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

OBJECTIVE: 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. MATERIALS AND METHODS: 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. RESULTS: 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). CONCLUSION: 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.

What to do with incidental thyroid nodules identified on imaging studies? Review of current evidence and recommendations.

PURPOSE OF REVIEW: To discuss the problem of incidental thyroid nodules (ITN) detected on imaging; summarize the literature for workup methods; and provide recommendations based on current evidence. RECENT FINDINGS: ITN are a common problem, seen in 40-50% of ultrasound and 16% of computed tomography (CT) and MRI studies that include the thyroid. The personal and financial costs of workup frequently outweigh the benefits when considering that the majority of ITN are benign; 25-41% of patients undergo surgery after biopsy, of which more than half ultimately result in a benign diagnosis, and small thyroid cancers have an indolent course. Workup should consider reduction in unnecessary workup in addition to cancer diagnosis. The Society of Radiologists in Ultrasound recommendations have been proposed for ITN detected on ultrasound and found to reduce workup by 30%. For ITN detected on CT, MRI, or PET/CT, a three-tiered system categorization method reduces workup of ITN by 35-46%. SUMMARY: The ideal approach to selecting ITN detected on imaging for workup would not be to diagnose all cancers, but to diagnose cancers that have reached clinical significance, while avoiding unnecessary tests and surgery in patients with benign nodules, especially those who have limited life expectancy. The three-tiered system and the Society of Radiologists in Ultrasound recommendations are supported by existing studies and focus on reducing unnecessary biopsy.

The biochemical role of the heat shock protein 90 chaperone complex in establishing human telomerase activity.

Telomerase is a ribonucleoprotein complex that synthesizes the G-rich DNA found at the 3'-ends of linear chromosomes. Human telomerase consists minimally of a catalytic protein (hTERT) and a template-containing RNA (hTR), although other proteins are involved in regulating telomerase activity in vivo. Several chaperone proteins, including hsp90 and p23, have demonstrable roles in establishing telomerase activity both in vitro and in vivo, and previous reports indicate that hsp90 and p23 are required for the reconstitution of telomerase activity from recombinant hTERT and hTR. Here we report that hTERT and hTR associate in the absence of a functional hsp90-p23 heterocomplex. We also report that hsp90 inhibitors geldanamycin and novobiocin inhibit recombinant telomerase even after telomerase is assembled. Inhibition by geldanamycin could be overcome by allowing telomerase to first bind its primer, suggesting a role for hsp90 in loading telomerase onto the telomere. Inhibition by novobiocin could not similarly be overcome but instead resulted in destabilization of the hTERT polypeptide. We propose that the hsp90-p23 complex fine tunes and stabilizes a functional telomerase structure, allowing primer loading and extension.