THYROID PAPERS from AJR

ABSTRACT :

OBJECTIVE. We aimed to establish the malignancy rate of thyroid nodules initially characterized as atypia of undetermined significance or follicular lesion of undetermined significance (AUS/FLUS) and whether they differ according to histologic subcategory. We also investigated the value of ultrasound features that predict malignancy and BRAF^V600E mutation analysis and suggest strategies for the management of AUS/FLUS nodules.

MATERIALS AND METHODS. A total of 165 AUS/FLUS nodules were investigated. There are nine histologic subcategories of AUS/FLUS nodules. We compared the risk of malignancy in thyroid nodules according to the histologic subcategory using ultrasound findings and of those exhibiting the BRAF^V600E mutation.

RESULTS. The malignancy rate of nodules with an initial diagnosis of AUS/FLUS was 55.2% (91/165). The malignancy rates by histologic subcategory were 0% in groups 1 (0/2), 2 (0/3), 4 (0/3), 7 (0/3), and 8 (0/1); 76.5% (13/17) in group 3; 83.1% (59/71) in group 5; and 29.2% (19/65) in group 9. The malignancy rate of nodules with suspicious ultrasound features was 79.3% (73/92), and the malignancy rate of nodules with indeterminate ultrasound features was 24.7% (18/73). AUS/FLUS nodules exhibiting taller-than-wide shape, illdefined margins, and microcalcifications or macrocalcifications showed significantly higher odds ratios. The likelihood of BRAF^V600E mutation–positive nodules showing malignancy was 97.5% (39/40), whereas 39.7% (25/63) of BRAF^V600E mutation–negative nodules were malignant (p < 0.05).

CONCLUSION. The malignancy rate of AUS/FLUS nodules in our study cohort was higher than previously reported. Nodules with suspicious features on ultrasound had a higher malignancy rate than did those with indeterminate features on ultrasound. The malignancy rate differed according to histologic subcategory; therefore, management of AUS/FLUS nodules should be tailored according to histologic subcategory.

Keywords: Bethesda System for Reporting Thyroid Cytopathology, BRAF^V600E mutation, thyroid gland, thyroid nodules, ultrasound

ABSTRACT :

OBJECTIVE. Fine-needle aspiration biopsy (FNAB) is the current primary test to risk stratify thyroid nodules. However, in up to one third of biopsies, cytology is indeterminate. The Bethesda System for Reporting Thyroid Cytopathology categorizes thyroid cytology findings into six groups, with each group assigned a putative malignancy risk. This article reviews the Bethesda System, emphasizing the key facts necessary to understand thyroid biopsy results and effectively manage patients after FNAB.

CONCLUSION. It is important to diagnose and stratify the risk of malignancy in thyroid nodules. A working knowledge of the Bethesda System permits accurate, evidence-based risk stratification of patients with thyroid nodules and thereby facilitates their management. Because it is a uniform diagnostic approach, the Bethesda System allows comparisons of different management strategies across different institutions.

Keywords: atypia of undetermined significance (AUS), Bethesda System for Reporting Thyroid Cytopathology, cytology, fine-needle aspiration biopsy, follicular lesion of undetermined significance (FLUS), follicular neoplasm, nondiagnostic thyroid biopsy, thyroid

Presented at the 2012 annual meeting of the Radiological Society of North America, Chicago, IL.

NUỐT KHÓ VÙNG KHẨU HẦU

Ultrasonography, a portable, noninvasive, and radiation-free technique, had been applied for assessment of oropharyngeal swallowing function for decades. The most common application is for observing the tongue, larynx, and hyoid-bone movement by B-mode ultrasonography. Although some studies describing techniques of ultrasonography have been published, its clinical application is still not well known. Other methods such as M-mode ultrasonography, Doppler ultrasonography, three-dimensional reconstruction, or pixel analysis had been reported without promising results. The techniques of ultrasonography examination of the tongue and larynx/hyoid movement are introduced in this work; in addition, a brief review about the methods and application of ultrasonography in assessing swallowing function in different groups of patients had been described. Ultrasonography, instead of a substitution of videofluoroscopic swallowing study (VFSS), may be able to complement VFSS as a rapid examination tool for screening and for follow-up of swallowing function. Further large-scale quantitative analyses that provide diagnostic value and correlation with functional outcome are mandatory.

Fig. 1.

(A) Anatomy of the oral cavity and position of the sector transducer. (B) Submental midsagittal ultrasonography image showing the genioglossus muscle (G), geniohyoid (arrows), and mylohyoid muscles (arrowheads) at the mouth floor. The tongue surface appears as hyperechoic lines (broad arrows).

Fig. 2.

Calculation of tongue thickness: The dashed lines “a” and “b” indicate the border of the ultrasonographic beam. The dashed line “c” is the bisection of the ultrasonographic beam, in which the midtongue thickness is measured (two-end arrow).

Fig. 3.

(A) B-mode ultrasonographic imaging of the tongue. M-mode ultrasonography was extracted at a vertical scan line (dashed line). The arrowheads indicate the tongue surface. (B) M-mode ultrasonography. Point a indicates the onset of tongue movement, while point b indicates the return of tongue to its resting position. The two-end arrow indicates the peak-to-peak amplitude of tongue movement at the scan line.

Fig. 4.

Transverse view of submental ultrasonography. The mylohyoid muscle (MH) is a thin layer of tissue. Below are the geniohyoid (GH) and genioglossus (GG) muscles; the cross-section of anterior belly of the digastric muscle (DG) appears as an hypoechoic, oval-shaped structure.

Fig. 5.

(A) The positioning of the transducer and (B) the anatomy of examination of thyroid–hyoid approximation. (C) Ultrasonography image showing the hyoid bone (H) and thyroid cartilage (T); the dashed line is the distance between the thyroid cartilage and the hyoid bone.

Fig. 6.

(A) Anatomy of the oral cavity and position of the curvilinear transducer. (B) Submental midsagittal ultrasonography image showing the hyoid bone (H) and the mandible (M) and muscles at the mouth floor (arrowheads). The tongue surface appears as hyperechoic lines (arrows).

Fig. 7.

Calculation of the hyoid bone displacement. (A) The position of the mandible (black arrow) was used as the reference point, and the resting position of the hyoid bone (white arrow) was designated as a pair of coordinates (X₁, Y₁). (B) During swallowing, the hyoid bone moves upward and forward into a new position (arrow) designated by X₂, Y₂, with the mandible as the reference point. The distance between the two coordinates before and after swallowing denotes the hyoid bone displacement (thin arrow).