ACR calls on solid science to shape its Appropriateness Criteria

August 21, 2006

Sound clinical data, not anecdotal reference, should mold the American College of Radiology’s manual, Appropriateness Criteria, according to ACR officials. Their stand eases concerns about imaging technology’s influence on the guidelines’ latest updates.

Sound clinical data, not anecdotal reference, should mold the American College of Radiology's manual, Appropriateness Criteria, according to ACR officials. An ACR official said the process they followed should ease concerns about imaging technology's influence on the guidelines' latest updates.

The panels of experts appointed to put together the criteria can't overlook the tremendous technological advances in recent years. But the experts' challenge is to write not what individual radiologists would do, regardless of their technical prowess, but what the data show is the most appropriate approach, said Dr. Michael A. Bettmann, FACR, ACR's chair of the Appropriateness Criteria Committee.

"During some of the [Appropriateness Criteria] conference calls, somebody would say, 'Well, I always use multidetector CT for this particular entity. We had a 16-slice scanner in the emergency room. We now have a 64-slice scanner, and we've found it very useful.' What we say then is, 'Okay, that's what we do, but what do the data show?'" Bettmann said.

Many physicians may be wondering, for instance, whether CT is the most accurate test for the diagnosis of deep vein thrombosis. The criteria indicate that the best documented study currently is duplex ultrasound. Many physicians rely on CT, however. They believe that it is equivalent to or more effective than ultrasound. But even though some articles make a good case for CT, they are not definitive, Bettmann said.

"The Appropriateness Criteria manual does not represent expert consensus. It primarily represents or is designed to represent what studies prove," he said.

In several areas, the clinical data are either missing or inconclusive. The ACR follows two approaches for such tricky situations. One is to provide comments in the respective appropriateness criterion table, indicating that there is controversy or an expectation of results in certain areas. The other one is to review these topics frequently and update them as more data appear.

The criteria include more than 160 topics ranging from cardiovascular to interventional radiology, women's imaging, and radiation oncology. The ACR reviewed more than 30 topics last January and has updated about 100 since 2005. The expert physician panels comprise more than 200 diagnostic and interventional radiologists, radiation oncologists, and nonradiology specialists.

Recent criteria changes also reflect practice trends where the intersection of increasing clinical awareness and evolving imaging technologies has led to either controversy or confusion. Relevant topics include imaging of renal calculi, venous claudication, lower and upper extremity venous thrombosis, headache, liver metastases, and chest pain, Bettmann said.

The diagnosis of deep vein thrombosis is a case in point. Some physicians, rarely, use radionuclide venograms. Others occasionally use contrast venograms. Many are increasingly using MR and CT venography. Duplex ultrasound with compression remains the gold standard, however, because no conclusive studies prove that CT or MR should replace it.

The criteria address changing times. Ultrasound may not be available around the clock in some facilities. In that setting, imaging standards should keep up with resources. If a modality is unavailable, the expertise to perform it isn't present, or results are equivocal, then physicians should consider appropriate alternatives, Bettmann said.

"The criteria can serve as guidance for radiologists, medical students, or residents and for referring clinicians as they consider what kind of imaging studies might be useful in any given clinical condition," he said.

For more information from the Diagnostic Imaging archives:

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