Thyroid Nodule Margin Assessment Using ACR TI‐RADS: Adding Points for Macrolobulation Impairs Performance

Abstract

Objective We evaluated the performance of ACR TI‐RADS when points for lobulated margins are applied only when the margins meet a quantified measure of margin microlobulation and not applied when nodules only demonstrate macrolobulation. Methods We retrospectively reviewed ultrasound and pathology records (May 01, 2018 to July 31, 2020) to find all thyroid nodules at one institution characterized as having lobulated margins using the ACR TI‐RADS lexicon and subsequently undergoing fine needle aspiration (FNA). Nodule margins were evaluated to note the presence or absence of microlobulation, quantitatively defined as a protrusion with a base <2.5 mm in length. The impact to detection of malignant nodules and avoidance of benign FNA when margin points for lobulation were added only when microlobulated was analyzed. Results 58 of 516 thyroid nodules undergoing US‐guided FNA were classified as lobulated, comprising the study population. 21 (36.2%) had microlobulated margins, with 12 of the 21 (57.1%) being malignant. Comparatively, of the 37 nodules showing only macrolobulated margins without microlobulation, only 2 (5.4%) were malignant (P < .0001). For 53 nodules ≥10 mm, 15 (28.3%) benign nodules would not have met size criteria for FNA had points for margins not been applied when only showing macrolobulation, whereas all 10 malignant nodules would still have been sampled. Conclusion Adding two points to the ACR TI‐RADS score for lobulated thyroid nodules should only apply when microlobulations are present.

Association of Ultrasonography Features of Follicular Thyroid Carcinoma With Tumor Invasiveness and Prognosis Based on WHO Classification and TERT Promoter Mutation

“…According to the revised Korean Thyroid Imaging Reporting and Data System (K-TIRADS) and American College of Radiology-TIRADS (ACR-TIRADS) [ 23 24 ], all FTC lesions were described according to the following criteria: 1) composition (cystic with no obvious solid component, predominantly cystic with > 50% of cystic portion, predominantly solid with ≤ 50% of cystic portion, or solid with no cystic component), 2) echogenicity (hyperechoic, isoechoic, mild hypoechoic, or marked hypoechoic), 3) margin (smooth, ill defined, or irregular including spiculated and microlobulated), 4) echogenic foci (punctate echogenic foci, macrocalcification, rim or peripheral calcification, or intracystic echogenic foci with comet tail artifact), and 5) orientation (parallel or nonparallel). In addition, lobulation (defined as rounded projection areas where the base of the outward protrusion measures ≥ 2.5 mm) [ 25 26 ] and heterogeneity (defined as the presence of two different portions of echogenicity [iso or hyperechoic vs. mild or marked hypoechogenicity] within the solid portion) were also evaluated.…”