Comparison of I-123 and I-131 for whole-body imaging after stimulation by recombinant human thyrotropin: a preliminary report

PURPOSE: Many studies have established I-123 whole-body scanning (WBS) as an alternative to I-131 WBS in the evaluation of differentiated thyroid cancer. Similarly, recombinant human thyroid-stimulating hormone (rhTSH) has been shown to be an effective alternative to thyroid hormone withdrawal in the stimulation of TSH levels for WBS. The purpose of the current investigation was to compare the ability of rhTSH-stimulated I-123 WBS to that of rhTSH-stimulated I-131 WBS in the evaluation of thyroid cancer. METHODS: The reports of 101 consecutive I-123 WBS and 101 consecutive I-131 WBS were analyzed. All patients had undergone near-total thyroidectomy, were considered to have a low risk for recurrence, and had rhTSH-stimulated serum thyroglobulin levels measured at the time of imaging. Findings of an examination were considered positive if either residual thyroid tissue was detected on imaging or the serum thyroglobulin level was greater than 2 ng/dl. RESULTS: The results of rhTSH-stimulated I-123 scans and thyroglobulin levels were concordant in 91 (90%) cases, whereas the results of rhTSH-stimulated I-131 scans and thyroglobulin levels were concordant in 85 (84%) cases. I-123 WBS detected 9 foci of disease in 6 patients, whereas I-131 WBS detected 10 foci of disease in 9 patients. CONCLUSION: The results of this preliminary investigation are promising regarding the utility of rhTSH-stimulated I-123 WBS as an alternate approach to rhTSH-stimulated I-131 WBS in patients at low risk for recurrence.     

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.     

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.     

Use of fusion images of I-131 metaiodobenzylguanidine, SPECT, and magnetic resonance studies to identify a malignant pheochromocytoma

Pheochromocytoma is a chromaffin tumor in which 10% are extra-adrenal and 10% are malignant. I-131 metaiodobenzylguanidine (MIBG) scintigraphy has an important role in the identification of these tumors and investigation of metastatic lesions. The authors describe a 36-year-old woman who underwent resection of a malignant left adrenal pheochromocytoma who was thought to have metastases in the liver and para-aortic lymph nodes. Fusion images of I-131 MIBG SPECT and magnetic resonance studies were obtained to properly identify the metastatic lesions. These fusion images helped greatly in subsequent surgery.     

131I标记B细胞淋巴瘤Fab抗体荷瘤裸鼠体内分布和显像

目的 研究131I标记B细胞淋巴瘤Fab抗体(131I-Fab抗体)在荷人B细胞淋巴瘤裸鼠体内的分布和放射免疫显像效果.方法 应用免疫组织化学和流式细胞仪检测经噬菌体抗体库技术获得的B细胞淋巴瘤Fab抗体的免疫活性.以Iodogen法对Fab抗体和CD20单克隆抗体(简称单抗,对照)进行131I标记.标记物经尾静脉注入荷瘤裸鼠后2,4,8和24 h分别进行显像,并测定荷瘤裸鼠体内主要组织的放射性分布.结果 免疫组织化学和流式细胞仪检测结果表明Fab抗体和131I-Fab抗体均能与Raji细胞膜抗原结合,结合率＞87%.显像结果显示131I-Fab抗体在注入荷瘤裸鼠体内8 h即可使肿瘤清晰显影,24 h基本被清除.131I-CD20单抗注入后24 h肿瘤可见放射性浓聚.荷瘤裸鼠体内分布结果表明在2,4和8 h 131I-Fab抗体组肿瘤每克组织百分注射剂量率(%ID/g)分别为(1.37±0.28),(1.84±0.13)和(2.21±0.15)%ID/g,均高于对照组[分别为(0.33±0.06),(0.62±0.08)和(1.46±0.24)%ID/g;F=52.22,278.42和29.00,P均＜0.05],24 h则明显低于对照组[分别为(0.44±0.07)和(3.56±0.66)%ID/g;F=89.7,P＜0.05].2,4,8,24 h 131I-Fab抗体组肿瘤/非肿瘤组织放射性(T/NT)比值分别为(0.22±0.03)～(5.44±0.31),(0.43±0.11)～(21.01±3.97),(1.09±0.07)～(20.28±2.77),(1.12±0.02)～(10.29±1.78);而对照组T/NT比值分别为(0.04±0.01)～(3.10±0.29),(0.11±0.05)～(7.99±1.81),(0.48±0.06)～(23.55±1.69),(2.32±0.34)～(33.23±6.83).结论 131I-Fab抗体具有相对分子质量小、活体定位准确高效、显像早和清除快速等优点, 对临床放射免疫显像诊断B细胞淋巴瘤具有潜在的应用价值.     

Radioimmunodetection of lung cancer with IMACIS-1, I-131 labeled monoclonal antibodies to CEA and CA19-9

IMACIS-1 is a radiopharmaceutical containing a mixture of Iodine-131 labeled monoclonal antibodies to CEA and CA19-9. IMACIS-1 immunoscintigraphy was evaluated for tumor detection in 7 primary lung cancer and 2 metastatic lung cancer patients who received radiotherapy. No adverse side effects due to IMACIS-1 were observed in this study. Positive detection was achieved in 5 of 9 patients (55.6%). It was less, but nearly the same as the detection rate obtained with Gallium-67 citrate (⁶⁷Ga-citrate) in these patients. There was no clear correlation between IMACIS-1 accumulation and the CEA or CA19-9 serum levels. The IMACIS-1 positive detection rate decreased in many of the irradiated lesions. We considered that the decreased number of tumor cells and changes in blood perfusion are some of the factors controlling accumulation in tumors.     

Medullary thyroid carcinoma: localization of a mediastinal metastasis with I-131 MIBG

An I-131 metaiodobenzylguanidine (MIBG) scan was performed in a patient with a familial history of multiple endocrine neoplasia (MEN) type 2 and recurrent medullary thyroid carcinoma (MTC). The scan revealed a mediastinal metastasis from her MTC and there was also an imaging pattern of bilateral adreno-medullary hyperplasia. Although the literature indicates that I-131-MIBG scanning is not sufficiently sensitive for the detection of MTC, this procedure has proven to be of value in the management of chosen patients with MEN-associated MTC.     

Recombinant human thyroid-stimulating hormone-aided scintigraphy: comparison of imaging at multiple times after I-131 administration

PURPOSE: Recombinant human thyroid-stimulating hormone (rhTSH) may be used in lieu of thyroid hormone withdrawal for the evaluation of thyroid cancer. Scintigraphy using the existing rhTSH protocol is performed 48 hours after I-131 administration. The authors investigated the feasibility of whole-body imaging at 72 hours and evaluated thyroid tissue uptake at 48 to 144 hours. METHODS: Thirty-two patients who previously had thyroidectomy for thyroid cancer were examined. Whole-body imaging was performed routinely at 48 and 72 hours after I-131 administration. Thyroid tissue was visualized in 12 patients, and large foci were imaged for as long as 144 hours. Activity ratios for thyroid tissue to background were determined for 10 patients. RESULTS: Whole-body images at 48 and 72 hours were comparable, generally with lower background activity at 72 hours, and thyroid tissue was well visualized at all times after 48 hours. Thyroid tissue-to-background activity ratios at 72 to 144 hours were equal to or greater than those at 48 hours in 9 of 10 patients. CONCLUSIONS: Recombinant human TSH-aided whole-body scintigraphy is possible 72 hours after I-131 administration, adding flexibility and convenience to the existing protocol and permitting confirmation of findings at 48 hours. Tracer uptake in thyroid tissue persists at later times. Therefore, rapid clearance of background activity appears to be the primary cause of the previously reported decrease in radioiodine retention in euthyroid persons receiving rhTSH.     

Iodine-131 metaiodobenzylguanidine scintigraphy for the location of neuroblastoma: preliminary experience in ten cases

Ten patients with histologically proven neuroblastoma were studied by [131I]MIBG scintigraphy. Tumor uptake of the radiopharmaceutical showed a spectrum varying from no uptake in one case, to slight uptake in two, moderate uptake in two and intense uptake in five cases. Iodine-131 MIBG scintigraphy was more effective in demonstrating the extent of neuroblastoma spread than were conventional bone scan and CT in one patient, equal to these modalities in four cases, almost equal in two cases and significantly inferior in three cases. These preliminary results suggest that [131I]MIBG scintigraphy is useful in detecting the presence and delineating the distribution of neuroblastoma and may, in certain cases, have therapeutic potential.     

Immunoreactivity and biodistribution of indium-111-labeled monoclonal antibody to a human high molecular weight-melanoma associated antigen

The anti-human, high molecular weight-melanoma associated antigen (HMW-MAA) MoAb 225.28S was chelated with 111In and then tested for its in vitro reactivity with cultured human melanoma cells and for its biodistribution in human melanoma bearing nude mice. In vitro studies showed that the radiolabeled antibody reacted specifically with cultured melanoma cells. However, binding of DTPA to the monoclonal antibody reduced its titer with cultured melanoma cells from 1:1024 to 1:512. Further labeling of the DTPA-antibody conjugate with 111In caused an additional reduction of its titer to 1:128. Injection of the radiolabeled monoclonal antibody into nude mice resulted in the accumulation of significantly (p less than 0.001) higher radioactivity in melanoma tissue than in nude mice injected with either [111In] chloride or 111In-labeled antibody to human acid phosphatase. The specificity of the distribution of the radiolabeled antibody in nude mice also was indicated by its poor localization in lesions other than melanoma (e.g., human prostate carcinoma and chronic abscess). The localization of antibody in liver and kidney was also high, although lower than that achieved in tumor. These results indicate that 111In-labeled monoclonal antibodies to human tumor associated antigens may be useful for localizing malignant lesions. However, there is a need to improve labeling and/or purification of antibody in order to decrease renal and hepatic activity.     

Tissue distribution of 14C-, 125I-, and 131I-diphenylhydantoin in the toadfish, rat, and human with insulinomas.

Carbon-14-diphenylhydantoin (DPH) concentrated maximally in pancreatic islet cells of the toadfish 10 min after its intravenous administration. The islet cell-to-acinar-tissue ratio at this time was 6:1. The islet cell-to-liver ratio was 20:1. Iodine-125-paroiodo-DPH at 10 min in the toadfish showed an islet cell-to-acinar-tissue ratio of 1.7:1 and an islet cell-to-liver ratio of 2.3:1. When 14C-DPH was given to four patients 10-17 min before removal of norma pancreatic tissue and of an insulinoma in three of the patients, the concentration of radioactivity in the insulinoma was never greater than in the pancreas and concentrations in insulinoma and pancreas were always less than in liver in the same individual. Forty-five to 90 min after administration of 131I-DPH, the liver and pancreas were delineated in three patients but the insulinoma was not imaged. Five days after administration of 131I-DPH, the concentration of 131I radioactivity in excised tissue was greater in the insulinomas than in the pancreas of two patient but not sufficient to produce positive images of the insulinoma in the pancreas.     

Functioning liver metastases on an I-131 whole-body scan: a case of malignant struma ovarii

A 46-year-old women was examined for severe constipation. Pelvic examination revealed a large pelvic mass extending to the level of the umbilicus. Computed tomography showed a large multicystic, septated mass in the pelvis and a small amount of fluid in the cul de sac. In addition, multiple ill-defined, mixed-attenuation hepatic lesions were identified. A malignant ovarian neoplasm with liver metastases was considered, so the pelvic mass was resected. Interestingly, histopathologic analysis revealed malignant struma ovarii of the follicular type. Biopsy of the liver lesions confirmed metastatic disease with similar histopathologic findings. All thyroid laboratory values were in the normal range. The patient then had a total thyroidectomy to optimize thyroid ablation therapy with I-131. This revealed a small follicular adenoma but no evidence of cancer. An I-131 whole-body scan was performed and showed uptake in multiple functioning liver metastases.     

Late presentation of metastatic pheochromocytoma: a problem case solved by I-131 MIBG scintigraphy.

A patient presented with recurrent pheochromocytoma 10 years following the apparently successful surgical cure of a right adrenal pheochromocytoma. Conventional medical imaging techniques, (chest radiograph, abdominal ultrasound, and abdominal CT) suggested local recurrence for which surgery was planned. I-131 MIBG scintigraphy revealed disseminated metastatic disease that rendered attempts at surgical cure futile. The patient was treated with three therapeutic doses of I-131 MIBG with good symptomatic palliation and improvement of some biochemical parameters.     

Simultaneous treatment of toxic diffuse goiter with I-131 and antithyroid drugs: a prospective study.

We report a prospective study to avaluate the effect of antithyroid drugs containing the sulfhydryl radical on the outcome of I-131 (RAI) therapy. Twenty-four male patients withe toxic diffuse goiter were assigned randomly into tow treatment groups: Group A received RAI treatment while on antighyroid drugs after attainment of euthyroidism; Group B received no antithyroid drugs before, or when, RAI was given. Patients in each group received a dose of RAI calculated to deliver approximately 5000 rads per treatment. The incidence of hypothyroidism at 12 mo was 8% for Group A and 36% for Group B (p less than 0.01). During 12-102 mo of follow-up, no additional hypothyroidism was encountered in Group A. Two patients with significantly elevated TSH levels were found in Group B, one at 20 mo and one at 75 mo after RAI. The mean time to cure was 15.2 +/- 9.1 mo for Group A and 19.7 +/- 8.2 mo. for Group B (NS: p more than 0.45). The improved therapeutic outcome of patients in Group A suggests that further validation of the method in a larger patient population, including females, is warranted.     

Counting efficiency of a double-well single-plastic scintillation counter to commercially available radionuclides (Tl-201, Tc-99m,I-123, Ga-67, In-111 and I-131)

A new type of well-scintillation counter with a double-well and single-plastic scintillator (DW-counter) was developed to simplify time consuming and cumbersome dilution procedures inherent to in-vivo sample measurement. It has the potential to measure many radionuclides which emit a gamma ray or positron. We tested the counting efficiency (CE) of the DW-counter (DCM-200, Aloka Co., Tokyo, Japan) with respect to 6 radionuclides. MATERIALS AND METHODS: The outline of DW-counter is altered to a single unit as compared to the prototype, while its basic mechanical constitution was not changed. Six commercially available radionuclides (Tl-201, Tc-99m, I-123, Ga-67, In-111, I-131) were used in this study. For each radionuclide, we prepared two standard solutions containing high (>100 MBq/ml) and relatively low radioactivity (10-20 MBq/ml). The radioactivity (Bq) of the radionuclide in each sample at time = 0 was measured with a dose calibrator. Afterwards, it was determined from a decay-time with correction by the physical half-life of each radionuclide. Count rate (cps) of each standard sample was measured in each well ten times per sample. The counting efficiency (CE) of the counter for each radionuclide was determined by measured count rate (cps)/standard radioactivity (Bq) x 100 (%). The conversion constant (CC) which predicts standard radioactivity (Bq) from measured count rate (cps) was obtained as a reciprocal value of the CE. RESULTS: The CE (mean +/- SD) in well-A to Tl-201, Tc-99m, I-123, Ga-67, In-111 and I-131 was 5.90 +/- 0.285%, 8.56 +/- 0.0981%, 8.33 +/- 0.344%, 7.77 +/- 0.15%, 16.4 +/- 0.495% and 10.2 +/- 0.139%, respectively. They were significantly different. The coefficient of variation of the measured count rates was less than 1% in radioactive range higher than 10(3) Bq in well-A and 106 Bq in well-B. The difference in the CE between well-A and -B ranged from 7.614 x 10(2) (I-131) to 9.395 x 10(2) (Tl). The CC ranged from 6.14 (In) to 17.15 (Tl) in well-A and from 5.05057 x 10(3) (In) to 15.83773 x 10(3) (Tl) in well-B. The CE was not significantly affected by a sample volume from 1 to 4 ml in well-A, but showed a slight difference in well-B, which seemed due to a collimation. CONCLUSION: The measurement error of the DW-counter was less than 1% and the measured count rate (cps) was exactly converted to the standard radioactivity (Bq) by determined CC. The counter is considered useful in the easy evaluation of in-vivo tracer kinetics by avoiding time consuming and cumbersome dilution techniques.