Results of preoperative ultrasound guided fine needle aspiration biopsy of solitary thyroid nodules as compared with the histology. A retrospective analysis of 538 patients

AIM

The goal of this study was to assess the accuracy and limitations of ultrasound guided fine-needle aspiration biopsy (ug-FNAB) of solitary thyroid nodules.

METHODS

The ug-FNAB results of 538 patients with solitary thyroid nodules, who afterwards underwent thyroid surgery, were compared retrospectively with the histology. Patients with multinodular goiter were excluded from the study. Ug-FNAB was performed on growing and/or hypoechoic and/or hypofunctional nodules. The ug-FNAB results were grouped as follows: group 1: malignant (n = 44); group 2: malignancy cannot be ruled out (n = 173); group 3: non-malignant (n = 296), group 4: inadequate (n = 25).

RESULTS

When the cytological results of group 1 and group 2 were interpreted as being malignant and those of group 3 as being benign, sensitivity, specificity and accuracy of ug-FNAB were 96.7%, 65.8% and 69.5% respectively. The 62 thyroid carcinomas (TC) biopsied presented in 59 cases a suspicious or malignant cytology (95.2%). The smallest TC diagnosed by ug-FNAB had a diameter of 0.5 cm and 36.4% of all papillary TC < or = 1 cm displayed stage pT4. The histology verified a TC in 18 cases out of the 173 ug-FNABs in group 2. Non-malignant ug-FNABs were confirmed by histology in 294 patients (99.3%) in group 3. In 4.65% of the ug-FNABs inadequate material was aspirated.

CONCLUSION

Nodules with non-suspicious ug-FNAB results can be safely followed-up by sonography, as the cytological diagnoses were verified in more than 99% by histology. Papillary TC can be diagnosed with ug-FNAB very accurately. As stage pT4 was present in more than one third of patients with papillary TC < or = 1 cm, ug-FNAB is also recommended for thyroid nodules 0.5-1 cm in diameter located adjacent to the thyroid capsule. However, microfollicular proliferations remain the limitation of ug-FNAB, as the cytology cannot distinguish between benign adenoma and follicular TC.

Evaluation of head and neck cancer with 18F-FDG PET: a comparison with conventional methods

The aim of this study was to evaluate the usefulness of 18F-FDG PET in the diagnosis and staging of primary and recurrent malignant head and neck tumours in comparison with conventional imaging methods [including ultrasonography, radiography, computed tomography (CT) and magnetic resonance imaging (MRI)], physical examination, panendoscopy and biopsies in clinical routine. A total of 54 patients (13 female, 41 male, age 61.3+/-12 years) were investigated retrospectively. Three groups were formed. In group I, 18F-FDG PET was performed in 15 patients to detect unknown primary cancers. In group II, 24 studies were obtained for preoperative staging of proven head and neck cancer. In group III, 18F-FDG PET was used in 15 patients to monitor tumour recurrence after radiotherapy and/or chemotherapy. In all patients, imaging was obtained at 70 min after the intravenous administration of 180 MBq 18F-FDG. In 11 of the 15 patients in group I, the primary cancer could be found with 18F-FDG, yielding a detection rate of 73.3%. In 4 of the 15 patients, CT findings were also suggestive of the primary cancer but were nonetheless equivocal. In these patients, 18F-FDG showed increased 18F-FDG uptake by the primary tumour, which was confirmed by histology. One patient had recurrence of breast carcinoma that could not be detected with 18F-FDG PET, but was detected by CT. In three cases, the primary cancer could not be found with any imaging method. Among the 24 patients in group II investigated for staging purposes, 18F-FDG PET detected a total of 13 local and three distant lymph node metastases, whereas the conventional imaging methods detected only nine local and one distant lymph node metastases. The results of 18F-FDG PET led to an upstaging in 5/24 (20.8%) patients. The conventional imaging methods were false positive in 5/24 (20.8%). There was one false positive result using 18F-FDG PET. Among the 15 patients of group III with suspected recurrence after radiotherapy and/or chemotherapy, 18F-FDG was true positive in 7/15 (46.6%) and true negative in 4/15 (26.6%). The conventional imaging methods were true positive in 5/15 (33.3%) and true negative in 4/15 (26.6%). One false negative (6.6%) and three false positive findings (20%) on 18F-FDG PET were due to inflamed tissue. The conventional imaging methods were false positive in three (20%) and false negative in three cases (20%). It is concluded that in comparison to conventional diagnostic methods, 18F-FDG PET provides additional and clinically relevant information in the detection of primary and metastatic carcinomas as well as in the early detection of recurrent or persistent head and neck cancer after radiotherapy and/or chemotherapy. 18F-FDG PET should therefore be performed early in clinical routine, usually before CT or MRI.

Suppressive levothyroxine therapy has no significant influence on bone degradation in women with thyroid carcinoma: a comparison with other disorders affecting bone metabolism

The aim of this study was to examine different influences on bone degradation (estrogen status, thyroid function, parathyroid function, bone metastases) with special interest focusing on the significance of suppressive levothyroxine therapy (LT4) on bone degradation in patients with differentiated thyroid carcinoma (DTC). Two markers of bone degradation (ELItest NTx = U-NTx; Serum CrossLaps = S-CTx) were used (1) to quantify the influence of different metabolic influences on bone degradation and (2) to compare these two markers with each other. One hundred forty samples of 98 female patients ages 23-86 years were analyzed. The correlation between the two assays of bone degradation was high (r = 0.825; p < 0.001). Both assays demonstrated that estrogen deficiency, hyperparathyroidism, and bone metastases caused significant increases of bone degradation. A suppressive LT4 therapy, as used for patients with DTC, led to no significant increases of S-CTx and U-NTx. The study indicates that a well-controlled suppressive LT4 therapy has only a minor effect on the degree of bone degradation and that a possible estrogen deficiency in patients with DTC has a greater impact on bone degradation. Thus, female patients with DTC on suppressive LT4 therapy and estrogen deficiency may benefit from hormone replacement therapy, as patients with DTC and normal estrogen levels presented similar results to euthyroid controls.

[Osteoporosis in Turner syndrome with chromosomal mosaicism (45,XO/46,XY). A case report]

We report a rare case of Turner's syndrome (UTS) due to a gonosomal mosaic 45,X0/46,XY with the main clinical feature of several fractures in the course of osteoporosis. The bone mineral density (BMD) of the lumbar spine and the hip measured by DXA showed osteoporosis. The other clinical investigations including laboratory parameters presented beside an estrogen deficiency due to primary amenorrhea, a small thyroid with hypothyroidism, increased renal calciuria and increased markers of bone metabolism. Beside the supplementation of estrogen and thyroid hormone deficits, only a combination of different bone-associated drugs could normalize the bone mineral density and the bone turnover. During a two years' follow-up period no further fractures occurred. Furthermore, theories regarding the occurrence of osteoporosis and other complex pathologies in UTS are discussed with the conclusion that osteopenia in UTS is probably based on a multifactorial genesis. Due to these complex pathologies during adulthood, patients with UTS should get multidisciplinary care in order to reduce morbidity and preserve quality of life.

Comparison between 99mTc-tetrofosmin/pertechnetate subtraction scintigraphy and 99mTc-tetrofosmin SPECT for preoperative localization of parathyroid adenoma in an endemic goiter area

RATIONALE AND OBJECTIVES

Technetium-99m-((99m)Tc-) tetrofosmin, a cationic, lipophilic complex like (99m)Tc-sestamibi, has proved to be a potential tracer for parathyroid scintigraphy despite some differences in washout behavior from the thyroid gland. Previous results comparing a double-phase technique with single-proton emission computed tomography (SPECT) or with subtraction techniques demonstrated a high detection rate, especially when SPECT and subtraction techniques were used, whereas the double-phase protocol revealed only moderate results. In this study, a direct comparison was made between (99m)Tc-tetrofosmin/pertechnetate subtraction and SPECT to elucidate the optimal protocol for tetrofosmin parathyroid imaging.

METHODS

Twenty-three patients who were biochemically suspected of parathyroid adenoma or hyperplasia due to primary or tertiary hyperparathyroidism were included in our study. In all patients, serum calcium, phosphate, and intact parathormone levels were analyzed in a single blood sample before (99m)Tc-tetrofosmin/pertechnetate subtraction scintigraphy and SPECT. Ultrasound of the neck was performed in all patients to exclude false-positive results due to thyroid adenomas. All patients underwent parathyroidectomy with intraoperative revision of all parathyroid glands, and the histological results were compared with preoperative findings.

RESULTS

Both imaging modalities, ie, subtraction scintigraphy and SPECT, correctly identified 20 of 23 (87%) histologically confirmed adenomas preoperatively. The positive predictive value was calculated to be 95% and 100%, respectively, for these two methods. Subtraction scintigraphy and SPECT showed concordant results in 19 patients (18 positive, 1 false-negative) and discordant results in 4 patients (2 positive with subtraction, 2 with SPECT). The combined use of subtraction scintigraphy and SPECT techniques revealed a sensitivity of 95.7% (22/23) and a positive predictive value of 95%. The whole procedure can be performed in less than 90 minutes per patient. Whereas subtraction scintigraphy tended to show more false-positive retentions due to thyroid adenomas, the interpretation of SPECT may be difficult in small adenomas with missing thyroid/parathyroid differential washout.

CONCLUSIONS

Both imaging modalities, subtraction scintigraphy with pertechnetate and SPECT, are highly sensitive methods for parathyroid adenoma localization with (99m)Tc-tetrofosmin. However, our study did demonstrate that a combination of both modalities can further improve the diagnostic accuracy. Especially in an endemic goiter area, additional ultrasound may be required to avoid false-positive results due to thyroid adenomas.

The role of F-18FDG PET in thyroid cancer

Hypofunctioning nodules on scintiscan using Tc-99m Pertechnetate or I-123 have a higher probability of malignancy compared to eu- or hyperfunctioning nodules. However, in the preoperative assessment of thyroid nodules, ultrasonography and ultrasonography guided fine needle aspiration biopsy play the most important role, especially for papillary thyroid cancer. The problem of differentiating follicular adenoma from highly differentiated follicular carcinoma however remains. Also the additional use of a multi tracer imaging strategy (Tl-201/Tc-99m subtraction scan, Tc-99m Sestamibi, Tc-99m Tetrofosmin dual phase scintigraphy) has not solved this problem. Although it is unlikely, the question whether FDG PET is able to give a better differentiation between benign and malignant tumours in the preoperative assessment of thyroid nodules is not answered up to now. In contrast to preoperative diagnostics, FDG PET is of great value in the postoperative follow up of differentiated thyroid cancer. In case of elevated serum thyroglobulin but negative I-131 WBS FDG PET is the method of choice to detect I-131 negative recurrences and metastases. FDG uptake in metastases from differentiated thyroid cancer is correlated to low differentiation and maybe bad prognosis. There is also evidence that FDG PET may have a role in the follow up of anaplastic and especially in medullary thyroid cancer in the future.

Scintigraphic and ultrasonographic appearance in different tumor stages of thyroid carcinoma

RATIONALE AND OBJECTIVES

Scintigraphy is routinely used in evaluating thyroid nodules. Functioning nodules are reported to have a low probability of being malignant. Therefore cancer should appear hypo-functioning or "cold" on scintiscan. The aim of the study was to compare the scintigraphic pattern in different tumor stages of thyroid carcinoma. In addition, sonographic results are evaluated. In 151 patients with thyroid carcinoma 99mTc-pertechnetate scans were evaluated retrospectively by a visual inspection scoring method (A = no significant uptake to D = nodular uptake superior to normal thyroid tissue). Planar images were taken using a small field thyroid gamma camera. There were 52 patients with pT1 carcinoma (2 x follicular and 50 x papillary). The mean tumor size was 0.56 +/- 0.26 cm. The scintigraphic results were A and B in 5.7% (n = 6), C in 73% (n = 38), D in 15.6% (n = 8). Out of 40 patients with pT2 carcinoma, 34 had a papillary, 6 a follicular histology. Mean tumor size was 1.66 +/- 0.49 cm. The scintiscan was A in 12.5% (n = 5), B in 32.5% (n = 13), C in 42.5% (n = 17) and D in 12.5% (n = 5). There were 11 patients with pT3 carcinoma (4 x papillary, 7 x follicular). The mean tumor size was 3.96 +/- 0.88 cm in diameter. Scintiscan was A in 72.7% (n = 8), C in 27.3% (n = 3). Among 48 patients with pT4 carcinoma (2 x follicular, 1 x nondifferentiated, 45 x papillary), scan was A in 41.6% (n = 20), B in 14.5% (n = 7), C in 33.3% (n = 16) and D in 10.4% (n = 5). Mean tumor size was 2.16 +/- 1.45 cm (7 carcinomas < or = 1 cm, 23 x 1-2 cm, the remaining > 2 cm). Tumor size plays an important role in routinely used planar scintigraphy. Nodules greater than 2 cm in diameter tend to appear cold but microcarcinomas (< or = 1 cm) are often indifferent on scan. Therefore, planar 99mTc-pertechnetate scintigraphy is of little value in evaluating small thyroid nodules. In order to diagnose small thyroid nodules, ultrasonography and ultrasonographically guided FNAB should be recommended as the initial diagnostic steps in clinical routine.

Unusual malabsorption of levothyroxine

We report a 50-year-old woman, with overt hypothyroidism undergoing thyrotropin (TSH)-stimulating hormone suppressive levothyroxine (LT4) treatment after subtotal thyroidectomy. At her first visit to our department, the laboratory results revealed a borderline low free thyroxine (FT4) level accompanied by a clearly elevated TSH level. Both parameters did not significantly change during therapy with an oral dose of 500 microg of LT4. Investigations revealed malabsorption of oral administrated LT4. Thyroid serum hormone levels only became normal during parenteral therapy with LT4.

Value of ultrasound-guided fine-needle aspiration biopsy of thyroid nodules in an endemic goitre area

The aim of this study was to determine the value, advantages and limitations of ultrasound-guided fine-needle aspiration biopsy (US-FNAB) in an endemic goitre area. US-FNAB was performed on all outpatients who presented with hypoechoic and/or hypofunctional and/or growing nodules. A total of 4518 US-FNABs were performed and 718 patients from this series underwent surgery. Cytological results of the primarily performed US-FNAB of these patients were compared retrospectively with the histological results. US-FNAB results were grouped as (1) non-malignant (n = 303), (2) non-malignant follicular proliferation (n = 177), (3) malignancy cannot be ruled out (n = 133), (4) malignant (n = 61), (5) inadequate (n = 34), and (6) sampling error; biopsy of a non-malignant nodule (n = 10). Nodules as small as 5 mm in diameter could be biopsied, gaining representative material. US-FNAB found a malignant or suspicious cytology in 65 out of 87 cases with malignant histology (74.71%). Diagnosis of early tumour stages was often possible: 12 of 18 thyroid carcinomas biopsied and smaller than 10 mm in diameter had malignant or suspicious cytology (groups 3 and 4). US-FNAB was performed incorrectly within non-malignant nodules in ten patients (1.39%) with multinodular goitre (ten papillary carcinomas, nine smaller than 10 mm). Regarding the cytology of groups 1 and 2 as benign and those of groups 3 and 4 as malignant, US-FNAB performance was as follows: sensitivity 87.84%, specificity 78.50%, negative predictive values 98.13%, positive predictive values 33.51% and accuracy 79.53%. Biopsies with inadequate material were obtained in 4.73% of all biopsies. No major adverse effects occurred. Re-biopsies in 61 cases did not alter the cytological outcome in those cases where adequate material was obtained. US-FNAB is a valuable method in the pre-operative assessment of thyroid nodules in order to select patients for surgery, as malignancy can often be detected even in early tumour stages. However, even with ultrasonographic guidance, the minimal tumour size detectable by US-FNAB is around 5 mm. The cytological interpretation in cases with regression and microfollicular proliferation also sets limits on the method. However, patients with non-malignant cytologies can be followed up safely by sonography due to the high NPV of US-FNAB as long as thyroid nodules do not become larger. Re-biopsies seem to be of limited value as long as adequate material was obtained by US-FNAB.

Thyroid hemiagenesis in an endemic goiter area diagnosed by ultrasonography: report of sixteen patients

During a period of 9 years, 71,500 patients underwent thyroid investigations at our department. Sixteen patients with thyroid hemiagenesis, 13 women and 3 men, were seen during this period. Fifteen had no left lobe and only 1 had no right lobe, the isthmus was present in 5 patients. Associated thyroid diseases of the lobe that was present could be observed in 11 patients (9 diffuse or nodular goiters, 2 thyroid autoimmune diseases). One patient was hyperthyroid and 7 were hypothyroid. Hypothyroidism associated with hemiagenesis has rarely been reported in the literature. In our survey, the high percentage of hypothyroidism may be explained by coexisting iodine deficiency, which could be verified in 4 hypothyroid patients. Ultrasonography is the key investigation to diagnose thyroid hemiagenesis. Fine-needle aspiration biopsies, laboratory tests, and scintigraphies are useful to diagnose other diseases within the remaining lobe or to visualize ectopic thyroid tissue. Review of the literature, including our cases, presented a total of 256 patients with thyroid hemiagenesis. Its prevalence can be estimated between 1:1900 and 1:2675. Left to right ratio of thyroid hemiagenesis is 3.6:1 with an isthmus present in 44%. The female-to-male ratio is 3:1; however, the larger number of females is probably based on a bias due to a female predominance of the populations investigated. On the basis of an equal distribution of both sexes, the female-to-male ratio of thyroid hemiagenesis would be only 1.3:1 in our survey.

Comparison of different tracers in the follow up of differentiated thyroid carcinoma

In the follow up of differentiated thyroid carcinoma (DTC) several scintigraphic methods are used in addition to the serum thyroglobulin and ultrasonography of the neck. Iodine-131 whole body scintigraphy (WBS), which is performed since many years, is able to detect iodine positive recurrence, lymph node metastases and distant metastases in a very specific way. However, the problem of I-131 WBS is the fact that only 67% of metastases from DTC accumulate iodine. Therefore non specific radionuclides like TI-201 or tracers such as Tc-99m Sestamibi or Tc-99m Tetrofosmin and new metabolic tracers like F-18 FDG were introduced in the diagnostic work up to detect iodine negative metastases as well. This study describes the comparison of different tracers in 35 patients with elevated thyroglobulin and suspicion of metastatic disease or already known metastases from DTC.

Comparison of two thyroglobulin immunoradiometric assays on the basis of comprehensive imaging in differentiated thyroid carcinoma

The aim was to compare two thyroglobulin-immunoradiometric assays (Tg-IRMA) in the follow-up of patients with differentiated thyroid carcinoma (DTC) in order to set up interassay correlation, correlation to clinical background, and to determine whether a lower functional sensitivity (kit A: 0.5 ng/mL, kit B: 0.3 ng/mL) would allow an earlier detection of recurrences. Three hundred eight samples from 181 patients with DTC were investigated. The clinical interpretation of the Tg-IRMA results was based on comprehensive imaging and the clinical history before and during the study period. Groups were formed against this background and against the thyrotropin (TSH) levels of the samples (LT4- on and LT4-off). During a follow-up period that lasted until September 1998, the clinical situation was reevaluated in order to determine any changes in the patients' clinical status. The two assays presented a good interassay correlation of 0.838. Both assays had a high and comparably good sensitivity in the detection of recurrence of malignancy or distant metastases. Patients in remission had, in most cases, nonmeasurable or Tg values below 1 ng/mL. Kit B presented slightly measurable Tg results in a larger number of patients in remission; however, during the follow-up most of these slightly measurable Tg results were not reproducible, thus being most likely artifacts. Consequently, the functional sensitivity of 0.3 ng/mL of kit B showed no advantages in terms of an earlier tumor detection and seems to be unacceptably low. Negative consequences may be an increase in the number of investigations during the follow-up, which may be disconcerting for both the clinicians and the patients.

Attenuation correction improves the detection of viable myocardium by thallium-201 cardiac tomography in patients with previous myocardial infarction and left ventricular dysfunction

The aim of this study was to determine the influence of attenuation-corrected thallium-201 stress/redistribution/reinjection single-photon emission tomography (SPET) on the number of viable segments in patients with previous myocardial infarction and dysfunctional myocardium. Fifty-one patients with previous myocardial infarction and left ventricular dysfunction were included in the study. In all patients, 201Tl non-corrected (NC) and attenuation-corrected (AC) SPET was performed using a stress/redistribution/reinjection protocol followed by coronary angiography. A semiquantitative analysis was performed using polar maps for NC and AC stress, redistribution and reinjection short-axis and vertical long-axis (apex) slices. Severe (perfusion defect below 50%/maximal count rate: PD < 50), mild and moderate persistent defects for redistribution and reinjection were evaluated for both NC and AC studies. A total of 1581 segments were evaluated by semiquantitative segmental analysis for both NC and AC studies for each redistribution and reinjection map. In the redistribution maps, NC revealed a total of 352 segments and AC a total of 222 segments with impaired perfusion below 50% of the maximal count rate (PD < 50). The mean number of affected segments was 6.9 +/- 5.5 in the case of NC and 4.4 +/- 4.8 in the case of AC (P < 0.001). In the reinjection maps, NC revealed a total of 263 non-viable segments (PD < 50) and AC a total of 169 non-viable segments. The mean number of affected segments was 5.2 +/- 5.3 in the case of NC and 3.3 +/- 4.2 in the case of AC (P < 0.001). Recovery of function was better predicted by AC than by NC in 20% of patients in the follow-up group. Therefore, the use of attenuation correction influences the extent of viable segments by showing more viable segments in either redistribution or reinjection maps. 201Tl imaging without attenuation correction may underestimate the extent of tissue viability, which may contribute to the lower sensitivity compared to fluorine-18-fluorodeoxyglucose positron emission tomography, where attenuation correction is a routinely performed procedure.

[Thyroid gland hemiagenesis with Graves' disease]

A case of Graves' disease occurring in a patient with hemiagenesis is presented. The detection of the rare occurrence of a congenital hemiagenesis is often made by either clinical symptoms of thyroid dysfunction or anatomical abnormalities such as nodular goiter. The symptoms of hyperthyroidism in the current case led to the diagnostic confirmation by scintiscanning and ultrasonography of an absent lobe. Anti-thyroid antibody studies documented the presence of Graves' disease within the remaining lobe.

Epidemiology of thyroid diseases in iodine sufficiency

Epidemiology of thyroid diseases in iodine-sufficient areas (ISA) deals with sporadic goiter, thyroid autoimmune diseases, and thyroid cancer. A comparison between the different studies performed is difficult because methods have changed over time and selection criteria and definitions such as prevalence or incidence were not used consistently by some authors. Sporadic goiter: in ISA, autoimmune processes play a major role in the development of sporadic goiter. In adults, sporadic diffuse goiter is most frequent in young women (16%), perhaps due to additional relative iodine deficiency especially in pregnancy, and declines with age (<10%). Sporadic nodular goiter increases from 5% in young women to 9% in older women. Autoimmune thyroid disease (AITD): thyroid autoantibodies (TAb) and histopathological lymphocytic infiltration of the thyroid is much more common in ISA (4.6% in women; 1.1% in men) than in iodine-deficient areas (IDA). The prevalence and incidence of hypothyroidism and hyperthyroidism varies, depending on whether overt and subclinical forms are included and whether newly or previously diagnosed dysfunction is considered. In an overview of the literature, the prevalence is 2 in 1000 for overt and 6 in 1000 for subclinical hyperthyroidism in ISA. The values for hypothyroidism are 5 in 1000 and 15 in 1000, respectively. Change from IDA to ISA: in former IDA, the percentage of hyperthyroidism increases up to 4 years after salt iodination. Whereas this effect is transient for Plummer's disease, a change from IDA to ISA seems to lead to a permanent increase in overt and subclinical Graves' disease. Thyroid cancer: most studies demonstrate that the histopathological types of thyroid cancer are different in IDA and ISA. There is a tendency toward an increase in differentiated and decrease of anaplastic cancer. The ratio of papillary to follicular thyroid cancer ranges from 6.5:1 to 3.4:1 in areas with high iodine intake, decreases 3.7:1 to 1.6:1 in areas with moderate iodine intake, and ranges from 1.7:1 to 0.19:1 in IDA.

Thyroglobulin and low-dose iodine-131 and technetium-99m-tetrofosmin whole-body scintigraphy in differentiated thyroid carcinoma

Determination of thyroglobulin (Tg) levels, determined under endogenous thyroid-stimulating hormone stimulation after withdrawal of L-thyroxin treatment (off-T4), has been proven to be the most sensitive method for evaluation of patients with recurrent malignancy or distant metastases. This study uses a comparative approach between low-dose 131I scan and the previously reported highly sensitive 99mTc-tetrofosmin whole-body scintigraphy, using Tg-off-T4 as a basis for comparison.

METHODS

Fifty-eight consecutive patients of our follow-up program with primary thyroid carcinoma ablated with thyroidectomy and radioiodine therapy were examined after L-thyroxin withdrawal over 3-4 wk with 131I (185 MBq) and 99mTc-tetrofosmin whole-body scintigraphy and Tg determination (off-T4) within 5 days. Patients with Tg levels above 0.5 ng/ml were defined as Group A (n = 29). Group B (n = 29) comprised patients who had Tg levels (off-T4) below 0.5 ng/ml.

RESULTS

Iodine-131 revealed only 19 of 44 tumor sites (43.18%). Additionally, three remnants could be demonstrated. Sensitivity showed decreasing values for local recurrences (4 of 7, 57.1%), bone lesions (7 of 13, 53.85%) and mediastinal (2 of 4, 50%), lung parenchymal (3 of 7, 42.85%) and lymph node (2 of 9, 22.2%) metastases. Whole-body scintigraphy with 99mTc-tetrofosmin revealed a total of 39 of 44 malignant lesions (88.6%). Sensitivity was superior for lung parenchymal metastases (9 of 9, 100%), mediastinum (4 of 4, 100%) and lymph nodes (9 of 10, 90%) and inferior for bone metastases (11 of 13, 84.6%). Local recurrences could be detected in 6 of 7 patients (85.7%), and thyroid remnants were detected in 2 cases (2 of 11, 18.2%). One liver metastasis could not be detected because of the physiologic tracer distribution of 99mTc-tetrofosmin. Thyroglobulin-off-T4 detected malignant recurrence or metastases in 18 of 19 patients (94.7%) when a cutoff of 3 ng/ml was used and in 16 of 19 patients (84.2%) when a cutoff of 10 ng/ml was used. Specificity was calculated as 71.8% when a cutoff of 0.5 ng/ml was used, 89.7% when a cutoff of 3 ng/ml was used and 100% when a cutoff of 10 ng/ml was used.

CONCLUSION

Scintigraphy with 99mTc-tetrofosmin showed clear advantages concerning sensitivity in most metastatic lesions when compared with low-dose 131I scan. Despite a slight lower specificity, 99mTc-tetrofosmin whole-body scintigraphy has, therefore, been proven to be a useful tool in the assessment of metastatic lesions in differentiated thyroid carcinoma.

Attenuation-corrected thallium-201 single-photon emission tomography using a gadolinium-153 moving line source: clinical value and the impact of attenuation correction on the extent and severity of perfusion abnormalities

The aim of the study was to test the clinical value of attenuation-corrected (AC) thallium-201 single-photon emission tomography using a moving gadolinium-153 line source in a group of patients in whom coronary angiography was planned because of clinically suspected coronary artery disease (CAD). Furthermore, we wanted to test the impact of AC on assessment of the extent and severity of perfusion abnormalities. A total of 107 patients planned to undergo coronary angiography were included in the study. In each patient, AC and NC (non-corrected) 201Tl SPET was performed. AC and NC images were evaluated visually as well as by a 31-segment semiquantitative analysis and the findings were correlated with angiographic results. Patients were assigned to two groups: group A with angina and no previous cardiac infarction or intervention and group B with known CAD because of previous myocardial infarction or intervention. With visual analysis, NC revealed a sensitivity of 88.9% in group A and 74.3% in group B, compared to 94.4% in group A and 94.3% in group B with AC. Specificity for NC was calculated to be 68.7% for group A and 91.3% for group B. AC demonstrated significantly higher specificity of 83.9% and 100% respectively. This effect was particularly demonstrated for males and bicycle workload. The extent and severity of perfusion abnormalities were significantly influenced by the use of AC, in that significantly fewer abnormal and less severely abnormal segments were demonstrated in the segmental analysis as compared to NC; this was especially true for the vascular territory of the left anterior descending artery and the right coronary artery. It is concluded that AC with a moving line source is feasible in patients with all degrees of probability of CAD. AC has a significant impact on the assessment of the severity and extent of myocardial ischaemia, especially in the posterior and septal wall.

Thallium-201 uptake with negative iodine-131 scintigraphy and serum thyroglobulin in metastatic oxyphilic papillary thyroid carcinoma

We report a case of a 48-yr-old woman who underwent surgery because of papillary oxyphilic thyroid carcinoma pT3. After total thyroidectomy, we administered 2960 MBq (131)I for ablation of the residual tissue. initial follow-up visits showed no clinical, radiological or scintigraphic evidence of residual or metastatic thyroid tissue. Serum thyroglobulin levels (Tg) and (131)I whole-body scintigraphy were negative. Three years after thyroidectomy, the patient experienced seizures, and as a consequence a brain tumor was removed. It was an undetected metastasis of the primary thyroid carcinoma. Histological examinations showed that neither the primary tumor nor the metastasis produced any Tg. With this fact in mind and the knowledge of negative (131)I whole-body scans we had to concentrate on radiological (CT and MRI scans) and nonspecific scintigraphic methods such as 201TI whole-body scintigraphy in our management of the patient. Further follow-up demonstrated multiple metastasis by 201TI whole-body scan (mediastinum, bones and soft tissue), and most of them have been removed by surgery. This case report demonstrates that, in addition to (131)I whole-body scans and measurement of serum Tg, the use of nonspecific tracers like 201TI is important to detect (131)I and/or Tg negative metastases.

Influence of human anti-mouse antibodies on thyrotropin in-vitro analysis: a comparison of 6 thyrotropin IRMA kits

OBJECTIVE

The aim of the study was to evaluate the influence of human anti-mouse antibodies on the measurement of thyrotropin.

INVESTIGATIONS

Samples from 11 patients with measureable human anti-mouse antibody titres (19 micrograms/l-3880 micrograms/l) after radioimmuno-scintigraphy were analysed with 6 different thyrotropin immuno-radiometric assay kits (IRMA). Each sample was analysed in the routine way (sample influenced by human anti-mouse antibodies), as well as after incubation with murine immunoglobulin to precipitate human anti-mouse antibodies (samples not influenced by human anti-mouse antibodies).

RESULTS

Two kits showed clear deviations of measured thyrotropin levels when the human anti-mouse antibody titres were higher than 1350 micrograms/l. A third kit was influenced to a lesser extent by human anti-mouse antibodies. Three of the 6 investigated thyrotropin IRMA kits produced thyrotropin values that were unaffected by the presence of elevated human anti-mouse antibodies. In comparison with former studies after immunotherapy, the thyrotropin deviations were marginal. However, differences were found between the commercially available thyrotropin assays. According to the results of this study only three out of the six investigated kits were unaffected by human anti-mouse antibodies.

CONCLUSION

Since thyrotropin is one of the key quantities for the endocrinologist dealing with the thyroid gland, every laboratory should ensure high quality thyrotropin assays by critically analysing their method for human anti-mouse antibody.

Technetium-99m-tetrofosmin uptake in sarcoidosis stage I

The uptake of 99mTc-tetrofosmin in enlarged lymph nodes, of the lung hilus, in the case of sarcoidosis Stage I (histopathologically confirmed by mediastinoscopic biopsy) is demonstrated. On a routine chest radiograph of a 78-yr-old woman, hilar lymphadenopathy was first detected. In the following mammography, disseminated micro calcifications were found in the left breast and a 99mTc-tetrofosmin study was performed for detection of breast cancer. Scintigraphy using 99mTc-tetrofosmin showed clear uptake in the hilar lymph nodes, but not in the left breast. The 99mTc-tetrofosmin uptake in the hilar lymph nodes was due to sarcoidosis confirmed by histology. Therefore, 99mTc-tetrofosmin scintigraphy may be useful in patients with suspected sarcoidosis, especially in Stage I.