Radioimmunotherapy with 131I-Rituximab in a Patient with Diffuse Large B-Cell Lymphoma Relapsed After Treatment with 90Y-Ibritumomab Tiuxetan

We report a case that demonstrates the efficacy of radioimmunotherapy (RIT) with radioiodinated rituximab (¹³¹I-rituximab) for relapsed diffuse large B-cell lymphoma (DLBCL). A 79-year-old male patient with DLBCL initially achieved a complete response (CR) after six cycles of R-CHOP (rituximab, cyclophosphamide, doxorubicin, vincristine and prednisone) therapy. However, the lymphoma relapsed 20 months later. Although the patient had achieved a second and a third CR after two cycles of ⁹⁰Y-ibritumomab tiuxetan, he experienced a third relapse approximately 3 years later. Between March and June 2011, the patient received three cycles of ¹³¹I-rituximab. Although he had achieved partial response after the second cycle, the disease progressed after the third cycle, and the total progression–free survival was thus 5 months. The patient suffered only relatively mild toxicity (grade 1 thrombocytopenia) during treatment. RIT with ¹³¹I-rituximab is therefore potentially effective in patients with relapsed DLBCL, even after the failure of ⁹⁰Y-ibritumomab tiuxetan therapy.     

Modification by nifedipine of 131I-meta-iodobenzylguanidine kinetics in malignant phaeochromocytoma

Following a case report that oral nifedipine can suppress the secretion of noradrenaline by phaeochromocytoma, we examined the effect of nifedipine on the tumour kinetics of tracer ¹³¹I-meta-iodobenzylguanidine (¹³¹I-mIBG) in five patients referred for mIBG radionuclide therapy for disseminated malignant phaeochromocytoma. In one subject a striking modification of mIBG kinetics was found that resulted in a doubling of the absorbed dose to tumour while the patient was taking nifedipine. At the same time, urinary excretion of noradrenaline was suppressed by a factor of three. The effect of nifedipine in this patient was confirmed when tracer studies were repeated nine months later. The changes in tumour kinetics were shown to be due to prolonged retention of mIBG rather than increased tumour blood flow or alteration of the curve of mIBG plasma concentration as a function of time.     

Preparation of (Re) Re-AEDP and its biodistribution studies

The synthesis of the Re (V) complex and preparation of ¹⁸⁸Re-AEDP are described using ¹⁸⁸Re which was obtained from the alumina-based ¹⁸⁸W/¹⁸⁸Re generator. Dependence of the radiolabeling yields of ¹⁸⁸Re-AEDP on reducing agent concentration, AEDP concentration, pH and addition of carrier was examined. In the case of optimum conditions, the radiolabeling yields of ¹⁸⁸Re-AEDP were 92–93% for carrier-free ¹⁸⁸Re and 95–98% for carrier-added ¹⁸⁸Re. The stability of ¹⁸⁸Re-AEDP at pH≈6 was studied and it is found that the carrier has a significant effect on the stability of ¹⁸⁸Re-AEDP. The biodistribution of carrier-free and carrier-added ¹⁸⁸Re-labelled compounds in rats was also measured. The results show that ¹⁸⁸Re (carrier-added)-AEDP is a potential bone palliation radiopharmaceutical due to its high skeletal uptake, rapid blood clearance and relatively low soft tissue absorption.     

The role of I-131-MIBG in the diagnosis and therapy of carcinoids

The successful use of ¹³¹I-MIBG for the diagnosis and treatment of pheochromocytoma and neuroblastoma has led to its application in patients with carcinoid, another neural crest tumor. The present report describes the scintigraphic findings, in correlation with clinical and biochemical parameters, in 20 patients with histologically proven carcinoids. ¹³¹I-MIBG total body scintigraphy was positive in 12 and equivocal in 1 of 19 patients with metastases. The necessity of delayed imaging and the possible advantage of single photon emission tomography for the detection of this tumor are emphasized. The results of ¹³¹I-MIBG treatment in five patients with progressive carcinoid metastases are discussed. It is concluded that ¹³¹I-MIBG has a role in the work up of patients with proven carcinoid and can be used for palliative treatment of this tumor.     

In vivo and in vitro studies into the immunological changes following iodine 131 therapy for Graves' disease

Radio-iodine therapy for Graves' disease is followed by immunological changes in addition to effects on thyroid hormone production. The present study examined these changes and the mechanisms responsible for them. Of the 15 patients enrolled in the study, 10 became hypothyroid in the first year after iodine 131 therapy. Patients who became hypothyroid had a tendency to show a rise in serum thyrotropin receptor antibody levels (30 ± 14 to 40 ± 9 units; NS) and a significant rise in immunoglobulin production (324 ± 153 to 740 ±200 ng/ml; P < 0.0005) from mitogen-stimulated peripheral blood lymphocytes (a measure of B-cell activity) 2 months after iodine 131 therapy. The increases were not seen in the patients who remained euthyroid at 1 year. In vitro studies suggested that the rise in B-cell activity is due to a fall in suppressor T cell numbers, a change shown to occur following iodine 131 therapy in previous studies. Our results indicate that immunological changes do arise after iodine 131 therapy for Graves' disease but appear to be confined to patients who subsequently became hypothyroid. It is not possible from this study to determine whether the immunological changes appear as a consequence of thyroidal destruction leading to hypothyroidism or whether they contribute directly to it. Offprint requests to: R. Wilson     

Dosimetry of iodine 131 metaiodobenzylguanidine for treatment of resistant neuroblastoma: results of a UK study

In 1987, the United Kingdom Children's Cancer Study Group (UKCCSG) set up a multi-centre study to investigate the toxicity of iodine 131 metaiodobenzyl-guanidine (mIBG) in the treatment of resistant neuroblastoma. Since December 1987, 25 children suffering from neuroblastoma have been treated with¹³¹I-mIBG at six UK centres. All centres followed standardised physics and clinical protocols to provide consistent toxicity and dosimetry data. These protocols describe the methods employed for both the tracer study using¹³¹I-mIBG and the subsequent therapy. Whole-body dosimetry calculations were performed on data from the tracer study. The activity administered for therapy was the amount predicted to deliver a predefined whole-body dose. Estimates of doses delivered to various organs during treatment are given in Table 1.On behalf of the mIBG Targetting Group of the United Kingdom Children's Cancer Study Group (UKCCSG), University of Leicester, Leicester, UK:Members of the mIBG Targetting Group: Christie Hospital, Manchester- P. Nuttall, S. Owens (Physics), H.R. Gattamaneni (Radiotherapy); Cookridge Hospital, Leeds - M. Sheppard, S. Packar (Physics), S. Cartright, R. Taylor (Radiotherapy); Newcastle General Hospital - A. Simpson, P. Bartholomew (Physics), H. Lucraft (Radiotherapy); Medical School, University of Newcastle upon Tyne - A. Pearson (Paediatric Oncology); Royal Hospital for Sick Children, Edinburgh - T. Eden (Paediatric Oncology); Royal Manchester Childrens' Hospital - P. Morris-Jones (Paediatric Oncology); Royal Marsden Hospital, Sutton - R. Ott, M. Rosenbloom (Physics), S. Meller, R. Corbett, R. Pinkerton (Paediatric Oncology); Royal South Hants Hospital, Southampton - V. Hall (Radiotherapy); Royal Victoria Infirmary, Newcastle upon Tyne - A. Craft (Paediatrics); Southampton General Hospital - G. Blake, M. Tristam (Physics), J. Kohler (Paediatric Oncology), V. Lewington (Nuclear Medicine); St Bartholomews Hospital, London - K. Britton, L. Hawkins (Nuclear Medicine), J. Kingston, J. Moyes (Paediatric Oncology), J. Malpas (Oncology), N. Plowman (Radiotherapy); Western General Hospital, Edinburgh - J. Hannan (Physics), M. Merrick (Nuclear Medicine), A. Rodger (Radiotherapy); Western Infirmary, Glasgow - T. Hilditch (Physics), A. Barrett (Radiotherapy), T. Wheldon, J. O'Donoghue (Radiobiology); Amersham International, Bucks-R. Bayly; UKCCSG Offices, Leicester-J. Barnes.     

Uptake of 131I-MIBG by medullary carcinoma of thyroid in familial cases

Medullary carcinoma of the thyroid (MCT) and pheochromocytoma are APUD tumors. MIBG (Meta Iodo Benzyl Guanidine) uptake by pheochromocytomas is now well known but very few cases of MIBG uptake in sporadic MCT have been described. We report here the two first cases of inherited MCT with MIBG uptake.     

Iodine-131 MIBG scintigraphy in small cell lung cancer

There is a well documented relationship between small cell carcinoma of the lung and the amine precursor uptake and decarboxylation system of endocrine cells (APUD). We attempted to exploit this association by employing the unique radiopharmaceutical,¹³¹I-MIBG, which is recognized and taken up by the APUD system to monitor disease activity in patients with small cell carcinoma of the lung. A total of eight patients with biopsy proven, metastatic small cell carcinoma of the lung were studied.¹³¹I-MIBG was synthesized in our laboratory by reacting metaiodobenzylamine synthesized in our laboratory by reacting metaiodobenzylamine hydrochloride with cyanamide with subsequent solid phase radioiodination. A dose of 0.5 mCi radiopharmaceutical was injected and images obtained on a large field of view gamma camera with a high energy parallel hole collimator at 2, 24, and either 48 or 72 h. Images were compared with known focal areas of metastatic disease demonstrable on computed tomographic scan, chest roentgenogram or bone scan. We were unable to detect reproducible correlations between the images produced by conventional radiographic techniques and the images produced by our radiopharmaceutical. We conclude that this agent will probably not be useful for localization of metastatic small cell lung carcinoma.This work was supported by a Pilot Research Grant from the Education and Research Foundation of the Society of Nuclear Medicine     

Evaluation of [C]laniquidar as a tracer of P-glycoprotein: radiosynthesis and biodistribution in rats

At present, P-glycoprotein (P-gp) function can be studied using positron emission tomography (PET) together with a labelled P-gp substrate such as (R)-[¹¹C]verapamil. Such a tracer is, however, less suitable for investigating P-gp (over)expression. Laniquidar is a third-generation P-gp inhibitor, which has been used in clinic trials for modulating multidrug resistance transporters. The purpose of the present study was to develop the radiosynthesis of [¹¹C]laniquidar and to assess its suitability as a tracer of P-gp expression.The radiosynthesis of [¹¹C]laniquidar was performed by methylation of the carboxylic acid precursor with [¹¹C]CH₃I. The product was purified by HPLC and reformulated over a tC₁₈ Seppak, yielding a sterile solution of [¹¹C]laniquidar in saline. For evaluating [¹¹C]laniquidar, rats were injected with 20 MBq [¹¹C]laniquidar via a tail vein and sacrificed at 5, 15, 30 and 60 min after injection. Several tissues and distinct brain regions were dissected and counted for radioactivity. In addition, uptake of [¹¹C]laniquidar in rats pretreated with cyclosporine A and valspodar (PSC 833) was determined at 30 min after injection. Finally, the metabolic profile of [¹¹C]laniquidar in plasma was determined.[¹¹C]Laniquidar could be synthesized in moderate yields with high specific activity. Uptake in brain was low, but significantly increased after administration of cyclosporine A. Valspodar did not have any effect on cerebral uptake of [¹¹C]laniquidar. In vivo rate of metabolism was relatively low. Further kinetic studies are needed to investigate the antagonistic behaviour of [¹¹C]laniquidar at tracer level.     

The biodistribution and pharmacokinetics of meta-iodobenzylguanidine in childhood neuroblastoma

MIBG is generating considerable interest for the treatment of neuroblastoma. This study has investigated the biological variation in handling of the compound in children with neuroblastoma. The biodistribution of the compound has been characterised in children undergoing tracer administrations of¹²³I and¹³¹I-mIBG. Estimates of hepatic and whole body radiation dose delivery have been made. The results indicate substantial interpatient variation in hepatic dose delivery. This organ may be critical in some patients undergoing targeted radiotherapy with mIBG.     

碘治疗工作人员甲状腺131I活度的测量与评价

目的 了解核医学科碘治疗工作人员甲状腺内¹³¹I的活度,并估算年待积有效剂量,分析碘治疗人员的内照射现状。方法 选择甲状腺内照射碘测量仪,对山东省6家医院进行调查并进行甲状腺¹³¹I活度测量,得出6家医院核医学科碘治疗工作人员甲状腺¹³¹I的检出率和活度值,进而计算摄入量和年待积有效剂量。结果 6家医院共有63名碘治疗工作人员接受测量,其中有52人甲状腺内检测到¹³¹I,检出率83%,测得¹³¹I活度大多低于200 Bq。估算的年待积有效剂量范围为0.23~7.78 mSv,其中有84.6％的人年待积有效剂量＜2 mSv。结论 核医学科碘治疗工作人员应进行常规内照射个人监测,各医院在辐射防护制度方面需进一步完善。     

<Superscript>68</Superscript>Ga-DOTANOC: biodistribution and dosimetry in patients affected by neuroendocrine tumors

Objectives The aim of this work was the evaluation of biodistribution and radiation dosimetry of ⁶⁸Ga-DOTANOC in patients affected by neuroendocrine tumors. Materials and methods We enrolled nine patients (six male and three female) affected by different types of neuroendocrine tumors (NETs). Each patient underwent four whole body positron emission tomography (PET) scans, respectively, at 5, 20, 60, and 120 min after the intravenous injection of about 185 MBq of ⁶⁸Ga-DOTANOC. Blood and urine samples were taken at different time points post injection: respectively, at about 5, 18, 40, 60, and 120 min for blood and every 40–50 min from injection time up to 4 h for urine. The organs involved in the dosimetric evaluations were liver, heart, spleen, kidneys, lungs, pituitary gland, and urinary bladder. Dosimetric evaluations were done using the OLINDA/EXM 1.0 software. Results A physiological uptake of ⁶⁸Ga-DOTANOC was seen in all patients in the pituitary gland, the spleen, the liver, and the urinary tract (kidneys and urinary bladder). Organs with the highest absorbed doses were kidneys . The mean effective dose equivalent (EDE) was . Discussion and conclusions The excretion of the compound was principally via urine, giving dose to the kidney and the urinary bladder wall. As SSTR2 is the most frequently expressed somatostatin receptor and ⁶⁸Ga-DOTANOC has high affinity to it, this compound might play an important role in PET oncology in the future. The dosimetric evaluation carried out by our team demonstrated that ⁶⁸Ga-DOTANOC delivers a dose to organs comparable to, and even lower than, analogous diagnostic compounds.     

肝胆肿瘤患者68Ga-FAPI-04 PET显像的内照射剂量及分布研究

目的 评估⁶⁸Ga-FAPI-04 PET/CT检查在肝胆肿瘤患者中的内照射剂量及生物分布。方法 本研究纳入因肝脏占位于北京协和医院接受PET/CT检查的6例患者,经静脉注射⁶⁸Ga-FAPI-04（170.57 ±14.43） MBq后分别于第3、10、15、20、30和60 min进行全身显像。观察显像剂的生物分布;手动勾画感兴趣区;所有靶器官的内照射剂量应用OLINDA/EXM软件计算。结果 ⁶⁸Ga-FAPI-04在肝脏内放射性本底消退较快,在肿瘤组织内放射性摄取较为稳定,病灶平均SUV_max在注射后20 min达到最大（13.87 ±2.55）;病灶平均靶本比逐渐升高,在注射后30 min达到最大（10.09 ±8.17）。1次⁶⁸Ga-FAPI-04 PET/CT扫描的全身有效剂量为（0.020 ±0.002） mSv/MBq,吸收剂量最高的器官是膀胱壁,为（0.146 ±0.035） mSv/MBq。结论 ⁶⁸Ga-FAPI-04与¹⁸F-FDG全身有效剂量相近;肿瘤摄取快速,肝脏背景低,且不受血糖水平影响,有望成为潜在的肝胆肿瘤PET/CT显像药物。     

Iodine-123 as a diagnostic imaging agent in differentiated thyroid carcinoma: a comparison with iodine-131 post-treatment scanning and serum thyroglobulin measurement

Purpose Using ¹²³I for diagnostic purposes avoids the risk of stunning for subsequent radioiodine treatment and affords an excellent image quality. In this study we assessed the role of ¹²³I in comparison with ¹³¹I post-treatment imaging in patients with thyroid cancer. Methods We compared a total of 292 ¹²³I scans with their corresponding post-treatment ¹³¹I images. Patients received a therapeutic dose of ¹³¹I following diagnostic scanning with 50–111 MBq of ¹²³I. All patients were in a hypothyroid state (>30 μIU/l) before radioiodine administration for either diagnostic or therapeutic purposes. Results In 228 out of 263 patients with a positive diagnostic scan, ¹²³I whole-body scan findings were concordant with those of corresponding post-treatment ¹³¹I images (concordance rate 87%). However, there were 44 additional foci of abnormal uptake on post-treatment ¹³¹I scans in 22 discordant cases with no impact on therapeutic management of the patients. In 13 patients, there was at least one new site on post-treatment images that had been missed on pretreatment ¹²³I images. Twenty-nine patients with a negative diagnostic scan were treated with ¹³¹I owing to a high serum thyroglobulin level (range 11.3–480 ng/ml). Radioiodine uptake sites were seen in eight post-treatment scans. In 21 pairs of whole-body scans, both the pre- and the post-treatment scan were negative (concordance rate 72.4%). Conclusion ¹²³I scanning is comparable to high-dose ¹³¹I post-treatment imaging in thyroid carcinoma patients, and ¹²³I offers excellent image quality as a diagnostic agent. It avoids disadvantages such as stunning before treatment and delivery of a high radiation dose to patients.     

123I-2-iodo-tyrosine, a new tumour imaging agent: human biodistribution, dosimetry and initial clinical evaluation in glioma patients

Purpose ¹²³I-2-iodo-tyrosine (¹²³I-2IT) has been identified as a promising new amino acid tracer in animals. Uptake is mediated by LAT1 transport, which is increased in tumour cells. In this study we present the human biodistribution and first clinical results in glioma patients. Methods For the biodistribution study, six male volunteers received 60–95 MBq ¹²³I-2IT. Whole-body scans and blood and urine samples were obtained up to 24 h after injection; dosimetry was calculated using OLINDA 1.0 software. Initial clinical evaluation of ¹²³I-2IT SPECT was performed in 35 patients with suspected or known glioma, either as primary diagnosis or for detection of recurrence. Tumour-to-background (T/B) ratios were calculated for semi-quantitative analysis. The results were correlated with clinical and MRI follow-up data or histology. Results ¹²³I-2IT showed both renal and intestinal clearance. Bladder (0.12 mGy/MBq) and small intestine (0.03 mGy/MBq) received the highest absorbed doses. The effective dose equivalent and effective dose were estimated at 0.020 and 0.016 mSv/MBq, respectively. In patients, ¹²³I-2IT SPECT did not differentiate between neoplastic and non-neoplastic lesions after an indeterminate MRI. In follow-up of known glioma, 13/15 patients with disease recurrence had increased T/B values (range 1.39–3.91). Out of seven recurrence-negative patients, two showed an important increase in T/B, in one case due to radionecrosis (T/B 1.59) and in the other probably due to residual but stable disease (T/B 2.07). Conclusion ¹²³I-2IT has a favourable biodistribution for a tumour imaging agent. It shows increased uptake in central nervous system glioma and is potentially useful in the follow-up of glioma patients. M. Keyaerts is an “aspirant” of the FWO-Vlaanderen.     

Excretion of radioiodine in human milk following a therapeutic dose of I-131

An investigation of ¹³¹I excretion into human milk after a therapeutic dose of 5142 MBq (139 mCi) ¹³¹I, in a patient who has had a thyroidectomy is presented. During the first 36 h, 17.4% of the administered dose was excreted into the milk. In addition to the known radiation risk, this may affect the quantity of ¹³¹I retained by the thyroid and metastases.     

99mTc-NC100668, a new tracer for imaging venous thromboemboli: pre-clinical biodistribution and incorporation into plasma clots in vivo and in vitro

Purpose

^99mTc-NC100668 is a new radiotracer being developed to aid the diagnosis of thromboembolism. The structure of NC100668 is similar to a region of human α₂-antiplasmin, which is a substrate for factor XIIIa (FXIIIa). The purpose of this study was to confirm the uptake of ^99mTc-NC100668 into forming plasma clot and to establish the biodistribution of ^99mTc-NC100668 in Wistar rats.

Methods

The in vitro plasma clot uptake of ^99mTc-NC100668 and other compounds with known affinities to FXIIIa was measured using a plasma clot assay. The biodistribution and blood clot uptake of radioactivity of ^99mTc-NC100668 in normal Wistar rats and those bearing experimentally induced deep vein thrombi were investigated.

Results

The in vitro uptake of ^99mTc-NC100668 was greater than that for [¹⁴C]dansyl cadaverine, a known substrate of FXIIIa in the plasma clot assay. The biodistribution of ^99mTc-NC100668 in male and female Wistar rats up to 24 h p.i. showed that radioactivity was rapidly excreted, predominantly into the urine, with very little background tissue retention. In vivo the uptake and retention of ^99mTc-NC100668 into the blood clot was greater than could be accounted for by non-specific accumulation of the radiotracer within the blood clot.

Conclusion

^99mTc-NC100668 was retained by plasma clots in vitro and blood clots in vivo. No significant tissue retention which could interfere with the ability to image thrombi in vivo was observed. This evidence suggests that ^99mTc-NC100668 might be useful in the detection of thromboembolism.     

<Superscript>131</Superscript>I-MIBG Therapy in metastatic phaeochromocytoma and paraganglioma

Purpose ¹³¹Iodine metaiodobenzylguanidine (¹³¹I-MIBG) is a radiopharmaceutical used for scintigraphic localisation of phaeochromocytomas and paragangliomas. The experience with its therapeutic use is limited. We report our experience for the treatment of malignant phaeochromocytoma and paraganglioma. Materials and methods The charts of 19 patients with malignant phaeochromocytoma (n = 12) or paraganglioma (n = 7), who were treated with ¹³¹I-MIBG, were retrospectively reviewed. Four patients (21%) received radiotherapy, three (16%) chemotherapy, and in one patient (5%), both chemotherapy and radiotherapy was given before ¹³¹I-MIBG therapy. Response to ¹³¹I-MIBG treatment was evaluated by objective as tumour response, biochemical and subjective response. Results Of the 19 patients, 13 (68%) were men, 6 (32%) were women. Ages ranged from 22 to 68 years (median, 47). The median initial dose was 7.4 GBq (200 mCi; range, 6.7 GBq–25.9 GBq, 180–700 mCi); median cumulative dose was 22.2 GBq (600 mCi; range, 6.8 GBq–81.4 GBq, 183–2200 mCi). Objective tumour response was achieved in 47% of the patients. Biochemical response rate was 67%, and symptomatic response was seen in 89% of the patients. Overall median follow-up was 29 months, with a range of 3–93 months. Haematologic complications were the most common side effects and were observed in 26% of the patients. Conclusion Our data support that symptomatic and biochemical response can be reached with ¹³¹I-MIBG therapy in patients with metastatic phaeochromocytoma and paraganglioma. Although complete tumour response was not observed, the palliation and control of tumour function by ¹³¹I-MIBG therapy may be valuable for the patients.     

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.