Magnetic Resonance Imaging Features of Normal Thyroid Parenchyma and Incidental Diffuse Thyroid Disease: A Single-Center Study

Abstract

Background: No previous studies have investigated the feasibility of magnetic resonance imaging (MRI) diagnosis for detecting incidental diffuse thyroid disease (DTD). This study investigated MRI features of normal thyroid parenchyma and incidental DTD. Methods: From January 2008 to December 2017, 387 patients underwent neck MRI in our hospital due to tumor/nodal staging (n = 137), lymphadenopathy (n = 122), inflammatory neck lesion (n = 85), congenital neck lesion (n = 12), and patient request (n = 31). Among them, 375 patients were excluded because of a lack of appropriate histopathological data on the thyroid parenchyma. Results: Among the patients included, 10 had normal thyroid parenchyma, 1 had Hashimoto thyroiditis, and 1 had diffuse hyperplasia. The common MRI features of normal thyroid parenchyma include iso-/slightly high and homogeneous signal intensity on T1/T2-weighted images, normal anteroposterior diameter of the thyroid gland, smooth margin, and homogeneously increased enhancement as compared to adjacent muscle. Hashimoto thyroiditis exhibited high and inhomogeneous signal intensity on T2-weighted images, while diffuse hyperplasia revealed an increased anteroposterior diameter and lobulated margin of the thyroid gland, and inhomogeneous enhancement. Conclusions: MRI may be helpful for detection of incidental DTD.

Keywords: Hashimoto thyroiditis; autoimmune; diffuse thyroid disease; magnetic resonance imaging; thyroid.

Figure 1

A 51-year-old man with normal thyroid parenchyma confirmed by histopathology after thyroid surgery for the treatment of papillary thyroid carcinoma. In the non-enhanced axial T1- (A) and T2- (B) weighted images, the thyroid gland (arrows) exhibits homogeneous, iso-, and slightly high signal intensities, respectively, when compared with adjacent muscle. In both images, the thyroid gland (arrows) exhibits a normal size and smooth margin. In the enhanced axial, fat-suppression T1-weighted image (C), the thyroid gland (arrows) exhibits homogeneously increased enhancement, when compared with adjacent muscle.

Figure 2

A 27-year-old woman with Hashimoto thyroiditis confirmed in cytology after ultrasound-guided fine-needle aspiration. In the non-enhanced axial T1- (A) and T2- (B) weighted images, the thyroid gland (arrows) exhibits homogeneous, iso-signal intensity, and inhomogeneous, high signal intensity, respectively, when compared with adjacent muscle. In both images, the thyroid gland (arrows) exhibits a normal gland size and smooth margin. In the enhanced axial, fat-suppression T1-weighted image (C), the thyroid gland (arrows) exhibits homogeneously increased enhancement, when compared with adjacent muscle.

Figure 3

A 44-year-old woman with diffuse hyperplasia confirmed by histopathology after thyroid surgery for the treatment of papillary thyroid carcinoma. In the non-enhanced axial T1- (A) and T2-(B) weighted images, the thyroid gland (arrows) exhibits homogeneous, iso-. and slightly increased signal intensity, respectively, when compared with the adjacent muscle. In both images, the thyroid gland (arrows) exhibits increased size and a lobulated margin. In the enhanced axial, fat-suppression T1-weighted image (C), the thyroid gland (arrows) exhibits increased, but inhomogeneous enhancement, when compared with adjacent muscle.