose levels, smoking cessation, and new exercise activity.

In terms of Framingham Risk Score, there was a mean rise among those who didn't get scanned, but risk score remained static among those who were scanned, the researchers said.

They also found, in the scanned group, an inverse relationship between increasing baseline coronary calcium scores and systolic and diastolic blood pressure (P<0.001), total cholesterol (P<0.001), LDL cholesterol (P<0.001), triglycerides (P<0.001), weight (P<0.001), and Framingham Risk Score (P=0.003).

Subsequent medical testing and costs were comparable between groups.

There were no differences in four-year utilization of stress tests, carotid ultrasound studies, noninvasive and invasive coronary angiogram studies, and revascularization procedures, the researchers said, and overall medical procedure costs were comparable.

Yet drug costs tended to be higher in the scan group, likely due to the fact that more scan subjects were started on antihypertensives and lipid-lowering medications.

Though there were no differences in rates of myocardial infarction or fatal events, the researchers said overall rates were low and thus the study was underpowered statistically to adequately address this question.

They noted that the study was limited in general liability because patients were highly educated, fairly affluent, and were all motivated to volunteer for the study.

Still, they said that the results "are consistent with the hypothesis that coronary artery calcium scanning can improve cardiac management without incurring significant increase in downstream medical costs."

They called for further study of calcium scanning, including pre-specified treatment recommendations, to assess its impact on cardiovascular outcomes.

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

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