Clin. Radiol. (1975) 26, 191-197

ULTRASONICS

IN THE DIAGNOSIS

OF THYROID

DISEASE

I A N R A M S A Y and H Y L T O N M E I R E

Departments of Medicine and Radiology, King's College Hospital, London Ultrasonic 'A' scans of the thyroid have been carried out on 47 patients with suspected thyroid disease. It was possible to measure the antero-posterior diameter of each lobe and to identify whether the tissue was homogeneous, nodular or cystic. Measurement of individual nodules or cysts was accurate to within 5 m m when compared with the tissue removed at operation. Ultrasonic examination was able to differentiate other lumps in the neck from those arising in the thyroid gland. It is concluded that ultrasonic examination of the thyroid is a useful adjunct to other conventional tests and deserves to be used more widely.

MOST thyroid diagnoses can be made with accuracy by a combination of history, examination, in vitro tests of thyroid function, thyroid antibody studies and radioactive isotope uptake and scan. However, in some circumstances the diagnosis remains uncertain. The most common of these is the solitary thyroid nodule which is non-functioning on isotope scanning. The usual practice is to refer them to a surgeon for removal. Most are found to be benign (Means et al., 1963) and often the nodule is found to be cystic. I f there were some means of elucidating the nature of these nodules with confidence, operation might be avoided. Information is also needed about the change in size of goitres on thyroid suppression therapy and of the suppressed thyroid tissue in the patient With a solitary toxic nodule. Since the use of ultrasound has proved successful in obstetrics and gynaecology and in liver and renal disease (Wells, 1972) and experience with it in thyroid disease was limited (Yamakawa and Naito, 1966; Fujimoto et al., 1967; Damascelli et al., 1968; Thijs, 1971; Rasmussen et al., 1971) we decided in 1971 to investigate the possibilities of its use in thyroid diagnosis.

APPARATUS The machine used was the 'A' scan section of an Aloka SSD10 which incorporates a distance marker on the display screen, thus enabling Correspondence: Dr Ian Ramsay, Regional Endocrine Centre, North Middlesex Hospital, Silver Street, London, N18 1QX, England.

measurements of internal structure to be made. An operating frequency of 2-25 M H z was used since the apparatus was optimised for this frequency and use of 5 M H z was found to give inadequate penetration in the larger, more dense, lesions. The 'swept gain' controls of the machine were set to give accurate representation of echo amplitude irrespective of depth or origin of the echoes over a range of 1 to 8 cm and were kept at a constant level. The overall gain required to produce full-scale amplification of the largest echoes was recorded in each case. By this means some index of the reflectivity and attenuation of the tissues was obtained, 'softer' tissues producing smaller echoes which required greater instrument gain settings to amplify them up to the standard magnitude. The ultrasound probe was applied to the area of interest using ' K Y jelly' as a coupling medium between the probe surface and the skin. The 'A' scans were photographed from the cathode-ray screen on to Polaroid film. f

METHODS Forty-seven patients referred for 131I or 99NTc scans of the thyroid were asked to take part in this research project and informed consent was obtained in all cases. Blood was taken for total thyroxine, thyroxine resin uptake (Maclagan and Howorth, 1969) and for thyroid antibodies. In most cases 131I neck uptake and serum protein bound iodine estimations were also carried out. The patients were placed on a reclining couch and the thyroid was carefully palpated. The results of the palpation were compared with the isotope scan, using the

191

192

CLINICAL

RADIOLOGY

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FIG. 1 Showing the different ' A ' scan appearances. A. Cystic. B. N o d u l a r . c. H o m o g e n e o u s .

suprasternal notch as reference point. The ultrasound probe was then placed over several different areas of the thyroid and 'A' scans were obtained. Particular attention was paid to solitary nodules. The patients were categorised on the basis of the history, physical signs, palpation of the thyroid, in vitro tests of thyroid function, including the free thyroxine index (Maclagan and Howorth, 1969), thyroid antibodies, radioactive iodine uptake, isotope scanning of the thyroid and in some cases, thyroid histology. Classification of the type of ultrasound pattern was carried out independently without prior knowledge of any available histology.

The information which could be obtained by ultrasound included whether or not thyroid tissue could be found, the antero-posterior diameter of various parts of the thyroid and the echo characteristics of the thyroid tissue. Three basic patterns of the latter could be recognised: cystic, nodular and homogeneous (Fig. 1). In addition there were two other groups which consisted of mixtures of cystic and nodular and of nodular and homogeneous. The size of individual cysts could also be measured. Echoes seen between the thyroid and the skin, on the left hand side of the 'A' scan, represent the sternomastoid muscle.

FIG. 2 The normal thyroid gland. A. °A' scan of the right lobe of the thyroid (AP diameter 1.2 cm). B_ 'A' scan of the left lobe (AP diameter 0.8 cm). c. 131Iscan of the thyroid showing a higher uptake in the right lobe.

ULTRASONICS

RESULTS

IN

THE

DIAGNOSIS

OF T H Y R O I D

DISEASE

193

referring clinician had had difficulty in palpating the thyroid. The ultrasound pattern was usually Normal Thyroid. - Four men and five women homogeneous, though in two patients there was a were found to have no thyroid disease. The average slight nodular pattern in one lobe. I n the patients antero-posterior (AP) diameter of each lobe of the w h o had had previous thyroid surgery the ultrasonic thyroid was 1.0 era. In all cases the ultrasound scan showed a considerable difference in the AP pattern was homogeneous and there was good diameter o f the two lobes which corresponded with agreement between the AP diameter of each lobe the type o f surgical procedure as recorded in the and the intensity of the uptake as seen on the operation note (Fig. 3). In one patient who had not isotope scan. Figl 2 shows a comparison of the had an operation we were unable to detect the right 'A' scans of each lobe with the isotope scan. The lobe of the thyroid and are unable to give an uptake is higher in the thicker lobe. explanation for this. There was a good correlation Simple Colloid Goitre. - Two patients had this between the ultrasonic and the isotope scans. condition. The average AP diameter of the lobes Autonomous, Functioning Thyroid Nodules ('Hot was 1.5 cm. In one patient both lobes showed a Nodules'). - In five patients who had a hypernodular pattern on ultrasound and the thyroidal functioning nodule with lack of isotope uptake in uptake as seen on the isotope scan was patchy. the contralateral lobe there was either no detectable The ultrasound pattern was homogeneous in the contralateral lobe on ultrasound (three patients) or other patient and the isotope scan showed a uniform a lobe with a small (0"4 cm) AP diameter (two uptake over both lobes. In these two patients 'soft' patients). The mean AP diameter of the nodules in echoes were seen in the centre of the lobes, and it is these patients was 2.2 cm. Fig. 4 shows a comthought possible that these may be low level echoes parison between the isotope and ultrasound scan reflected from the colloid. in one patient. Graves' Disease - The mean AP diameter of The AP diameter of the five non-toxic nodules those patients who had not had previous surgery tended to be smaller (mean 1-5 cm) than in the were only slightly greater than those of the normal three toxic patients, while that of the contralateral thyroids, but these seven cases were not representalobe (mean 0-7 cm) was larger. Four of the eight tive of Graves' disease as a whole, since many of nodules showed a homogeneous pattern, two were them had been sent for isotope scanning because the more nodular and two showed a mixed nodular/ cystic pattern. In the one patient who had had previous 131I treatment for a hyperfunctioning nodule of the left lobe, the ultrasound showed that the formerly inactive right lobe had become larger than the left. Colloid Nodular Goitre. - The AP diameter of the thyroid glands in these ten patients, as assessed by ultrasound, was on average nearly twice that of normals. The mean diameter of the right lobe was 1'8 cm and that of the left lobe 2.0 cm. The ultrasound pattern was nodular or cystic in the majority although in three cases some homogeneous areas were seen. There was a good correlation between the ultrasound and the pathological findings available in seven cases. Solid nodules and cysts were all correctly identified by ultrasound and the accuracy of their measurement was within 5 ram. In four patients we observed an ultrasound pattern which looked like small cysts ('pseudocysts') less than 6 m m in diameter. Pathologically no cysts were present but there were numerous foci of fibrosis or calcification. In these cases low gain settings were necessary due to the strong echoes from the hard tissues and thus the smaller echoes from the intervening thyroid tissue were not suffi-

194

C L I N I C A L RADIOLOGY

FIG. 3 Graves' disease in a patient with a previous partial thyroidectomy. A. 'A' scan of the right lobe of the thyroid (AP diameter

2-0 cm). B. 'A' scan of the left lobe (AP diameter 0.3 cm). c. 131Iscan of the thyroid showing that most of the uptake is in the right lobe, the left, previously operated upon, having only a little uptake.

ciently amplified to be detected and gave rise to echo free spaces indistinguishable from cysts. Repeat scans at higher, more normal, gain settings may have obviated this problem. There was g o o d agreement between the ultrasound findings and those of isotope scanning. Where the picture was nodular or cystic the isotope scan generally showed a patchy uptake; where a large cyst was identified the isotope scan showed a cold area (Fig. 5). In two patients where one lobe o f the thyroid was thought to be normal on ultrasound the isotope scan was also normal. Three additional patients with multinodular g o i t r e s also had thyrotoxicosis. All had enlarged A P diameters. The ultrasound patterns were nodular or cystic and the isotope scans showed patchy, high uptake. Carcinoma of the Thyroid. - One patient who had previously had a thyroidectomy for a papillary carcinoma o f the thyroid re-presented with a mass in the front of her neck. This was cold on lalI scanning and the ultrasound showed a mass 4 cm in A P diameter which had a solid pattern with numerous cystic areas. Another elderly patient with a large mass in the front of her neck was shown to have a solid lesion with a cystic area in the centre on ultrasound. A t

operation she was f o u n d to have an anaplastic carcinoma with haemorrhage in the centre. Ectopic Thyroid. - Ultrasonic examination confirmed the total absence o f the thyroid in one case and its position on the left side of the neck in another. It failed to locate an ectopic, sublingual thyroid which was 1"2 x 1.5 cm in diameter on the isotope scan. Pseudo-thyroid Lumps. - One patient with a soft mobile mass on the right side of his neck had a normal isotope scan. N o echoes were obtained f r o m the lump and it was concluded that it was fatty tissue. Histologically it proved to be a subcutaneous lipoma. A n o t h e r patient presented with a hard mass on the right side of her neck. Ultrasonic examination showed that there was a clear area with no echoes between the mass and a normal thyroid gland. Squamous carcinoma of the lung was shown by biopsy. A w o m a n with a nodule in front o f her neck was found on ultrasound to have an 8 m m solid lesion above a normal thyroid. A t biopsy it was found to be a sarcoid lymph node. Hashimoto's Thyroiditis. - One 59-year-old w o m a n had Hashimoto's disease, proved by positive thyroid antibodies and by thyroid biopsy. The

ULTRASONICS

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IN

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DIAGNOSIS

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3C ultrasound pattern showed varying homogeneous and nodular areas. This was mirrored to some extent in the biopsy in which there was a diffuse infiltration of lymphocytes and a moderate increase of fibrous tissue. Thyroid Adenoma. - A girl aged 24 had a nodule in the left lobe of her thyroid which did not take up radioactive iodine. The ultrasound showed that the nodule had a solid homogeneous pattern. The histology was that of a follicular adenoma. DISCUSSION Our experience has been that the ultrasonic examination of the thyroid is a rapid and useful adjunct to other conventional investigations of thyroid disease. Histological examination confirmed the ultrasonic findings in all 13 cases in which it was performed. After a little practice each examination can be done in 5 to 10 rain. Ideally the physician interested in thyroid disease should carry out the test because it is he who should interpret the thyroid scan, palpate the gland and indicate which areas are of special interest. The normal thyroid has a homogeneous echo pattern and the antero-posterior diameter measured on ultrasound varied between 0-6 cm and 1-6 cm.

OF

THYROID

DISEASE

195

This is rather smaller than the values sometimes quoted, which vary between 2'0 cm and 3"9 cm (Means et al., 1963; Ingbar and Woeber, 1968). However, the latter figures are presumably derived • from post-mortem material and it m a y be that the thyroid is engorged with blood in this situation. In those patients in whom one lobe was thicker than the other the isotope scan usually showed a correspondingly higher uptake. Patients with colloid goitres or with Graves's disease have homogeneous patterns on the whole and there were no definite differentiating features. Blum and his colleagues (1972) found similar appearances in Graves' disease. The results of ultrasonic examination in patients with autonomous functioning thyroid nodules were interesting, for they showed that, in the patients who were thyrotoxic, the contralateral lobe was either not detectable or was very small. In patients who were euthyroid the contralateral lobe was of normal size, presumably because TSH had not been inhibited. There was generally good agreement between the isotope scan and the results of the ultrasound examination. In those patients in whom the contralateral lobe could not be found on ultrasound the thyroid scan showed no isotope uptake. In one patient who had had previous radioactive iodine treatment for a 'hot nodule' in the left lobe, the thyroid scan, having formerly showed no uptake on the right, now demonstrated a greater concentration of isotope on the right and the AP diameter on ultrasound was 2-0cm, showing that it had hypertrophied. It seems likely that one of the uses of thyroid ultrasound will be in following the response to treatment in these patients and also in estimating the size of the thyroid in patients on suppressive thyroxine therapy (Blum et al., 1972). Our experience with thyroid cysts and solid nodules is in agreement with the findings of others (Blum et al., 1971 ; Rasmussen et al., 1971), in that we were able to estimate the size of a cyst or nodule, verified pathologically, to within 5 ram. Blum and his co-workers (1972) have emphasised that, in their experience, ultrasonic examination has proved of most value in determining whether solitary 'cold' nodules 1 to 3 cm in diameter are cystic or solid. It has been estimated that only one cystic nodule in 250 is malignant (Miller et al., 1974) and the suggested course of action is aspiration needle biopsy and histological examination of the cellular debris (Crile and Hawk, 1973). The very strong echoes seen in some patients with colloid nodular goitres agree well with the findings of Thijs (1971). Our two patients with carcinoma

196

CLINICAL RADIOLOGY

FIG. 4 Patient with an autonomous hyperfunctioning nodule in the left lobe of the thyroid. A. 'A' scan of the left lobe, AP diameter 1-8 cm, pattern nodular. B. 'A' scan of the right lobe, AP diameter 0.4cm, pattern homogeneous. c. Isotope scan showing 'hot nodule' in left lobe with suppression of uptake in the right lobe.

FIG 5A

FIG 4C

FIG. 5 Patient with a cyst in a colloid nodular goitre. h. 'A' scan of the lower pole of the left lobe showing a cystic area, the width of the wall being 2 mm and the external diameter 1.8 cm. n. Isotope scan showing a 'cold' area at the left lower pole. The rest of the thyroid is enlarged and shows a patchy uptake.

ULTRASONICS IN THE DIAGNOSIS OF THYROID DISEASE

of the t h y r o i d h a d solid echo patterns, one with numerous cystic areas a n d the other with a solitary large central cystic area. These were almost certainly n o t true cysts b u t h a e m o r r h a g e into the tumour and i n d e e d the second patient was shown at operation to have h a d a massive h a e m o r r h a g e into the centre o f her a n a p l a s t i c carcinoma. Blum a n d his colleagues (1972) f o u n d t h a t t h y r o i d masses more t h a n 4.0 c m in diameter frequently have a mixed solid/cystic p a t t e r n a n d they felt that in such a case it was impossible to tell whether the lesion was a m u l t i - n o d u l a r goitre or a neoplasm. T h e y did, however, find that the u l t r a s o u n d was o f value in determining whether a s u d d e n increase in size was due to h a e m o r r h a g e or the progression o f neoplastic change. W e f o u n d the u l t r a s o u n d to be o f value in differentiating other lumps in the neck f r o m those arising f r o m the thyroid. W e correctly d i a g n o s e d a lipoma, a P a n c o a s t t u m o u r and an enlarged l y m p h node, largely because we were able to show a lack

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FIG 5a

13

197

o f c o n t i n u i t y between the l u m p a n d n o r m a l t h y r o i d tissue. In conclusion our experience is that the t h y r o i d u l t r a s o u n d is likely to prove to be o f use in estim a t i n g t h y r o i d size and in differentiating cystic from solid lesions. I n 13 cases in which p a t h o logical e x a m i n a t i o n o f the t h y r o i d was possible there was a very close c o r r e l a t i o n with the ultras o u n d examination. W e believe that ultrasonics are o f value in t h y r o i d diagnosis and deserve to be used m o r e widely. Acknowledgements. - We would like to thank Dr P. J. N. Howorth for doing the total thyroxine and the thyroxine resin uptake measurements and Dr Deborah Doniach for the thyroid antibody studies.

REFERENCES BLUM, M., WEISS,B. & HERNBERG,J. (1971). Evaluation of thyroid nodules by A-mode echography. Radiology, 101, 651-656. BLUM, M., GOLDMAN,A. B., HERSKOVIC,A. ~ HERNBERG,J. (1972). Clinical applications of thyroid echography. New England Journal of Medicine, 287, 1164-1169. CRILE, G_ JR & HAWK, W. A. (1973). Aspiration biopsy of thyroid nodules. Surgery, Gynecology and Obstetrics, 136, 241-245. DAMASCELLI,B., CASCINELLI,N., L1VRAGHI,T. & VERONESI, O. (1968). Preoperative approach to thyroid tumours by a two-dimensional pulsed echo technique. Ultrasonics, 6, 242-243. FUJIMOTO, Y., OKA, A., OMOTO, R. & HIROSE, M. (1967). Ultrasound scanning of the thyroid gland as a new diagnostic approach. Ultrasonics, 5, 177-180. INGBAR, S. H_ & WOEBER, K. A. (1968). In Textbook of Endocrinology, ed. Williams, R. H., p. 108. Saunders, Philadelphia. MACLAGAN,N. F. • HOWORTH, P. J. N. (1969). Thyroid function studies using uptake of radioactive thyronines from serum and total thyroxine assay; the free thyroxine index. Clinical Science, 37, 45-60. MEANS, J. H., DE GROOT, L. J. & STANBURY,J. ]~. (1963). The Thyroid and its Diseases, pp. 6, 488. McGraw-Hill Book Company Inc., New York. MILLER, J. M., ZAFAR, S. U. & KARO, J. J. (1974). The cystic thyroid nodule; recognition and management. Radiology, ll0, 257-261. RASMUSSEN,S. N., CHRISTIANSEN,N. J. B., JORGENSEN,J. S. ~¢ HOLM, H. H. (1971)_ Differentiation between cystic and solid thyroid nodules by ultrasonic examination. Acta Chirurgica Scandinavica, 137, 331-333. THIJS, L. G. (1971). Diagnostic ultrasound in clinical thyroid investigation. Journal of Clinical Endocrinology and Metabolism, 32, 709-716. WELLS, P. N. T. (1972). Ultrasonics in Clinical Diagnosis. Churchill, Livingstone, Edinburgh and London. YAMAKAWA,K. & NAITO,S. (1966). Diagnostic ultrasound. Proceedings of the First International Conference, Pittsburgh, 1965, ed. Grossman, C., Holmes, J. H., Poyner, C. & Purnell, E. W., p. 41. Plenum Press, New York.

Ultrasonics in the diagnosis of thyroid disease.

Ultrasonic A scans of the thyroid have been carried out on 47 patients with suspected thyroid disease. It was possible to measure the antero-posterior...
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