Ultrasonographic Findings in Common Thyroid and Parathyroid Disorders—Advantages of Real Time Observation by the Endocrinologist with Their Own Ultrasound Machine

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Review Ultrasonographic Findings in Common Thyroid and Parathyroid Disorders—Advantages of Real Time Observation by the Endocrinologist with their Own Ultrasound Machine

Jack Wall 1,*, Bernard Champion 1, Samer El-Kaissi 2 and Hooshang Lahooti 3

1 Department of Health Sciences, Macquarie University Balaclava Rd, Macquarie Park, NSW 2109, Australia; [email protected] 2 Cleveland Clinic, Island-59 Hamouda Bin Ali Al Dhaheri St, Jazeerat Al Maryah, Abu Dhabi FR27613, United Arab Emirates; [email protected] 3 Department of Medicine, Nepean Clinical School, The University of Sydney, Camperdown, NSW 2006, Australia; [email protected] * Correspondence: [email protected]; Tel.: +61-0402-890-919

Abstract: In this review we discuss the significance of the main ultrasonographic features of common thyroid and parathyroid conditions, with a focus on the advantages of real time observation. The thyroid specialist, defined as an endocrinologist with a major interest in thyroid disorders and access to a portable ultrasound machine, can correlate what they see with the thyroid blood test results and clinical findings in a way that is not available to the general endocrinologist who relies on the interpretation by the consultant radiologist of ultrasound images prepared by a technician. We also discuss the significance of the small, very bright, intra nodular microcalcifications found in benign Citation: Wall, J.; Champion, B.; colloid nodules, which we call “colloid spots” and the difference between these and the 3–4 mm soft El-Kaissi, S.; Lahooti, H. microcalcifications that are 90% specific for papillary thyroid cancer and provide a new system for Ultrasonographic Findings in staging the inflammatory changes in Hashimoto thyroiditis, as observed on ultrasonography. Common Thyroid and Parathyroid Disorders—Advantages of Real Time Keywords: ultrasonography; ultrasound machine; thyroid; parathyroid; intra nodular microcalcifica- Observation by the Endocrinologist tion; Graves’ hyperthyroidism; Hashimoto thyroiditis with their Own Ultrasound Machine. Reports 2021, 4, 8. https://doi.org/ 10.3390/reports4010008 1. Introduction Academic Editor: Jolanta Krajewska Thyroid ultrasonography has become a routine tool for the endocrinologist in the Received: 25 January 2021 diagnosis and management of thyroid and parathyroid disorders [1,2]. However, it is now Accepted: 18 March 2021 clear that the thyroid specialist (“thyroidologist”) with a portable ultrasound machine is in Published: 23 March 2021 the best position to correlate the features of thyroid nodules and other thyroid disorders with the clinical findings and blood test results. In addition, the thyroid specialist can Publisher’s Note: MDPI stays neutral provide “one stop shopping” for their patients as they also perform their own fine needle with regard to jurisdictional claims in aspiration biopsies (FNAB) of suspicious nodules. published maps and institutional affil- In this review we describe the ultrasound features of the common types of thyroid iations. disorders, how to correctly interpret what is seen, when to repeat the imaging and when to carry out FNAB of suspicious nodules. We will describe some newly recognised features of thyroid sonograms and briefly discuss the sonographic appearances of parathyroid adenomas, the usual cause of primary hyperparathyroidism. The purpose of the review Copyright: © 2021 by the authors. is to provide an understanding of the utility of real time thyroid, parathyroid and neck Licensee MDPI, Basel, Switzerland. ultrasound for the aspiring thyroid specialist, its scope in the office and how can it help This article is an open access article in the patient’s management. All figures are derived from one of the authors’ (JW) own distributed under the terms and patients and were obtained using his M-Tubo Sonosite portable ultrasound machine and a conditions of the Creative Commons 5 MHZ small parts transducer. Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/).

Reports 2021, 4, 8. https://doi.org/10.3390/reports4010008 https://www.mdpi.com/journal/reports Reports 2021, 4, 8 2 of 16

2. The Normal Thyroid Gland Critical to being able to recognize ultrasonographic abnormalities in patients with thyroid disorders, it is necessary to fully understand the sonographic characteristics of the normal thyroid gland, an example of which is shown in Figure1. The overall size of the thyroid gland is determined by measuring its width, depth and length, from which the volume of each lobe can be calculated. With experience, the user can develop their own reference ranges for adult males and adult females, and for pregnancy (the volume of the thyroid gland increases by approx. 30% during pregnancy). While there is a big variation in the size of the normal gland which reflects both genetic and environmental factors, such as local iodine availability and the effect of pregnancy, each lobe of the normal gland measures approx. 50 × 30 × 10 mm with a thin isthmus connecting the two lobes [3]. Some euthyroid subjects have an enlarged gland that otherwise looks normal, reflecting either a normal variation, rare abnormalities of thyroid hormone metabolism or iodine deficiency goitre, which is presumed to be rare in Australia. An extra small lobe arising from the top of the left lobe, called the pyramidal lobe, is present in approximately 20% of people. This can be misdiagnosed as a nodule and even biopsied. The overall shape of the normal thyroid also varies, and some subjects have one or two thin and elongated lobes that extend laterally into the neck. Finally, a transverse view of the oesophagus can often Reports 2021, 4, 8 be seen to the medial side of the left lobe, that to the uninitiated could also be mistaken3 of for 16

a nodule.

FigureFigure 1. 1.Right Right lobe lobe of of the the thyroid thyroid gland gland of of a 34-year-olda 34-year-old female female with with no no personal personal or familyor family history history of of thyroid disease. The gland is of “normal size” and the texture throughout is described as thyroid disease. The gland is of “normal size” and the texture throughout is described as “isoechoic”. “isoechoic”. The texture of the normal thyroid texture, or echogenicity, as determined using the ultrasound3. Nodules grey scale, is described as isogenous or isoechoic. Features of an abnormal gland, such asThyroid cysts or nodules nodules, are that very are common, less white increasing than normal, to a prevalence ranging from of about grey 60% through in adult to black,women are aged described 60 or asmore. being Most variably benign hypoechoic. nodules Someare “colloid” nodules according and areas ofto inflammationthe dominant thatpresence are whiter of fluid than and normal few cells are ( describedlow cell:fluid as being ratio), hyperechoic. i.e., the nodule Thyroid comprises cysts, scattered which arenormal fluid-containing thyroid follicular sacs, andcells the within “black a background holes” of end of stagethick, Hashimotoviscous fluid thyroiditis, [4]. Although are uniformlythe prevalence black. ofBenign cancer colloidis about nodules 8% in patients are usually with isoechoic one or more or slightly nodules, hypoechoic, the risk of whilstcancer more is greater cellular in follicularpatients with nodules a single may benodule slightly since hyperechoic. multi nodular, The ability or colloid, to recognize goitre is variationsa benign disease in the echogenicity and all of the of nodules the thyroid are expected gland itself to andbe the nodules, same, differing cysts or infiltrations only in size. withinA micro the gland cancer can incidentally only be obtained found by in extensive, a multi longnodular term can experience, be considered even surpassing to be an thatincident of thealoma general that radiologist. would not have harmed the patient if left alone. An example of a benign colloid nodule with a sharp edge, halo (a black ring thought to represent compressed blood vessels) and isogenic texture, which is <3 cm and wider than tall, is shown in Figure 2.

Figure 2. Thyroid ultrasound from a patient with a nodule that was shown to be benign on biopsy. The nodule is isogenic, wider than tall, with a sharp edge and halo.

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Another feature of the thyroid gland to be assessed is its vascularity. The normal vascularity of the thyroid reflects the distribution of the thyroid arteries and veins, which will vary from subject to subject and include several anatomical variations, all of which are “normal”, and the overall blood flow into and out of the gland. In Graves’ hyperthyroidism, the overall blood supply is greatly increased due to the diffuse and intense inflammatory reaction, whereas in Hashimoto thyroiditis, the blood supplyFigure to1. Right the thyroid lobe of isthe initially thyroid increasedgland of a 34 when-year the-old inflammatoryfemale with no reactionpersonal or is active,family history then decreasesof thyroid asdisease. the gland The gland is progressively is of “normal destroyed size” and the over texture time throughout and replaced is described by fibrosis as and scarring.“isoechoic”. Abnormalities of the blood supply in the various thyroid disorders will be discussed in more detail below. 3. Nodules 3. Nodules Thyroid nodules are very common, increasing to a prevalence of about 60% in adult womenThyroid aged nodules 60 or more. are very Most common, benign increasingnodules are to “colloid” a prevalence according of about to 60%the dominant in adult womenpresence aged of fluid 60 or and more. few Most cells benign (low cell:fluid nodules ratio), are “colloid” i.e., the accordingnodule comprises to the dominant scattered presencenormal thyroid of fluid follicular and few cellscells (lowwithin cell:fluid a background ratio), i.e., of thick, the nodule viscous comprises fluid [4]. scattered Although normalthe prevalence thyroid follicular of cancer cells is about within 8% a background in patients ofwith thick, one viscous or more fluid nodules, [4]. Although the risk the of prevalencecancer is greater of cancer in ispatients about 8%with in a patients single nodule with one since or more multi nodules, nodular, the or riskcolloid, of cancer goitre is is greatera benign in patientsdisease and with all a of single the nodules nodule sinceare expected multi nodular, to be the or same, colloid, differing goitre isonly a benign in size. diseaseA micro and cancer all of the incidentally nodules are found expected in a to multi be the nodular same, differing can be only considered in size. A to micro be an cancer incidentally found in a multi nodular can be considered to be an incidentaloma that incidentaloma that would not have harmed the patient if left alone. An example of a would not have harmed the patient if left alone. An example of a benign colloid nodule benign colloid nodule with a sharp edge, halo (a black ring thought to represent with a sharp edge, halo (a black ring thought to represent compressed blood vessels) and compressed blood vessels) and isogenic texture, which is <3 cm and wider than tall, is isogenic texture, which is <3 cm and wider than tall, is shown in Figure2. shown in Figure 2.

FigureFigure 2. 2.Thyroid Thyroid ultrasound ultrasound from from a a patient patient with with a a nodule nodule that that was was shown shown to to be be benign benign on on biopsy.biopsy. TheThe nodule nodule is is isogenic, isogenic, wider wider than than tall, tall, with with a a sharp sharp edge edge and and halo. halo.

Some intra nodular “microcalcifications” are actually colloid, which may be lined up like a comet tail or dispersed around the inner edge of the nodule (Figure3). Others, brighter and sharper, are probably colloid crystals. In many nodules there is a single bright spot, often at one side of the nodule, like a nucleus of a cell, that might be the source of the colloid fluid, that could be called a “colloidoma”. Although radiologists describe these as “microcalcifications”—implying suspicion for papillary thyroid cancer—this is probably not correct as, in the authors’ experience, they are quite different from the microcalcifications of papillary thyroid cancer. Finally, some of these colloid bright spots may represent what has been called “the ring down resonance artifact”. Overall, our experience suggests that colloid bright spots are mislabelled as microcalcifications in approximately 30% of cases. Reports 2021, 4, 8 4 of 16

Some intra nodular “microcalcifications” are actually colloid, which may be lined up like a comet tail or dispersed around the inner edge of the nodule (Figure 3). Others, brighter and sharper, are probably colloid crystals. In many nodules there is a single bright spot, often at one side of the nodule, like a nucleus of a cell, that might be the source of the colloid fluid, that could be called a “colloidoma”. Although radiologists describe these as “microcalcifications”—implying suspicion for papillary thyroid cancer—this is probably not correct as, in the authors’ experience, they are quite different from the microcalcifications of papillary thyroid cancer. Finally, some of these colloid bright spots may represent what has been called “the ring down resonance artifact”. Overall, our Reports 2021, 4, 8 4 of 16 experience suggests that colloid bright spots are mislabelled as microcalcifications in approximately 30% of cases.

FigureFigure 3. 3.A benignA benign nodule nodule with with a series a series of bright of bright intramodular intramodular microcalciﬁcations microcalcifications (arrow). These (arrow). These spotsspots need need to beto differentiatedbe differentiated from thefrom larger the softer larger (less softer bright) (less microcalciﬁcations bright) microcalcifications which are often which are foundoften in found papillary in papillary thyroid cancer. thyroid cancer.

4. Follicular Nodules 4. Follicular Nodules Follicular nodules are much less common than colloid nodules with a different ap- pearanceFollicular on ultrasound; nodules they are are more much cellular, less common giving a solid than appearance, colloid nodules with a whitish with a different colour,appearance i.e., less on hypoechoic. ultrasound; They they too have are a more sharp edgecellular, and halo giving and growa solid slowly appearance, over with a timewhitish [5]. The colour, problem i.e., withless thesehypoechoic. lesions is They that FNABtoo have is unable a sharp to differentiateedge and halo between and grow slowly aover benign time follicular [5]. The adenoma problem and follicular with these cancer, lesions and if is the that latter FNAB is suspected, is unable thyroid to differentiate surgerybetween is thea benign ﬁnal arbitrator. follicular About adenom 10%a of and benign follicular thyroid cancer nodules, and are follicular,if the latter and is suspected, most of them end up being removed. Two examples of follicular nodules that were ﬁnally proventhyroid to surgery be benign is are the shown final inarbitrator. Figure4. On About follow-up 10% of ultrasound benign thyroid (US), 6–12 nodules months are follicular, Reports 2021, 4, 8 and most of them end up being removed. Two examples of follicular nodules5 of 16 that were later, repeat biopsy might be indicated if a nodule has grown by 20% or more in two or morefinally dimensions; proven benignto be b nodulesenign are also shown grow, but in lessFigure quickly. 4. On follow-up ultrasound (US), 6–12 months later, repeat biopsy might be indicated if a nodule has grown by 20% or more in two or more dimensions; benign nodules also grow, but less quickly.

Figure 4. Two examples of follicular nodules that were shown at surgery to be benign. The nodules are roughly oval shaped, Figureslightly 4. hyper Two echoicexamples and of have follicular sharp edgesnodules and, that particularly, were shown the biggerat surgery of the to two, be benign. thick halos. The nodules are roughly oval shaped, slightly hyper echoic and have sharp edges and, particularly, the bigger of the two, thick halos. 5. Hot Nodules 5. Hot Nodules Nodules shown to be “hot” or “toxic” on technetium scan are “never” cancerous as theyNodules are at least shown partially to be differentiated, “hot” or “toxic” in other on techne words,tium producing scan are thyroid “never” hormones. cancerous It as is they are at least partially differentiated, in other words, producing thyroid hormones. It is however sometimes appropriate to carry out FNAB in order to reassure the patient and confirm the benign nature of the nodule. On occasion, hot nodules may contain fluid on biopsy, but on needling the nodule, a cellular specimen is obtained, as in the case of the example shown in Figure 5. The appearance of toxic nodules varies, but they are usually similar to the colloid nodules. Occasionally they are markedly hypoechoic, or cystic, as in this case.

Figure 5. Thyroid nodule in a patient with hyperthyroidism shown, from technetium uptake and scan, to be “hot” or “toxic”.

6. Thyroid Cysts Thyroid cysts are important because it may be possible to relieve the patient’s neck symptoms by removing the fluid. However, a cyst tends to refill, which can be a sign that it has a solid component which, in about 10% of cases, is cancerous [6]. Sometimes it is difficult to differentiate a cyst from a hyperechoic colloid or “toxic” nodule, even after biopsy, since fluid may be drawn off from both lesions. Both may look hypoechoic (black) but a cyst is usually larger and more round, somewhat blacker and has a thin, sharp edge, as shown in Figure 6. The cyst has a specific feel on palpation (whereas a colloid nodule, where palpable, feels firm, even hard) and, if tested for, is translucent. Cysts may have a

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Figure 4. Two examples of follicular nodules that were shown at surgery to be benign. The nodules are roughly oval shaped, slightly hyper echoic and have sharp edges and, particularly, the bigger of the two, thick halos.

Reports 2021, 4, 8 5. Hot Nodules 5 of 16 Nodules shown to be “hot” or “toxic” on technetium scan are “never” cancerous as they are at least partially differentiated, in other words, producing thyroid hormones. It howeveris however sometimes sometimes appropriate appropriate to to carry carry out out FNAB FNAB in in order order to to reassure reassure the the patient patient and and conﬁrmconfirm the the benign benign nature nature of of the the nodule. nodule. On On occasion, occasion, hot hot nodules nodules may may contain contain ﬂuid fluid on on biopsy,biopsy, but but on on needling needling the the nodule, nodule, a a cellular cellular specimen specimen is is obtained, obtained, as as in in the the case case of of the the exampleexample shown shown in in Figure Figure5 .5. The The appearance appearance of of toxic toxic nodules nodules varies, varies but, but they they are are usually usually similarsimilar to to the the colloid colloid nodules. nodules. Occasionally Occasionally they they are are markedly markedly hypoechoic, hypoechoic, or or cystic, cystic, as as in in thisthis case. case.

FigureFigure 5. 5.Thyroid Thyroid nodulenodule inin aa patientpatient withwith hyperthyroidismhyperthyroidism shown, from technetium uptake uptake and and scan, to be “hot” or “toxic”. scan, to be “hot” or “toxic”.

6.6. Thyroid Thyroid Cysts Cysts ThyroidThyroid cysts cysts are are important important because because it it may may be be possible possible to to relieve relieve the the patient’s patient’s neck neck symptomssymptoms by by removing removing the the fluid. fluid. However, However, a a cyst cyst tends tends to to refill, refill, which which can can be be a a sign sign that that itit has has a a solid solid component component which, which, in in about about 10% 10% of of cases, cases, is is cancerous cancerous [ 6[].6]. Sometimes Sometimes it it is is difficultdifficult to to differentiate differentiate a a cyst cyst from from a a hyperechoic hyperechoic colloid colloid or or “toxic” “toxic” nodule, nodule, even even after after biopsy,biopsy, since since fluid fluid may may be be drawn drawn off off from from both both lesions. lesions. Both Both may may look look hypoechoic hypoechoic (black) (black) Reports 2021, 4, 8 6 of 16 butbut a a cyst cyst is is usually usually larger larger and and more more round, round, somewhat somewhat blacker blacker and and has has a a thin, thin, sharp sharp edge, edge, asas shown shown in in Figure Figure6 .6. The The cyst cyst has has a a specific specific feel feel on on palpation palpation (whereas (whereas a a colloid colloid nodule, nodule, wherewhere palpable, palpable, feels feels firm, firm, even even hard) hard) and, and, if if tested tested for, for, is is translucent. translucent. Cysts Cysts may may have have a a solidsolid component component whose whose echogenicity echogenicity may may be be hypo hypo or or hyper hyper echoic, echoic, sometimes sometimes only only seen seen afterafter removal removal of of the the fluid. fluid.

FigureFigure 6. 6.Large Large thyroidthyroid nodulenodule of mixed appearance, i.e., i.e., comprising comprising both both solid solid (lower (lower half) half) and and cysticcystic (upper (upper half) half) components. components. FNABFNAB ofof thethe solidsolid componentcomponent showedshowed that the lesion was benign benign,, whereas biopsy of the upper region obtained a large amount of chocolate coloured fluid. whereas biopsy of the upper region obtained a large amount of chocolate coloured ﬂuid. 7. Oncocytic Nodules About 10% of thyroid nodules contain a predominance of oncocytes, or Hürthle cells, which are characterised from their eosinophilic granular cytoplasm, vesicular nucleus and large nucleolus. A Hürthle cell is larger than a follicular cell, and its cellular material stains pink with ethanol fixed haematoxylin–eosin stain. These cells can also be identified and enumerated in Papanicolaou-stained smears or with air-dried Romanowsky stain. Hürthle cells are also seen in Hashimoto thyroiditis and in association with benign nodules. An oncocytic tumour comprises 70% or more oncocytes and is shown at surgery to be benign in 90% of cases and malignant in 10% of cases. An example of a benign oncocytic adenoma is seen in Figure 7.

Figure 7. This 20 mm hypoechoic nodule has a slightly irregular edge and is hypoechoic and thus considered suspicious for papillary cancer. However, biopsy showed that it was an oncocytic tumour and, following hemi-thyroidectomy and pathological examination, benign.

8. Calcification The normal gland does not contain any calcification. The presence of calcification in association with nodules generally indicates that the nodules are long standing and therefore likely to be benign. However, breaks in the wall of a calcified nodule suggest that the nodule is a cancer which has invaded into the surrounding thyroid tissue and is

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solid component whose echogenicity may be hypo or hyper echoic, sometimes only seen after removal of the fluid.

Figure 6. Large thyroid nodule of mixed appearance, i.e., comprising both solid (lower half) and cystic (upper half) components. FNAB of the solid component showed that the lesion was benign, Reports 2021, 4, 8 6 of 16 whereas biopsy of the upper region obtained a large amount of chocolate coloured fluid.

7. Oncocytic Nodules 7. OncocyticAbout Nodules10% of thyroid nodules contain a predominance of oncocytes, or Hürthle cells, whichAbout are 10%characterised of thyroid nodulesfrom their contain eosinophilic a predominance granular of oncocytes,cytoplasm or, vesicular Hürthle cells, nucleus and whichlarge arenucleolus. characterised A Hürthle from their cell eosinophilicis larger than granular a follicular cytoplasm, cell, and vesicular its cellular nucleus material and stains large nucleolus. A Hürthle cell is larger than a follicular cell, and its cellular material stains pink with ethanol fixed haematoxylin–eosin stain. These cells can also be identified and pink with ethanol ﬁxed haematoxylin–eosin stain. These cells can also be identiﬁed and enumeratedenumerated in Papanicolaou-stained in Papanicolaou-stained smears or smears with air-dried or with Romanowsky air-dried stain. Romanowsky Hürthle stain. cellsHürthle are also cells seen are in Hashimoto also seen thyroiditisin Hashimoto and in thyroiditis association and with in benign association nodules. with An benign oncocyticnodules. tumour An oncocytic comprises tumour 70% or comprises more oncocytes 70% or and more is shown oncocytes at surgery and tois beshown benign at surgery into 90% be of benign cases and in 90% malignant of cases in 10% and of cases.malignant An example in 10% of of a benign cases. oncocytic An example adenoma of a benign isoncocytic seen in Figure adenoma7. is seen in Figure 7.

FigureFigure 7. 7.This This 20 20 mm mm hypoechoic hypoechoic nodule nodule has ahas slightly a slightly irregular irregular edge and edge is hypoechoicand is hypoechoic and thus and thus consideredconsidered suspicious suspicio forus papillaryfor papillary cancer. cancer. However, However, biopsy showedbiopsy thatshowed it was that an oncocytic it was an tumour oncocytic and,tumour following and, hemi-thyroidectomyfollowing hemi-thyroidectomy and pathological and examination, pathological benign. examination, benign.

8.8. Calcification Calcification The normal gland does not contain any calcification. The presence of calcification The normal gland does not contain any calcification. The presence of calcification in in association with nodules generally indicates that the nodules are long standing and thereforeassociation likely with to be nodules benign. However,generally breaks indicates in the that wall the of a nodules calcified are nodule long suggest standing and thattherefore the nodule likely is ato cancer be benign. which hasHowever, invaded breaks into the in surrounding the wall of thyroid a calcified tissue nodule and is suggest consideredthat the nodule a suspicious is a cancer feature which of a nodule has invaded [7]. Calcification into the is surrounding sometimes seen thyroid as spots tissue or and is sheets scattered throughout the thyroid. Calcification surrounding a thyroid nodule, giving it the appearance of a “bone ball”, can be felt as a hard, mobile lump on neck palpation that is crunchy on biopsy. Chronic linear or egg shell calcification is associated with shadowing because the ultrasound waves are unable to pass through calcified tissue (Figure8A,B). Calcification is also seen in the thyroid of patients with chronic Hashimoto thyroiditis and Graves’ disease. Reports 2021, 4, 8 7 of 16

Reports 2021, 4, 8 7 of 16 considered a suspicious feature of a nodule [7]. Calcification is sometimes seen as spots or sheets scattered throughout the thyroid. Calcification surrounding a thyroid nodule, giving it the appearance of a “bone ball”, can be felt as a hard, mobile lump on neck palpationconsidered that a issuspicious crunchy featureon biopsy. of a noduleChronic [7 ]linear. Calcification or egg shell is sometimes calcification seen is as associated spots or withsheets shadowing scattered because throughout the ultrasound the thyroid. waves Calcification are unable surrounding to pass through a thyroid calcified nodule, tissue giving it the appearance of a “bone ball”, can be felt as a hard, mobile lump on neck (Figure 8A,B). Calcification is also seen in the thyroid of patients with chronic Hashimoto palpation that is crunchy on biopsy. Chronic linear or egg shell calcification is associated thyroiditis and Graves’ disease. with shadowing because the ultrasound waves are unable to pass through calcified tissue Reports 2021, 4, 8 (Figure 8A,B). Calcification is also seen in the thyroid of patients with chronic Hashimoto7 of 16 thyroiditis and Graves’ disease.

(A) (B)

Figure 8. In (A) linear calcification(A in) the anterior aspect of a benign 15 mm nodule is seen(B) as a curved bright hypoechoic shelf (arrow) that blocks the transmission of the ultrasound waves, so the nodule behind appears to be very hypoechoic, as inFigureFigure a cyst. 8. 8. InIn ( (ABA)) linearis linear seen calcification calcification a small hypoechoic in in the the anterior anterior calcified aspect aspect nodule of of a a benign benign (upper 15 15 mmarrow) mm nodule nodule and is isbelow seen seen as asit, a aa curved curvedlarger bright brightnodule hypoechoic hypoechoic with linear calcificationshelfshelf (arrow) (arrow) in its that that anterior blocks blocks surface the the transmission transmission (lower arrow). of of the the ultrasound ultrasound waves, waves, so so the the nodule nodule behind behind appears appears to to be be very very hypoechoic, hypoechoic, asas in in a a cyst. In In ( (BB)) is is seen seen a a small small hypoechoic hypoechoic calcified calcified nodule nodule (upper (upper arrow) arrow) and and below below it, it, a a larger larger nodule nodule with with linear linear calcification in its anterior surface (lower arrow). calcification in its anterior9. surfaceVasculari (lowerty arrow). 9. VasculariThe bloodty supply to thyroid nodules is an important feature to be documented in the 9. Vascularity course Theof real blood time supply ultrasonography. to thyroid nodules There is are an importantthree types feature of vascularity to be documented to be discussed. in the The blood supply to thyroid nodules is an important feature to be documented in the Firstly,course theof real so -timecalled ultrasonography. hypoechoic halo There surrounding are three types a of benign vascularity nodule to be is discussed. caused b y course of real time ultrasonography. There are three types of vascularity to be discussed. compressedFirstly, the blood so-called vessels hypoechoic which can halo be seen surrounding when the a “colour” benign nodulebutton is engaged. caused b yAn Firstly, the so-called hypoechoic halo surrounding a benign nodule is caused by compressed examplecompressed of this blood is seenvessels in whichFigure can 9A. be Secondly, seen when the the degree “colour” of button vascularity is engaged. around An the blood vessels which can be seen when the “colour” button is engaged. An example of this outsideexample of ofa nodule this is seen is reflective in Figure of 9A. its activitySecondly, and the prominent degree of vascularity blood supply around around the a is seen in Figure9A. Secondly, the degree of vascularity around the outside of a nodule noduleoutside maybe of a nodulea sign isof reflectivethyroid cancer of its activity(Figure and9B) prominent[8] but can blood also be supply present around around a is reflective of its activity and prominent blood supply around a nodule maybe a sign of nodulesnodule shownmaybe bya sign biopsy of thyroid to be benign.cancer ( ItFigure has recently9B) [8] but been can shown also be that present blood around vessels thyroid cancer (Figure9B) [ 8] but can also be present around nodules shown by biopsy to withinnodules a nodule, shown especially by biopsy if to it has be benign. other suspicious It has recently features been (F shownigure 9B) that, may blood be a vessels reliable be benign. It has recently been shown that blood vessels within a nodule, especially if it signwithinhas of other cancer a nodule, suspicious [9]. especially features if it (Figure has other9B), suspicious may be a reliablefeatures sign (Fig ofure cancer 9B), may [9]. be a reliable sign of cancer [9].

(A()A ) ((BB)) Figure 9. Examples of vascularity around the edge of a benign nodule and (A) associated with blotchy macrocalciﬁcations in a hard, irregular edged nodule that is suspicious for papillary cancer (B). Another example of macrocalciﬁcations in papillary thyroid cancer.

In Figure 10 is shown matching images of a benign nodule without (A) and with (B) blood ﬂow in the halo around the nodule. Reports 2021, 4, 8 8 of 16

Figure 9. Examples of vascularity around the edge of a benign nodule and (A) associated with blotchy macrocalcifications Reportsin 2021 a hard,, 4, 8 irregular edged nodule that is suspicious for papillary cancer (B). Another example of macrocalcifications8 of 16 in

papillary thyroid cancer.

Figure 9. Examples of vascularity aroundIn Figure the edge 10 ofis ashown benign nodulematching and ( Aimages) associated of a with benign blotchy nodule macrocalcifications without (A) and with (B) in a hard, irregular edged noduleblood that flow is suspicious in the halo for papillaryaround cancerthe nodule (B). Another. example of macrocalcifications in papillary thyroid cancer. Reports 2021, 4, 8 8 of 16 In Figure 10 is shown matching images of a benign nodule without (A) and with (B) blood flow in the halo around the nodule.

(A) (B)

Figure 10. A small 8 mm benign nodule in the left thyroid lobe shown as an ultrasound image (A) and with surrounding vascularity in (B). (A) (B) FigureFigure 10. 10. A Asmall small 8 mm 8 mm benign benign nodule nodule in inthe the left left thyroid thyroid lobe lobe shown shown as asan an ultrasound ultrasound image image (A ()A and) and with with surrounding surrounding vascularityvascularity in in(B ().B ). 10. Thyroid Cancer The thyroid specialist using their own portable US machine will, with experience, 10.10. Thyroid Thyroid Cancer Cancer learn to recognize those characteristics of nodules which are suspicious for malignancy. The thyroid specialist using their own portable US machine will, with experience, TheseThe include thyroid taller specialist than wide using, theirindicating own portable that the UStumour machine is growing will, with through, experience, rather than learnlearn to torecognize recognize those those characteristics characteristics of ofnodules nodules which which are are suspi suspiciouscious for for malignancy. malignancy. along, the tissue planes; absence of a peripheral halo (compressed blood vessels in a TheseThese include include taller taller than than wide wide,, indicating indicating that that the the tumour tumour is isgrowing growing through, through, rather rather than than along,benignalong, the the nodule), tissue tissue planes planes; the 3; – absenceabsence4 mm “fluffy” of of a a peripheral peripheral intra nodular halo halo (compressed (compressed microcalcifications blood blood vessels vessels (actually in a benign in a psamoma benignbodiesnodule), nodule), rather the 3–4 the than mm 3– 4true “fluffy” mm calcification)“fluffy” intra nodularintra ,nodular which microcalcifications microcalcificationsare 90% specific (actually for (actually papillary psamoma psamoma cancer bodies [1,2,10]; bodiesintrarather rathernodular than than true hypervascularity calcification),true calcification) which,, which are 90% areis presumed 90% specific specific for to papillaryfor be papillary feeding cancer cancerthe [ 1cancer,2 ,[101,2,10];; intra and]; size > 3 intracm.nodular nodular hypervascularity, hypervascularity which, which is presumed is presumed to be to feeding be feeding the cancer;the cancer and; sizeand >size 3 cm. > 3 cm. ThreeThree examples examples of of papillary papillary thyroid thyroid cancer cancer are shown are shown here. Firstly,here. Firstly, a large typicala large typical papillaryThree examples cancer cancer with with of thepapillary the characteristic characteristic thyroid microcalcifications cancer microcalcifications are shown ishere seen. isFirstly, in seen Figure ina large 11Figure. typical 11. papillary cancer with the characteristic microcalcifications is seen in Figure 11.

Figure 11. Thyroid ultrasound from a patient with confirmed papillary thyroid cancer. The nodule Figure 11. Thyroid ultrasound from a patient with confirmed papillary thyroid cancer. The nodule is is large (3 cm) and hypoechoic with an indistinct irregular edge and central microcalcifications. Figurelarge (3 11. cm) Thyroid and hypoechoic ultrasound with from an indistinct a patient irregular with confirmed edge and centralpapillary microcalcifications. thyroid cancer. The The nodule iscalcifications large (3 cm) are and softer hypoechoic (less white) with than an seen indistinct above inirregular some benign edge and nodules central and microcalcifications larger, around . 2–3 mm (arrow). There is no halo. Not seen here, the blood supply was increased in the lesion and there was a feeding vessel on one side of the lesion. Another example of macrocalcifications in papillary thyroid cancer.

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The calcifications are softer (less white) than seen above in some benign nodules and larger, around 2–3 mm (arrow). There is no halo. Not seen here, the blood supply was increased in the lesion and there was a feeding vessel on one side of the lesion. Another example of Reports 2021, 4, 8 macrocalcifications in papillary thyroid cancer. 9 of 16 Reports 2021, 4, 8 9 of 16

Secondly, a smaller but more hypoechoic lesion with obvious and larger soft Themicrocalcifications calcificationsSecondly, a smallerare softer but (less and more white) hypoechoican tha irregularn seen above lesion edgein with some obvious isbenig shownn andnodules larger in and Figure soft larger, microcal- 12. These two nodules are ciﬁcationsaround 2–3 andmm an(arrow). irregular There edge is no ishalo. shown Not inseen Figure here, the12. blood These supply two nodules was increased are typical in the for papillarylesiontypical and cancer there for was and papillary a arefeeding reported vessel cancer from on one FNAB andside of as arethe “suspicious lesion. reported Another for papillary example from FNABofthyroid cancer”. as “suspicious for papillary Inmacrocalcificationsthyroid both cases cancer”. this wasin papillary conﬁrmed In both thyroid at cases thyroidectomy cancer. this was confirmed at thyroidectomy

Secondly, a smaller but more hypoechoic lesion with obvious and larger soft microcalcifications and an irregular edge is shown in Figure 12. These two nodules are typical for papillary cancer and are reported from FNAB as “suspicious for papillary thyroid cancer”. In both cases this was confirmed at thyroidectomy

FigureFigureFigure 12.12. PapillaryPapillary12. Papillary cancercancer lesionlesion cancer withwith lesion largelarge ﬂuffyfluffy with microcalciﬁcations, microcalcifications large fluffy anmicrocalcifications, an irregular irregular edge edge and and overall , an irregular edge and hypoechoicoveralloverall hypoechoic hypoechoic texture. texture. texture.

Thirdly,Thirdly, an an example example of of a a much much smaller smaller lesion lesion that that turned turned out out to to be be papillary papillary cancer cancer is shownis shown inThirdly, Figure in Figure 13 .an The13. example nodule The nodule is only of is 10–12a only much mm10–12 insmaller mm size, in hypoechoic size, lesion hypoechoic andthat has turned anand unusual has out an to be papillary cancer andunusualis irregular shown and irregular edge. in Figure Three edge years . 13.Three earlier The years the nodule earlier same the lesion is same only was lesion seen 10 was– on12 ultrasound,seen mm on ultrasound in size,and its , hypoechoic and has an sizeand thenits size was then 8 × was9 mm 8 × 9 with mm nowith other no other suspicious suspicious features features and noand microcalciﬁcations no microcalcifications nor feedingnorunusual feeding vessels and vessels or blood irregular or vessels,blood vessels, indicatingedge . indicatingThree that it hadyears that grown it earlier ha veryd grown little the over very same the little intervening lesion over the was seen on ultrasound, 3interveningand years .its It wassize 3 years. considered then It waswas suspiciousconsidered 8 × 9 mm on suspicious ultrasoundwith no on other becauseultrasound suspicious of itsbecause shape of andfeatures its edge.shape Theand and no microcalcifications lesion was shown to be suspicious for papillary cancer at FNAB and conﬁrmed at hemi edge.nor The feeding lesion was vessels shown toor be blood suspicious vessels, for papillary indicating cancer at FNAB that and it haconfirmedd grown very little over the thyroidectomy.at hemi thyroidectomy. intervening 3 years. It was considered suspicious on ultrasound because of its shape and edge. The lesion was shown to be suspicious for papillary cancer at FNAB and confirmed at hemi thyroidectomy.

FigureFigure 13.13. SmallSmall 1010 mmmm nodulenodule withwith anan overalloverall blurry blurry irregular irregular edge edge (arrow) (arrow) that that is is taller taller than than wide andwide hypoechoic, and hypoechoic, shown shown from FNABfrom FNAB to be papillaryto be papillary cancer. cancer.

Figure 13. Small 10 mm nodule with an overall blurry irregular edge (arrow) that is taller than wide and hypoechoic, shown from FNAB to be papillary cancer.

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It is not possible to differentiate the more common papillary cancer from the very muchIt is less not possible common to folliculardifferentiate neoplasms the more common by ultrasound, papillary cancer although from follicular the very lesions are muchmore less cellular common and follicular less neoplasmshypoechoic by ultrasound, and do not although usually follicular contain lesions microcalcifications are more , the cellulardiagnosis and lessbeing hypoechoic made at and open do biopsy. not usually contain microcalciﬁcations, the diagnosis being madeOn follow at open up biopsy. after treatment, usually total thyroidectomy followed by radioiodine, On follow up after treatment, usually total thyroidectomy followed by radioiodine, oneone looks looks for for abnormal abnormal lymph lymph nodes nodes in the neck,in the indicating neck, indicating local relapse. local In therelapse. case of In the case of papillarypapillary carcinoma, carcinoma, involved involved nodes are nodes round, hypoare round, echoic and hypo may contain echoic microcal- and may contain ciﬁcationsmicrocalcifications (Figure 14). They(Fig mayure have14). a They cystic structure may have with a posterior cystic enhancement. structure with It posterior isenhancement. recommended that It is the recommended cervical lymph nodes that be the examined cervical in lymphall patients nodes who undergo be examined in all ultrasonographypatients who undergo for whatever ultrasonography reason. for whatever reason.

FigureFigure 14. 14.Neck Neck ultrasound ultrasound of enlarged of enlarged cervical cervical lymph nodes lymph from no ades patient from with a patient papillary with thyroid papillary cancer.thyroid The cancer. enlarged The node enlarged is oval node in shape, is oval very in hypoechoic shape, very and hypoechoic contains a fewand of contains the blotchy a few of the microcalciﬁcationsblotchy microcalcifications typical of papillary typical cancer. of papillary The arrow cancer. heads indicate The arrow the corners heads of indicate the node. the The corners of the littlenode. arrow The inside little referring arrow inside to an echogenic referring focus. to an echogenic focus.

11.11. Graves’ Graves’ Hyperthyroidism Hyperthyroidism In Graves’ hyperthyroidism, the gland is typically diffusely enlarged to a degree that reflectsIn the Graves severity' hyperthyroidism, of the hyperthyroidism. the Itsgland vascularity is typically is increased, diffusely often enlarged dramatically, to a degree that andreflects is generalised. the severity As the disease of the becomes hyperthyroidism. chronic, e.g., after Its one vascularity or more relapses is increased, post often antdramatically, thyroid medication, and is generalised. the gland shrinks As the and disease becomes becomes scarred and chronic nodular,, e.g., so calledafter one or more “nodularrelapses Graves’ post ant disease”. thyroid However, medication, it is not the uncommon gland shrinks for patients and with becomes Graves’ scarred disease and nodular, toso have called incidental “nodular nodules, Graves’ in which disease”. case the differential However, diagnosis it is not is as uncommon follows: (1) Graves’ for patients with disease which has become thickened and nodular due to its chronicity; (2) Graves’ disease Graves’ disease to have incidental nodules, in which case the differential diagnosis is as with distinct nodules; and (3) Graves’ disease with one or more hot (toxic) nodules, i.e., twofollows: different 1) diseases.Graves’ disease which has become thickened and nodular due to its chronicity; 2) Graves’The blood disease supply with in typical distinct Graves’ nodules disease; and is diffusely 3) Graves’ increased disease (and with associated one or more hot with(toxic) a murmur), nodules, sometime i.e., two up different to 100 times diseases. normal, and the gland texture on ultrasound is usuallyThe heterogeneous blood supply (patchy) in withtypical a fine Graves’ cystic appearance disease throughout,is diffusely which increased reflects (and the associated diffusewith a nature murmur) of the, inflammatorysometime up process to 100 (Figure times 15normal,). Following and radiothe gland iodine texture treatment, on ultrasound the normal gland architecture is disrupted because the follicles are destroyed, and scar tissueis usually predominates. heterogeneous (patchy) with a fine cystic appearance throughout, which reflects the diffuse nature of the inflammatory process (Figure 15). Following radio iodine treatment, the normal gland architecture is disrupted because the follicles are destroyed, and scar tissue predominates.

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(A)

(B)

Figure 15. Cont.

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(C)

Figure 15. Thyroid ultrasoundFigure 15. fromThyroid two patients ultrasound with from Graves two'patients hyperthyroidism. with Graves’ In hyperthyroidism.(A) is shown an example In (A) is shownof early an Graves’ hyperthyroidismexample manifest of early as multiple Graves’ hyperthyroidism small inflammatory manifest and as lymphoid multiple small lesions, inflammatory often described and lymphoid by the consultant radiologist as “nodules” blue arrow. In (B) is shown an enlarged thyroid, with a thick isthmus and a generalized lesions, often described by the consultant radiologist as “nodules” blue arrow. In (B) is shown patchy hypo echoicity due to the lymphocytic inflammation and thyroid cell proliferation. In (C) is shown the increased an enlarged thyroid, with a thick isthmus and a generalized patchy hypo echoicity due to the vascularity in the thyroid of the patient shown in (B). lymphocytic inflammation and thyroid cell proliferation. In (C) is shown the increased vascularity in the thyroid12. Hashimoto of the patient Thyroiditis shown in (B). 12. HashimotoHashimoto Thyroiditis thyroiditis is common, especially when diagnosed cytologically from biopsyHashimoto of thyroid thyroiditis nodules, is common, as an incidental especially finding, when being diagnosed demonstrated cytologically in 13.4% from of a biopsygroup of thyroidof 811 patients nodules, [11 as]. an The incidental disease is finding, approximately being demonstrated 10 times more in 13.4%common of a in group females of 811than patients males. [ 11 Ultrasonography]. The disease is approximately should be performed 10 times more in all common patients in with females Hashimoto than males.thyroiditis Ultrasonography to identifyshould any nodules. be performed Although in allnot patients clearly established, with Hashimoto it seems thyroiditis likely that to identifythere is any an increased nodules. Although prevalence not of clearly cancer established,in patients with it seems this likely chronic that inflammatory there is an increasedcondition prevalence compared of to cancer patients in patients without with nodules this chronic Ultrasonography inflammatory is also condition useful in comparedfollowing to patientsindividual without patients nodules with Hashimoto Ultrasonography thyroiditis isalso as an useful aid to in management following in- with dividualthyroxine patients replacement with Hashimoto [12] and to thyroiditis recognize as the an uncommon, aid to management but not rare, with situation thyroxine where replacementGraves’ hyperthyroidism [12] and to recognize changes the (“flips”) uncommon, to Hashimoto but not rare, thyroiditis situation [13 where]. Graves’ hyperthyroidismAs a result changes of the (“flips”) senior to author’s Hashimoto (JW) thyroiditis extensive [13 experience]. of the ultrasound appearancesAs a result ofof the Hashimoto senior author’s thyroiditis (JW), extensivehe and his experience colleagues of thehave ultrasound developed appear- a 5-stage ancesclassification of Hashimoto of the thyroiditis, inflammatory he and changes his colleagues from early have (stages developed 1, 2) through a 5-stage later classifica- (stages 3, tion4, of 5), the as inflammatoryfollows: Stage changes1 is characterised from early by (stages mild inflammatory 1, 2) through laterchanges (stages manifest 3, 4, 5), as assmall follows:cystic Stage lesions 1 is representing characterised the by lymphoid mild inflammatory nodules andchanges inflammatory manifest as infiltrations small cystic in a lesionsnormal representing or slightly the enlarged lymphoid thyroid. nodules In stage and inflammatory 2, the gland is infiltrations enlarged and in athe normal cystic orareas slightlyare better enlarged defined, thyroid. more In frequent stage 2, and the glandlarger; is the enlarged blood supply and the to cystic the gland areas is are increased better in defined,stages more 1 and frequent 2. In stage and 3, larger; the thyroid the blood is generally supply to bigger the gland and isthe increased signs of ininflammation stages 1 andincreased 2. In stage with 3, the larger thyroid inflammatory is generally nodules bigger, and the the blood signs ofsupply inflammation is now patchy. increased In stage with4 largerthe gland inflammatory is becoming nodules, avascular and the, and blood the supplynodules is are now replaced patchy. Inby stage hypoechoi 4 the glandc (black) is becomingspaces with avascular, scar tissue and (fibrosis) the nodules, and are there replaced are increased by hypoechoic sheets (black) of fibrosis, spaces giving with the scarappearance tissue (fibrosis), of pseudo and therenodules. are increasedIn the final sheets stage ofthe fibrosis, gland is giving shrunken the appearance and scarred of with pseudoabsent nodules. blood supply In the finaland stagedevoid the of glandthyroid is shrunkentissue [14]. and Further scarred uses with of this absent classification blood supplysystem and, such devoid as ofthe thyroid correlation tissue between [14]. Further inflammation uses of this stage classification and the need system, for thyroxin such as thereplacement correlation, are between currently inflammation being addressed stage and by the authors need for. thyroxin replacement, are currentlyIn being Hashimoto addressed thyroiditis by the authors. the blood supply to the gland increases during the early inflammatory stages, but later, when the inflammation has burnt out and the gland is

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In Hashimoto thyroiditis the blood supply to the gland increases during the early inﬂammatory stages, but later, when the inﬂammation has burnt out and the gland is scarred and empty, the overall blood supply is markedly reduced. Examples of the two scarred and empty,scarred the overalland empty, blood the supply overall is bloodmarkedly supply reduced. is markedly Examples reduced. of the Examplestwo of the two types of end stage disease are seen in Figure 16. types of end stagetypes disease of end are stage seen diseasein Figure are 16. seen in Figure 16.

(A) (A) (B) (B)

Figure 16. FigureThyroid 16. ultrasound ThyroidFigure ultrasound findings 16. Thyroid in findings 2 patients ultrasound in with2 patients different findings with features differentin 2 patients of features late-stage with ofdifferent Hashimotolate-stage features thyroiditis. of late-stage In (A ) the dominantHashimoto feature is diffuse thyroiditis. hypoHashimoto echoicity,In (A) thethyroiditis. seendominant as blackIn feature(A) “holes” the isdominant diffuse indicating hypo feature the echoicity, is absence diffuse seen of hypo thyroid as blackechoicity, tissue, “holes” seen some as scarring, black “holes” indicating the absence of thyroid tissue, some scarring, decreased vascularity and architectural decreased vascularity and architecturalindicating the damage absence in anof thyroid overall tissue, enlarged some gland. scarring, In (B ),decreased the thyroid vasculari glandty is nowand architectural shrunken, damage in an overalldamage enlarged in an gland. overall In enlarged (B), the thyroid gland. Ingland (B), isthe now thyroid shrunken, gland scarredis now shrunken,and scarred and scarred and shrivelled with pseudo nodules and scattered fibrous bands in a small gland; this is the final stage and the shrivelled with pseudoshrivelled nodules with and pseudo scattered nodules fibrous and bands scattered in a fibroussmall gland; bands this in ais small the final gland; stage this is the final stage patient has no thyroid function. and the patient hasand no thethyroid patient function. has no thyroid function.

13. Transient Thyroiditis13.13. TransientTransient Thyroiditis Thyroiditis The sonographicTheThe appearance sonographic sonographic of the appearanceappearance various forms of of the the of various various transient formsforms thyroiditis ofof transient transient, namely thyroiditis, thyroiditis , namely namely subacute thyroiditis,subacutesubacute silent thyroiditis, thyroiditis, thyroiditis silent silent and thyroiditis post thyroiditis-partum and and thyroiditis post-partum post-partum, is thyroiditis,worthy thyroiditis of mention is, worthy is worthy of mention of mention as as this has not beenthisas this hasdescribed has not not been in been describeddetail described by others. in detail in detailTaking by others. by subacute others. Taking Taking thyroiditis subacute subacute as thyroiditis a model thyroiditis as a as model a model for for the changesthe thatfor changes the occur changes during that occurthat inflammation occur during during inflammation and inflammation on recovery, and on and recovery, we onsee recovery, that we seethe that glandwe thesee glandthat the appears gland appears very abnormalveryappears abnormal whenvery abnormal when the patient the patient when is hyperthyroid the is hyperthyroid patient is wi hyperthyroidth with hypoechoic hypoechoic wi “streaks”th “streaks” hypoechoic infiltrating “streaks” infiltrating the gland,theinfiltrating gland, as seen as the seenin gland,Figure in Figure as 17. seen On 17 recovery,in. OnFigure recovery, 17.the On gland therecovery, glandreturns returnsthe to glandnormal to returns normal as the to as normal the thyroid as the follicular cells recover. Even though the tissue damage in subacute thyroiditis reflects virus thyroid follicularthyroid cells recover. follicular Even cells though recover. the Even tissue though damage the in tissue subacute damage thyroiditis in subacute thyroiditis infection, or a post viral reaction, and that in the latter two disorders, an immunological reflects virus infection,reflects orvirus a post infection, viral reaction or a post, and viral that reaction in the, latterand that two in disorders, the latter an two disorders, an process, the ultrasound changes seen in all three disorders are similar. immunological process,immunological the ultrasound process, changes the ultrasound seen in allchanges three disordersseen in all are three similar. disorders are similar.

Figure 17. ThyroidFigure ultrasound 17. Thyroid from a ultrasoundpatient with from sub -aacute patient thyroiditis. with sub -Theacute impressive thyroiditis. looking The impressive looking Figure 17. Thyroid ultrasound from a patient with sub-acute thyroiditis. The impressive looking black streaks seen blackin the streaks acute phase seen inrapidly the ac disappearute phase rapidlyas the gland disappear recovers as the and gland the texture recovers and the texture black streaks seen in the acute phase rapidly disappear as the gland recovers and the texture returns returns to normal. returns to normal. to normal. 14. Parathyroid D14.isease Parathyroid Disease Because the seniorBecause author the (JW) senior routinely author measures (JW) routinely serum measures calcium, serum parathyroid calcium, parathyroid hormone (PTH) hormone and vitamin (PTH) D inand his vitamin patients, D hyperparathyroidismin his patients, hyperparathyroidism due to a benign due to a benign

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adenoma of one of the parathyroid glands appears to be much more common than 14. Parathyroid Disease previously thought. The parathyroid glands are hidden behind the thyroid and so may be obscuredBecause by thethyroid senior nodules, author (JW)although routinely they measurescan often serumbe seen calcium, in the longitudinal parathyroid view hor- monebelow (PTH) the lobes, and vitaminas a hypoechoic D in his patients,lesion of hyperparathyroidismaround 1 cm in diameter due to(Figure a benign 18). adenoma of one of the parathyroid glands appears to be much more common than previously The parathyroid adenoma is typically hypoechoic by comparison to the nearby thought. The parathyroid glands are hidden behind the thyroid and so may be obscured thyroid tissue, which is consistent with the author’s experience. However, only about 50% by thyroid nodules, although they can often be seen in the longitudinal view below the of subsequently proven parathyroid adenomas are seen on ultrasound and even the lobes, as a hypoechoic lesion of around 1 cm in diameter (Figure 18). Sestamibi nuclear scan fails to pick them up in about 30% of cases.

Figure 18. Thyroid ultrasound from a patient with hyperparathyroidism showing a hypoechoic Figure 18. Thyroid ultrasound from a patient with hyperparathyroidism showing a hypoechoic lesion below the right thyroid lobe that was confirmed to be a parathyroid adenoma at surgery. lesion below the right thyroid lobe that was conﬁrmed to be a parathyroid adenoma at surgery.

15. DoesThe parathyroid the Thyroid adenoma Specialist is typically have Advantages hypoechoic over by comparisonthe Consultant to the R nearbyadiologist? thyroid tissue,The which consultant is consistent radiologist with does the author’snot always experience. report on those However, features only of thyroid about 50% lesions of subsequentlythat are essential proven to interpreting parathyroid the adenomas clinical areand seen other on findings. ultrasound For and example, even the in Sestamibithe senior nuclearauthor’s scan (JW) fails experience, to pick them the updiffuse in about familial 30% fibrotic of cases. variant of papillary thyroid cancer has been described as “localised Hashimoto thyroiditis”, which does not exist, and the 15.inflammatory Does the Thyroid lesions Specialist of Hashimoto have thyroiditisAdvantages and over Graves’ the Consultant hyperthyroidism Radiologist? are often referredThe consultant to as “nodules” radiologist and doesare counted not always and report measured. on those Recommending features of thyroid biopsy lesions of a thatthyroid are essential nodule to based interpreting on its size the onlyclinical—rather and other than findings. the presence For example, or not of in the suspicious senior author’sfeatures— (JW)is problematicexperience,, the since diffuse it familialwrongly fibrotic assumes variant that of small papillary nodules thyroid are cancer never hascancerous. been described as “localised Hashimoto thyroiditis”, which does not exist, and the inflammatoryMore recently, lesions the of Hashimoto emphasis has thyroiditis shifted to and classifying Graves’ hyperthyroidism nodules according are to often their referreddegree toof assuspicion “nodules” for and cancer, are counted regardless and measured.of their size. Recommending In the context biopsy of this of acha thyroidnging noduleapproach based to assessing on its size thyroid only—rather nodules than, a new the scoring presence system, or not known of suspicious as TI-RADS features—is [15,16], problematic,has been developed since it wronglyto allow assumeseveryone that who small carries nodules out thyroid are never ultrasonography, cancerous. whether technician,More recently, radiologist the or emphasis endocrinologist, has shifted to be to consistent classifying in nodules how they according characterise to their and degreereport features of suspicion of thyroid for cancer, nodules. regardless As a result of theirof the size.now almost In the contextuniversal of use this of changing TI-RADS, approachthe tendency to assessing is to carry thyroid out nodules, more ultrasounds a new scoring and system, fewer biopsies. known as This TI-RADS seems [ 15 logical,16], hasbecause been developedwe should toremember allow everyone that only who about carries 5% out of thyroidpatients ultrasonography,with one or more whether thyroid technician,nodules turn radiologist out to have or thyroid endocrinologist, cancer. Finally, to be consistentin respect to in who how is they best characterisequalified to carry and reportout thyroid features ultrasonography, of thyroid nodules. we As a recommend result of the nowthat almostthe role universal of clinician use of TI-RADS, practiced theultrasound tendency in is either to carry confirming out more of ultrasounds changing ultrasound/radiology and fewer biopsies. findings This seems of patients logical becausepresenting we with should imaging remember performed that only before about referral 5% of be patients addressed with in onea prospective or more thyroid study. nodules turn out to have thyroid cancer. Finally, in respect to who is best qualified to carry

out thyroid ultrasonography, we recommend that the role of clinician practiced ultrasound in either conﬁrming of changing ultrasound/radiology ﬁndings of patients presenting with imaging performed before referral be addressed in a prospective study.

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16. Vocal Cord Assessment Recently, the thyroid specialist has found a new use for their portable ultrasound machine. Although thyroid surgeons generally send their patients to an ENT specialist for direct laryngoscopic assessment of the vocal cords to identify any problem that was present before surgery, the thyroid specialist can learn to recognize and quantify normal abduction and adduction of the true vocal cord, especially in female patients. They do this by placing the small parts probe in a transverse plane across the anterior wall of the larynx just below the thyroid notch, with the patient speaking or humming (preferably in tune).

17. The Future New approaches to the use of ultrasound to assess thyroid nodules including shear wave elastography, which measures tissue stiffness, are being developed in order to help identify those nodules that need to be biopsied. Thyroid specialists in Europe often treat thyroid cysts by injecting 90% alcohol to replace the ﬂuid removed, and some solid nodules are treated by laser ablation. These procedures are rarely used in North America and Australia, countries where the senior author (JW) has worked, and it is unlikely that this approach will ever become mainstream outside of Europe.

Author Contributions: J.W. designed the studies. B.C. and S.E.-K. read for technical and clinical accuracy of data. J.W., B.C., S.E.-K. and H.L. participated in data analysis, discussion, manuscript preparation and editing. J.W. wrote the paper. All authors have read and agreed to the published version of the manuscript. Funding: No funding requested. Institutional Review Board Statement: This review includes deidentiﬁed anonymous ultrasound images from Dr Wall’s private practice. Ethics review is not needed for this review. No new data are included in the review which is therefore not a “study” (but a review) We refer to the ultrasound staging system and include the reference for this published paper. Informed Consent Statement: Not applicable. Data Availability Statement: Not applicable. Acknowledgments: Not applicable. Conﬂicts of Interest: Authors have declared that no competing interests exist.

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