Radionuclide imaging in primary permanent congenital hypothyroidism.

Thyroid scintigraphy was performed in 69 consecutive infants with permanent primary congenital hypothyroidism (CH) detected by systematic neonatal thyroid screening using a rectilinear scanner or a gamma camera 15 minutes after the intravenous injection of 250 microCi Tc-99m sodium pertechnetate, immediately after the infants were fed. Immobilization of the infant in a supine position with the neck in hyperextension was achieved by a vacuum cushion without any sedation. Thyroid scintigraphy showed thyroid ectopia in 43 of the 69 CH infants, thyroid agenesis in 19, and goiter in the last 7 infants, respectively. The images were easily interpretable in all cases, even in very small ectopic glands in the lingual area, as there was no interference with extra-thyroidal uptake of the tracer, especially by the salivary glands. Our experience indicates that thyroid scintigraphy in the CH newborns can be performed immediately at the time of diagnosis of CH without technical difficulties. As thyroid scintigraphy is the only procedure allowing the distinction between thyroid agenesis and ectopia, and as the neurointellectual prognosis might be lower in the former than in the latter situation, thyroid scintigraphy in CH newborns contributes not only to the diagnosis but also the prognosis of the disorder.     

Impaired trapping of Tc-99m pertechnetate in the salivary glands of patients with congenital hypothyroidism

This paper describes diminished concentration of Tc-99m pertechnetate in the salivary glands of infants with congenital hypothyroidism. The salivary glands' abnormalities were incidentally noted on the neck images acquired for suspected lingual thyroid or athyrosis. None of the 11 infants with congenital hypothyroidism revealed normal Tc-99m pertechnetate trapping in the salivary glands.     

Thyroid screening in congenital hypothyroidism: a review of 41 cases

Forty-one infants have been referred for thyroid scintigraphy following routine screening for congenital hypothyroidism: 14 (35%) were athyreotic, 19 (45%) had an ectopic thyroid, four (10%) were normal and four (10%) demonstrated other abnormalities. There was a female: male ratio of 4:1. Thyroid scintigraphy is a useful adjunct to biochemical screening.     

Scintigraphic evaluation of primary congenital hypothyroidism: results of the Greek screening program

The Greek screening program for primary congenital hypothyroidism was initiated in 1979. By early 2000, thyrotropin measurements had been performed in 1,976,719 newborns, using dried blood spots obtained by heel prick. Among these children, 584 were diagnosed with congenital hypothyroidism (incidence: 1/3,384 births) and were given L-thyroxine (L-T4) replacement therapy. In order to further evaluate and classify the children as having either an aplastic (AT) or an ectopic thyroid gland (ET) or as showing thyroidal dyshormonogenesis (DN, with a nomotopic gland), scintigraphic studies were performed at the age of 2-3 years. In 413 children of this age group (including 24 subsequently diagnosed as having had transient hypothyroidism, in whom L-T4 therapy was not resumed), thyroid hormones were measured and scintigraphic studies were done after withdrawal of L-T4 replacement treatment for 3 weeks. Given the long duration of the study, we used various scintigraphic modalities. In 96 children (group A), scintigraphy was performed using technetium-99m pertechnetate (99mTcO4-; 18.5 MBq given i.v.) and a rectilinear scanner. Seventy-three children (group B) were studied with 99mTcO4- (18.5 MBq given i.v.) and a gamma camera equipped with a pinhole collimator. In these groups, atropine was administered 30 min prior to the study (0.02 mg/kg i.v. or i.m.) in order to reduce the secretion of saliva from the salivary glands. Finally, in the remaining 220 children (group C) iodine-123 sodium iodide (123I-Na) (0.74-1.85 MBq i.v.) and the same gamma camera were used. Between-group comparisons of scintigraphic findings were done with the chi square test. In 191 children from group C, thyroglobulin (Tg) was measured and in 49 children ultrasound (US) was performed (categorising the gland as AT or ET/DN). Comparison of these modalities was done with the kappa statistic. In group A, 61.5% of children had AT, 26.0% had ET and 12.5% had DN; in group B, 28.8% of children had AT, 52.0% had ET and 19.2% had DN; in group C, 23.2% of children had AT, 63.2% had ET and 13.6% had DN. Statistically significant differences in group A versus groups B and C were noted for AT and ET. The implementation of newer scintigraphic modalities, and especially the use of 123I-Na, indicates that the commonest finding in congenital hypothyroidism is ET. Scintigraphy was more concordant with Tg measurements (though at a moderate level) than with US. The latter was even less concordant with Tg values. These results show that the most appropriate approach for the evaluation and classification of congenital hypothyroidism is 123I-Na scanning.     

A unique case of thyroid dysgenesis in a neonate

Neonates with congenital hypothyroidism often demonstrate ectopic thyroid tissue. However, 2 sites of abnormally located thyroid tissue are exceptionally rare with only one other published case on a neonate. The authors present a unique case of a neonate who was found to have congenital hypothyroidism on laboratory screening; Tc-99m pertechnetate scintigraphy demonstrated 2 sites of abnormal uptake: one at the base of the tongue and the other in the midline at the expected location of the thyroid bed.     

Scintigraphic evaluation of primary congenital hypothyroidism: results of the Greek screening program

The Greek screening program for primary congenital hypothyroidism was initiated in 1979. By early 2000, thyrotropin measurements had been performed in 1,976,719 newborns, using dried blood spots obtained by heel prick. Among these children, 584 were diagnosed with congenital hypothyroidism (incidence: 1/3,384 births) and were given L-thyroxine (L-T₄) replacement therapy. In order to further evaluate and classify the children as having either an aplastic (AT) or an ectopic thyroid gland (ET) or as showing thyroidal dyshormonogenesis (DN, with a nomotopic gland), scintigraphic studies were performed at the age of 2-3 years. In 413 children of this age group (including 24 subsequently diagnosed as having had transient hypothyroidism, in whom L-T₄ therapy was not resumed), thyroid hormones were measured and scintigraphic studies were done after withdrawal of L-T₄ replacement treatment for 3 weeks. Given the long duration of the study, we used various scintigraphic modalities. In 96 children (group A), scintigraphy was performed using technetium-99m pertechnetate (^99mTcO₄^-; 18.5 MBq given i.v.) and a rectilinear scanner. Seventy-three children (group B) were studied with ^99mTcO₄^- (18.5 MBq given i.v.) and a gamma camera equipped with a pinhole collimator. In these groups, atropine was administered 30 min prior to the study (0.02 mg/kg i.v. or i.m.) in order to reduce the secretion of saliva from the salivary glands. Finally, in the remaining 220 children (group C) iodine-123 sodium iodide (¹²³I-Na) (0.74-1.85 MBq i.v.) and the same gamma camera were used. Between-group comparisons of scintigraphic findings were done with the chi square test. In 191 children from group C, thyroglobulin (Tg) was measured and in 49 children ultrasound (US) was performed (categorising the gland as AT or ET/DN). Comparison of these modalities was done with the kappa statistic. In group A, 61.5% of children had AT, 26.0% had ET and 12.5% had DN; in group B, 28.8% of children had AT, 52.0% had ET and 19.2% had DN; in group C, 23.2% of children had AT, 63.2% had ET and 13.6% had DN. Statistically significant differences in group A versus groups B and C were noted for AT and ET. The implementation of newer scintigraphic modalities, and especially the use of ¹²³I-Na, indicates that the commonest finding in congenital hypothyroidism is ET. Scintigraphy was more concordant with Tg measurements (though at a moderate level) than with US. The latter was even less concordant with Tg values. These results show that the most appropriate approach for the evaluation and classification of congenital hypothyroidism is ¹²³I-Na scanning.     

99 Tcm-MIBI显像定位诊断功能亢进性异位甲状旁腺

目的：探讨99Tc^m-甲氧基异丁基异腈（MIBI）显像对于异位甲状旁腺所致原发性甲状旁腺功能亢进（简称甲旁亢）的显像特点，提高甲状旁腺术前定位的准确性。方法：61例原发性甲旁患者采用99Tcm-MIBI显像（减影法6例，双时相法55例），其中52例有B超（US），15例有CT检查，全部病例均经手术和病理检查证实。结果：61例中发现异位甲状帝腺16例（26．2％），位置分别为：颈动脉鞘内3例，下颈部处伸至胸骨后6例，纵隔内7例，99Tcm-MIBI显像全部检出（100％），与手术部位一致，US检查15例，检出8例（53．3％），均位于颈部，纵隔内6例及颈动脉鞘内1例未检出。CT检查7例，纵隔内6例检出2例（28．6％），病理检查诊断：腺瘤14例，增生2例，病灶最小1g，最大＞60d,99Tcm-MIBI显像示病灶小者为放射性均匀浓聚，大者常有囊性变，甚至完全为囊肿样。位于甲状腺影像外者，双时相法的初始相即可显示，但位于纵隔深部病变的解剖关系不能精确表达，结论：99Tcm-MIBI显像是最有效的探测异位甲状旁腺的方法，缺点是对于纵隔深部病灶的解剖定位不够清楚，应加断显像或加做CT检查。     

Neonatal hypothyroid disease: absent salivary gland evident on technetium-99m pertechnetate scan

PURPOSE: Technetium-99m pertechnetate scintigraphy is a well-established technique for diagnosing congenital hypothyroid disease. However, the biodistribution of pertechnetate (TcO4-) in neonates and young infants is not well documented. The purpose of this study was to analyze and document the biodistribution of TcO4- in young infants. MATERIALS AND METHODS: Scintigraphic studies of 31 patients being examined for hypothyroid disease were analyzed. All patients had elevated levels of thyroid-stimulating hormone. Dyshormonogenesis was diagnosed in 7 patients, ectopic thyroid glands in 19, and agenesis in 5. RESULTS: Images of the neck, chest, and abdomen taken in the anterior and left lateral positions using a low-energy, all-purpose collimator were reviewed. Twenty-six of the patients had no accumulation of the isotope in the salivary glands and 11 had no gastric uptake on either view. CONCLUSIONS: Based on the absence of salivary gland activity in the patients examined, this study suggests that this is a normal finding in infants younger than 3 months. A lateral view of the neck with markers is sufficient to localize the thyroid gland, because any activity in the neck region would belong to the thyroid. Furthermore, poor and variable uptake of the isotope in the stomach may lead to false-negative results, so caution is urged in the use of this tracer in Meckel's scintigraphy in young infants, particularly if the study findings are within normal limits.     

Localization of ectopic parathyroid glands using technetium-99m sestamibi imaging: Comparison with magnetic resonance and computed tomographic imaging

The aim of the study was to compare the accuracy of technetium-99m sestamibi imaging for localization of ectopic parathyroid glands in patients with hyperparathyroidism with that of magnetic resonance (MR) and computed tomographic (CT) imaging. Eleven patients with primary (n=3) or secondary (n=8) hyperparathyroidism were studied with^99mTc sestamibi parathyroid imaging CT and MR imaging. Images of the neck were acquired at 10 min and 2–3 after tracer injection. The three patients with primary hyperparathyroidism and five patients with secondary hyperparathyroidism underwent parathyroidectomy. The ectopic glands were confirmed by histopathological examination of the resected specimens. In respect of 20 parathyroid glands in the eight patients explored surgically, the sensitivity and specificity of sestamibi imaging were 70% (14/20) and 88%, respectively, those of CT, 40% (8/20) and 88%, and those of MR imaging, 60% (12/20) and 88%. Of these patients, three had parathyroid adenomas while five had hyperplasia (17 glands). Sestamibi imaging localized eight ectopic parathyroid glands, which were surgically confirmed (six were located in the thymus and two in the mediastinum). In one patient explored surgically, the ectopic gland was located outside the field of the MR coil. Although the remaining three cases of secondary hyperparathyroidism were not confirmed surgically, these patients demonstrated sestamibi uptake in five parathyroid glands, including three ectopic glands. MR images demonstrated abnormal parathyroid glands in the same regions as sestamibi imaging. Our data indicate that^99mTc-sestamibi imaging should be used initially to localize the ectopic parathyroid glands in patients with hyperparathyroidism for anatomical guidance prior to MR or CT imaging.     

Role of SPECT/CT in the preoperative assessment of hyperparathyroid patients

PURPOSE: Our purpose was to assess the clinical value and additional benefit of fusion single-photon computed tomography (SPECT) and computed tomography (CT) images in locating the parathyroids in a selected group of patients affected by primary (PHP) and secondary hyperparathyroidism (SHP). MATERIALS AND METHODS: Sixteen patients (11 women and five men; age range 35-80 years) with severe hyperparathyroidism (HP) (ten PHP, six SHP) were studied by ultrasound (US), and, after i.v. injection of 370 MBq of 99mTc-sestamibi, by planar parathyroid scintigraphy, SPECT and SPECT/CT using a dual-detector scintillation camera GE Infinia Hawkeye. All patients underwent parathyroidectomy. RESULTS: US findings were inconclusive in 12/16 patients affected by multinodular goitre, and two probable eutopic parathyroid glands were identified. "Double phase" parathyroid scintigraphy identified 14 probable parathyroid glands, SPECT 23 (14 ectopic and nine eutopic) and SPECT/CT confirmed all 23 probable parathyroid lesions, offering more precise localisation and an evident improvement in diagnostic accuracy. Sixteen of these foci of increased uptake were hyperplastic parathyroid glands, six were adenomas, one was a parathyroid carcinoma and one was a thyroid follicular carcinoma. Surgical detection of the 23 sestamibi-positive lesions was correctly matched with 100% of SPECT/CT images and 61% of SPECT data alone. Hybrid imaging thus provided additional data in 39% of lesions, and in three patients with retrotracheal glands, it modified the surgical approach. CONCLUSIONS: We believe 99mTc-sestamibi SPECT/CT to be a more reliable presurgical method to study a patient subgroup affected by PHP or SHP in whom conventional US and other scintigraphic methods have failed for intrinsic reasons due to the concomitant presence of multinodular goitre or ectopic parathyroid gland. The additional practical benefit derived from this methodology was evident. In fact, anatomical information provided by CT enables precise localisation of the functional abnormalities highlighted by SPECT, and both are essential to a correct surgical approach.     

MR IMAGING OF THE LINGUAL THYROID: Comparison to other submucosal lesions

Purpose: To study MR findings for clues to the diagnosis of lingual thyroid.Material and Methods: MR findings and clinical and scintigraphic data of 5 cases of lingual thyroid were reviewed and the MR findings were compared to those of 16 cases of other submucosal lesions in the base of the tongue.Results: Four of the 5 patients with lingual thyroid were women and all had hypothyroidism. MR imaging depicted lingual thyroid in the midline in the base of the tongue (n=5) and additional ectopic thyroid glands in the floor of the mouth (n=2) or between the right and left sternohyoid muscles (n=1). Ectopic thyroid glands appeared isointense or hyperintense relative to muscle tissue on T1-weighted images and showed slight or fair contrast enhancement. All glands had low to intermediate T2 signal, which was also seen in 1 case of non-Hodgkin's lymphoma and 1 case of adenoid cystic carcinoma. All ectopic thyroid glands had well-defined margins, whereas malignant tumors tended to have ill-defined margins and to invade the surrounding structures. All but the 5 cases of lingual thyroid had an MR-demonstrable thyroid gland in the normal cervical position.Conclusion: A well-defined mass of low-intermediate T2 signal in the midline base of the tongue, neither with invasive tendency nor with a cervical thyroid gland in the normal site on MR imaging, may strongly indicate lingual thyroid.     

Ultrasonography of Various Thyroid Diseases in Children and Adolescents: A Pictorial Essay

Thyroid imaging is indicated to evaluate congenital hypothyroidism during newborn screening or in cases of a palpable thyroid mass in children and adolescents. This pictorial essay reviews the ultrasonography (US) of thyroid diseases in children and adolescents, including normal thyroid gland development, imaging features of congenital thyroid disorders (dysgenesis, [aplasia, ectopy, hypoplasia], dyshormonogenesis, transient hypothyroidism, thyroglossal duct cyst), diffuse thyroid disease (Grave''s disease, Hashimoto''s thyroiditis, and suppurative thyroiditis), and thyroid nodules. The primary imaging modalities for evaluating thyroid diseases are US and radionuclide scintigraphy. Additionally, US can be used to guide aspiration of detected nodules.     

Dual Pathologies of Parathyroid Adenoma and Papillary Thyroid Cancer on Fluorocholine and Fluorodeoxyglucose PET/CT

¹⁸F-Fluorocholine (FCH) PET/CT is evolving as a functional imaging modality for the preoperative imaging of abnormal parathyroid tissue(s) helping to localize eutopic and ectopic parathyroid tissue and limit the extent of surgery. FCH PET/CT may show incidental uptake in various thyroid lesions necessitating further evaluation, whereas the role of ¹⁸F-fluorodeoxyglucose (FDG) PET/CT in the detection of incidental thyroid nodules is well documented. The case of a middle-aged woman with dual pathology of parathyroid adenoma and papillary thyroid cancer detected on FCH and FDG PET/CT is presented.     

Congenital hypothyroidism: assessment with ultrasound.

PURPOSETo determine the clinical utility of cervical ultrasound in patients suspected of having congenital hypothyroidism.METHODSThirty-seven patients with suspected congenital hypothyroidism underwent ultrasound and scintigraphic evaluation of the thyroid anatomy, morphology, and function. The ultrasound findings and laboratory data were compared with the standard-of-reference scintigraphic findings and laboratory data for diagnosing specific causes in those patients, and prognosis was correlated with the ultrasound findings.RESULTSUltrasound was not reliable for detecting ectopia (n = 8) or differentiating ectopia from aplasia (n = 1). Ultrasound showed ectopia in six (four in the mouth floor and two in the tongue base) of eight cases (75% sensitivity). Ultrasound did not show one ectopia in the floor of mouth because its echogenicity was similar to that of surrounding tissues. A second ectopia, in the hypopharynx, was missed because of hindrance of the laryngeal air. Radioactive iodine uptake and scintigraphy was required for the patients with enlarged glands in the normal place to differentiate dyshormonogenesis from other categories. Specific causes were diagnosed correctly with ultrasound findings and laboratory data alone in all of the 20 patients who had hemiaplasia or small or normal-size glands in the normal location. Incidences of heterogeneity and hypoechogenicity of the thyroid gland in patients with prolonged clinical course (whose replacement therapy or follow-up extended for more than 1 year) were significantly higher than those in patients with short clinical course.CONCLUSIONUltra-sound can obviate the need for scintigraphy in more than half (54%) of patients with possible congenital hypothyroidism. Ultrasound has a potential to predict prognosis of these patients.     

Dual thyroid ectopy: case report and review of the literature

Dual ectopic thyroid glands rarely occur, and only six cases have been reported in the literature. The authors describe a 14-year-boy who had a midline neck swelling for 8 to 9 years. The swelling increased gradually, but he had no pressure symptoms. The thyroid hormone profile showed a moderately increased thyroid-stimulating hormone value and normal T3 and T4 levels. A Tc-99m sodium pertechnetate thyroid scan showed dual ectopic thyroid glands in the sublingual and subhyoid regions.     

Scintigraphic visualization of glossal thyroid tissue during the follow-up of thyroid cancer patients

PURPOSE: Nests of thyroid tissue in the tongue are described in about 10% of necropsies. This ectopic thyroid tissue usually lies dormant, but may manifest itself during times of increased stimulation. The aim of our study was to assess the frequency of lingual thyroid visualization on I-131 diagnostic whole-body scan during the follow-up of thyroid cancer patients. MATERIAL AND METHODS: We reviewed the files of 548 consecutive patients who underwent a diagnostic whole-body scan with 200 MBq of I-131 between January 2000 and December 2005, as part of the follow-up for a differentiated thyroid cancer. Every patient had been previously treated with a total thyroidectomy and had received 3.7 GBq (100 mCi) of I-131 for remnant ablation. RESULTS: A focus of uptake located between the 2 submandibular salivary glands, suggestive of ectopic thyroid tissue in the tongue or in the upper part of the thyroglossal duct, was found in 5 of the 548 patients (0.9%). In only one of these patients was the uptake visible at the time of postsurgery thyroid remnant ablation scan. Thyroglobulin (Tg) levels were positive under stimulation in 3 of the 5 patients, and another patient had undetectable Tg, but positive anti-Tg antibodies. Radiologic imaging (MRI and/or ultrasound) was performed in 3 patients and confirmed the presence of a mass suggestive of ectopic thyroid tissue in two. Invasive lingual biopsy was not performed to verify the benign nature. CONCLUSION: When examining whole-body scans (therapeutic or diagnostic) in a patient with persistent Tg detection after thyroid ablation, one should carefully search for any uptake between the submandibular glands that may be suggestive of ectopic tissue.     

Scintigraphic patterns in patients with subclinical hyperthyroidism

The occurrence of suppressed thyroid stimulating hormone (TSH) levels in the presence of normal free thyroxine (fT4) and free triiodothyronine (fT3) is not rare. Although this entity may be defined as "subclinical hyperthyroidism", many patients presented with the above laboratory findings, suffer from non-specific signs and symptoms that could be related to hyperthyroidism. The aim of this study was to evaluate this entity using the standard method of radionuclide thyroid imaging by (99m)Tc-pertechnetate ((99m)TcO(4)(-)). Fifty-two patients (18 males; mean age: 45+/-9 years and 34 females; mean age: 43+/-11 years) with suppressed serum TSH levels and normal fT3 and fT4 levels, who were referred to our nuclear medicine department for thyroid scintigraphy were prospectively included in the study. Any thyroidal or non-thyroidal medication, thyroid surgery or non-thyroidal diseases constituted the main exclusion criteria. Thyroid scintigraphy was performed 15 min after the i.v. injection of 111 MBq (99m)TcO(4)(-) using a pinhole collimator. Scintigraphic findings were visually evaluated. All patients had normal serum levels of fT4 (mean value 1.53+/-0.14 ng/dl, normal range: 0.89-1.8 ng/dl) and fT3 (mean value 3.9+/-0.17 ng/dl, normal range: 2.3-4.2 ng/dl). Mean value of serum TSH levels was 0.09+/-0.12 microIU/ml (normal range: 0.35-5.5 microIU/ml). The above hormones were tested by the chemiluminescent method. Patients showed seven different scintigraphic patterns in their thyroid scintigrams as follows: hyperactive+hypoactive multinodular goiters, 27%; hyperactive multinodular goiters, 23%; hypoactive multinodular goiters, 15%; solitary hypoactive nodular glands, 14%; normal glands, 9%; solitary hyperactive nodular glands, 8%; and diffuse hyperactive glands, 4%. All but two patients (50/52 = 96%) showed mild to moderate hyperplasia of the thyroid gland. It is concluded that most patients with subclinical hyperthyroidism, (96%) show mild to moderate hyperplasia of the thyroid, and many (65%) show multinodularity with at least one hyperactive nodule.     

核医学显像(SPECT/CT)鉴别头颈部可疑异位甲状腺的价值

目的研究SPECT/CT对头颈部可疑异位甲状腺(ETG)的诊断及鉴别诊断价值。资料与方法对34例可疑异位甲状腺行平面显像,使用99mTcO4-作为显像剂,4例加做131I扫描,19例可疑或需定位的患者行SPECT/CT断层显像,以此判断头颈部正常甲状腺位置外占位的性质。结果 34例患者中共有10例异位甲状腺被准确诊断,4例误诊或未被明确诊断,20例其他病种被排除异位甲状腺的可能,总体准确率为88.24%。结论核医学显像(SPECT/CT)对鉴别头颈部有功能的异位甲状腺具有很高的价值。缺点在于无法发现无功能或功能较低的甲状腺组织,需要结合其他方法明确诊断。     

Limited sensitivity of parathyroid imaging with (99m)Tc-sestamibi/(123)I subtraction in an endemic goiter area.

Double-phase single-tracer scintigraphy with (99m)Tc-sestamibi is now generally used for parathyroid imaging but, at least in endemic goiter areas, complementary thyroid scintigraphy is recommended. Although (123)I-sodium iodide is considered to be the optimal thyroid agent, it is hardly ever used because of high costs and logistic difficulties. Our study presents the results of using the (99m)Tc-sestamibi/(123)I subtraction technique in a region with a high goiter prevalence. Special attention was paid to the changes in sensitivity and specificity and their relationship to thyroid volume as well as to autonomous and nodular thyroid disease. METHODS: One hundred three scintigraphic parathyroid examinations on 96 patients were included in this study. Fifty-eight of all patients had concomitant morphologic or functional alterations of the thyroid. Initially, 10 MBq (123)I-sodium iodide were injected. Then, 150 MBq (99m)Tc-sestamibi were administered after 3-5 h, followed by planar scintigraphic imaging of the neck and upper chest region using a double-isotope technique. RESULTS: An area with increased tracer uptake on the subtraction image was found in 44 cases. Forty-three of them proved to be true-positive. No suspicious lesions were detected scintigraphically on the remaining 59 examinations. However, histologic examination revealed a parathyroid adenoma or hyperplasia in 11 of these cases. The mean parathyroid volume of these false-negative patients was 0.9 mL. Secondary hyperparathyroidism with multiple enlarged parathyroid glands was found in 4 of these cases. The sensitivity of the parathyroid scintigraphy was 80% (43/54) and the specificity was 98% (48/49). There was a distinct difference in the sensitivity between the subgroups with thyroid volumes of >15 mL and <15 mL (76% vs. 88%), although the resected parathyroid glands had a similar size in both subgroups. The specificity was 97% and 100%, respectively. No significant difference in the sensitivity and specificity was observed between the subgroups with and without morphologic or functional alterations of the thyroid (80% vs. 79% and 96% vs. 100%, respectively). CONCLUSION: The sensitivity of parathyroid imaging with (99m)Tc-sestamibi/ (123)I subtraction depends mainly on the thyroid and parathyroid volumes rather than on the presence of nodular or autonomous thyroid disease.     

The role of technetium-99m sestamibi whole-body scans in diagnosing metastatic Hurthle cell carcinoma of the thyroid gland after total thyroidectomy: a comparison with iodine-131 and thallium-201 whole-body scans

Thirty-seven patients with Hürthle cell carcinoma of the thyroid gland underwent total thyroidectomy and then technetium-99m sestamibi (2-methoxyisobutylisonitrile), iodine-131 and thallium-201 wholebody scans. Twenty-two of them had elevated human serum thyroglobulin (HTg) levels. Among these 22 patients, abnormal uptake of ¹³¹I was seen in four (18.1%), abnormal uptake of ²⁰¹Tl chloride in 15 (68.1%), and abnormal ^99mTc-sestamibi accumulation in 18 (81.8%). No patients with normal levels had a positive whole-body scan. In comparison with the 1311 and 201T1 chloride images, the ^99mTc-sestamibi images were of superior quality and detected significantly more (P < 0.05) metastatic lesions of Hurthle cell carcinoma of the thyroid gland in patients with elevated HTg after total thyroidectomy. A mechanism is proposed that may explain these findings.