SUMMARY OF THE STUDY
This study examined 307 patients who had had a thyroid ultrasound over a two year period because an incidental thyroid nodule was previously found (within 6 months) on CT, MRI or PET-CT. Nodule size was compared between the image and subsequent thyroid ultrasound. The authors also determined the number of cases of thyroid cancer that would have missed if the ACR recommendations had been followed from the outset.
Of the 307 patients included, 229 had thyroid nodules discovered on CT scan, 69 on MRI scan and 9 on PET-CT scan. The average nodule size from all imaging studies was 15.6 mm. The average nodule size of the same nodules when measured by ultrasound was 17.5 mm indicating a tendency for other imaging studies to underestimate nodule size. If the ACR recommendations were applied, ultrasound would not have been recommended for 151 patients (49.2%). Applying the ACR recommendations would have decreased the number of ultrasounds by 24% of the total study group and only a single cancer would have been missed.
WHAT ARE THE IMPLICATIONS OF THIS STUDY?
This study addresses a common clinical problem. Incidental thyroid nodules are commonly identified on imaging studies done for other reasons than thyroid problems, but recommending further ultrasound evaluation for each one would be very expensive, may lead to increased patient anxiety and may be unecessary. The investigators found that CT, MRI or PET-CT are more likely to underestimate the size of a thyroid nodule as compared with ultrasound. However, the size difference does not appear to be clinically significant. More importantly, this study shows that using the ACR recommendations effectively identifies most cases of thyroid cancer while reducing the number of unnecessary thyroid ultrasounds. Physicians now have a means of determining which incidental nodules identified on non-ultrasound imaging need to be further evaluated with an ultrasound and which do not.
— Phillip Segal, MD
ATA THYROID BROCHURE LINKS
Thyroid Nodules: https://www.thyroid.org/ thyroid-nodules/