Arrival-Time Parametric Imaging in Contrast-Enhanced Ultrasound for Thyroid Nodule Differentiation

Abstract

BACKGROUND Solitary thyroid nodules present a challenge in differentiating between benign and malignant conditions using ultrasound (US). Arrival time parameter imaging (At-PI) following contrast-enhanced ultrasound (CEUS) can effectively visualize the vascular architectural patterns of the nodules, providing valuable diagnostic information. This study aimed to explore the application value of At-PI in differentiating thyroid nodules, specifically focusing on a sample of 127 cases. MATERIAL AND METHODS From October 2020 to December 2023, 127 thyroid nodules from 108 patients who underwent ultrasound and CEUS examinations at the General Hospital of Northern Theater Command were reviewed. Pathological outcomes served as the criterion standard, categorizing the nodules into a benign group (44 cases) and a malignant group (83 cases). At-PI was employed to analyze the CEUS videos, allowing for a comparison of parameters between the 2 groups. Additionally, the diagnostic performance of 2 quantitative parameters was assessed using receiver operating characteristic (ROC) curves. RESULTS After conducting the chi-square test, the differences between the 2 groups regarding enhancement time, perfusion pattern, and perfusion defect were found to be statistically significant (P<0.05). There was a significant difference between the 2 groups over the time span (ΔT) (P<0.05). The areas under the curve (AUCs) for ΔT₄₋₃ and ΔT₆₋₅ were 0.715 (95% CI: 0.624-0.805) and 0.763 (95% CI: 0.676-0.851). CONCLUSIONS At-PI can offer more effective parameters for differentiating thyroid nodules. Additionally, some of these parameters exhibit notable diagnostic performance in the detection of thyroid cancer.

Figure 1

Color-coded bar used by At-PI. The At-PI time color scale indicates time in seconds, with a progression from red to purple through intermediate colors such as orange, yellow, green, and blue. As time passes, the contrast agent shifts from orange to purple in a sequential manner.

Figure 2

Schematic diagram illustrating the three perfusion modes of At-PI in thyroid nodules. The left image depicts the US image in the double-image condition, while the right image illustrates the At-PI image. The white arrow indicates the target nodule. (A) The US reveals a solid hypoechoic lesion in the right lobe of the thyroid gland, characterized by irregular edges, a regular shape, and uniform echogenicity. This nodule is classified as C-TIRADS category 4b. The At-PI demonstrates a centripetal perfusion pattern, with yellow and green hues on the periphery (indicating earlier arrival) and purple in the center (indicating late arrival). (B) The US shows a solid hypoechoic lesion in the left lobe of the thyroid gland with well-defined boundaries and a regular shape; however, the echogenicity is uneven, and this nodule is categorized as C-TIRADS 4a. The At-PI reveals a centrifugal perfusion pattern, featuring orange and yellow colors in the center (indicating earlier arrival) and purple at the periphery (indicating later arrival). (C) The US displays a solid hypoechoic lesion in the right lobe of the thyroid gland with poorly defined boundaries and indistinct edges. The aspect ratio is greater than 1, and this nodule is classified as C-TIRADS category 4c. The At-PI indicates a diffuse perfusion pattern. Figure was generated using PowerPoint version 2016 (Microsoft Corporation, Washington, USA).

Figure 3

(A–C) Schematic diagram illustrating early ring enhancement of At-PI in thyroid nodules. A thyroid nodule was identified in the right lobe of a 48-year-old woman. The left image displays the US in double condition, the middle image presents the At-PI image and the right image illustrates the pathological image. The white arrow indicates the target nodule. The US revealed hypoechoic nodules with an irregular shape, unclear edges, uniform echogenicity, and an aspect ratio greater than 1. These nodules were classified as C-TIRADS category 4b. The At-PI image demonstrates a centripetal perfusion pattern, characterized by early enhancement of the tissue surrounding the nodule, which is color-coded in orange. Notably, there is clear early ring enhancement observed on the At-PI image at 10 seconds. Figure was produced using PowerPoint version 2016 (Microsoft Corporation, Washington, USA).

Figure 4

Schematic diagram illustrating a perfusion defect of At-PI in thyroid nodules. The left image depicts the US image in the double-image condition, the right image represents the At-PI image. The white arrow indicates the area of filling defect. (A) The US image reveals a solid hypoechoic lesion in the right lobe of the thyroid gland, characterized by clear borders, a regular shape, and uneven echoes. There are thick and strong echoes present within the lesion, accompanied by attenuation in the posterior region. The nodules are classified as C-TIRADS category 4a. The At-PI image shows a perfusion defect, which, when compared to the US image, highlights the presence of thick calcification and a significant sound shadow behind it. The pathology indicates nodular goiter with calcification and fibrosis. (B) The US image again shows the solid right lobe of the thyroid gland, where the hypoechoic lesions exhibit clear borders, irregular shapes, and uneven echoes. The nodules are classified as C-TIRADS category 4b. The At-PI image displays a combination of local abundant perfusion and defect, with the maximum diameter of the lesion measuring approximately 3.23 cm; the pathology is consistent with papillary thyroid carcinoma (PTC). Figure was created using PowerPoint version 2016 (Microsoft Corporation, Washington, USA).

Figure 5

ROC curves for ΔT_4-3 (the time span from the periphery to the central area or vice versa) and ΔT_6-5 (the time span [absolute value] for the contrast agent to reach the lesion and the surrounding thyroid tissue at the same depth). The Figure was produced using MedCalc version 11.4.2.0 (MedCalc Software, Ostend, Belgium).