Logistic regression analysis of contrast-enhanced ultrasound and conventional ultrasound of follicular thyroid carcinoma and follicular adenoma

Abstract

Background: Follicular thyroid carcinoma (FTC) is prone to recurrence and hematogenous metastasis, preoperative accurate diagnosis is still needed to help clinicians select the best surgical methods to improve the prognosis of patients. The aim of this study was to find specific conventional ultrasound (US) and contrast-enhanced ultrasound (CEUS) characteristics of FTC and to explore their diagnostic value in the differential diagnosis between FTC and follicular adenoma (FA).

Methods: This retrospective study included 258 thyroid follicular neoplasms (172 FAs and 86 FTCs) in 244 consecutive patients who underwent preoperative conventional US, and 72 of them underwent both conventional US and CEUS. Sonograms were reviewed in consensus by two experienced radiologists for various conventional US and CEUS features. Multivariate logistic regression analysis was performed to determine independent risk factors for FTC.

Results: Independent risk factors of conventional US for FTC were heterogenicity (OR =7.477, 95% CI: 2.848-19.629), unevenly thick halo (OR =5.643, 95% CI: 3.234-9.848) and calcifications (OR =1.748, 95% CI: 1.098-2.783). While independent risk factors determined with the combination of CEUS and conventional US were unevenly thick halo (OR =5.770, 95% CI: 1.310-25.409) and absent or irregular rim enhancement (OR =27.000, 95% CI: 2.445-298.178). The area under the receiver operating characteristic curve of the final two logistic regression models was 0.835 and 0.838.

Conclusions: Conventional US is an efficient diagnostic tool in the differential diagnosis of FTC and FA to help clinicians in making appropriate decisions while CEUS failed to provide additional diagnostic value in the study, thus the value of CEUS remains to be verified by further studies with larger sample sizes.

Keywords: Follicular thyroid carcinoma (PTC); contrast-enhanced ultrasound; conventional ultrasound; follicular adenoma; logistic regression.

Figure 1

Conventional US images of follicular adenoma and follicular carcinoma. (A,B) A 61-year-old female patient with follicular adenoma. Gray-scale ultrasound image shows the transverse and longitudinal views of an isoechoic and slightly heterogeneous nodule with smooth halo (white arrow) in the right lobe of the thyroid. (C,D) A 52-year-old female patient with follicular carcinoma. Gray-scale ultrasound image shows the transverse and longitudinal views of a hypoechoic and heterogeneous nodule with calcification and an unevenly-thick halo (white arrow) in the left lobe of the thyroid gland.

Figure 2

Conventional US and CEUS images of follicular adenoma and follicular carcinoma. (A,B) A 40-year-old male patient with follicular adenoma. Gray-scale and contrast-enhanced ultrasound image shows the longitudinal views of a hypoechoic and heterogeneous nodule with thin and regular rim enhancement (white arrow) in the right lobe of the thyroid. (C,D) A 43-year-old female patient with follicular carcinoma. Gray-scale and contrast-enhanced ultrasound image shows the longitudinal views of an extremely hypoechoic and heterogeneous nodule with irregular rim enhancement (white arrow) in the right lobe of the thyroid.

Figure 3

Receiver operating characteristic (ROC) curve of the final two logistic regression models for defining the preoperative diagnostic value of the factors in differentiating follicular adenomas from follicular carcinomas. The AUC (area under the curve) of multivariable logistic regression model of conventional ultrasound was 0.835 (A), while the AUC of multivariable logistic regression model of contrast-enhanced US in combination with conventional ultrasound was 0.838 (B).