Effect of the categorization method on the diagnostic performance of ultrasound risk stratification systems for thyroid nodules

Optimizing the screening process for TIRADS could reduce the number of unnecessary thyroid biopsies

Objective

Current Thyroid Imaging Reporting and Data Systems (TIRADS) exhibit considerable variability in size thresholds for fine-needle aspiration biopsy. This study harnesses the systematic variations among dissimilar TIRADS optimization strategies for biopsy selection.

Methods

The analysis focused on the discrepancies observed among the four widely utilized TIRADS systems: ACR-TIRADS, Kwak-TIRADS, C-TIRADS and EU-TIRADS. Subsequently, several methods derived from the combination of two TIRADS were constructed via serial testing. Last but not least, diagnostic performance was assessed through unnecessary biopsy rate (UBR), missed malignancy rate and the frequency of clinically significant missed diagnoses.

Results

A total of 699 nodules were included in the study. The accuracy for nodules consistently recommended for biopsy by the four TIRADS was merely 50.8%. Without elevating the risk of missed diagnoses, which could potentially influence prognosis as per the current literature, for eligible nodules recommended for biopsy by original TIRADS, incorporating another TIRADS in serial could further reduce the number of biopsies by 7.8-19.2%.

Conclusions

Conspicuous disparities exist in biopsy guidelines among TIRADS systems, urging increased caution among healthcare providers, particularly when they are extensively applied in patient evaluations. As evidently demonstrated by our research findings, combining recommendations from two TIRADS systems could effectively and safely lessen UBRs. These findings also advocate for the integration of prognostic-impact assessment in developing novel biopsy optimization strategies.

Thyroid Imaging Reporting and Data Systems: Applicability of the "Taller than Wide" Criterium in Primary/Secondary Care Units and the Role of Thyroid Scintigraphy

BACKGROUND

To examine the applicability of the "taller than wide" (ttw) criterium for risk assessment of thyroid nodules (TNs) in primary/secondary care units and the role of thyroid scintigraphy therein.

METHODS

German bicenter study performed in a setting of primary/secondary care. Patient recruitment and analysis in center A was conducted in a prospective manner. In center B, patient data were retrieved from a database that was originally generated by prospective data collection. TNs were assessed by ultrasound and thyroid scans, mostly fine needle biopsy and occasionally surgery and others. In center A, only patients who presented for the first time were included. The inclusion criterion was any TN ≥ 10 mm that had at least the following two sonographic risk features: solidity and a ttw shape. In center B, consecutive patients who had at least ttw and hypofunctioning nodules ≥ 10 mm were retrieved from the above-mentioned database. The risk of malignancy was determined according to a mixed reference standard and compared with literature data.

RESULTS

In center A, 223 patients with 259 TNs were included into the study. For further analysis, 200 nodules with a reference standard were available. The overall malignancy rate was 2.5% (upper limit of the 95% CI: 5.1%). After the exclusion of scintigraphically hyperfunctioning nodules, the malignancy rate increased slightly to 2.8% (upper limit of the 95% CI: 5.7%). Malignant nodules exhibited sonographic risk features additional to solidity and ttw shape more often than benign ones. In addition to the exclusion of hyperfunctioning nodules, when considering only nodules without additional US risk features, i.e., exclusively solid and ttw-nodules, the malignancy rate decreased to 0.9% (upper limit 95% CI: 3.7%). In center B, from 58 patients, 58 ttw and hypofunctioning TNs on thyroid scans with a reference standard were available. Malignant nodules from center B were always solid and hypoechoic. The overall malignancy rate of hypofunctioning and ttw nodules was 21%, with the lower limit of the 95% CI (one-sided) being 12%.

CONCLUSIONS

In primary/secondary care units, the lowest TIRADS categories for indicating FNB, e.g., applying one out of five sonographic risk features, may not be appropriate owing to the much lower a priori malignancy risk in TNs compared to tertiary/quaternary care units. Even the combination of two sonographic risk features, "solidity" and "ttw", may only be appropriate in a limited fashion. In contrast, the preselection of TNs according to hypofunctioning findings on thyroid scans clearly warranted FNB, even when applying only one sonographic risk criterion ("ttw"). For this reason, thyroid scans in TNs may not only be indicated to rule out hyperfunctioning nodules from FNB but also to rule in hypofunctioning ones.