Newsletter #39–Dec. 1996/Jan. 1997
New Ultrasound Device May Boost Diagnostic Accuracy
An new ultrasound application may spare many of the 700,000 women who undergo breast biopsies each year the trauma and expense of a surgical biopsy. In April, the U.S. Food and Drug Administration approved Advanced Technology Laboratories’ HDI (high-definition imaging) digital ultrasound device for evaluation of solid breast masses.
Now, in a 15-minute painless and noninvasive procedure, an experienced radiologist can single out common benign masses with striking accuracy.
Moreover, because it allows the radiologist to see lesions that are obscured by dense tissue, HDI ultrasound may increase the reliability of mammographic screening in premenopausal women who have naturally dense breast tissue.
Quieting the Critics
The impressive results obtained in a 14-center clinical trial of the HDI device may finally bring breast ultrasound more respect and acceptance.
Until now, ultrasound's primary role in breast evaluation has been to differentiate fluid-filled cysts from solid tumors. The images formed with many older-generation ultrasound devices weren’t clear enough to provide much more information than that. By contrast, HDI ultrasound offers precise and detailed images of solid lumps. It’s too early to tell whether it will be as effective in characterizing calcifications or diffused disease.
Researchers tested the technique on nearly 1,000 women who were scheduled for a biopsy because of an abnormal mammogram or palpable mass. Based on the initial mammogram, each woman’s lesion was characterized as benign, probably benign, indeterminate, probably malignant or malignant. The women were then screened with HDI ultrasound, and the investigators reassigned the masses. Finally, the HDI predictions were checked against the biopsy results.
Accuracy Rates Encouraging
The HDI ultrasound technique was 99% accurate in identifying lumps that turned out to be benign. However, the false-positive HDI readings made nailing down a diagnoses of malignant more difficult. Among those lesions assigned to malignant categories, 41% were later found to be benign.
Eva Rubin, M.D., professor of radiology at the University of Alabama at Birmingham, points out that this seemingly high false-positive rate actually represents an improvement over mammography alone. “With mammography, 70% to 90% of biopsied masses turn out to be benign: ultrasound’s 41% false-positive rate cuts that number in half,” says Dr. Rubin, one of the study investigators. “You can double your accuracy in defining breast masses” by using HDI ultrasound to double-check mammography findings, she says.
Ultrasound’s primary advantage is that it allows the radiologist to see the margins of a mass that’s obscured by dense tissue-something mammography doesn’t do well.
Malignant masses tend to have irregular, knobby borders, and they’re often more rounded or taller than they are wide, Dr. Rubin says. Benign masses tend to have smooth borders; the most common kind—fibroadenomasare elongated and parallel to the skin.
The bottom line appears to be that if a solid mass is found via mammography and HDI ultrasound indicates that the mass is benign, a woman can feel safe in watching and waiting, with regular follow-up screening. If HDI ultrasound suggests a malignancy, a biopsy is essential. Even so, if the study’s results hold in real-world experience, the odds are that four of every 10 solid lumps will turn out to be benign.
Low Cost Another Plus
Radiologists estimate that widespread use of HDI ultrasound could decrease the number of breast biopsies performed each year by 40%. The HDI device isn’t a high-dollar item, Dr. Rubin notes, so availability shouldn’t be a problem. (A typical breast ultrasound exam costs between $75 and $300, versus $2,500 to $5,000 for surgical biopsy.)
But just as a mammogram is only as good as the radiologist reading it, the value of these high-resolution images lies in the interpretation. As part of its approval, the FDA is requiring HDI ultrasound's manufacturer to conduct extensive physician training programs.
This article was adapted from the Women’s Health Advocate Newsletter, July 1996.