Usefulness of technetium-99m hydroxymethylene diphosphonate scans in localizing bone metastases of differentiated thyroid carcinoma

Iodine-131 is uniquely able to demonstrate iodine uptake of differentiated thyroid carcinoma (DTC), but precise localization may be difficult, especially in the thorax, due to the quality of image resolution with 1311 and the lack of anatomical landmarks. When bone metastases do not show radioiodine uptake, bone scintigraphy can be used to detect them. We studied two groups of patients. In group 1, 15 patients with known bone metastases of DTC were treated with 3.7 GBq ¹³¹I. After 4 or 5 days, technetium-99m hydroxymethylene diphosphonate (HMDP; 740 MBq) was injected and a whole-body scan with simultaneous acquisition of ¹³¹I and ^99mTc-HMDP images was carried out using a large field of view gamma camera fitted with a high-energy collimator. Technetium uptake was abnormal in 47 of 63 localizations, being increased in 29 foci, decreased in 7 and heterogeneous in 11. The superimposition of ¹³¹I and ^99mTc-HMDP scans permitted an accurate localization in 80% of spine metastases and in 46% of osseous thoracic localizations, even in the presence of lung metastases. In group 2, 9 patients, who had bone pain, neurological signs or elevated serum thyroglobulin, had DTC bone metastases without iodine uptake. They received a diagnostic dose of ^99mTc-HMDP 3h prior to scintigraphy with a large field of view gamma camera fitted with a low-energy collimator. Technetium uptake was abnormal in 37 of 38 localizations, being increased in 34 foci and decreased in 3. One false-negative was found in a skull metastasis. In both groups of patients, ^99mTc-HMDP scans were useful. The procedure allows accurate localization of bone metastases and can be used as a guide for subsequent radiological investigations.     

99mTc-sestamibi thyroid uptake in euthyroid individuals and in patients with autoimmune thyroid disease

Purpose We investigated the biokinetics of ^99mTc-sestamibi in the thyroid of euthyroid volunteers (EVs) and in patients with autoimmune thyroid diseases and determined the best time interval between ^99mTc-sestamibi injection and calculation of uptake.Methods Forty EVs, 30 patients with Graves disease (GD), 15 patients with atrophic Hashimotos thyroiditis (AHT) and 15 patients with hypertrophic Hashimotos thyroiditis (HHT) underwent ^99mTc-sestamibi thyroid scintigraphy. Dynamic images were acquired for 20 min, and static images were obtained 20 min, 60 min and 120 min post injection. Five-, 20-, 60- and 120-min uptake, time to maximal uptake (T_max) and T_1/2 of tracer clearance were calculated. Thyroid hormones and antibodies were measured. ^99mTc-pertechnetate uptake was investigated in GD patients.Results T_max was approximately 5 min in all four groups. The mean T_1/2 value for EVs was similar to the GD value and lower than the HHT and AHT values. The mean (±SD) 5-min uptake was 0.13% (±0.05%) for EVs. The 5-min uptake in GD was higher than that in EVs(P<0.001) and correlated with free thyroxine (r=0.54) and with ^99mTc-pertechnetate uptake (r=0.68). Uptake in HHT was higher than that in AHT (P=0.0003) and EVs (P=0.002). Uptake in AHT was lower than uptake in EVs (P=0.0001).Conclusion Five minutes is the optimal time interval between ^99mTc-sestamibi injection and calculation of thyroid uptake. Five-minute uptake differentiates euthyroid individuals from GD patients. There is a high correlation between ^99mTc-sestamibi and ^99mTc-pertechnetate uptake in GD. The reduced ^99mTc-sestamibi uptake in AHT patients is probably due to glandular destruction and fibrosis. Inflammatory infiltrate and high mitochondrial density in thyrocytes possibly explain the increased uptake in GD and HHT.     

Value of technetium scintigraphy and iodine uptake measurement during follow-up of differentiated thyroid cancer

Measurement of serum thyroglobulin (Tg) levels and I-131 whole body scintigraphy (WBS) are used in the follow-up of patients with differentiated thyroid cancer (DTC). This study was designed to evaluate the significance of persistent I-131 uptake in the thyroid bed in patients with DTC following surgery and/or radioactive iodine ablation. Tc-99m thyroid scintigraphy (TS) and I-131 thyroid uptake (IU) were also performed to determine their clinical impact on patient management. PATIENTS AND METHODS: Sixty-two non-metastatic patients (14 men, 48 women) with a mean age of 44 years (range: 16-75) who had undergone surgical thyroidectomy for DTC were evaluated prospectively. All patients had undergone technetium and iodine scintigraphy (IS). Although serum Tg levels were measured in all patients, IU was available in 36. RESULTS: Tg values were in the range of 0.2-24 ng/ml (median: 0.2 ng/ml) when patients were in the hypothyroid state. I-131 WBS detected residual tissue in the neck in 30 patients (48%); however TS was positive in only 12 (19%). I-131 uptake in the thyroid bed ranged from 0 to 14% (median: 0.1%). Twelve of 13 patients with positive IS and negative TS had uptake values < or = 0.3% (p < 0.00001). When IU values were < or = 0.3%, 54% of our patients did not have any uptake in the thyroid bed on TS or IS, whereas when IU was > 0.3%, 80% of patients had neck uptake on both TS and IS (p < 0.00001). CONCLUSION: The results of this study demonstrate that the concordance of IS and TS depends on the IU level after suspension of replacement therapy. Measurements of IU and TS are of considerable value in evaluating patient response to therapy and will substantially reduce the need for repetitive radioiodine scans and unnecessary treatment doses in patients with undetectable Tg values.     

Scintigraphic studies in patients with medullary carcinoma of the thyroid

Findings on pre-operative thyorid scintiscans in 29 patients with medullary carcinoma of the thyroid were compared with results of palpation and pathological findings. Six patients had a normal uptake of ¹³¹I or ^99mTc in tumours 1.5–8 cm in diameter. When compared with 111 pre-operative scintiscans in other thyroid carcinomas, the frequency of normal uptake in medullary carcinomas was high, 19% versus 0–6%. Gallium-67 scintiscans were performed in nine patients. Six patients had extensive tumours, but accumulation of ⁶⁷Ga appeared in only one patient.     

A comparative study of 99mTc and 131I in thyroid scanning

Thyroid scans performed with both ^99mTc pertechnetate (^99mTcO₄) and (¹³¹I) were compared in 46 patients with palpable thyroid nodules to determine whether ¹³¹I scanning is any longer a necessary procedure. A discrepancy between the two types of scan existed in only three cases, in one of which the thyroid nodule showed uptake of ^99mTcO₄ but not of ¹³¹I. Subsequent surgery revealed a thyroid malignancy in this patient. In each of the other two discrepancies a nodule cold on ^99mTcO₄ scanning was apparently functioning on ¹³¹I scanning, and was found to be benign at surgery. As the convenience and lower radiation absorbed dose of ^99mTcO₄ compared with ¹³¹I make it a better scanning agent, it is recommended that ^99mTcO₄ scans of the thyroid be first performed in the assessment of patients with thyroid nodules. If these nodules prove to be functioning equally with paranodular tissue, a ¹³¹I scan should also be performed to help exclude a possible thyroid malignancy.     

The study of influence factors on 131I treatment of differentiated thyroid carcinoma with lymph node metastases

ObjectiveThyroid carcinoma is the most common malignant endocrine tumor, which comprises 1% in all human tumors. As for differentiated thyroid carcinoma (DTC), lymph nodes are the most common metastatic site for which the major treatment is ¹³¹I therapy. This retrospective study aimed to investigate the therapeutic effect and analyze the influence factors on ¹³¹I treatment of DTC with lymph node metastases.MethodsCollecting clinical data of 66 DTC patients with lymph node metastases at the Department of Nuclear Medicine, Xin Hua Hospital from January 1996 to January 2006. Investigating the therapeutic effect firstly and then dividing 66 patients into an eliminated group and an uneliminated group according to the evaluation criteria of the therapeutic effect. Finally, observing the differences between the two groups. The significant differences in the following 10 influence factors were determined: gender, age, pathological type, the periods from the thyroidectomy to the first ¹³¹I therapy, when the metastases were found, the history of resection of the lymph node metastases, the uptake of ¹⁸F-FDG in the lymph node metastases, remnant thyroid, multiple metastases, and the cumulative dose of ¹³¹I. This retrospective study was analyzed by Student t test, χ² test, and Fisher's exact test.ResultsOf all 66 patients with lymph node metastatic DTC treated by ¹³¹I therapy, 31 patients (46.97%) had complete elimination. Twenty-seven patients were improved or controlled, and the overall effective rate reached 87.88%. The elimination rate of lymph node metastases in patients with resection was significantly higher than in those without resection (χ²=5.561, P=.018<0.05). The elimination rate of lymph node metastases in patients with ¹⁸F-FDG uptake was significantly higher than in those without ¹⁸F-FDG uptake (χ²=4.014, P=.045<.05). There was no significant difference in the elimination rate among the patients with various values in the other eight factors.Conclusions¹³¹I Therapy is an effective treatment of lymph node metastatic DTC. The history of resection of the lymph node metastases and the uptake of ¹⁸F-FDG in the lymph node metastases were the influence factors on the therapeutic effect, whereas the other eight factors were probably not.     

Influence of thyroid-stimulating hormone on 18F-fluorodeoxyglucose and 99mTc-methoxyisobutylisonitrile uptake in human poorly differentiated thyroid cancer cells in vitro

Objective  In poorly differentiated thyroid cancer originating from thyroid follicular cells, the ability to concentrate iodine is lost. This makes recurrence undetectable by ¹³¹I whole-body scan. In this situation, other radiopharmaceuticals, such as ¹⁸F-fluorodeoxyglucose (¹⁸F-FDG) and technetium-99m-methoxyisobutylisonitrile (^99mTc-MIBI), are used to evaluate recurrence or metastasis. Some reports suggest that ¹⁸F-FDG uptake is increased by thyroid-stimulating hormone (TSH) stimulation. This study aimed to determine the influence of TSH on ¹⁸F-FDG and ^99mTc-MIBI uptake in human poorly differentiated thyroid cancer cells in vitro. Materials and methods  The cells were stimulated with 1000 μU/ml of recombinant human thyroid-stimulating hormone (rhTSH) for 1 day, 3 days, and 5 days. Each cell was incubated with 0.5 MBq/ml-1 MBq/ml of ¹⁸F-FDG or 0.5 MBq/ml-1 MBq/ml of ^99mTc-MIBI for 1 h at 37°C. The uptake of each radiopharmaceutical in the cells was quantified as a percent of whole radioactivity per total viable cell number. The quantification of glucose transporter 1, 2, 3 and 4 mRNA expression was measured using RT-PCR. Results  TSH stimulation increased ¹⁸F-FDG uptake in a time-dependent manner. Following 5 days of rhTSH stimulation, ¹⁸F-FDG uptake was approximately 2.2 times that of the control. The increase in ¹⁸F-FDG uptake following rhTSH stimulation was correlated to the increase in GLUT4 mRNA level. The GLUT1 mRNA level was unchanged. An increased uptake of ^99mTc-MIBI was observed with a pattern similar to that of ¹⁸F-FDG. The ^99mTc-MIBI uptake was approximately 1.5 times that of the control 5 days later. Conclusions  These results suggest that TSH stimulates ¹⁸F-FDG and ^99mTc-MIBI uptake in poorly differentiated papillary thyroid cancer, and therefore ¹⁸F-FDG-PET or ^99mTc-MIBI scans under TSH stimulation may be more accurate than under suppression.     

Clinical utility of technetium-99m methoxisobutylisonitrile imaging in differentiated thyroid carcinoma: comparison with thallium-201 and iodine-131 Na scintigraphy,and serum thyroglobulin quantitation

Recently, technetium-99m methoxyisobutylisonitrile (^99mTc-MIBI) has been used to image thyroid carcinoma. A prospective study was performed to compare the efficacy of^99mTc-MIBI to thallium-201 (²⁰¹T1) scintigraphy in patients with differentiated thyroid carcinoma. The clinical utility of all radionuclide imaging modalities, i.e.,^99mTc-MIBI,²⁰¹Tl, and iodine-131 Na (¹³¹I-Na), as well as serum thyroglobulin estimation, was evaluated. Thirty-four post-thyroidectomy patients (age range: 26–76 years) underwent 45 studies. Histopathologies studied included fourteen papillary, eight papillaryfollicular, ten follicular, one Hürthle cell, and one medullary carcinoma of the thyroid. Following optimal stimulation of endogenous thyroid stimulating hormone (i.e, TSH >-50 mU/ml), the patients underwent²⁰¹Tl and^99mTc-MIBI scintigraphy. Concomitant¹³¹I-Na scintigraphy was performed and serum thyroglobulin levels were measured. Sixteen scan sets were performed prior to¹³¹I-Na ablation therapy. Twenty-nine scan sets were performed following¹³¹I-Na ablation therapy. The presence or absence of thyroid cancer was established by clinical, biochemical, radiologic, and/or biopsy findings. There was no significant difference in sensitivity and specificity of²⁰¹Tl scintigraphy versus^99mTc-MIBI scintigraphy in pre- and postablation studies.¹³¹I-Na scintigraphy with determination of thyroglobulin level was sufficient in preablation studies. Among postablation patients, the addition of^99mTc-MIBI or²⁰¹Tl offered a higher diagnostic yield. Between the²⁰¹Tl and^99mTc-MIBI studies, there was a concordance of 69% in preablation and 97% among postablation patients (P=0.027). It is concluded that^99mTc-MIBI is a suitable alternative to²⁰¹Tl scintigraphy in thyroid carcinoma, especially following thyroidectomy and¹³¹I-Na therapy.¹³¹I-Na scintigraphy with serum thyroglobulin is adequate in both pre- and postablation patients. Among the post-¹³¹I-Na ablation patients,^99mTc-MIBI or²⁰¹Tl is extremely valuable for tumor localization, especially when the¹³¹I-Na whole-body scan is negative. The combination of^99mTc-MIBI or²⁰¹Tl scintigraphy with¹³¹I-Na and serum thyroglobulin offers the highest diagnostic yield.This paper is based on a presentation at the 76th Annual Meeting of the American Radium Society, South Hampton, Bermuda, 22–26 April 1994.     

Prediction of remission in Graves' disease treated with long-term carbimazole therapy: Evaluation of technetium-99m thyroid uptake and TSH concentrations as prognostic indicators

Computerized technetium-99m thyroid uptake and thyrotropin (TSH) estimation using a sensitive immunoradiometric assay were performed at presentation and following completion of an 18-month course of antithyroid drug therapy in 45 patients with Graves' disease. All patients had increased^99mTc thyroid uptake and subnormal TSH levels before the start of treatment. Twenty-two patients developed recurrent hyperthyroidism in a 3-year follow-up period. Of these 22 patients with relapse, 20 had had a persistently increased^99mTc thyroid uptake at the end of the course of carbimazole treatment, whereas TSH had remained subnormal in 18 of the 22. All 23 patients who remained in remission until the end of the 3-year follow-up had had normal^99mTc thyroid uptake following completion of antithyroid drug treatment. TSH levels had reverted to normal in 19 cases, but remained subnormal in four cases in this group at the end of treatment. The results suggest a high likelihood of relapse in patients who have persistently increased^99mTc thyroid uptake and subnormal TSH after a full course of carbimazole treatment. Patients whose^99mTc thyroid uptake and TSH levels have reverted to normal are likely to stay in long-term remission. Assessment of^99mTc thyroid uptake and TSH levels following completion of carbimazole therapy for Graves' disease offers useful information regarding long-term prognosis.     

Assessment of inflammatory jaw pathologies using bone SPECT/CT maximum standardized uptake value

Objectives:To investigate the assessment of inflammatory jaw pathologies using bone single-photon emission CT-CT (SPECT/CT) maximum standardized uptake value (SUV_max).Methods:44 patients with inflammatory jaw pathologies (7 chronic osteomyelitis, 8 osteoradionecrosis and 29 medication-related osteonecrosis of the jaw (MRONJ)) underwent SPECT/CT at 4 h after injection of ^99mTc hydroxymethylene diphosphonate. The SPECT/CT parameters SUV_max of the inflammatory jaw pathologies were analyzed. Statistical analyses for the SUV_max were performed by one-way repeated measures analysis of variance with Tukey''s honestly significant difference test. A p-value lower than 0.05 was considered statistically significant.Results:The mean and standard deviation of SUV_max for 7 chronic osteomyelitis, 8 osteoradionecrosis and 29 MRONJ were 24.94 ± 3.65, 12.27 ± 5.47 and 16.55 ± 9.12, respectively. The SUV_max for chronic osteomyelitis were significantly higher than those for osteoradionecrosis (p = 0.011) and MRONJ (p = 0.043).Conclusions:Bone SPECT/CT SUV_max in the uptake of ^99mTc hydroxymethylene diphosphonate reflecting bone physiological changes for chronic osteomyelitis were significantly higher than those of osteonecrosis, such as osteoradionecrosis and MRONJ. Bone SPECT/CT SUV_max should be useful for the assessment of inflammatory jaw pathologies, such as chronic osteomyelitis, osteoradionecrosis and MRONJ.     

Decreased uptake after fractionated ablative doses of iodine-131

Purpose In an attempt to obviate the necessity for hospitalisation, the ablative dose of ¹³¹I in the treatment of thyroid cancer is divided into two or three fractions at weekly intervals in some hospitals with no special bed for ¹³¹I treatment. Thyroid stunning has been observed in patients receiving a ¹³¹I dose between 74 and 370 MBq (2–10 mCi). However, the influence of ¹³¹I uptake after administration of a higher dose, such as 1,110–1,850 MBq of ¹³¹I, has never been reported. In this study, we evaluated the degree of reduction in ¹³¹I uptake after patients received 1,480 MBq of ¹³¹I and evaluated the clinical value of fractionated ablative doses of ¹³¹I.Methods Thirty-five patients with functional thyroid cancer received a total of 4,440 MBq (120 mCi) of ¹³¹I which was divided into three fractions administered at weekly intervals. In all patients two ¹³¹I whole-body scans were performed. The first scan was performed directly prior to the second dose of ¹³¹I (7 days after the first administration of ¹³¹I), and the second scan was performed 7 days after the second administration of ¹³¹I and directly prior to the third administration. Regions of interest including the neck and lungs were drawn to calculate the uptake of ¹³¹I in the thyroid remnant and possible cervical lymph node and lung metastases.Results The mean uptake of ¹³¹I was 2.73% 7 days after the first administration, and decreased significantly to 0.26% 7 days after the second administration. The mean decrease was as high as 80.7%. The decrease in ¹³¹I uptake was significant in all patients except the two with lung metastases. In the two patients with lung metastases, no definite evidence of decreased uptake was noted; the uptake of ¹³¹I in the lung metastases even increased on the second ¹³¹I image in one of these patients. After administration of 1,480 MBq of ¹³¹I, the decreased uptake was significant in all neck lesions but not in lung metastases.Conclusion The use of fractionated ablative doses of ¹³¹I is not to be recommended in patients without lung metastases. However, the influence of fractionated ablative doses of ¹³¹I in patients with lung metastases is worthy of further study.     

Decreased uptake of therapeutic doses of iodine-131 after 185-MBq iodine-131 diagnostic imaging for thyroid remnants in differentiated thyroid carcinoma

We performed a prospective random study to assess possible thyroid stunning by a 185-MBq iodine-131 dose used to diagnose thyroid remnants. Patients with differentiated thyroid carcinoma were included after total or near-total thyroidectomy. They were randomly assigned to two groups. In group 0 (G0, 32 patients), iodine-123 administration only was used to diagnose thyroid remnants and/or metastasis, so that no thyroid stunning by ¹³¹I would occur. In group 1 (G1, 19 patients), diagnostic imaging was performed with ¹²³I and 185 MBq ¹³¹I. ¹²³I imaging was less sensitive than ¹³¹I imaging in identifying thyroid remnants in both groups (94%). Thyroid uptake of ¹²³I was measured in both groups (at 2 h) and was not significantly different between the groups. Patients with thyroid remnants who remained in the study (28/32 in G0, 17/19 in G1) were treated with 370 MBq ¹³¹I, 5 weeks after treatment (mean time, range 12–84 days). In 12/17 G1 patients thyroid uptake measurement was repeated immediately before treatment. Uptake was equal to 1.97%±0.71% and significantly lower (P<0.05) than the previous measurement (3.76%±1.50%). Patients were imaged 7 days after administration of the therapeutic dose and the images were compared with the diagnostic images. In 28/28 G0 patients thyroid remnants were unchanged and clearly seen. In 5/17 G1 patients, however, the remnants were hardly identified, although they had been clearly seen at the time of diagnosis. We conclude the following: (1) a diagnostic dose of 185 MBq ¹³¹I decreases thyroid uptake for several weeks after administration and can impair immediate subsequent ¹³¹I therapy; (2) ¹²³I is slightly less sensitive than ¹³¹I in identifying thyroid remnants; and (3) the need to scan for thyroid remnants remains to be confirmed, since only 2/51 patients enrolled in this study were not treated with ¹³¹I. Received 6 August and in revised form 24 October 1997     

Early kinetics of the human thyroid trap estimated with 99mTc and 131I

Kinetic parameters of ^99mTc and ¹³¹I thyroid trapping were compared in 13 patients (30 dynamic studies). The data were analyzed with a six-compartment model including three compartments for extrathyroid spaces. There was a good correlation between the estimates of the total iodide and pertechnetate pools (V₄+V₅). As expected, the ₁₄ loss rate constant for technetium was always higher than that for iodide.In five euthyroid patients, the unidirectional clearances (R₄₁) with TcO₄ ^– and I^– were generally of the same magnitude. The effect of TSH stimulation appears to be identical for both isotopes: an increase of R₄₁ and the total iodide and pertechnetate pool (V₄+V₅), a decrease of the isotope loss rate constant (₁₄).In two untreated thyrotoxic patients, the unidirectional clearance of ^99mTc was 2.5 times higher than that estimated with ¹³¹I. Under administration of antithyroid drug, unidirectional TcO₄ ^– clearance was lower than that of iodide in the six patients studied.A similar and greater discrepancy between early ¹³¹I and ^99mTc kinetics was observed in a patient with congenital goiter. The technetium thyroid trap was only slightly elevated, whereas unidirectional iodide clearance and (V₄+V₅) were clearly increased.This series of patients suggests that whereas there is a good correlation between early ¹³¹I and ^99mTc kinetics in euthyroid subjects, a discrepancy exists in patients with spontaneous or acquired dyshormonogenesis. This is confirmed by the segmentary study of a patient with a nodule appearing hot on the ^99mTc scintigram and cold on the ¹³¹I scan.Research supported by INSERM (CRL 7750943 B)     

High pre-therapy [99mTc]pertechnetate thyroid uptake, thyroid size and thyrostatic drugs: predictive factors of failure in [131I]iodide therapy in Graves' disease

BACKGROUND AND OBJECTIVE: Several factors may interfere with the success rate of radioiodine therapy (RIT) in Graves' disease. Our aim was to evaluate, retrospectively, some of these factors in the outcome of RIT. METHODS: Patient gender, age at diagnosis, ophthalmopathy, disease duration, thyroid size, drug used as clinical treatment, thionamide withdrawal period during RIT preparation, FT4, TSH and [99mTc]pertechnetate thyroid uptake prior to RIT were studied as potential interference factors for RIT success. Eighty-two Graves' disease patients were submitted to RIT after thionamide treatment failure. Prior to RIT, 67 patients were receiving methimazole and 15 propylthiouracil. Thirty-three patients received thionamides during RIT; in 49 patients the medication was withdrawn for 2-30 days. [99mTc]pertechnetate thyroid uptake was determined before RIT. Fixed doses of 370 MBq of [131I]iodide were administered to all patients. RESULTS: Eleven patients became euthyroid; 40 became hypothyroid and 31 remained hyperthyroid. There was no association between outcome and age at diagnosis, gender, ophthalmopathy, pre-RIT FT4, TSH, antithyroid antibodies or thyrostatic drug. Multiple logistic regression showed higher probability of treatment success in patients with thyroid mass <53 g (odds ratio (OR)=8.9), with pre-RIT thyroid uptake <12.5% (OR=4.1) and in patients who withdrew thionamide before RIT (OR=4.9). CONCLUSIONS: Fixed doses of 370 MBq of radioiodine seem to be practical and effective for treating Graves' disease patients with [99mTc]pertechnetate uptake <12.5% and thyroid mass <53 g. This treatment is clearly not recommended for patients with large goitre. In contrast to what could be expected, patients with a high pre-RIT thyroid uptake presented a higher rate of RIT failure.     

Measurement of iodine-123 thyroid uptake using a gamma camera with LEAP collimator.

OBJECTIVE: This study compared the 123I thyroid uptake measurements obtained from a gamma camera fitted with a low-energy all-purpose (LEAP) collimator to those obtained from a thyroid uptake probe and gamma camera fitted with a pinhole (PH) collimator. METHODS: Thirty-one patients (27 female and 4 male patients) were studied for comparison between a probe and a gamma camera fitted with LEAP collimators. A different group of 25 patients (20 female and 5 male patients) were studied for comparison between LEAP and PH collimators. The patients were given 7.4-11 MBq (200-300 pCi) 123I capsules orally. Uptake with both the probe and the gamma camera was measured at 5 h and 24 h. The uptake measurements by these 3 methods were compared. RESULTS: Comparison of all the camera uptake values with the probe system correlated well with correlation coefficient values ranging from 0.912-0.988. The probe system yielded uptake ratios slightly higher than those measured by the gamma camera with LEAP collimator. Comparison between LEAP and PH uptake values resulted in a correlation coefficient of 0.979 for 5 h and 0.931 for 24 h uptake. CONCLUSION: Iodine-123 uptake with a gamma camera fitted with a LEAP collimator can accurately and consistantly be used to determine the thyroid uptake of 123I if proper ROIs are applied.     

Indium-111 octreotide scintigraphy for the detection of non-functioning metastases from differentiated thyroid cancer: diagnostic and prognostic value

In this prospective study, we evaluated the diagnostic and prognostic value of ¹¹¹In-octreotide scintigraphy (SRS) in papillary and follicular thyroid carcinoma (DTC) with increasing thyroglobulin (Tg) levels but no response to treatment with ¹³¹I. Twenty-three consecutive patients (13 female, 10 male; mean age 55 years, range 13–81 years) with progressive DTC were selected for the study. All patients had non-functioning metastases, defined by no or slight uptake of ¹³¹I in metastases. Diagnosis of tumour progression was based on rising Tg levels during follow-up and was confirmed by radiological examination. Uptake on SRS was scored from 0 to 4. Data on initial tumour stage, histology, age, gender, Tg values, TSH levels, ¹³¹I treatment doses, intervals and survival were gathered. Seven patients died during follow-up. The overall sensitivity for the detection of metastases was 74%. The sensitivity was better in patients in whom ¹³¹I whole-body scintigraphy did not show any abnormal uptake (82%; 14/17) than in patients with faint ¹³¹I uptake (50%; 3/6). The 10-year survival rate was significantly different between patients with an uptake score of 0 or 1 (100%) and those with an uptake score of 2, 3 or 4 (33%) (P=0.001). Gender, log Tg and uptake on SRS significantly correlated with survival, but in stepwise analysis, ¹¹¹In-octreotide uptake was selected as the most prognostic independent variable (hazard rate 6.25, P=0.006). We conclude that ¹¹¹In-octreotide scintigraphy is a valuable clinical tool for the detection of non-functioning DTC metastases. The uptake seems to correlate with prognosis and survival.     

Comparative scanning of thyroid nodules with technetium-99m pertechnetate and technetium-99m methoxyisobutylisonitrile

Thyroid imaging was performed using technetium-99m methoxyisobutylisonitrile and technetium-99m pertechnetate in 58 patients. The ^99mTc-pertechnetate scans showed a total of 77 nodules: 60 cold, 13 hot and 4 of normal activity. There was no ^99mTc-MIBI accumulation in 46.4% of ^99mTc-pertechnetate cold nodules; 27 (45%) of these nodules showed ^99mTc-MIBI uptake with the same intensity as the surrounding normal tissue, and five (8.6%) became hot with ^99mTc-MIBI. Of the ^99mTc-pertechnetate hot nodules 11 (84.6%) could not be differentiated from the normal extranodular tissue on the ^99mTc-MIBI scan. The histopathology of 34 surgically removed nodules proved that increased, normal or decreased ^99mTc-MIBI accumulation is not specific for thyroid malignancy and that the ^99mTc-MIBI uptake depends mainly on the viability of thyroid tissue.Correspondence to: I. Földes     

Examining recombinant human TSH primed 131I therapy protocol in patients with metastatic differentiated thyroid carcinoma: comparison with the traditional thyroid hormone withdrawal protocol

Purpose

Recombinant human thyroid-stimulating hormone (rhTSH)-based protocol is a promising recent development in the management of differentiated thyroid carcinoma (DTC). The objectives of this prospective study were: (1) to assess the feasibility and efficacy of the rhTSH primed ¹³¹I therapy protocol in patients with DTC with distant metastatic disease, (2) to perform lesional dosimetry in this group of patients compared to the traditional protocol, (3) to document the practical advantages (patient symptoms and hospital stay) of the rhTSH protocol compared to the traditional thyroid hormone withdrawal protocol, (4) to document and record any adverse effect of this strategy, (5) to compare the renal function parameters, and (6) to compare the serum TSH values achieved in either of the protocols in this group of patients.

Methods

The study included 37 patients with metastatic DTC having lung or skeletal metastases or both. A comparison of lesional radiation absorbed dose, hospital stay, renal function tests, and symptom profile was undertaken between the traditional thyroid hormone withdrawal protocol and rhTSH-based therapy protocol. Dosimetric calculations of metastatic lesions were performed using lesion uptake and survey meter readings for calculation of effective half-life. Non-contrast-enhanced CT was used for assessment of tumor volume. Quality of life was assessed using the European Organization for Research and Treatment of Cancer (EORTC) QOL forms. A comparison of pretreatment withdrawal thyroglobulin (TG) was done with the withdrawal TG level 3 months after treatment.

Results

The mean effective half-life of ¹³¹I in metastatic lesions was less during the rhTSH protocol (29.49 h) compared to the thyroid hormone withdrawal protocol (35.48 h), but the difference was not statistically significant (p?=?0.056). The mean 24-h % uptake of the lesions during the traditional protocol (4.84 %) was slightly higher than the 24-h % uptake during the rhTSH protocol (3.56 %), but the difference was not found to be statistically significant (p?=?0.301). The mean tumor radiation absorbed dose per mCi was less during the rhTSH protocol (6.04 rad/mCi) than during the thyroid hormone withdrawal protocol (8.68 rad/mCi), and the difference was statistically significant (p?=?0.049), though visual analysis of the rhTSH posttherapy scans showed avid concentration of ¹³¹I in the metastatic sites and revealed more lesions in 30 % of the patients compared to the traditional large dose scan and equal number of lesions in 65 % of the patients. Visual analysis of the traditional large dose scan, rhTSH pretreatment scan, and rhTSH posttherapy scans showed that the traditional large dose scan is better compared to the rhTSH 1 mCi scan as it showed more lesions in 19 of 37 patients (51.35 %). rhTSH posttherapy scans were better compared to the traditional large dose scans and rhTSH pretreatment scans. More lesions were seen on rhTSH posttherapy scans in 11 of 37 patients (29.7 %) compared to the traditional large dose scans and in 24 of 37 (64.86 %) patients compared to the rhTSH 1 mCi scans. Our findings demonstrate that the rhTSH primed pretreatment scan undertaken at 24 h after diagnostic dose is suboptimal to evaluate whether a metastatic lesion concentrates ¹³¹I. The majority of these lesions demonstrated radioiodine accumulation in the posttreatment scan. Quality of life as assessed using EORTC QOL-3 forms clearly showed that rhTSH improved the quality of life of patients compared to the thyroid hormone withdrawal protocol. Functional scale and global health status were significantly better in the rhTSH protocol compared to the thyroid hormone withdrawal protocol (p?<?0.001). The mean symptom scale score was significantly higher in the thyroid hormone withdrawal protocol (45.25) compared to the rhTSH protocol (13.59) (p?<?0.001). Of the 20 patients, 4 (20 %) had more than 25 % increase in the TG value on follow-up. The median hospital stay of patients receiving ¹³¹I therapy with the rhTSH protocol was shorter (2 days, range 2–8 days) compared to the thyroid hormone withdrawal protocol (3 days, range 1–8 days) and the difference was found to be statistically significant (p?=?0.007). The mean serum creatinine level was significantly lower in the rhTSH protocol (0.826 mg/dl) than the thyroid hormone withdrawal protocol (0.95 mg/dl) (p?=?0.013), though the mean blood urea level of patients during the rhTSH therapy protocol was slightly higher (22.81 mg/dl) than during the thyroid hormone withdrawal protocol (21.91 mg/dl) without statistical significance (p?=?0.55). The mean serum TSH on day 2 of the rhTSH protocol was 140.99 μIU/ml (range 71–176 μIU/ml) compared to 72.62 μIU/ml (range 2.05–154 μIU/ml) in the traditional protocol after around 4–6 weeks of thyroid hormone withdrawal (p?<?0.05).

Conclusion

Overall, the rhTSH primed ¹³¹I therapy protocol was found to be feasible and a good alternative to the thyroid hormone withdrawal protocol in patients with metastatic DTC. The lesional dosimetry findings need to be further examined in subsequent studies. The rhTSH primed pretreatment scan at 24 h after diagnostic dose is suboptimal to determine whether a metastatic lesion concentrates ¹³¹I and the posttreatment scan is important for the correct impression.     

Estimation of 24-hour thyroid uptake of I-131 sodium iodide using a 5-minute uptake of technetium-99m pertechnetate

The authors have developed a method to estimate the 24-hour sodium iodide thyroid uptake based on a 5-minute Tc-99m pertechnetate thyroid uptake using the equation: Estimated Iodide Uptake = 17.72*In(Pertechnetate Uptake) + 30.40. This estimation has a correlation coefficient of 0.90. It is based on a data pool of 44 patients who underwent I-131 and Tc-99m studies within 2 weeks of each other from 1978-1988, with established diagnoses as follows: 12 euthyroid, 6 hyperthyroid with multinodular goiters, 15 hyperthyroid with diffuse goiters, 4 with subacute thyroiditis, and 7 unknown. The population consisted of 30 women and 14 men with a mean age of 52.0 +/- 17.5 years; this sample was screened for use of thyroid hormone, propylthiouracil, and radiographic contrast. The authors believe this estimation method is of value whenever a 24-hour iodide uptake is desired, and where speed and minimizing radiation dose are factors. This method is strongly recommended for thyroid uptake evaluation before I-131 therapy.