Dosimetry of iodoantipyrine

Dosimetry of iodoantipyrine labeled with radioactive iodine was determined by measuring the biodistribution of ¹³¹I-iodoantipyrine in 41 female rabbits. Following administration of the radiopharmaceutical, subjects were killed at 0.5, 6, 12, 17, 24, 36, and 48 h. Organs and samples of tissues and body fluids were assayed. Results were corrected for physical decay. Exponential functions were employed to describe the time-concentration curves; representative value would be the biological half life of 9.96±0.55 h for blood. Cumulated activity estimates for ¹²³I, ¹²⁵I and ¹³¹I were then computed. Extrapolation to absorbed dose in humans followed the formulation of the Medical International Radiation Dose (MIRD) Committee of the Society of Nuclear Medicine. The whole body absorbed doses are 7 Gray, 5 Gray and 29 Gray per MBq of ¹²³I, ¹²⁵I, and ¹³¹I administered respectively.This work was supported by a research grant from the Veterans Administration     

Fukushima radionuclides in Vilnius/Lithuania aerosols: Modelling of aerosol transport

Measurements of activity concentrations of ¹³¹I; ^129mTe, ¹³²Te, ¹³⁴Cs and; ¹³⁶Cs, ¹³⁷Cs in aerosol were carried out in daily samples after the Fukushima accident during the period of March–April, 2011 in Vilnius. The maximum activity concentrations of ¹³¹I and ¹³⁷Cs were found to be 3700 μBq m⁻³ and 1040 μBq m⁻³, respectively. Variations in activity ratios of ¹³²Te/^129mTe and ¹³⁷Cs/¹³⁶Cs observed after the accident were explained by the decay of the short-lived isotopes, while those in ¹³⁴Cs/¹³⁷Cs by the dilution effect of the Chernobyl-derived ¹³⁷Cs. It was found that different behaviours of highly volatile ¹³¹I and ¹³⁷Cs resulted in enrichment of ground level aerosol particles by ¹³¹I with respect to ¹³⁷Cs. Simulated activity concentrations of ¹³⁷Cs attached to aerosol particles for the Vilnius site reasonably agreed with measured activities in aerosol samples during the Fukushima accident.     

Does 131I Radioactivity Interfere with Thyroglobulin Measurement in Patients Undergoing Radioactive Iodine Therapy with Recombinant Human TSH?

Objectives

Recombinant human thyroid-stimulating hormone (rhTSH) is widely used in radioactive iodine therapy (RIT) to avoid side effects caused by hypothyroidism during the therapy. Owing to RIT with rhTSH, serum thyroglobulin (Tg) is measured with high ¹³¹I concentrations. It is of concern that the relatively high energy of ¹³¹I could interfere with Tg measurement using the immunoradiometric assay (IRMA). We investigated the effect of ¹³¹I administration on Tg measurement with IRMA after RIT.

Methods

A total of 67 patients with thyroid cancer were analysed retrospectively. All patients had undergone rhTSH stimulation for RIT. The patients’ sera were sampled 2 days after ¹³¹I administration and divided into two portions: for Tg measurements on days 2 and 32 after ¹³¹I administration. The count per minute (CPM) of whole serum (200 μl) was also measured at each time point. Student’s paired t-test and Pearson’s correlation analyses were performed for statistical analysis.

Results

Serum Tg levels were significantly concordant between days 2 and 32, irrespective of the serum CPM. Subgroup analysis was performed by classification based on the ¹³¹I dose. No difference was noted between the results of the two groups.

Conclusions

IRMA using ¹²⁵I did not show interference from ¹³¹I in the serum of patients stimulated by rhTSH.     

核医学场所空气中131I浓度监测及工作人员内照射剂量评价探讨

目的 了解医疗机构¹³¹I治疗工作场所空气中¹³¹I核素的活度浓度水平，探讨通过空气采样方法估算工作人员内照射剂量的方法并分析其影响因素。方法 选取郑州市10家开展¹³¹I核素治疗的工作场所，采用空气采样方法采集¹³¹I治疗工作场所中放射性气溶胶，用高纯锗γ能谱仪进行γ放射性核素测定并推算工作场所空气中¹³¹I核素的活度浓度水平，根据测量结果和现场调查结果估算放射工作人员因¹³¹I核素吸入导致的内照射剂量。结果 19个分装间空气样品的¹³¹I活度浓度为0.087~570 Bq/m³，平均为（51.04±128.58）Bq/m³；11个病房空气样品的¹³¹I活度浓度为0.162~54.6 Bq/m³，平均为（7.97±15.89）Bq/m³。根据GBZ 129-2016《职业性内照射个人监测规范》推荐的典型工作时间估算，放射工作人员由于吸入¹³¹I核素导致的年待积有效剂量范围为2 μSv~10 mSv，平均为（0.61±1.80）mSv，年有效剂量均未超过国家标准所规定的剂量限值。结论 郑州市10家医疗机构核医学工作场所中¹³¹I核素活度浓度较高的样品多分布在甲状腺癌住院患者较多、核素操作量较大的三甲医院，由此导致的工作人员内照射剂量不容忽视。根据空气样品的测量结果估算内照射剂量带有很大不确定度，但空气采样方法可及时发现异常或事故情况下的放射性污染，为工作人员开展体外直接测量和内照射评价提供预警。     

日本福岛核事故对辽宁省局部地区环境放射性水平的影响

目的 评价日本福岛第一核电站核泄漏事故对辽宁省局部地区环境放射性水平的影响程度.方法 对大气气溶胶、沉降灰、饮用水、蔬菜、牛奶、海产品进行γ核素的能谱测量和总放射性分析;对人工裂变核素131I、134Cs和137Cs等放射性水平进行应急监测.结果 核事故发生20 d后,在大气中陆续监测到了人工核素131I以及134Cs、137Cs,最高浓度分别为4.6 ×10-3、2.9 ×10-4和4.2×10-4Bq/m3,并分别持续存在25、4和6d.沈阳采集的蔬菜、牛奶、饮用水以及丹东产的海产品中未发现人工核素.结论 日本核事故对辽宁省大气造成了轻度污染,但未对蔬菜、牛奶及饮用水造成污染.     

应对福岛核事故我国食品和饮用水的放射性监测

目的 汇总分析日本福岛核电站事故发生后我国沿海城市和主要内陆城市食品和饮用水放射性的抽样监测结果,评价是否对我国居民的健康造成影响.方法 根据国家标准方法,制定应对日本福岛核事故对我国食品和饮用水的监测方案,统一数据报送格式,对数据进行对比分析.结果 4月2日北京露天生长菠菜样品中,监测到极微量的人工放射性核素131I,此后在全国范围内10种露天生长的蔬菜中也检测出131I,最高值为菠菜样品3.1 Bq/kg,到5月初未再检测出.牛奶、海产品和饮用水样品中未检测到人工放射性核素.结论 监测到的蔬菜中131I来自日本福岛核电站事故释放,与此次事故期间欧洲一些国家食品中的的131I水平相一致,远低于1986年切尔诺贝利核电站事故时我国蔬菜中131I活度,其对公众所致吸收剂量极其微小,不会对我国境内公众造成影响.     

Impact of <Superscript>131</Superscript>I-SPECT/CT images obtained with an integrated system in the follow-up of patients with thyroid carcinoma

Purpose The purpose of the study was to determine the diagnostic impact of ¹³¹I-SPECT/CT imaging compared with conventional scintigraphic evaluation in the follow-up of patients with thyroid carcinoma.Methods Seventy-one patients with thyroid carcinoma underwent concurrent ¹³¹I-SPECT/CT, using an integrated imaging system, at various stages of their disease in order to evaluate foci of uptake detected on planar whole-body images.Results SPECT/CT imaging had an incremental diagnostic value in 57% (41/71) of patients. Uptake in the neck was evaluated in 61 patients, and SPECT/CT imaging in this region had an incremental diagnostic value in 27% of the whole patient population (19/71). Low-resolution integrated CT images allowed for the precise characterization of equivocal neck lesions on planar imaging in 14/17 patients and changed the assessment of the lesion location in five patients as compared with planar studies. Thirty-six patients underwent SPECT/CT for evaluation of foci of uptake distant from the neck. SPECT/CT imaging improved characterization of equivocal foci of uptake as definitely benign in 13% (9/71) of patients. Precise localization of malignant lesions to the skeleton was possible in 17% (12/71) and to the lungs versus the mediastinum in 6% (5/71) of patients.Conclusion Integrated ¹³¹I-SPECT/CT was found to have an additional value over planar imaging in patients with thyroid cancer for correct characterization of equivocal tracer uptake seen on planar imaging as well as for precise localization of malignant lesions in the neck, chest, and skeleton. SPECT/CT optimized the localization of ¹³¹I uptake to lymph node metastases versus remnant thyroid tissue, to lung versus mediastinal metastases, and to the skeleton. It also had a further clinical impact on patient management by influencing referral for ¹³¹I treatment, tailoring of the administered radioiodine dose, and/or the addition of surgery or external radiation therapy when indicated.     

Radioprotective action of carbimazole in radioiodine therapy for thyrotoxicosis — influence of the drug on iodine kinetics

Pretreatment with carbimazole of patients given radioiodine (¹³¹I) therapy for thyrotoxicosis reduces the incidence of early hypothyroidism. The possibility that this radioprotective effect might be a consequence of drug induced alteration in thyroidal iodide turnover, leading to a reduction in thyroid irradiation, was investigated in a prospective study of 24 thyrotoxic patients. Subjects were randomly assigned to receive ¹³¹I alone or to be treated with carbimazole for a minimum of three months before ¹³¹I. Thyroxine supplements were given in the latter group to prevent iatrogenic hypothyroidism. The effective half-life of therapeutic ¹³¹I in the thyroid was measured using a gamma camera/computer system after oral administration of the dose, allowing the biological half life of the anion and estimated radiation dose to the thyroid to be derived. Effective half life of ¹³¹I, biological half life of ¹³¹I and estimated radiation dose to the thyroid were similar in the two groups of subjects. It is concluded that the radioprotective action of carbimazole is not a consequence of altered thyroidal iodide kinetics.     

New measurements and evaluation of excitation functions for (p,xn), (p,pxn) and (p,2pxn) reactions on 133Cs up to 70 MeV proton energy

Cross sections for production of the therapeutic radioisotope ¹³¹Cs via the ¹³³Cs(p,3n)¹³¹Ba→¹³¹Cs route were investigated at cyclotrons. Excitation functions of the ¹³³Cs(p,x)^{133m,133mg,131mg,129g,129m,128}Ba, ^{132,129cum,127cum}Cs and ^{129m(ind),127cum,125cum}Xe nuclear reactions were measured up to 70 MeV proton energy. The experimental data were compared to the results of model calculations performed by means of ALICE-IPPE, EMPIRE-II and TALYS computer codes. Good overall agreement was observed. On the basis of the measured excitation functions integral yields were deduced. Charged particle production routes of ¹³¹Cs are discussed.     

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     

河南郑州“7·20”特大暴雨灾害后核医学衰变池周围土壤中131I放射性水平调查及分析

目的探究"7·20"特大暴雨灾害后核医学衰变池是否存在放射性废水泄漏或溢出, 分析其发生原因, 为今后核医学衰变池的设计、建设、维护及核医学放射防护管理提供科学依据。方法选择郑州市3家开展131I治疗的医院(A、B、C医院), 根据核医学衰变池周围环境辐射水平检测结果按标准方法设置采样点位, 采集不同深度土壤样品。用高纯锗γ能谱仪测量土壤中131I的放射性水平, 对检测结果进行处理和分析。结果除B医院未检出131I放射性核素外, A和C医院核医学衰变池周围土壤中均检出不同活度浓度的131I放射性核素, A医院131I的活度浓度范围为16.4～98 111.8 Bq/kg, C医院131I的活度浓度范围为10.6～7 176.6 Bq/kg。经过一段时间衰变后, 对A医院和C医院进行复测, A医院131I的活度浓度范围为1.3～17.0 Bq/kg, C医院131I的活度浓度范围为3.9～7.1 Bq/kg。同一采样点位0～5 cm土壤中131I活度浓度均高于5～10 cm土壤中131I活度浓度, 两者比值范围为1.3～13.1, 比值中值为5.9。结论 "7·20"特大暴雨灾害后, 部...     

Visualization of nasolacrimal drainage system after radioiodine therapy in patients with thyroid cancer

The objective of this study was to report three cases with an accumulation of ¹³¹I in the nasolacrimal duct after radioiodine therapy for papillary thyroid cancer. A whole-body scan was taken 3 days after the administration of 3.7 GBq of ¹³¹I. Single-photon emission computed tomography (SPECT)/CT images were added when the location of a focal tracer uptake was undetermined on whole-body scans. In case 1, a 62-year-old woman complained of epiphora of the left eye after nine radioiodine therapies with a cumulative dose of 31.08 GBq. The left nasolacrimal duct was visualized at her tenth treatment with ¹³¹I. In case 2, a series of three radioiodine therapies had been given to a 73-year-old woman with a cumulative dose of 11.1 GBq. The accumulation of ¹³¹I was noted in the left nasolacrimal duct at her fourth treatment. She complained of epiphora of the left eye. In case 3, bilateral nasolacrimal ducts were visualized at the second radioiodine therapy in a 75-year-old woman. The patient had received 3.7 GBq of ¹³¹I at the first therapy. She did not complain of epiphora. It is possible that radiation from ¹³¹I that is secreted in tears and/or actively accumulated in the nasolacrimal duct may induce nasolacrimal duct obstruction. ¹³¹I in tears would be responsible for the visualization of nasolacrimal duct in the first two cases. ¹³¹I actively accumulated in the nasolacrimal duct might have been visualized in the third case. In summary, ¹³¹I is excreted in tears and is actively accumulated in the nasolacrimal duct. Obstruction of the lacrimal drainage system could occur after high-dose radioiodine therapy.     

Relative value of thallium-201 and iodine-131 scans in the detection of recurrence or distant metastasis of well differentiated thyroid carcinoma

Radioactive iodine (¹³¹I) has been found to be more sensitive and more specific than thallium-201 for the detection of distant metastases and thyroid remnants in the neck in cases of well-differentiated thyroid carcinoma. ²⁰¹Tl has been deemed particularly useful in localizing metastases or recurrence in patients with a negative ¹³¹I scan and abnormal levels of serum thyroglobulin (Tg). This study aimed to: (1) determine the value of ²⁰¹Tl imaging in localizing metastases or recurrence in patients with well-differentiated thyroid carcinoma, and (2) evaluate the false-positive and false-negative results of ¹³¹I and ²⁰¹Tl scintigraphy. Sixty-two thyroid remnant ablated patients who underwent simultaneous postoperative ²⁰¹Tl and ¹³¹I scans and and serum Tg determinations were evaluated. Fifty patients had papillary thyroid carcinomas and 12 had follicular thyroid carcinomas. ²⁰¹Tl imaging was performed before the ¹³¹I studies. Of the 62 patients who underwent ²⁰¹Tl imaging studies, 24 were found to have positive results, with local recurrence or distant metastases. Patients with positive results in the ²⁰¹Tl imaging studies tended to be older, were mor often male, had higher Tg levels and had a higher recurrence rate. Of these 24 patients, ten had negative diagnostic or therapeutic ¹³¹I scans. Concurrently, serum Tg levels were less than 5 ng/ml in five of these ten patients. Three patients were deemed false positive by ²⁰¹Tl scans; one had a parotid tumour, one a periodontal abscess and one lung metastasis. Among the 38 patients with negative ²⁰¹Tl scans, 11 had positive findings on ¹³¹I scans. Three had distant metastases: two with lung metastases and one with bone metastases. Patients with false-positive results on ¹³¹I scans included those with biliary tract stones, ovarian cysts, and breast secretion. Of the 27 patients with negative ²⁰¹Tl and ¹³¹I scans, 15 had elevated serum Tg levels. Among these, local recurrence followed by lung metastases was manifested in a 49-year-old male with papillary thyroid carcinoma. In conclusion, both ¹³¹I and ²⁰¹Tl scans are useful in the detection of recurrence or distant metastasis of well differentiated thyroid cancers. ²⁰¹Tl scan could in particular be used in patients with a negative ¹³¹I scan in conjunction with an elevated Tg level. Received 16 January and in revised form 8 April 1998     

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.     

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.     

Study on the environmental behavior of chernobyl-derived radionuclides in Kyushu Island,Japan

The environmental behavior of Chernobyl-derived radionuclides in Kyushu Island was investigated for one month after the accident. The radioactivity level in airborne dusts was two orders of magnitude lower than that observed in Western Europe. The distribution of ¹³¹I in airborne dusts shifted to a larger particle size compared with other radionuclides. The radionuclide concentration in seaweeds varied depending on the geographical situation where the sampling was done. The biological half-lives in red algae were calculated to be 17.4 d and 32.9 d for ¹³¹I and ¹⁰³Ru, respectively. The concentration factors in red algae were estimated to be 3 × 10³ and 5 × 10³ for ¹³¹I and ¹⁰³Ru, respectively. The cooking effect of ¹³¹I in seaweeds and the committed effective dose equivalent through ingestion of seaweed were also evaluated.     

接触131I放射性核素工作人员内照射剂量估算方法的初步研究

目的 探索接触¹³¹I放射性核素放射工作人员内照射剂量估算方法。方法 选择某¹³¹I放射性药物生产企业和某开展¹³¹I甲亢和甲状腺癌治疗的医院核医学科放射工作人员,使用便携式高纯锗（HPGe）γ谱仪,以7 d为周期,连续4次测量甲状腺部位¹³¹I活度,结合人员接触¹³¹I的轮岗方式,估算内照射剂量。结果 以监测月份为典型月份估算人员内照射剂量时,调查企业从事¹³¹I放射性药物分装的生产人员年待积有效剂量为0.09~1.93 mSv,调查医院核医学科工作人员内照射年待积有效剂量为0.06~0.58 mSv。对监测结果进行校正和结合轮岗方式后估算的工作人员内照射年待积有效剂量,放射性药物生产工作人员和核医学科工作人员分别为0.06~1.22 mSv和0.03~0.16 mSv。结论 在进行接触¹³¹I放射性核素工作人员内照射剂量估算时,仅以单次测量的结果估算全年受照剂量会带来较大的误差。在连续监测时,应根据前续监测周期的结果对后续监测周期结果进行校正。为准确估算人员内照射剂量,应充分考虑工作人员接触¹³¹I的方式、接触的时间、接触的频率、内污染的途径等因素。对于接触¹³¹I内照射剂量可能>1 mSv/年的工作人员,以14 d作为常规监测周期较为适宜。     

Radiosynthesis of [131I]IAZGP via nucleophilic substitution and its biological evaluation as a hypoxia marker — is specific activity a factor influencing hypoxia-mapping ability of a hypoxia marker?

IntroductionThe hypoxia marker IAZGP, 1-(6-deoxy-6-iodo-β-d-galactopyranosyl)-2-nitroimidazole, has been labeled with ¹²³I/¹²⁴I/¹²⁵I/¹³¹I via iodine–radioiodine exchange, which gives the radiotracer in a specific activity of 10–90 MBq/μmol. We synthesized the same radiotracer possessing several hundred to thousand times higher specific activity (high-SA IAZGP) via nucleophilic substitution and compared its biological behavior with that of conventionally produced IAZGP (low-SA IAZGP) to determine if specific activity is a factor influencing cell uptake kinetics, biodistribution and intratumor microregional localization of the radiotracer.MethodsHigh-SA [¹³¹I]IAZGP was prepared by substitution of the tosyl functionality with [¹³¹I]iodide. In vitro uptake of high- and low-SA [¹³¹I]IAZGP by HCT8 and HT29 cells was assessed in normoxic and hypoxic conditions. Biodistribution and intratumor localization of high- and low-SA [¹³¹I]IAZGP were determined by injection into HT29 tumor-bearing mice.ResultsThe nucleophilic substitution reaction proceeded efficiently in acetonitrile at 150°C, giving the final product in an average yield of 42% and an average specific activity of 30 GBq/μmol. In vitro, high-SA [¹³¹I]IAZGP was incorporated into the tumor cells with similar kinetics and oxygen dependence to low-SA [¹³¹I]IAZGP. In HT29 tumor-bearing mice, biodistributions of high- and low-SA [¹³¹I]IAZGP were equivalent. Ex vivo autoradiography revealed heterogeneous intratumor localization of high-SA [¹³¹I]IAZGP corresponding closely to distributions of other exogenous and endogenous hypoxia markers. Comparable microregional distribution patterns were observed with low-SA [¹³¹I]IAZGP.ConclusionsRadiolabeled IAZGP produced via nucleophilic substitution is validated as an exogenous hypoxia marker. Specific activity does not appear to influence the in vivo hypoxia-mapping ability of the radiotracer.     

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.     

Radioiodine treatment of non-toxic multinodular goitre: effects of combination with lithium

Purpose This study aimed to evaluate the effects of radioiodine (¹³¹I), alone or in combination with lithium, on thyroid volume and the prevention of radioiodine-induced thyrotoxicosis. This is the first clinical trial including only patients with multinodular goitre, normal TSH values and negative anti-thyroid auto-antibodies at baseline.Methods Eighty consecutive patients were randomised to receive ¹³¹I plus lithium (group I+L) or ¹³¹I alone (group I). Thyroid ultrasonography and biochemical analyses were performed at baseline and at 1, 3, 6, 12 and 24 months after treatment.Results At 1–4 weeks after treatment, ¹³¹I-induced hyperthyroidism was observed in 58.8% of patients and was prevented by lithium administration. A low incidence of hypothyroidism (19%) was recorded at 24 months, whereas up to 44% of patients developed anti-thyroid antibodies. A significant reduction in thyroid volume was observed after ¹³¹I, with a mean decrease of 47.2% (median 48.2%) at 24 months, without differences between the groups. Moreover, it was shown that the decrease in thyroid volume after ¹³¹I was also due to the significant shrinkage of thyroid nodules.Conclusion This demonstrates that adjunctive lithium is able to reduce radioiodine-induced hyperthyroidism. Therefore, such treatment appears to be safe in older patients and those with underlying cardiovascular disease. In the present large series, ¹³¹I therapy was demonstrated to be highly effective in reducing thyroid and nodular volume even in patients treated with low ¹³¹I doses (2.5 MBq/ml of thyroid tissue), further supporting the view that radioiodine therapy represents a real alternative to surgery.