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Ultrasound diagnosis of radiation-induced childhood thyroid cancer in Belarus: 10 years of practical experience
International Congress Series 1234 (2002) 221 – 229
Ultrasound diagnosis of radiation-induced childhood thyroid cancer in Belarus: 10 years of practical experience Valentina M. Drozd a,*, Andrej P. Lyshchik a, Evgueni P. Demidchik a, Evgeny D. Cherstvoy b, Vladislav A. Ostapenko a, Christoph Reiners c a
Research and Clinical Institute of Radiation Medicine and Endocrinology, 23 Filimonova Str., Minsk, Belarus b Minsk State Medical Institute, Minsk, Belarus c Clinic and Polyclinic for Nuclear Medicine of the University of Wu¨rzburg, Wu¨rzburg, Germany
Keywords: Ultrasound diagnosis; Childhood thyroid cancer; Ultrasonography
1. Introduction Because of its superficial location, thyroid gland is ideally situated for high-frequency ultrasound examination. Nowadays, ultrasound examination of thyroid is recognized as the most useful radiological examination for screening and early diagnosis of nodular thyroid disease, thyroid cancer in particular. Initial clinical application of ultrasound in diagnosis of thyroid diseases was made by Fujimoto et al. [1] in 1967. Technical possibilities of the equipment used at that time did not allow the assessment of morphological organ structure because there was no gray-scale estimation in the real scale of time. It was only possible to detect the thyroid gland itself and differentiate solid nodules from cyst. The improvement in the ultrasonic diagnostic equipment in the 1970s and usage of high frequency probes increased sensitivity of this examination [2]. At present, ultrasound is used to distinguish diffused pathological processes from local ones, cystic formations from solid ones; conduct topic, and, in some cases, nosology diagnosis [3,4]. Besides using ultrasound examination, it is possible to measure the exact thyroid volume. This information is extremely important for dose calculation in radio-iodine therapy. Ultrasonography is particularly useful during follow-up to control the patients’ response for suppressive L-thyroxin therapy. One of the most important applications of *
Corresponding author. E-mail address: [email protected] (V.M. Drozd).
0531-5131/02 D 2002 Elsevier Science B.V. All rights reserved. PII: S 0 5 3 1 - 5 1 3 1 ( 0 1 ) 0 0 6 11 - 2
222
V.M. Drozd et al. / International Congress Series 1234 (2002) 221–229
ultrasound in thyroid diagnosis is fine-needle aspiration biopsy (FNA) guidance. Continuing improvements in image quality and development of more sophisticated Doppler techniques will lead to an increased role of ultrasound in clinical management of thyroid patients [5]. After the Chernobyl accident, there was a tendency to a considerable increase in the incidence of thyroid cancer in Belarus. The frequency of thyroid cancer in children from Belarus, Ukraine, and the southwestern part of Russia had been increasing since 1990. There is no doubt that systematic screening of the thyroid gland in children that started in the most contaminated regions in 1990 contributed to it. However, the increase in the number of carcinoma cases was considerably higher than it could be expected due to the implementation of screening alone. In Belarus, by the end of 2000, 710 children with thyroid carcinoma were operated. Of these cases, pT1 was diagnosed in 21.7%, pT2 –3 in 41.1%, and pT4 in 37.2% of the patients. In 69% of the children, lymph node metastases have been observed during surgery (pN1). Distant metastases (pM1) were diagnosed postoperatively in 17% of the children. An analysis showed that child thyroid carcinoma is more aggressive compared to that of the adult, and characterized by a high frequency of complications required after additional surgery. These particularities make the problem of early diagnosis of thyroid cancer one of the most important. The paper aimed to show our results in clinical application of ultrasound examinations for early diagnosis of thyroid cancer in children of Belarus.
2. Materials and methods All children with thyroid pathology (nodes and diffuse changes in the thyroid at ultrasonic scanning) were thoroughly examined in ‘‘Aksakovschina’’, the hospital of Research and Clinical Institute of Radiation Medicine and Endocrinology, to prove or disprove thyroid pathology. A fine-needle aspiration was performed for those patients who had thyroid nodes of more than 0.5 cm. Since 1990, 122 cases of thyroid carcinoma in children have been diagnosed in the Aksakovschina Clinic and all these patients were involved in our study. The male/female ratio was 1:1.6, age, 6– 16 years. 2-D ultrasound thyroid examination was performed with the ultrasonic real-time scanner, ‘‘Toshiba’’ SSA 240A (7.5 MHz sector probe) and Hewlett Packard ‘‘Image Point’’ (7.5 MHz linear probe). Both gray-scale and Power Doppler images were analyzed. Sonography was performed with the patient in the spine position with the neck slightly hyperextended. Using 2-D ultrasound examination, thyroid volume (V ) measurements were done by measuring the height (H ), width (W ), and length (L) of the thyroid lobes from two selected orthogonal scans (transverse and sagittal). Calculation of thyroid volume, as that of the corresponding ellipsoid, was done by Brunn et al. [6]: V=HWL0.479. The volumes of the right and left lobes were added together to give the total volume. During the Power Doppler examination, we detected a pattern of nodule vascularisation. Power Doppler patterns of thyroid node vascularisation were classified into three
V.M. Drozd et al. / International Congress Series 1234 (2002) 221–229
223
Fig. 1. Classification of 122 thyroid cancer cases by pTNM staging. The figure on the bar indicates the number of cases.
types: I —nodules without vascularisation, II — nodules with perinodular vascularisation, III — nodules with intra- and perinodular vascularisation [7]. All cases of thyroid carcinoma were verified by morphological study after surgery.
Fig. 2. Patterns of the ultrasound images of 114 thyroid carcinomas. The figure on the bar indicates the number of cases.
224
V.M. Drozd et al. / International Congress Series 1234 (2002) 221–229
Statistical analysis was performed with parametric and nonparametric methods in the electronic tables Excel 5 of Microsoft Windows.
3. Results The early recognition of thyroid carcinoma has become possible now due to the conducted mass ultrasonic screening and follow-up of patients from the risk group exposed to radiation (children exposed to ionising radiation in utero and during the first 4 years of their lives, and children with changes in the echoimage of the thyroid or with small nodules in thyroid in diameter up to 0.5 cm.) As a result of the intensive screening and follow-up program, we diagnosed patients with T1 stage of thyroid cancer (microcarcinoma) in 48.4% of our 122 patients (Fig. 1). Meanwhile, regional lymph node metastasis was found in 60.7% of the patients. We have studied particularities of ultrasonic picture in thyroid cancer patients before surgical removal. Our experience showed that visualization of thyroid carcinoma is possible in two forms: nodular (114 patients — 93.5%) and diffuse (8 patients — 6.5%). The nodular variant of thyroid carcinoma is visualized as a node that is located within the enlarged gland. The enlargement of the gland can be up to 1.5 times compared to the normal size of thyroid. Mean diameter of the nodules was 1.5 cm. Patterns of the ultrasound images of thyroid cancer are shown in Fig. 2. Single node was registered in 88% of the cases. Two or more nodular formations were visible in 12% of the cases. The node was topically located next to the thyroid capsule in 95.5% of patients.
Fig. 3. Thyroid cancer with regular outline.
V.M. Drozd et al. / International Congress Series 1234 (2002) 221–229
225
Fig. 4. Thyroid cancer with irregular outline.
The nodular formation looked more frequently like an inhomogeneous structure (84%) with both regular (37%) (Fig. 3) and irregular outline (63%) (Fig. 4). A ‘‘halo’’, a hypoechogenic margin, was observed in 12.4% of the children with thyroid cancer (Fig. 5). Thyroid nodes were hypoechogenic in the majority of the patients, 62% of the cases,
Fig. 5. Thyroid cancer with halo sign.
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V.M. Drozd et al. / International Congress Series 1234 (2002) 221–229
Fig. 6. Papillary carcinoma (T4N1Mx). Multiple metastases in lymph nodes, (a) transverse scan, (b) longitudinal scan.
isoechogenic in 24%, and mixed in 14% of the cases. Pathological study showed that the isoechogenic feature of the node might indicate either the dissemination or multifocal growth of tumor within the thyroid gland [8]. In general, regional lymphatic nodes of different echogeneicity (hypo-, iso- and mixed) were visible in 66% of the children with the nodular form of thyroid cancer. By FNA, we proved that the isoechogenis pattern of lymph node visualization was typical for metastatic lymphatic nodes (Fig. 6). The diffuse variant is characterized by essential volume enlargement of the thyroid (more than two times) with a diffuse structure modification, hypo- or mixed, inhomogenous echogeneicity (Fig. 7). Enlarged lymphatic nodes were visible in all cases. Although a hypoechogenic character of the thyroid was found in three out of eight children, mixed echogeneicity occurred more frequently (in five children). In the homogeneous and hypoechogenic character of the enlarged thyroid, children with the diffuse form of car-
Fig. 7. Papillary carcinoma diffuse variant in transverse scan (looks like autoimmune thyroiditis) (T4N1BM0).
V.M. Drozd et al. / International Congress Series 1234 (2002) 221–229
227
Fig. 8. 3-D reconstruction and Power Doppler images of thyroid carcinoma.
cinoma looked like an ultrasonic picture of autoimmune thyroiditis, and it was diagnosed only due to the fine-needle aspiration puncture. Power Doppler examinations of the thyroid nodes were carried out in 11 thyroid cancer patients. Absence of intranodular vasularisation was registered only in three patients: type I of nodule vascularisation was registered in two patients, type II in one patient. Type III was registered much more often, in eight patients (Fig. 8).
4. Discussion Nowadays, ultrasound plays a significant role in the early diagnosis of thyroid cancer. Particularities obtained in our study of ultrasound visualization of the thyroid carcinoma correspond to other reports. For example, 78% out of the 506 cases of thyroid carcinoma that were described from 1968 to 1983 were hypoechoic [9]. Besides, the most reliable ultrasound pattern of the nodular form the thyroid carcinoma in other reports was of an irregular outline [10,11]. In our study, ultrasound characteristics of thyroid carcinoma in children were more variable. For example, in 11.4% of the cases of thyroid carcinoma in children, we detected the ‘‘halo’’ sign. Therefore, in contrast to some authors [12], we cannot rely on the absence of ‘‘halo’’ as the good sign of malignancy. In the current literature related to ultrasound investigations, we did not find any reference on the diffuse variant of thyroid carcinoma. The majority of authors analyze ultrasound images only for the nodular form of cancer with regular and irregular outline [13,14]. In children exposed to radiation, we observed the diffuse variant of thyroid
228
V.M. Drozd et al. / International Congress Series 1234 (2002) 221–229
carcinoma. This diffuse form may result from the multifocal growth and rapid progression of the disease. In some cases, diffuse forms were caused by diffuse sclerosing variant of papillary thyroid carcinoma. One of the most important parts of ultrasound examination of children with thyroid carcinoma is the determination of affected regional lymph nodes. According to the pathological study, up to 18.2% of the cases of thyroid microcarcinoma [15] and 38– 90% of all the cases of thyroid carcinoma are associated with regional lymph node metastasis [16]. Detection of multiple isoechogenic lymph nodes is one of the most reliably and frequently unique criteria for the early diagnosis of thyroid carcinoma metastasis. Criteria for ultrasound diagnostic of differentiation of benign and malignant lymph nodes in children are similar to those in adults [17]. Increased sensitivity in detecting slow blood flow using Power Doppler Sonography, in contrast to Color Doppler, enables to improve the detection of intranodal vascularity. As thyroid cancer growth is associated with tumor neoangiogenesis and neovascularisation [18], a high percentage of Power Doppler pattern III was more often found in children with thyroid malignancy than in children with benign nodes [12]. Future development of ultrasound diagnostics will be in the clinical application of the 3-D reconstruction of US images. This method can provide much more exact volume measurements, detailed topic diagnostics of node location, and its relation with surrounding tissues. Our experience in this sphere is unique, but our results fully correspond to the in vitro study on cadaver thyroids and phantoms [19,20], 3-D reconstruction allows to conduct a comparison of the ultrasound and morphological composition of the tumor. It could result in the improvement of early ultrasound verification of thyroid cancer.
5. Conclusion Ultrasonic particularities of thyroid carcinoma in children exposed to radionuclides could be characterized as follows; 1. The ultrasonic picture of thyroid carcinoma, with respect to spread, can be distinguished into two forms: nodular and diffuse. The nodular variant can be divided into nodes with the limited spread (which have either regular or rather regular outlines) and nodes with a vast spread (with an irregular outline). 2. More frequently, the tumor is visualized as a hypoechogenic node. However, the isoechogenic feature of the node might indicate either the dissemination or multifocal growth of the tumor within the thyroid gland or diffuse sclerosing variant of papillary thyroid carcinoma. 3. Thyroid carcinoma is frequently followed by metastasis in regional lymph nodes. Isoechogenic character of visualized cervix lymph nodes is likely to indicate the presence of malignancy in the thyroid. 4. Location of the node next to the thyroid capsule might cause extra capsule dissemination of tumor (T4). 5. Recent improvement of early diagnosis of thyroid cancer increases a part of the patients with T1 stage and decreases T4.
V.M. Drozd et al. / International Congress Series 1234 (2002) 221–229
229
6. 3-D ultrasound and Power Doppler Sonography could improve the early diagnosis of thyroid nodular pathology.
References [1] Y. Fujimoto, A. Oka, R. Omoto, M. Hirose, Ultrasound scanning of the thyroid gland as a new diagnostic approach, Ultrasonics 5 (1967) 177 – 180. [2] D.S. Ross, Evaluation of thyroid nodule, J. Nucl. Med. 32 (1991) 2181 – 2192. [3] C.J. Garcia, A. Daneman, K. McHugh, et al., Sonography in thyroid carcinoma in children, Br. J. Radiol. 65 (1992) 977 – 982. [4] F.N. Tessler, M.E. Tublin, Thyroid sonography: current applications and future directions, AJR Am. J. Roentgenol. 173 (2) (Aug. 1999) 437 – 443. [5] K.S. Naik, R.F. Bury, Imaging the thyroid, Clin. Radiol. 53 (1998) 630 – 639. [6] J. Brunn, U. Block, G. Ruf, et al., Volumetrie der Schilddrusenlappen mittels Real-time-Sonographie, Dtsch. Med. Wochenschr. 106 (41) (1981) 1338 – 1340. [7] R. Lagalla, G. Caruso, M. Romano, M. Midiri, V. Novara, F. Zappasodi, Echo-color Doppler in thyroid disease, Radiol. Med. (Torino) 85 (5 Suppl. 1) (1993) 109 – 113. [8] Chr. Reiners, V.M. Drozd, E.D. Cherstvoy, E.P. Demidchik, A.M. Nerovnya, M. Luster, Ultrasonography of the Thyroid in Children and Adolescents: Sonographic and Pathological Studies in a Population from Belarus After the Chernobyl Accident, Schattauer, Stuttgart, 2000. [9] W. Wiedemann, Sonographie und Szintigraphie der Schilddruse: Lehrbuch und Atlas, Verlag, Stuttgart, 1993. [10] L.A. Loevner, Imaging of the thyroid gland, Semin. Ultrasound CT MR 17 (6) (1996) 539 – 562. [11] G.W. Gooding, Sonography of the thyroid and parathyroid, Radiol. Clin. North Am. 31 (1993) 967 – 973. [12] T. Rago, P. Vitti, et al., Role of conventional ultrasonography and color flow-doppler sonography in predicting malignancy in ‘‘cold’’ thyroid nodules, Eur. J. Endocrinol. 138 (1998) 41 – 46. [13] D. Lorenz, G. van Kaick, Echographische Diagnostik bei Erkrankungen der Schilddruse und der Nebenschilddruse, Rontgenpraxis 34 (1881) S315 – S323. [14] Chr. Reiners, I. Sieper, G. Simons, Schilddrusendiagnostik, Behringwerke, Germany, 1994, p. 143S. [15] W. Lang, H. Borrusch, L. Bauer, Ocult carcinomas of thyroid: evaluation of 1020 sequential autopsies, Am. J. Clin. Pathol. 90 (1988) 72 – 76. [16] D. Hay, Papillaty thyroid carcinoma, Endocrinol. Metab. North Am. 19 (1990) 719 – 739. [17] P. Vassalo, K. Wernecke, N. Roos, P.E. Peters, Differentiation of benign from malignant superficial lymphadenopathy: the role of high-resolution US, Radiology 183 (1992) 215 – 220. [18] J. Folkman, Tumor angiogenesis: role in regulation of tumor growth, Symp. Soc. Dev. Biol. 30 (1974) 43 – 52. [19] E. Werner, S. Schloegl, J. Terechova, M. Lassmann, Chr. Reiners, Accuracy of the volumetric of the thyroid by 3D ultrasound: suitability for epidemiological studies? Results of a post mortem study, in: Endocrinologia Japonica. vol. 47, Suppl. 12-th International Thyroid Congress, p. 157. [20] D. King, M. Shao, Evaluation of in vitro measurement accuracy of three-dimensional ultrasound scanner, J. Ultrastruct. Med. 10 (1991) 77 – 82.
Ultrasound diagnosis of radiation-induced childhood thyroid cancer in Belarus: 10 years of practical experience Valentina M. Drozd a,*, Andrej P. Lyshchik a, Evgueni P. Demidchik a, Evgeny D. Cherstvoy b, Vladislav A. Ostapenko a, Christoph Reiners c a
Research and Clinical Institute of Radiation Medicine and Endocrinology, 23 Filimonova Str., Minsk, Belarus b Minsk State Medical Institute, Minsk, Belarus c Clinic and Polyclinic for Nuclear Medicine of the University of Wu¨rzburg, Wu¨rzburg, Germany
Keywords: Ultrasound diagnosis; Childhood thyroid cancer; Ultrasonography
1. Introduction Because of its superficial location, thyroid gland is ideally situated for high-frequency ultrasound examination. Nowadays, ultrasound examination of thyroid is recognized as the most useful radiological examination for screening and early diagnosis of nodular thyroid disease, thyroid cancer in particular. Initial clinical application of ultrasound in diagnosis of thyroid diseases was made by Fujimoto et al. [1] in 1967. Technical possibilities of the equipment used at that time did not allow the assessment of morphological organ structure because there was no gray-scale estimation in the real scale of time. It was only possible to detect the thyroid gland itself and differentiate solid nodules from cyst. The improvement in the ultrasonic diagnostic equipment in the 1970s and usage of high frequency probes increased sensitivity of this examination [2]. At present, ultrasound is used to distinguish diffused pathological processes from local ones, cystic formations from solid ones; conduct topic, and, in some cases, nosology diagnosis [3,4]. Besides using ultrasound examination, it is possible to measure the exact thyroid volume. This information is extremely important for dose calculation in radio-iodine therapy. Ultrasonography is particularly useful during follow-up to control the patients’ response for suppressive L-thyroxin therapy. One of the most important applications of *
Corresponding author. E-mail address: [email protected] (V.M. Drozd).
0531-5131/02 D 2002 Elsevier Science B.V. All rights reserved. PII: S 0 5 3 1 - 5 1 3 1 ( 0 1 ) 0 0 6 11 - 2
222
V.M. Drozd et al. / International Congress Series 1234 (2002) 221–229
ultrasound in thyroid diagnosis is fine-needle aspiration biopsy (FNA) guidance. Continuing improvements in image quality and development of more sophisticated Doppler techniques will lead to an increased role of ultrasound in clinical management of thyroid patients [5]. After the Chernobyl accident, there was a tendency to a considerable increase in the incidence of thyroid cancer in Belarus. The frequency of thyroid cancer in children from Belarus, Ukraine, and the southwestern part of Russia had been increasing since 1990. There is no doubt that systematic screening of the thyroid gland in children that started in the most contaminated regions in 1990 contributed to it. However, the increase in the number of carcinoma cases was considerably higher than it could be expected due to the implementation of screening alone. In Belarus, by the end of 2000, 710 children with thyroid carcinoma were operated. Of these cases, pT1 was diagnosed in 21.7%, pT2 –3 in 41.1%, and pT4 in 37.2% of the patients. In 69% of the children, lymph node metastases have been observed during surgery (pN1). Distant metastases (pM1) were diagnosed postoperatively in 17% of the children. An analysis showed that child thyroid carcinoma is more aggressive compared to that of the adult, and characterized by a high frequency of complications required after additional surgery. These particularities make the problem of early diagnosis of thyroid cancer one of the most important. The paper aimed to show our results in clinical application of ultrasound examinations for early diagnosis of thyroid cancer in children of Belarus.
2. Materials and methods All children with thyroid pathology (nodes and diffuse changes in the thyroid at ultrasonic scanning) were thoroughly examined in ‘‘Aksakovschina’’, the hospital of Research and Clinical Institute of Radiation Medicine and Endocrinology, to prove or disprove thyroid pathology. A fine-needle aspiration was performed for those patients who had thyroid nodes of more than 0.5 cm. Since 1990, 122 cases of thyroid carcinoma in children have been diagnosed in the Aksakovschina Clinic and all these patients were involved in our study. The male/female ratio was 1:1.6, age, 6– 16 years. 2-D ultrasound thyroid examination was performed with the ultrasonic real-time scanner, ‘‘Toshiba’’ SSA 240A (7.5 MHz sector probe) and Hewlett Packard ‘‘Image Point’’ (7.5 MHz linear probe). Both gray-scale and Power Doppler images were analyzed. Sonography was performed with the patient in the spine position with the neck slightly hyperextended. Using 2-D ultrasound examination, thyroid volume (V ) measurements were done by measuring the height (H ), width (W ), and length (L) of the thyroid lobes from two selected orthogonal scans (transverse and sagittal). Calculation of thyroid volume, as that of the corresponding ellipsoid, was done by Brunn et al. [6]: V=HWL0.479. The volumes of the right and left lobes were added together to give the total volume. During the Power Doppler examination, we detected a pattern of nodule vascularisation. Power Doppler patterns of thyroid node vascularisation were classified into three
V.M. Drozd et al. / International Congress Series 1234 (2002) 221–229
223
Fig. 1. Classification of 122 thyroid cancer cases by pTNM staging. The figure on the bar indicates the number of cases.
types: I —nodules without vascularisation, II — nodules with perinodular vascularisation, III — nodules with intra- and perinodular vascularisation [7]. All cases of thyroid carcinoma were verified by morphological study after surgery.
Fig. 2. Patterns of the ultrasound images of 114 thyroid carcinomas. The figure on the bar indicates the number of cases.
224
V.M. Drozd et al. / International Congress Series 1234 (2002) 221–229
Statistical analysis was performed with parametric and nonparametric methods in the electronic tables Excel 5 of Microsoft Windows.
3. Results The early recognition of thyroid carcinoma has become possible now due to the conducted mass ultrasonic screening and follow-up of patients from the risk group exposed to radiation (children exposed to ionising radiation in utero and during the first 4 years of their lives, and children with changes in the echoimage of the thyroid or with small nodules in thyroid in diameter up to 0.5 cm.) As a result of the intensive screening and follow-up program, we diagnosed patients with T1 stage of thyroid cancer (microcarcinoma) in 48.4% of our 122 patients (Fig. 1). Meanwhile, regional lymph node metastasis was found in 60.7% of the patients. We have studied particularities of ultrasonic picture in thyroid cancer patients before surgical removal. Our experience showed that visualization of thyroid carcinoma is possible in two forms: nodular (114 patients — 93.5%) and diffuse (8 patients — 6.5%). The nodular variant of thyroid carcinoma is visualized as a node that is located within the enlarged gland. The enlargement of the gland can be up to 1.5 times compared to the normal size of thyroid. Mean diameter of the nodules was 1.5 cm. Patterns of the ultrasound images of thyroid cancer are shown in Fig. 2. Single node was registered in 88% of the cases. Two or more nodular formations were visible in 12% of the cases. The node was topically located next to the thyroid capsule in 95.5% of patients.
Fig. 3. Thyroid cancer with regular outline.
V.M. Drozd et al. / International Congress Series 1234 (2002) 221–229
225
Fig. 4. Thyroid cancer with irregular outline.
The nodular formation looked more frequently like an inhomogeneous structure (84%) with both regular (37%) (Fig. 3) and irregular outline (63%) (Fig. 4). A ‘‘halo’’, a hypoechogenic margin, was observed in 12.4% of the children with thyroid cancer (Fig. 5). Thyroid nodes were hypoechogenic in the majority of the patients, 62% of the cases,
Fig. 5. Thyroid cancer with halo sign.
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V.M. Drozd et al. / International Congress Series 1234 (2002) 221–229
Fig. 6. Papillary carcinoma (T4N1Mx). Multiple metastases in lymph nodes, (a) transverse scan, (b) longitudinal scan.
isoechogenic in 24%, and mixed in 14% of the cases. Pathological study showed that the isoechogenic feature of the node might indicate either the dissemination or multifocal growth of tumor within the thyroid gland [8]. In general, regional lymphatic nodes of different echogeneicity (hypo-, iso- and mixed) were visible in 66% of the children with the nodular form of thyroid cancer. By FNA, we proved that the isoechogenis pattern of lymph node visualization was typical for metastatic lymphatic nodes (Fig. 6). The diffuse variant is characterized by essential volume enlargement of the thyroid (more than two times) with a diffuse structure modification, hypo- or mixed, inhomogenous echogeneicity (Fig. 7). Enlarged lymphatic nodes were visible in all cases. Although a hypoechogenic character of the thyroid was found in three out of eight children, mixed echogeneicity occurred more frequently (in five children). In the homogeneous and hypoechogenic character of the enlarged thyroid, children with the diffuse form of car-
Fig. 7. Papillary carcinoma diffuse variant in transverse scan (looks like autoimmune thyroiditis) (T4N1BM0).
V.M. Drozd et al. / International Congress Series 1234 (2002) 221–229
227
Fig. 8. 3-D reconstruction and Power Doppler images of thyroid carcinoma.
cinoma looked like an ultrasonic picture of autoimmune thyroiditis, and it was diagnosed only due to the fine-needle aspiration puncture. Power Doppler examinations of the thyroid nodes were carried out in 11 thyroid cancer patients. Absence of intranodular vasularisation was registered only in three patients: type I of nodule vascularisation was registered in two patients, type II in one patient. Type III was registered much more often, in eight patients (Fig. 8).
4. Discussion Nowadays, ultrasound plays a significant role in the early diagnosis of thyroid cancer. Particularities obtained in our study of ultrasound visualization of the thyroid carcinoma correspond to other reports. For example, 78% out of the 506 cases of thyroid carcinoma that were described from 1968 to 1983 were hypoechoic [9]. Besides, the most reliable ultrasound pattern of the nodular form the thyroid carcinoma in other reports was of an irregular outline [10,11]. In our study, ultrasound characteristics of thyroid carcinoma in children were more variable. For example, in 11.4% of the cases of thyroid carcinoma in children, we detected the ‘‘halo’’ sign. Therefore, in contrast to some authors [12], we cannot rely on the absence of ‘‘halo’’ as the good sign of malignancy. In the current literature related to ultrasound investigations, we did not find any reference on the diffuse variant of thyroid carcinoma. The majority of authors analyze ultrasound images only for the nodular form of cancer with regular and irregular outline [13,14]. In children exposed to radiation, we observed the diffuse variant of thyroid
228
V.M. Drozd et al. / International Congress Series 1234 (2002) 221–229
carcinoma. This diffuse form may result from the multifocal growth and rapid progression of the disease. In some cases, diffuse forms were caused by diffuse sclerosing variant of papillary thyroid carcinoma. One of the most important parts of ultrasound examination of children with thyroid carcinoma is the determination of affected regional lymph nodes. According to the pathological study, up to 18.2% of the cases of thyroid microcarcinoma [15] and 38– 90% of all the cases of thyroid carcinoma are associated with regional lymph node metastasis [16]. Detection of multiple isoechogenic lymph nodes is one of the most reliably and frequently unique criteria for the early diagnosis of thyroid carcinoma metastasis. Criteria for ultrasound diagnostic of differentiation of benign and malignant lymph nodes in children are similar to those in adults [17]. Increased sensitivity in detecting slow blood flow using Power Doppler Sonography, in contrast to Color Doppler, enables to improve the detection of intranodal vascularity. As thyroid cancer growth is associated with tumor neoangiogenesis and neovascularisation [18], a high percentage of Power Doppler pattern III was more often found in children with thyroid malignancy than in children with benign nodes [12]. Future development of ultrasound diagnostics will be in the clinical application of the 3-D reconstruction of US images. This method can provide much more exact volume measurements, detailed topic diagnostics of node location, and its relation with surrounding tissues. Our experience in this sphere is unique, but our results fully correspond to the in vitro study on cadaver thyroids and phantoms [19,20], 3-D reconstruction allows to conduct a comparison of the ultrasound and morphological composition of the tumor. It could result in the improvement of early ultrasound verification of thyroid cancer.
5. Conclusion Ultrasonic particularities of thyroid carcinoma in children exposed to radionuclides could be characterized as follows; 1. The ultrasonic picture of thyroid carcinoma, with respect to spread, can be distinguished into two forms: nodular and diffuse. The nodular variant can be divided into nodes with the limited spread (which have either regular or rather regular outlines) and nodes with a vast spread (with an irregular outline). 2. More frequently, the tumor is visualized as a hypoechogenic node. However, the isoechogenic feature of the node might indicate either the dissemination or multifocal growth of the tumor within the thyroid gland or diffuse sclerosing variant of papillary thyroid carcinoma. 3. Thyroid carcinoma is frequently followed by metastasis in regional lymph nodes. Isoechogenic character of visualized cervix lymph nodes is likely to indicate the presence of malignancy in the thyroid. 4. Location of the node next to the thyroid capsule might cause extra capsule dissemination of tumor (T4). 5. Recent improvement of early diagnosis of thyroid cancer increases a part of the patients with T1 stage and decreases T4.
V.M. Drozd et al. / International Congress Series 1234 (2002) 221–229
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6. 3-D ultrasound and Power Doppler Sonography could improve the early diagnosis of thyroid nodular pathology.
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