Despite a 2005 consensus statement on the management of thyroid nodules detected at ultrasound, research presented at the 2006 RSNA meeting found wide variation in the criteria used to determine which nodules were chosen for aspiration. That shouldn"t be too surprising as even the panel of radiologists, endocrine surgeons, and endocrinologists who hammered out the consensus statement could not do so in perfect harmony.
Up to 67% of Americans have incidentally found thyroid nodules and many of these patients have multiple lesions. The incidence of cancer, however, is low, between 3% and 10%. Even when present, many thyroid cancers have an indolent course and would not prove fatal. What are clinicians supposed to do with the millions of nodules found each year?
'Some people say we"re finding disease and others say we"re overdiagnosing it,' said Dr. Lincoln Berland, vice chair for administration and planning in radiology at the University of Alabama at Birmingham and a fellow of the Society of Radiologists in Ultrasound. 'Defining exactly when to biopsy is difficult.'
Berland harkened back to the early days of prostate ultrasound, which led to an increase in biopsies, more cancer diagnoses, and many prostatectomies, but had little impact on the mortality rate. The agreement then was to observe longer.
'With thyroid nodules, there"s a concern we might be intervening too much,' he said.
The consensus statement (Management of thyroid nodules detected at US: Society of Radiologists in Ultrasound Consensus Conference Statement. Radiology 2005;237[3]:794-800) was 'consensus in the broadest terms, what we in the room could agree upon,' according to panel member Dr. Franklin Tessler, chief of body imaging at UAB.
One problem for the group was that ultrasound features-such as size, echogenicity, and composition-that help differentiate benign from malignant nodules often overlap. Finding consensus in that middle ground was often difficult, Tessler said.
Whereas the presence of microcalcifications is one of the strongest predictors of malignancy, size is not. Panelists couldn"t agree on whether to assign a size threshold for malignancy and, if they did, what it should be. While the panel recommended reaspiration of benign nodules if there is substantial growth, it did not concur on what constitutes significant growth.
'It"s fair to say that we would have liked to have more data on which to base our statement,' Tessler said.
In an invited commentary in Ultrasound Quarterly (SRU consensus conference on thyroid nodules. 2006;22[4]:231-240), Dr. Peter A. Singer, a professor of clinical medicine at the University of Southern California, noted that the panel did not emphasize the importance of including clinical data, such as history of childhood irradiation, family history, or laboratory tests. Referring physicians have this information, which makes a strong case for endocrinologists to perform ultrasound exams in real-time, Singer said.
'The truth is, there are more than enough nodules to go around,' Tessler said. 'The point is that whoever deals with these cases has to do it well, look for sonographic features, and take into account the clinical history, which is certainly available to radiologists.'
