US | Thyroid

Ultrasound of the Thyroid

Ashley Davidoff MD

Introduction

Features to be evaluated by ultrasound

Overall gland size for each lobe

Sagital images for length and depth

Transverse image for width

Nodules

for nodules > 1.0 cm and any other suspicious nodules

Measure three dimensions (sagital and transverse images)

Assess colour flow and record image

Primary features of malignancy for nodules

Irregular Margins

Thick and irregulkar halo

Microcalcifiction

Macrocalcification

Solid Nodule

Image to assess cystic areas and mural nodules

Colour flow central

Greater than surrounding thyroid

Features suggestive of benignancy

Cystic nodules

Peripheral (eggshell) calcification

Soft findings

Peripheral calcification – benign

Taller than wide – malignant

Profoundly hypoechoic < muscle – malignant

Which nodules to image

All nodules > 1 cm except for multinodular gland with diffuse similar nodules

Any smaller nodules noted to be highly suspicious for malignancy

Solid, microcalcifications, internal colour flow

When to recommend FNA

Microcalcification

If > 1.0 cm or smaller nodules if also solid and/or internal colour flow

Mainly solid or macrocalcification

If > 1.5 cm

Not purely cystic (no mural nodule)

If > 2.0 cm

Substantial interval growth

When to recommend follow up

None of the above described

Multinodular gland with diffuse bilateral similar nodules (little visible normal thyroid tissue)

Multiple nodules

Biopsy the largest or most suspicious 2 or 3 nodules > 1.0 cm

Timing of follow up

follow up at 6 months then 12, 24 and 36 months.

The Normal Ultrasound

A normal ultrasound of the thyroid gland is demonstrated. Image a and b are sagittal images, image c is a transverse view of both lobes and the isthmus, and image d and e are individual measurements of the right and left lobe respectively.. The normal right lobe (a,d) measures 4.9cms (length) x 1.1cms (A-P anteroposterior) X 1.6 cms (transverse TRV) and the left lobe (b,e) 25.09cms (craniocaudad), by 1.1cms (A-P) by 1.8cms (transverse).

The Normal Gland and Doppler Flow

A normal ultrasound of the thyroid gland is demonstrated. Image a and b are sagittal and transverse images, and images c and d are comparable views with color flow Doppler. The normal ultrasonographic characteristics demonstrating size shape position and character of the thyroid and normal color flow pattern is well demonstrated.

Diffuse Abnormality

Measuring Size, Evaluating Shape and Character

A normal ultrasound of the thyroid gland (a,b) is juxtaposed with the ultrasound of a 78 year female with hypothyroidism (c,d) A diffusely enlarged, heterogeneous thyroid gland is seen in the hypothyroid patient. The normal thyroid measures 5.0cms (length) x 1.1cms (A-P anteroposterior) X 1.4 cms (transverse TRV) and the abnormal thyroid measures 8.5cms (craniocaudad), by 3.9cms (A-P) by 4.8cms (transverse). Clinical findings were consistent with thyroiditis, with biochemical findings suggesting hypothyroidism. The enlarged gland in the transverse dimension is almost round. (d). This rounded shape in the transverse dimension is a clue to the presence of the enlarged gland, even before the measurements are taken and evaluated. The gland is heterogeneous particularly well seen on the sagittal view (c). The findings are consistent with a thyroiditis.

Hypervascularity of Thyroiditis

A diffusely enlarged, heterogeneous thyroid gland is seen in this 30 year old hypothyroid female patient. The thyroid measures 6.4cms (craniocaudad), by 3.2cms (A-P) by 2.4cms (transverse). Clinical findings were consistent with thyroiditis, with biochemical findings suggesting hypothyroidism. The sagittal view shows coarse heterogeneous echo texture with fine white bands consistent with fibrosis. The increased vascularity is seen throughout the gland (c,d), but is also seen particularly along some of the bands in the posterior aspect of the gland (c arrows). The enlarged gland in the transverse dimension is almost round. (b). This rounded shape in the transverse dimension is a clue to the presence of the enlarged gland, even before the measurements are taken and evaluated. The findings are consistent with a thyroiditis.

Lymphoma of the Thyroid

Normal Vascularity

The patient is a 62 year female who had a biopsy proven lymphoma of the thyroid. A heterogeneous thyroid gland is seen in this 62 year old female patient. The left lobe of the thyroid measures 4.7cms (craniocaudad), by 1.7cms (A-P) by 1.5cms (transverse) which is normal in size. The sagittal view shows coarse heterogeneous echo texture. The transverse view shows a rounded appearance and although the dimensions are normal the shape suggests abnormality. Additionally the isthmus is thicker than usual. The color flow Doppler study also is normal The differential diagnosis for this appearance includes thyroiditis and other infiltrative diseases such as amyloidosis. Biopsy showed lymphoma.

Normal (a,b) Lymphoma (c,d) and Post Chemo XRT (d,e)

The series ultrasounds demonstrate a normal patient (a sagittal ,b transverse) showing normal texture juxtaposed studies in the same projections of a 62 year female who had a biopsy proven lymphoma ((c,d). Following chemotherapy and radiation therapy she became hypothyroid and repeat ultrasound of her thyroid gland (e,f) are shown. The second series (c,d) with active lymphoma show a rounded gland in the transverse view, a thickened isthmus, with heterogeneous texture. The linear dimensions of the gland are within normal limits Following therapy the gland overall remains the same size but the texture shows many more hypoechoic amorphous regions likely due to necrosis.

Nodules

Malignant Nodule Occupying the Entire Gland

A large nodule in the thyroid occupies almost the entire right lobe (a). The nodule measures 2.9cms by 1.5cms. The gland is not enlarged and measures 3.5cms (craniocaudad), by 1.8cms (A-P) by 2.4cms (transverse). The nodule is almost isoechoic with normal thyroid but shows internal irregular areas of hypoechogenicity, regions of isoechogenicity, as well as microcalcifications (white arrows (c). There is irregularity of the border at the posterior aspect of the nodule green arrow a). The halo shows irregular borders in this region as well. Internal vascularity is minimal (d). The irregular surface is concerning for a malignant processes. The diagnosis in this patient was papillary carcinoma