Radiologists look over their shoulders, knees, and hips

April 1, 2005

Specialists such as rheumatologists, physiatrists, sports medicine physicians, and orthopedic surgeons increasingly use ultrasound in their clinical practices. But most radiologists find reassurance in their firm grip on musculoskeletal MR imaging. A number of them fear, however, that in forfeiting musculoskeletal ultrasound they risk losing musculoskeletal imaging altogether.

Specialists such as rheumatologists, physiatrists, sports medicine physicians, and orthopedic surgeons increasingly use ultrasound in their clinical practices. But most radiologists find reassurance in their firm grip on musculoskeletal MR imaging. A number of them fear, however, that in forfeiting musculoskeletal ultrasound they risk losing musculoskeletal imaging altogether.

Radiologists still control musculoskeletal ultrasound, but their share is rapidly declining, according to Dr. Levon Nazarian, chief of musculoskeletal ultrasound at Thomas Jefferson University Hospital, and other leading researchers in the field who spoke at the last RSNA meeting.

The main culprit may not be encroachment by other specialties as much as growing radiologist complacency.

"Disinterest is the prevailing attitude among radiologists right now," Nazarian said. "But when I lecture nonradiologists on this modality, they listen from the edge of their seats. The level of interest in this modality is far greater among the clinical physicians than it is among radiologists."

Some observers contend that the labor shortage affecting radiology in recent years has put time and resources at a premium. Citing ultrasound's main disadvantage-operator dependency-they think it makes practical sense to favor modalities that do not require such extensive technologist training.

The issue is a thorny one. While radiologists should take stronger possession of musculoskeletal ultrasound, patients need to benefit from it regardless of who conducts the examination, Nazarian said.

"I didn't work for 10 years helping to develop this field for nothing, just to see it die. The patients deserve the best care. If others outside radiology want to get their own ultrasound machines and start doing it, I'm not going to stop them," he said.

Sonologists say the issue has more to do with the economics of ultrasound imaging than its clinical performance. Many seem to share the notion that ultrasound scanning is time-consuming and hurts the bottom line. Others observe that the current reimbursement scenario makes MRI more attractive.

"If ultrasound paid better than MRI, we wouldn't be having this discussion," Nazarian said.

Though it is unlikely at this point, leveling the reimbursement field seems an appealing approach. Medicare, for instance, could hold or refuse payment for certain MRI indications in favor of ultrasound if the latter were proven to be more clinically convenient and cost-effective. Based on the literature, that is not a far-fetched proposition.

A study by Laurence Parker, Ph.D., and colleagues from Thomas Jefferson University analyzed musculoskeletal imaging utilization trends in the U.S. from 1996 to 2000. Their data included CT, MR, ultrasound, and x-ray, and their findings showed that subspecialty costs would approach $750 million per year by 2010. They also projected cost savings between $40.3 and $153.4 million if musculoskeletal MRI were replaced with ultrasound. Their findings were presented at the 2002 RSNA meeting.

Balancing MRI's higher reimbursement factor is ultrasound's shorter examination times. If observed clinical trends are correct, radiologists could do five times as many ultrasound examinations daily as MR scans, said Dr. Joseph H. Introcaso, director of interventional neuroradiology and endovascular neurosurgery at Lutheran General Hospital in Park Ridge, IL.

Ultrasound provides a diagnostic edge in many musculoskeletal applications. To boost MR's diagnostic accuracy, imagers must perform arthrography, which is relatively invasive. The time needed to plan and perform the arthrogram, inject contrast into the affected joint, scan the patient, and interpret the images reduces throughput capability. Financially, the balance leans in favor of ultrasound, Introcaso said.

"That's what a lot of people do not consider," he said.

MIGHTY MR

In spite of these favorable arguments, ultrasound faces long odds when stacked against MR. Though relatively fast, a musculoskeletal ultrasound study may still develop into a lengthy examination. The ultrasound beam may not be able to fully penetrate the body structures of obese patients, and it may have limited value in the evaluation of internal derangement of large joints.

Staffing issues can compound the reimbursement problem. When no sonographers are available, radiologists are more likely to use an MR scanner if one is accessible. An evaluation with MR helps both the patient and the radiologist when the workforce is strapped for time, said Dr. Douglas P. Beall, chief of musculoskeletal imaging at the University of Oklahoma Health Sciences Center.

"At least in the U.S., radiologists are less likely to use ultrasound because it takes time, they are already overworked, and MR is highly available. Would you rather read 30 MR scans a day or perform 12 ultrasound exams yourself? Probably a more thorough evaluation may be done with MR imaging," Beall said.

Patients often present with complex musculoskeletal conditions or injuries that only a powerful modality like MR can help diagnose. Injuries of the knee, for example, usually call for an MR scan. For many conditions, MR provides a field-of-view and degree of spatial resolution that helps radiologists better understand the type and extent of a patient's pathology, said Dr. Bruce Forster, an associate professor of radiology at the University of British Columbia in Vancouver.

Recent advances in MR technology could cut into another ultrasound edge, quick scan times. New techniques such as integrated parallel acquisition and multichannel coils can decrease scanner time substantially. And MRI can be cost-effective if it helps avoid arthroscopy or other invasive procedures.

"The single most important factor in the utility of MR in sports medicine imaging is that it is a one-stop shop," Forster said.

CLINICAL APPLICATIONS

Imagers weighing the two modalities can agree, however, that ultrasound makes the most sense as the first-line procedure in a long list of musculoskeletal indications:

- detection and characterization of rotator cuff tears;

- diagnosis of superficial tendon injuries, such as the Achilles or the patellar tendons;

- joint diffusions;

- ganglion cysts;

- soft-tissue masses;

- detection of small foreign bodies, such as splinters or thorns; and

- nerve problems, including carpal tunnel syndrome.

Most radiologists also agree that ultrasound retains an edge in two specific situations: when a given musculoskeletal condition requires dynamic, real-time visualization and when interventional guidance is needed.

The diagnosis of injuries such as the ulnar collateral ligament of the elbow in a baseball pitcher may not be apparent at rest. Static MR scanning simply won't work in a host of abnormalities. With ultrasound, multiple musculoskeletal conditions can be diagnosed and treated immediately by a radiologist.

"The only other modality that gives you reliable real-time imaging is x-ray fluoroscopy, but with fluoroscopy you can't see the soft tissues," Nazarian said.

Injections of the joints offer another example. The literature reports that clinicians blindly injecting joints or bursas may miss about 25% of their targets. Ultrasound guidance, on the other hand, affords up to 100% accuracy.

Sonologists say they often encounter situations in which they diagnose and solve problems that MR scannings failed to even spot. In a typical case, a patient struggles with hip pain for years. Once on the radiologist's table, the patient leads the sonologist's probe to the source of pain. Ultrasound then visualizes a scarred tendon whose intricate location MRI could never have picked up. Using the same guidance, the radiologist breaks the damaged tissue with the tip of a needle, sending the patient home soon afterward for a prompt and almost always total recovery.

"I wish this type of incident were an isolated one. But it's not. We see the same type of patients with negative MRs at least a couple of times per week," Nazarian said.

Evidence such as this explains the growing interest of clinical physicians in musculoskeletal ultrasound. They can increase the accuracy of their injections, capture a larger share of this imaging market, and make additional income they would otherwise lose to radiologists.

SAFEGUARDING TURF

As a counteracting measure to eroding turf, some radiologists like the idea of a shared clinical approach to this modality. Ultimately, imagers' intimate knowledge of anatomy and pathology heightens their role within multidisciplinary teams that can provide patients with a higher standard of care, Beall said.

Underscoring the debate, however, is the fear of some musculoskeletal ultrasound advocates that ceding too much ground in practice could destroy radiology's presence in the field: If radiologists let go of musculoskeletal ultrasound now, they may lose musculoskeletal MRI next and the entire musculoskeletal imaging field in the end, said Dr. Steven S. Winn, a musculoskeletal radiologist at Spectrum Medical Group in Portland, ME.

"If you perform musculoskeletal ultrasound, you are offering a facet of musculoskeletal imaging that is not offered in all departments or imaging centers. Patients are sent your way in acknowledgement of that expertise. This contributes to patient referral flow to your practice, preferentially over others, for all musculoskeletal imaging, including MRI," he said.

The decreasing cost of ultrasound equipment is another contributing factor, allowing more clinicians to enter the field. Musculoskeletal ultrasound is clearly valuable for clinicians, because of their interaction with patients. If clinicians cannot get that service from radiologists, they will do it themselves, Winn said.

And that prospect could have consequences beyond just ultrasound.

"Radiologists should always offer ultrasound. If it is conclusive, great. If not, they can refer clinicians to the next imaging modality. The idea is to let imaging stay within radiology," Nazarian said. "Some radiologists now believe that by doing ultrasound, they are going to lose their MRI business. What I believe is that if they don't do ultrasound, they will end up losing all business."

Mr. Abella is an assistant editor of Diagnostic Imaging.