Interobserver Agreement of visual and semi-quantitative methods in 99mTc-Methoxy-Isobuty-Isonitrile (MIBI) imaging for risk stratification of hypofunctional thyroid nodules.

AIM: 99mTc-Methoxy-Isobuty-Isonitrile (MIBI) imaging is used for risk stratifications of hypofunctioning thyroid nodules (TNs). MIBI uptake in the nodular tissue is compared to the uptake in the paranodular thyroid tissue. MIBI imaging may be interpreted visually and/or semi-quantitatively. This study aimed to evaluate the interobserver agreement (IOA) of different methods of interpreting MIBI imaging (visual and semi-quantitative approaches). METHODS: MIBI imaging data from 2018 to 2020 were collected. Four readers with varying work experience prospectively evaluated MIBI images (planar, SPECT/CT) visually and semi-quantitatively (Wash-Out Index (WOI)). After identifying the nodules on 99mTc-pertechnetate scintigram, the readers evaluated MIBI imaging data by using early, late, early-to-late, and SPECT late acquisitions. Region of interests (ROIs) were defined for semi-quantitative analysis and average counts were calculated using the WOI formula (by Campenni et al.) 1 2. IOA was assessed using Fleiss Kappa, Pearson correlation and Analysis of Variance (ANOVA). RESULTS: 23 patients with hypofunctioning nodules were included. Kappa analysis revealed an IOA of 0.57 for all readers for early imaging (moderate agreement); perfect matches were found in 57%. For late imaging, the IOA was 0.48 (moderate) for all, with perfect matches in 48%. The visual pattern (early-to-late) exhibited an IOA of 0.45 for all, with perfect matches in 57%. SPECT/CT evaluation showed an overall IOA of 0.44, with perfect matches in 48%. The semi-quantitative approach WOI yielded an overall result of 0.64 (good agreement) and perfect matches in 91%. CONCLUSION: The IOA for WOI was higher than for visual methods. The WOI is independent of the reader's experience level. Visual analysis requires a certain level of experience from the reader.

Thyroid Nodule Detection and Region Estimation in Ultrasound Images: A Comparison between Physicians and an Automated Decision Support System Approach.

BACKGROUND: Thyroid nodules are very common. In most cases, they are benign, but they can be malignant in a low percentage of cases. The accurate assessment of these nodules is critical to choosing the next diagnostic steps and potential treatment. Ultrasound (US) imaging, the primary modality for assessing these nodules, can lack objectivity due to varying expertise among physicians. This leads to observer variability, potentially affecting patient outcomes. PURPOSE: This study aims to assess the potential of a Decision Support System (DSS) in reducing these variabilities for thyroid nodule detection and region estimation using US images, particularly in lesser experienced physicians. METHODS: Three physicians with varying levels of experience evaluated thyroid nodules on US images, focusing on nodule detection and estimating cystic and solid regions. The outcomes were compared to those obtained from a DSS for comparison. Metrics such as classification match percentage and variance percentage were used to quantify differences. RESULTS: Notable disparities exist between physician evaluations and the DSS assessments: the overall classification match percentage was just 19.2%. Individually, Physicians 1, 2, and 3 had match percentages of 57.6%, 42.3%, and 46.1% with the DSS, respectively. Variances in assessments highlight the subjectivity and observer variability based on physician experience levels. CONCLUSIONS: The evident variability among physician evaluations underscores the need for supplementary decision-making tools. Given its consistency, the CAD offers potential as a reliable "second opinion" tool, minimizing human-induced variabilities in the critical diagnostic process of thyroid nodules using US images. Future integration of such systems could bolster diagnostic precision and improve patient outcomes.

Distribution of Functional Status of Thyroid Nodules and Malignancy Rates of Hyperfunctioning and Hypofunctioning Thyroid Nodules in Germany.

AIM: Thyroid scintigraphy enables the depiction of the functional status of thyroid nodules (TNs) with both, 99mTc-pertechnetate and 123Iodine. The functional status is relevant for diagnostic procedures for the differentiation of benign and malignant TNs. The aim of this study was to examine the current frequencies of hyper-, hypo- and isofunctioning TNs in Germany and to estimate the risk of malignancy with regard to functional status. METHODS: In 11 study centers, a minimum of 100 nodules per center were consecutively enrolled between July 2019 and April 2020. Inclusion criteria were: newly diagnosed nodule, nodule' size of 10 mm or more, thyroid scintigraphy. Exclusion criteria were: completely cystic TNs, patients with prior radioiodine therapy or thyroid surgery. The risk of malignancy was estimated for hyper- and hypofunctioning TNs. RESULTS: Overall, 849 patients (72 % women) with 1262 TNs were included. Patients' age ranged from 18 to 90 years. Most TNs were hypofunctioning (n=535, 42%) followed by isofunctioning TNs (n=488, 39%) and hyperfunctioning TNs (n=239, 19%). When only TNs with a maximum size of 2 cm or more were considered the rate of hyperfunctioning and hypofunctioning TNs increased (to 27% and 49%) while isofunctioning TNs decreased. Only one of all hyperfunctioning TNs was malignant. In hypofunctioning nodules, the malignancy rate was estimated at 10%. CONCLUSION: In Germany, the proportion of hyperfunctioning TNs is approximately 20% and increases in larger TNs to up to 27%. Due to the low risk of malignancy in hyperfunctioning TNs, no further procedures to rule out malignancy are necessary. The risk of malignancy of hypofunctioning TNs is significantly higher. Thus, a thyroid scintigraphy is a useful diagnostic tool in Germany.