Many radiologists complain that if the SRU guidelines were strictly followed, they would be recommending FNA of every nodule they see! While this may seem closer to truth than exaggeration, the American Thyroid Association (ATA) and American Association of Clinical Endocrinologists (AACE) have separate guidelines that include even more nodules for FNA than the SRU criteria.
There are multiple histological varieties of thyroid cancer. Papillary cancer is common and has an excellent prognosis. One series reports a 6% incidence of papillary cancer at autopsy, unrelated to cause of death. Some question whether papillary microcarcinomas will have any affect on life span if untreated. This seems to be the reason the SRU criteria use size criteria.
Using the SRU guidelines, we are willing to accept missing some papillary microcarcinomas that will likely never present clinically, so that we can draw a line on when to recommend FNA. That is why even a nodule with very suspicious microcalcifications does not receive a recommendation for FNA under SRU criteria if < 1cm (though it does under ATA). This is the cost-effectiveness of the SRU guidelines over other guidelines.
Recently, an article in AJR examined the management of incidental nodules found on cross sectional imaging, including CT, MR, PET/CT, and US. While no specific management was recommended, the authors assert that clinical factors play a large role in determining which nodules should undergo FNA and that while radiologists should report the presence of all nodules, clinicians should be primarily responsible for deciding on further imaging or FNA.
1. Ahmed S, Horton K, Jeffrey RJ, Sheth S, Fishman E. Incidental thyroid nodules on chest CT: Review of the literature and management suggestions. AJR 2010;195(5):1066-71.
2. Cooper DS, Doherty GM, Haugen BR, et al. Revised American Thyroid Association management guidelines for patients with thyroid nodules and differentiated thyroid cancer. Thyroid. 2009;19(11):1167-214.
3. Frates MC, Benson CB, Charboneau JW, et al. Management of thyroid nodules detected at US: Society of Radiologists in Ultrasound consensus conference statement. Radiology. 2005;237(3):794-800.