37 Thyroid Mass

10.1055/b-0040-176873

37 Thyroid Mass

Steven S. Chua, Eduardo J. Matta, Kaustubh G. Shiralkar, and Chakradhar R. Thupili

37.1 Case 1

A 49-year-old woman presents with left arm weakness. MRI of the cervical spine without contrast was performed to evaluate for possible cervical nerve root compression (▶ Fig. 37.1).

**Fig. 37.1** T2-weighted axial image of the cervical spine demonstrates a T2 hyperintense lesion (*yellow arrow*) within the right thyroid lobe, extending through the midline into the isthmus. This lesion measures about 5 cm in maximum dimension.

37.1.1 Imaging Impression

Incidentally detected, 5-cm solid mass in the right lobe of the thyroid gland, which is incompletely imaged on this cervical spine MRI (▶ Fig. 37.2).

**Fig. 37.2** Sagittal images of the cervical spine. The previously visualized right thyroid lesion is again depicted as isointense in the T1-weighted image **(a)**, hyperintense in the short tau inversion recovery (STIR) image **(b)**, and hyperintense in the T2 image **(c)**.

37.1.2 Additional Testing Needed: Thyroid Ultrasound

Given that thyroid nodules can have variable signal characteristics depending on their composition and that most MRIs of the cervical spine are not optimized for an accurate diagnosis, thyroid nodules meeting the criteria for size and age based on the ACR Appropriateness Criteria (> 1 cm for individuals younger than 35 years and > 1.5 cm for individuals older than 35 years without history of thyroid cancer or symptomatic thyroid disease) ¹ are often further evaluated by thyroid ultrasound. Please see ▶ Table 37.3 for more details. Thyroid ultrasound can provide a higher resolution method to better evaluate the nodules to determine the need for fine needle aspiration (FNA). The thyroid ultrasound is shown in ▶ Fig. 37.3.

**Fig. 37.3** Gray scale images of the right thyroid lobe were obtained in the longitudinal **(a)** and transverse **(b)** planes and demonstrated a 4.6 × 2.4 × 4 cm solid-appearing, hypoechoic, slightly lobulated nodule without significant internal punctate echogenic foci, wider-than-tall nodule, corresponding to the nodule seen on the prior MRI of the cervical spine.

37.1.3 Imaging Interpretation

Incidentally detected 4.6-cm thyroid mass is solid, hypoechoic without internal echogenic foci, wider than tall, and fairly well marginated with a slightly lobulated contour.

Based on TI-RADS v2017 criteria, ² the thyroid nodule scores a total of 6 points and is considered moderately suspicious, meeting the criteria for FNA.

The TI-RADS (Thyroid Imaging Reporting and Data System) v2017 ² grades nodules based on five criteria: nodule composition, nodule border, nodule shape, presence of echogenic foci, and nodule echogenicity; it also assigns points and stratifies nodules to benign (0 points), not suspicious (1–2 points), mildly suspicious (3 points), moderately suspicious (4–6 points), and highly suspicious (≥ 7 points). Please see ▶ Table 37.1 for more details.

**Table 37.1** TI-RADS v2017 scoring criteria and imaging attributes and points (pts)
Composition	Echogenicity	Shape	Margin	Echogenic foci
Cystic (0 pts)	Anechoic (0 pts)	Wider than tall (0 pts)	Smooth (0 pts)	None (0 pts)
Spongiform (0 pts)	Hyperechoic (1 pt)	Taller than tall (0 pts)	Ill-defined (0 pts)	Comet-tail (0 pts)
Mixed (1 pt)	Isoechoic (1 pt)		Lobulated (2 pts)	Macrocalcification/coarse (1 pt)
Solid (2 pts)	Hypoechoic (2 pts)		Extrathyroidal (3 pts)	Peripheral/rim calcifications (2 pts)
Cannot determine (2 pts)	Very hypoechoic (3 pts)		Cannot determine (1 pt)	Punctate/microcalcification (3 pts)
	Cannot determine (1 pt)
Source: Adapted from Tessler et al. ² Note: Nodule characteristics are evaluated based on five imaging attributes of composition, echogenicity, shape, margin, and echogenic foci based on the TI-RADS v2017 criteria.