Ust-medicine2 David Endocrinology Imaging Workshop 2
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Thyroid Ultrasound Sjoberg A. Kho, MD, FPCP
Principles
Ultrasound imaging begins with a transducer. Transducer serves both as transmitter and receiver of sound waves. This is done by converting an electrical signal to sound via piezoelectric elements and acoustic energy back to an electrical signal.
Principles
A complete firing sequence takes about 1/30 of a second. Transmission phase takes up less than 1% of the cycle with the remaining time devoted to detecting the returning echoes. Returning signals are then plotted as dots, forming a real time image representation of the anatomic structure being evaluated.
Factors affecting Image Quality
Frequency Higher frequencies give sharper image but loses depth Thyroid being superficial typically 7.5 to 13.0 MHz (detects 2-3 mm nodules) 3.0 to 5.0 MHZ maybe needed for bigger or substernal goiters
Factors affecting Image Quality
Type of Probe Linear array Curve array
Resolution Temporal – frames per second Gray scale – maximum number of gray shades (256) Spatial – depth and lateral
THYROID ULTRASOUN D
Image of the Thyroid Gland
Orientation Transverse scan – the right side of the patient is on the left of the screen or printed result Sagittal scan – cephalad presentation is depicted to the left
Image of the Thyroid Gland
Acoustic Impedance
Air – 0.004 Fat – 1.38 Water – 1.54 Blood – 1.61 Muscle – 1.7 Bone 7.8
Echogenecity
Hyperechoic – appears as white are from structures of higher acoustic impedance Hypoechoic – appears as black implies lower acoustic impedance
Echogenecity
Utility of the Thyroid Sonography
Defines size, shape, nature and extent of a palpable nodule Clarifies controversies about palpation (but not a substitute) Detects non-palpable nodules Color flow doppler provides data to static gray-scale image
Screening tool for high risk patients Identifies recurrence of tumor/ local metastasis Facilitates aspiration biopsy Facilitates percutaneous ethanol injection Monitor therapeutic goals
Pitfalls of Thyroid Sonography
Diversity of equipment within and among laboratories. Technician dependent. Clinicians often provide inadequate information or data of the clinical problem at hand. (Previous procedures, clinical findings and impression) Interpreting radiologists see the printed films only but not the real time images.
Thyroid size
Volume is estimated by = 0.5 (LxWxD) of each lobe
Lobar mass = 4.9D + 0.07L2W – 2.3
Normal Thyroid Transverse View
Longitudinal View
Normal Thyroid
Thyroid Cyst
Nodular goiter in treatment with thyroxine. Sudden pain in the right side of the neck, with a very painful swelling. Nodule in the right lobe, with irregular borders, 22x21x23 mm (5.7 cc); very hypoechoic, with echoes stratifications on the posterior wall, as for intraparenchymal hemorrage. That nodule was absent in a previous exam.
Thyroid Cyst
Large cyst (25.4 x 28.8 x 42.9 mm) in the left lobe. The nodule is very echopoor with posterior echoes enhancement. FNA: colloid cyst.
Thyroid Cyst
Large nodule in the left lobe (mm 41x46x69, 65 cc), very echopoor with posterior echoes enhancement. Aspiration of about 65 cc of very thick brown colloid.
Thyroid Cyst with Complex substance
Thyroid Cyst with Complex substance
Thyroid Nodule
Transverse (lower) and longitudinal (upper) section of the right lobe of the thyroid. Nodule in the lower pole (mm 15.4 x 21.0 x 27.2): hysoechoic and dishomogeneous structure, regular borders with halo sign. Fine needle aspiration: hyperplastic nodule.
Isoechoic Nodule with Halo sign
Nodule in the left lobe of the thyroid (mm 17.1 x 18.7 x 30.8). Rich periferic vascularization.
Multinodular Goiter: Longitudinal
Hashimoto’s Thyroiditis: Longitudinal
Graves Disease
Nornal size of the gland; the borders are shaded; very echopoor structure due to the presence of edema
Nornal size of the gland. Rich diffuse vascularization of the lobes.
Agenesis o the Left Lobe
Thyroid Calcificatons
Woman, 74 y.o. Large calcification in the base of the right lobe. Highly echogenic band with posterior acoustic shadow owing to total reflection of the ultrasound beam.
Large nodular goiter; micro calcification in thyroid tissue, with posterior acoustic shadow.
Papillary Cancer. Microcalcifications probably represent Psammoma bodies.
Man, 34 y.o. Solitary firm nodule in the left lobe of the thyroid. The nodule (21,1 x 17.7 x 26.8 mm) is hypoechoic, dishomogeneous; the borders are irregular with no halo sign and the anterior capsule of the gland is interrupted and infiltrated into the muscle. FNA: papillary carcinoma. Histological examination: papillary carcinoma, infiltrating the capsule and the muscle.
Characteristics of Benign vs. Malignant Nodules Malignant Almost all malignant nodules are hypoechoic but majority of benign nodules are also hypoechoic Microcalcifications may represent Psammoma bodies but calcifications can be a consequence of bleed
Benign Halo used to be believed to represent benign nodules but sometimes found in malignancy Sharp borders represent non-invasion but majority of malignant nodules also has sharp borders
Ultrasound-guided Fine Needle Aspiration Biopsy
Picture taken just after the needle insertion. The tip of the needle is just in the center of the nodule, between the second and the third dot of the guide.
Before and After Fine Needle Aspiration. Initially appearing as pure cyst but more solid component is visible after cystic fluid was removed. Improve yield of FNAB.
Advantages of UG-FNAB
Accurate needle placement for smaller and deeper nodules. Accurate aspiration of the walls of cysts or solid component of complex nodules. Several randomized trial comparing UG vs. palpation-guided FNAB showed improved sensitivity (62-100% vs. 4589%) with lower rate of inadequate specimen.
Ultrasound-guided Ethanol Injection
Summary
Ultrasound is not a substitute for a good physical examination. Indications for UTZ of Normal Thyroid External radiation during childhood History of familial thyroid cancer Thyroid cancer with hemithyroidectomy Lymph node that is TG positive
Summary
There is no single or combination of findings to determine whether nodule is benign or malignant. Used appropriately, ultrasonography of the thyroid gland can be very helpful in the decision making process of the clinician. In-office thyroid sonography may resolve some of the pitfalls associated in the interpretation of results.
Thank You
Principles
Ultrasound imaging begins with a transducer. Transducer serves both as transmitter and receiver of sound waves. This is done by converting an electrical signal to sound via piezoelectric elements and acoustic energy back to an electrical signal.
Principles
A complete firing sequence takes about 1/30 of a second. Transmission phase takes up less than 1% of the cycle with the remaining time devoted to detecting the returning echoes. Returning signals are then plotted as dots, forming a real time image representation of the anatomic structure being evaluated.
Factors affecting Image Quality
Frequency Higher frequencies give sharper image but loses depth Thyroid being superficial typically 7.5 to 13.0 MHz (detects 2-3 mm nodules) 3.0 to 5.0 MHZ maybe needed for bigger or substernal goiters
Factors affecting Image Quality
Type of Probe Linear array Curve array
Resolution Temporal – frames per second Gray scale – maximum number of gray shades (256) Spatial – depth and lateral
THYROID ULTRASOUN D
Image of the Thyroid Gland
Orientation Transverse scan – the right side of the patient is on the left of the screen or printed result Sagittal scan – cephalad presentation is depicted to the left
Image of the Thyroid Gland
Acoustic Impedance
Air – 0.004 Fat – 1.38 Water – 1.54 Blood – 1.61 Muscle – 1.7 Bone 7.8
Echogenecity
Hyperechoic – appears as white are from structures of higher acoustic impedance Hypoechoic – appears as black implies lower acoustic impedance
Echogenecity
Utility of the Thyroid Sonography
Defines size, shape, nature and extent of a palpable nodule Clarifies controversies about palpation (but not a substitute) Detects non-palpable nodules Color flow doppler provides data to static gray-scale image
Screening tool for high risk patients Identifies recurrence of tumor/ local metastasis Facilitates aspiration biopsy Facilitates percutaneous ethanol injection Monitor therapeutic goals
Pitfalls of Thyroid Sonography
Diversity of equipment within and among laboratories. Technician dependent. Clinicians often provide inadequate information or data of the clinical problem at hand. (Previous procedures, clinical findings and impression) Interpreting radiologists see the printed films only but not the real time images.
Thyroid size
Volume is estimated by = 0.5 (LxWxD) of each lobe
Lobar mass = 4.9D + 0.07L2W – 2.3
Normal Thyroid Transverse View
Longitudinal View
Normal Thyroid
Thyroid Cyst
Nodular goiter in treatment with thyroxine. Sudden pain in the right side of the neck, with a very painful swelling. Nodule in the right lobe, with irregular borders, 22x21x23 mm (5.7 cc); very hypoechoic, with echoes stratifications on the posterior wall, as for intraparenchymal hemorrage. That nodule was absent in a previous exam.
Thyroid Cyst
Large cyst (25.4 x 28.8 x 42.9 mm) in the left lobe. The nodule is very echopoor with posterior echoes enhancement. FNA: colloid cyst.
Thyroid Cyst
Large nodule in the left lobe (mm 41x46x69, 65 cc), very echopoor with posterior echoes enhancement. Aspiration of about 65 cc of very thick brown colloid.
Thyroid Cyst with Complex substance
Thyroid Cyst with Complex substance
Thyroid Nodule
Transverse (lower) and longitudinal (upper) section of the right lobe of the thyroid. Nodule in the lower pole (mm 15.4 x 21.0 x 27.2): hysoechoic and dishomogeneous structure, regular borders with halo sign. Fine needle aspiration: hyperplastic nodule.
Isoechoic Nodule with Halo sign
Nodule in the left lobe of the thyroid (mm 17.1 x 18.7 x 30.8). Rich periferic vascularization.
Multinodular Goiter: Longitudinal
Hashimoto’s Thyroiditis: Longitudinal
Graves Disease
Nornal size of the gland; the borders are shaded; very echopoor structure due to the presence of edema
Nornal size of the gland. Rich diffuse vascularization of the lobes.
Agenesis o the Left Lobe
Thyroid Calcificatons
Woman, 74 y.o. Large calcification in the base of the right lobe. Highly echogenic band with posterior acoustic shadow owing to total reflection of the ultrasound beam.
Large nodular goiter; micro calcification in thyroid tissue, with posterior acoustic shadow.
Papillary Cancer. Microcalcifications probably represent Psammoma bodies.
Man, 34 y.o. Solitary firm nodule in the left lobe of the thyroid. The nodule (21,1 x 17.7 x 26.8 mm) is hypoechoic, dishomogeneous; the borders are irregular with no halo sign and the anterior capsule of the gland is interrupted and infiltrated into the muscle. FNA: papillary carcinoma. Histological examination: papillary carcinoma, infiltrating the capsule and the muscle.
Characteristics of Benign vs. Malignant Nodules Malignant Almost all malignant nodules are hypoechoic but majority of benign nodules are also hypoechoic Microcalcifications may represent Psammoma bodies but calcifications can be a consequence of bleed
Benign Halo used to be believed to represent benign nodules but sometimes found in malignancy Sharp borders represent non-invasion but majority of malignant nodules also has sharp borders
Ultrasound-guided Fine Needle Aspiration Biopsy
Picture taken just after the needle insertion. The tip of the needle is just in the center of the nodule, between the second and the third dot of the guide.
Before and After Fine Needle Aspiration. Initially appearing as pure cyst but more solid component is visible after cystic fluid was removed. Improve yield of FNAB.
Advantages of UG-FNAB
Accurate needle placement for smaller and deeper nodules. Accurate aspiration of the walls of cysts or solid component of complex nodules. Several randomized trial comparing UG vs. palpation-guided FNAB showed improved sensitivity (62-100% vs. 4589%) with lower rate of inadequate specimen.
Ultrasound-guided Ethanol Injection
Summary
Ultrasound is not a substitute for a good physical examination. Indications for UTZ of Normal Thyroid External radiation during childhood History of familial thyroid cancer Thyroid cancer with hemithyroidectomy Lymph node that is TG positive
Summary
There is no single or combination of findings to determine whether nodule is benign or malignant. Used appropriately, ultrasonography of the thyroid gland can be very helpful in the decision making process of the clinician. In-office thyroid sonography may resolve some of the pitfalls associated in the interpretation of results.
Thank You
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