Incidental Thyroid Nodules on CT or MRI: Discordance Between What We Report and What Receives Workup

The objective of this study was to determine the proportion of incidental thyroid nodules (ITNs) reported on CT or MRI that receive additional workup and the factors that influence workup. A secondary aim was to evaluate the effect of the American College of Radiology (ACR) white paper recommendations for reporting of ITNs.

We retrospectively reviewed patients with ITNs reported on CT or MRI studies over 12 months. We identified patients with ITNs that underwent workup and the factors associated with workup. The ACR white paper recommendations were retrospectively applied to estimate how their use would have changed the number of nodules reported in the impression section of radiology reports and the number of cancers diagnosed. The recommendations are based on suspicious imaging features, patient age, and nodule size.

A total of 375 patients had ITNs reported. For 138 of these patients (37%), ITNs were reported by radiologists in the impression section of their reports; 26 patients (19%) received workup. Patients with ITNs reported in the impression section were 14 times more likely to undergo workup than were patients with ITNs reported only in the findings section of the radiology report. On multivariate analysis, the only factors associated with workup were younger patient age and larger nodule size (p ≤ 0.002). The ACR recommendations resulted in a 54% reduction in the number of ITNs reported in the impression section and one missed papillary cancer (TNM classification T1bN0M0).

Only one in five patients with ITNs reported in the impression section of CT or MRI reports underwent additional workup, and this decision was influenced by younger patient age and larger nodule size. These factors are components of the ACR recommendations, which have the potential to reduce the number of reported ITNs and improve the standardization of radiology reporting.