Strategies could lead way to a better grip on ultrasound

October 5, 2005

Today's log at the imaging center shows 15 patients scheduled for different examinations. Most come with abdominal or musculoskeletal symptoms, and almost half of them are overweight. The daytime sonographer called in sick earlier, so the radiologist needs to make a tough call: Does she perform 15 ultrasound exams herself or does she shuttle everyone through to any of the CT or MR scanners available?

Today's log at the imaging center shows 15 patients scheduled for different examinations. Most come with abdominal or musculoskeletal symptoms, and almost half of them are overweight. The daytime sonographer called in sick earlier, so the radiologist needs to make a tough call: Does she perform 15 ultrasound exams herself or does she shuttle everyone through to any of the CT or MR scanners available?

Tough call? No-brainer. The patients troop off to the CT and MR scanners.

Ultrasound has gradually been losing its place as an imaging modality in radiology departments. Despite technological enhancements that include more powerful probes and 3D imaging, ultrasound remains dependent on highly trained technicians to produce useful studies. Sonologists also cite the failure to apply advances that could make examinations more reproducible and streamlined and, therefore, more competitive.

A number of factors not directly dependent on ultrasound compound these shortcomings. Lack of approval for contrast agents for uses beyond echocardiography, the increasing obesity of the U.S. population, and a preference for other modalities have together gradually undermined ultrasound's use among radiologists. Its practitioners fear further deterioration of ultrasound education, and many also see greater competition from nonradiologists who use ultrasound in their routine clinical practice.

"Colleagues around the world are doing ultrasound diagnosis using contrast agents and saving lives, while here in the U.S. we can't use them. This is having a negative impact on diagnosis and treatment," said Dr. Barry Goldberg, director of the diagnostic ultrasound division at Thomas Jefferson University Hospital's radiology department. "It's sad to say, but the U.S. went from being the leader in ultrasound contrast research to falling several steps behind."

Some factors are obviously beyond physicians' control, but if radiologists are to maintain their position as providers of ultrasound interpretations, they need to improve in a number of ways. Ultrasound examinations must provide higher image quality and a wider coverage of the anatomy, according to Dr. Brian Garra, clinical director of ultrasound at the University of Vermont College of Medicine. Physicians across the nation should have the ability to replicate easily and uniformly certain techniques and the information these techniques can produce.

Another step would be better compliance with the standards set forth by the American Institute of Ultrasound in Medicine and the American College of Radiology. Radiologists could gain a new base of patients if they were able to offer advanced screening tests as recommended by the AIUM and the ACR.

IMPENDING CHALLENGES

The lack of contrast agents is no small setback. A mounting body of clinical literature shows that contrast agents can improve the detection and staging of tumors in the liver, and could potentially help guide interventions such as radiofrequency ablation or chemoembolization. Contrast agents could also help evaluate the performance of new cancer treatments such as angiogenesis agents, Goldberg said.

"If the FDA were more cooperative, we would be out of the research stage by now and performing contrast studies at the level seen in Canada, Europe, and Japan. Even emerging countries like China are actively using ultrasound contrast agents," he said.

The obesity epidemic in the U.S. population doesn't help. Body habitus can keep certain patients not only from ultrasound but from CT and MRI as well. Wider CT gantries and open magnet technology, however, can overcome some of obesity's challenges in those modalities. A study by Dr. Raul Uppot and colleagues at Massachusetts General Hospital found that obesity has significantly affected the ability of radiology departments to provide image interpretations, and ultrasound bears the brunt. Almost 2% of patients referred for ultrasound examinations cannot have the test or must be scanned with a different modality. Investigators presented their findings at the 2004 RSNA meeting.

The preference for higher paying modalities like CT, MRI, or PET has gradually undermined ultrasound's use among radiologists. Reimbursement for imaging-related procedures increased 30% between 2000 and 2003, according to Medicare data. Even though most procedures showed only slight increases in utilization, a few individual studies relying on higher end imaging-like pelvic CT-increased more than 40%.

Ultrasound utilization has remained steady for the past several years, and the field has been dominated by radiologists, cardiologists, and ob/gyn physicians. But new trends indicate that an increasing number of emergency physicians, internists, and other clinicians are using ultrasound as well.

"It is now quite common to find radiology residents who have no interest in ultrasound, who cannot themselves scan or interpret the examinations. They are very honest and simply state they are interested only in CT or MRI," said Dr. Michael Blaivas, chief of emergency ultrasound at the Medical College of Georgia in Augusta.

Good ultrasound requires dedication and, in many cases, more after-hours work. To complicate matters, sonographers increasingly refuse to work the night shift. The trend might be reversed by improved reimbursement compared with other imaging modalities. But reality dictates that as long as so-called easy-to-perform tests are available to radiologists and other specialists, U.S. physicians will never make full use of ultrasound the way their colleagues do in Europe, Asia, and Latin America, Blaivas said.

"That awareness will come only if suddenly there are only two CT scanners in a small city rather than 22. I am not sure cost-cutting and resource streamlining is ever going to happen, but from a patient advocate standpoint, someone needs to be available to perform ultrasound on a 24-hour basis, on short notice, and perform it well," Blaivas said. "Whether that is a radiologist or a clinician, it does not really matter. Someone needs to do it, and the clinician is in the best position by being at the patient's bedside."

Expert sonologists doubt this kind of competition could eliminate the need for radiologists. Current referral patterns suggest nonradiologists might take increasing control of simpler examinations but would send patients for more complex, specialized ultrasound imaging with radiologists.

"We get many referrals from general and family physicians and internists, who send people to us for second opinion. I'm convinced that a degree of excellence keeps volume up," Goldberg said.

Such a degree of excellence, however, can come only through reawakening awareness and interest in ultrasound. Sonologists worry that ultrasound practitioners-inside and outside radiology-are increasingly less educated. Some even fear that the RSNA might eliminate ultrasound permanently as a separate scientific category from its annual meeting program. Such a move could contribute to the further decline of ultrasound in radiology residency programs and to the alarming drop in the number of ultrasound fellowships taken each year.

"Many of the studies that are done in specific areas of ultrasound won't fit in other categories," said Dr. Carol B. Benson, director of ultrasound at Brigham and Women's Hospital in Boston. "If ultrasound were discontinued as a separate category, it would be a great disservice to the educational component of the RSNA program. It would be a really bad thing for the quality of research and advancement of ultrasound and for the training of radiology residents."

If sonologists' fears materialize, many important aspects of ultrasound could eventually fall through the cracks, discouraging radiology researchers and clinicians from doing serious work with ultrasound. This would encourage radiologists to jump to CT or MR whenever they have a simple question, according to Benson.

"Ultrasound technology is improving every year, so we get better and better. But the RSNA does not support this," she said.

BEST PRACTICES

Using new technologies and some ingenuity, some leading sonologists are making ultrasound interpretations more intuitive, accurate, and cost-effective. These researchers and practitioners argue that the new ways could bring excitement about ultrasound back to radiology. Most important, they think these practices could help radiologists retain a larger chunk of the increasingly competitive ultrasound imaging pie-but only if they use them. Several papers and discussions outline specific tools and strategies:

- Compound imaging. Also known as speckle reduction, compound imaging works by combining several different angles of insonation to produce a single image. Directing the ultrasound beam in this way increases dramatically the signal-to-noise ratio and reduces speckle, said Dr. Levon Nazarian, a professor of radiology and vice chair for education at Thomas Jefferson University Hospital. In a range of clinical settings as diverse as musculoskeletal, abdominal, and pelvic imaging, compound sonography has reduced artifacts and enhanced sensitivity and specificity in real-time examinations (Lin, Nazarian, et al. AJR 2002;179[6]:1629-1631; Oktar et al. AJR 2003;181[5]: 1341-1347).

- Tissue harmonic imaging. Harmonic imaging is another useful technique for improving image quality. The latest generation of ultrasound probes can operate with frequencies beyond 10 MHz to 50 MHz, producing images of superior resolution, but at the cost of a lessened tissue beam penetration. Harmonic imaging works on the physics principle that an object struck by a sound beam resonates at double the frequency of the initial beam. Sonologists thus rely on standard frequencies and use harmonic imaging to double the signal return. Tissue harmonics can be combined with other ultrasound techniques. A number of researchers have obtained promising results combining it with the use of contrast materials, though the FDA has restricted these to the lab.

"The use of contrast and harmonic imaging helps us clear up suspicious areas in the kidneys, such as cysts," said Dr. Arthur Fleischer, a professor of radiology and ob/gyn at Vanderbilt University. "When we get contrast agents approved, we will use harmonics to look at specific agents and applications."

- PACS, radiology information systems, and structured reporting. Integrated or separately, PACS and RIS allow physicians to save, transmit, reconstruct, and process ultrasound images while automatically merging data from corresponding clinical records in a filmless environment. The use of structured reports relying on language both simple and specific to the application can render the interpretation process more efficient. Overhead costs associated with processing, storing, and managing files, as well as time-consuming, error-prone administrative tasks, would be eliminated, said Joe Darby, chief technologist at Thomas Jefferson University.

"By improving scheduling in an automated way, for instance, we have seen some increase in throughput. Mistakes such as double appointments take slots that can never be retrieved. We are looking at technology to handle scheduling now," he said.

- Volumetric imaging. Several 3D-based applications have been making intriguing headlines. Champions of these applications state they could change ultrasound's reputation as an operator-dependent, time-consuming modality. In theory, sonologists could sweep the area of interest using the latest 3D probe technology, producing images of diagnostic quality much in the way CT or MRI operate. Patients could be scanned in a fraction of the time required by a standard ultrasound examination. Researchers from Harvard University, who implemented the concept recently, have reported credible and promising results (Benacerraf et al. J Ultrasound Med 2005;24:371-378).

- Ultrasound screening. A number of screening initiatives have been advanced by collegial clinical organizations. The federal government's recommendation earlier this year, for instance, that male smokers and former smokers 65 to 75 years of age receive abdominal aortic aneurysm screening, though somewhat restrictive, was highly praised. Protocols are also in place for screening of the carotid arteries and peripheral vascular disease. All of these screenings can be performed cheaply, quickly, and noninvasively using ultrasound. But if radiologists want to be a part of these initiatives, they need to act quickly.

"Screening is going to open a can of worms. There are clinical organizations that have already started it. If reimbursement is approved for a legitimate screening exam, we will need to have some control over the way is going to happen," said Dr. Teresita L. Angtuaco, a professor of radiology and chief of ultrasound at the University of Arkansas.

- Accreditation. The word is that accreditation provides the seal of approval to practice standards and helps ultrasound practitioners enhance their clinical performance. A multicenter study sponsored by the AIUM compared the original accreditation and reaccreditation scores of a group of practices over three years. It also compared the results against first-time accreditation applicants and found that practices that received accreditation significantly improved their scores the second time around (Abuhamad et al. J Ultrasound Med 2004;23:1023-1029).

SPREADING THE WORD

Sonologists are standing up for improved standards in ultrasound education. They stress the importance of keeping residency rotations in ultrasound, CT, and MRI to the same or equivalent levels. They are even willing to take ultrasound education somewhere else.

"Residency programs do not emphasize ultrasound, and most residents get out without the training they need," Angtuaco said.

Angtuaco and colleagues are evaluating the impact of ultrasound education in medical school. Among other things, they will study whether compact ultrasound systems can enhance the clinical skills of medical students, become a useful adjunct to the physical examinations they perform in patients, and help eliminate its operator dependency. They planned to report their preliminary findings at the Society of Radiologists in Ultrasound meeting this month.

"People without specific training are getting ultrasound machines. I don't know whether that is going to increase utilization in general. Some people even think that ultrasound is going to be the stethoscope of the future. We are testing that," she said.

Several other research groups are testing the waters as well. Dr. David Bahner and colleagues at Ohio State University compared the ultrasound skills of medical students who had extracurricular exposure to diagnostic ultrasound with those who had limited experience or none. They surveyed 37 students who had enrolled in an extracurricular course that exposed first-year students to diagnostic ultrasound and 166 students who did not take the course. The 37 who had specialized education performed several diagnostic ultrasound tests more confidently than those who had not. The investigators presented their results at the American Institute of Ultrasound in Medicine meeting in June.

An increasing number of sonologists and researchers advocate exploring new ideas and applications to boost ultrasound utilization and its presence (see accompanying article). Dr. Robert Harris, director of ultrasound at Darthmouth's Hitchcock Medical Center, and colleagues successfully transmitted ultrasound images from Serbia to the U.S. over standard phone lines. The investigators proved that ultrasound imaging and interpretation can be taken to remote or underdeveloped areas of the world that lack sonologists-even sonographers-using simple, compact equipment.

Despite a sometimes gloomy outlook, many sonologists remain positive about ultrasound's future in radiology. They declare that the technical means to make examinations more accurate, reproducible, and efficient already exist. The rest, they say, should take time, effort, a change of attitude toward the modality, and collaboration among peers. Even nonradiologists believe it would be worrisome if radiologists got out of the business of doing ultrasound. They think radiologists' expertise is simply superior and that specialists still have things to teach to the clinicians using the modality.

"The more people use ultrasound, the more interesting my world is, and the better-served patients are," Blaivas said.

Mr. Abella is an assistant editor of Diagnostic Imaging.