Hounsfield Unit Values in ACR TI-RADS 4-5 Thyroid Nodules with Coarse Calcifications: An Important Imaging Feature Helpful for Diagnosis.

PURPOSE: The purpose of this study is to investigate the diagnostic role of Hounsfield unit (HU) values on noncontrast computed tomography (CT) for differentiating benignity from malignancy in the American College of Radiology (ACR) Thyroid Imaging Reporting and Data System (TI-RADS) 4-5 nodules with coarse calcifications. PATIENTS AND METHODS: CT images of 216 ACR TI-RADS 4-5 nodules with coarse calcifications from 207 patients who underwent surgery in our hospital between 2017 and 2019 were retrospectively reviewed. The average HU values (AHUVs) and maximum HU values (MHUVs) of the nodules were measured on noncontrast CT. The distribution of AHUVs and MHUVs in benign and malignant nodules with coarse calcifications was analyzed using the Mann-Whitney test. Receiver operating characteristic (ROC) curves were used to identify the best cut-off values. Diagnostic performances were assessed according to the area under the ROC curve (AUC), sensitivity and specificity. RESULTS: Of the 216 ACR TI-RADS 4-5 nodules with coarse calcifications, 170 were benign and 46 were malignant. The AHUVs of benign and malignant nodules were 791 HU [interquartile range (IQR), 543-1025 HU] and 486 HU (IQR, 406-670 HU), respectively (P < 0.001). The MHUVs of benign and malignant nodules were 1084 HU (IQR, 717-1477 HU) and 677 HU (IQR, 441-986 HU), respectively (P < 0.001). The AUCs for AHUVs and MHUVs for predicting benign nodules with coarse calcifications were 0.759 and 0.732, and the cut-off values were 627.5 HU and 806.0 HU, with sensitivities of 67.6% and 68.8% and specificities of 73.9% and 67.4%, respectively. The sensitivity and specificity of the combination were 68.8% and 76.1%. CONCLUSION: AHUVs and MHUVs were helpful in differentiating benignity from malignancy in ACR TI-RADS 4-5 nodules with coarse calcifications. This may provide an important basis for reducing misdiagnosis and unnecessary aspiration or surgical trauma.

The clinical significance of ultrasound grayscale ratio in differentiating markedly hypoechoic and anechoic minimal thyroid nodules.

PURPOSE: This study explored ultrasound grayscale ratios (USGRs) for differentiating markedly hypoechoic and anechoic minimal thyroid nodules. MATERIALS AND METHODS: Longitudinal scan images of 193 markedly hypoechoic papillary thyroid microcarcinoma (PTMC) lesions from 184 patients were retrospectively reviewed using RADinfo and compared with 123 anechoic micronodular goiters (MNGs) from 110 patients. Final diagnosis was validated by pathological examination; MNGs predominantly manifested with cyst formation. Grayscale values of PTMC, MNG, and normal surrounding tissues were obtained from grayscale histograms; USGRs (grayscale ratios of pathologic tissue to surrounding normal tissue) of PTMC and MNG were calculated. Optimal USGRs for differentiating PTMC and MNG were determined with receiver operating characteristic (ROC) curves. RESULTS: Among 193 PTMC and 123 MNG lesions, USGRs were 0.24-0.51 (mean ± standard deviation [SD]: 0.41 ± 0.07) and 0.01-0.38 (mean ± SD: 0.12 ± 0.08), respectively. The area under the ROC curve for distinguishing markedly hypoechoic PTMC and anechoic MNG was 0.992. As USGRs decreased, sensitivity decreased and specificity increased for MNG diagnosis. At a USGR of 0.26, the Youden index was high (0.933), corresponding to 94.3% sensitivity and 99% specificity for predicting anechoic MNG. At a USGR of 0.23, sensitivity and specificity for diagnosing anechoic MNG were 92.7% and 100%, respectively. In contrast, as USGR increased, sensitivity decreased and specificity increased for predicting PTMC. At a USGR of 0.38, sensitivity and specificity for diagnosing markedly hypoechoic PTMC were 68.4% and 100%, respectively. CONCLUSIONS: USGRs could objectively quantize grayscale values of markedly hypoechoic and anechoic lesions, enabling accurate and quantitative determination of nodular properties.

Diagnostic value of computed tomography (CT) histogram analysis in thyroid benign solitary coarse calcification nodules.

This study was to investigate the diagnostic value of the computed tomography (CT) histogram in thyroid benign solitary coarse calcification nodules (BSCNs). A total of 89 thyroid solitary coarse calcification nodules (coarse calcification ≥5 mm, no definite soft tissue around calcification) confirmed either by surgery or histopathological examination in 86 cases enrolled from January 2009 to December 2015 were evaluated. These included 56 BSCNs and 33 malignant solitary coarse calcification nodules (MSCNs). Overall, 27 cut-off values were calculated by N (4≤N≤30) times of 50 Hounsfield units (HU) in the range of 200 to 1500 HU, and each cut-off value and the differences in the corresponding area percentages in the CT histogram were recorded for BSCN and MSCN. The optimal cut-off value and the corresponding area percentage were established by receiver operating characteristic (ROC) curve analysis. In the 19 groups with an ROC area under curve (AUC) of more than 0.7, at a cut-off value of 800 HU and at an area percentage of no more than 93.8%, the ROC AUC reached the maximum of 0.79, and the accuracy, sensitivity, and specificity were 75.3%, 80.4%, and 66.7%, respectively. At a cut-off value of 1050 HU and at an area percentage of no more than 93.6%, the accuracy, sensitivity, and specificity were 71.9%, 60.7%, and 90.9%, respectively. At a cut-off of 1150 HU and area of no more than 98.4%, the accuracy, sensitivity, and specificity were 70.8%, 57.1%, and 93.9%, respectively. At a cut-off of 600 HU and area of no more than 12.1%, the accuracy, sensitivity, and specificity were 61.8%, 39.3%, and 100.0%, respectively. Compared with the cut-off value of 800 HU and an area percentage of no more than 93.8%, the sensitivity of cut-off values and minimum areas of 1050 HU and 93.6%, of 1150 HU and 98.4%, and of 600 HU and 12.1%, was gradually decreasing; however, their specificity was gradually increasing. This can provide an important basis for reducing the misdiagnosis and unnecessary surgical trauma.

Value of computed tomography in determining the nature of papillary thyroid microcarcinomas: evaluation of the computed tomographic characteristics.

OBJECTIVE: This study was designed to assess the value of computed tomography (CT) in determining the nature of papillary thyroid microcarcinomas (PTMCs). METHODS: Four hundred fifty-two thyroid CT scan cases with pathological data at our department that were performed from January 2011 to January 2012 were analyzed, of which a total of 87 tumors in 73 cases were confirmed as 0.5-1.0 cm diameter PTMC; the CT images of PTMC were analyzed, suitable window width (W) and window level (L) of PTMC were determined, as well as observation of the density and shape of tumors, tumor boundaries before and after contrast enhancement, thyroid edge interruption, calcification, lymph node metastasis, and complications. RESULTS: Plain scan W 140-180, L 80-120 and contrast-enhanced scan W 160-200, L 110-150 were conducive to the display of PTMC. Among 87 tumors in this group, aside from 10 tumors and intratumoral calcification that were not shown up, plain CT scans of 77 (88.5%) tumors showed homogeneous low density; 59(67.8%) tumors were irregular shaped; 64 (73.6%) tumors showed plain thyroid scan edge interruption; after contrast enhancement, 65 (74.7%) tumor contours were relatively obscure compared with plain scan, and relative low-density range of the tumors narrowed down; 16 (18.4%) tumors were calcified, of which 15 (93.8%) were fine granular calcifications; lymph node metastasis were found pathologically in 18 (24.7%) cases, of which 8 (44.4%, 8/18) cases were CT findings. Among the 10 (11.4%) tumors that did not show up on CT, 7 were complicated with Hashimoto's thyroiditis, 2 were masked by clavicle artifacts, and 1 was masked by nodular goiter. CONCLUSION: Plain scan W 140-180, L 80-120 and contrast-enhanced scan W 160-200, L 110-150 were conducive to the display of PTMC. The tumor-shaped irregularity, smaller relative low-density area after contrast enhancement than plain scan, thyroid edge interruption, fine granular calcification, and neck lymph node abnormalities contributed to the diagnosis of PTMC; Hashimoto's thyroiditis, clavicle artifacts, and nodular goiter could mask the tumor, which required adequate attention.