[en] The purpose of this article is to study the preparation and biodistribution of ⁹⁹Tc^m-DTPA-folate in nude mice with a human tumor cell implant. DTPA-folate was synthesized by conjugating folic acid to diethylenetriaminepentaacetic (DTPA), then radiolabeled with ⁹⁹Tc^m. The radio-chemical purity and stability were evaluated. The biodistribution of ⁹⁹Tc^m-DTPA-folate in nude mice with a human tumor cell implant was studied. The result showed that the radiolabelling yield of ⁹⁹Tc^m-DTPA-folate was as high as 98%. After 4 h at room temperature, the radiochemical purity of ⁹⁹Tc^m-DTPA-folate was still over 90%. ⁹⁹Tc^m-DTPA-folate conjugation showed marked tumor-specific deposition in vivo. The tumor-to-muscle ratio at 8 h post intraperitoneal injection was 7.5. ⁹⁹Tc^m-DTPA-folate appears to be a potential radiopharmaceutical for targeting tumor-associated folate receptor. (authors)

[en] Background: Dimercaptosuccinic acid (DMSA) forms a complex with pentavalent rhenium-188, known as ¹⁸⁸Re(V)-DMSA. This radiopharmaceutical has been shown to localize in a number of tumour types, most notably medullary thyroid carcinoma (MTC) and in bone metastases and other bone lesions. We have previously shown that ¹⁸⁶Re(V)-DMSA could be strongly uptaked by the lesion of MTC similar to that observed in the images of ^99mTc(V)-DMSA and had potential therapeutic value in these patients. Compared with 186Re, the 188Re has the advantages of its ready availability from a generator. Thus the aim of this study was to establish a method of reliable preparation of ¹⁸⁸Re(V)-DMSA and to evaluate its potential as a targeted radiotherapy agent to patient with MTC. Material and Method: The complex was prepared by reducing ¹⁸⁸Re in the presence of DMSA with stannous chloride at the condition of pH 1.5. The reaction was taken to completion by heating the complex in a boiling water bath for 30 minutes. Excess stannous chloride was required and the presence of hydrochloric acid didn't reduce the yield of labelling. A large dose of ascorbic acid was used to minimize autoradiolysis. The products were analysed with high-performance liquid chromatograms (HPLC) and thin layer chromatography (TLC) using a mobile phase consisting of n-butanol: acetic: water = 3:2:3 by volume. The TLC chromatograms were also visualized and quantified by gamma camera imaging. With the agreement, a patient who had a liver metastatic lesion from MTC but no symptoms (patient I) and another who had bone metastatic MTC and severe symptoms (patient II) were recruited . Both volunteers confirmed by a prior ^99mTc(V)-DMSA scan received a dose of 74 MBq of ¹⁸⁸Re(V)-DMSA and imaged at 3 hours with a GE Millennium VG ECT/CT. Results: The preparation had a good results with a labeling rate more than 95% and a stability in vitro more than 24 hours. The complex was a clear yellow solution which can be adjusted to pH=7, ready for injection by adding a small volume of NaHCO2. Under these condition perrhenate has Rf=0.9, ¹⁸⁸Re(V)-DMSA have R_f=0.6, and the 'hydrophilic impurities' have R_f=0 at the analysis of TLC. All isomers of ¹⁸⁸Re(V)-DMSA, as reported as anti, syn-endo and syn-exo can be identified at the profiles of HPLC and have a distribution of 41:45:10 approximately. The lesion of the patient II showed a high uptake and the symptoms of bone pain and diarrhoea were obviously improved. Conclusion: The preparation and quality control of ¹⁸⁸Re(V)-DMSA are reliable. Patient with MTC could be treated with a lower dosage of ¹⁸⁸Re(V)-DMSA. (authors)

[en] The purpose is to measure the pharmacokinetic parameters of r-Sak in rats as well as the biodistribution and the excretion of r-Sak in rats. ¹²⁵I-r-Sak was applied for the purpose. The results showed that the pharmacokinetics of ¹²⁵I-r-Sak following intravenous injection with two doses (70 μg/kg and 840 μg/kg) in rats was in correspondence with 2-compartment-model. The T_1/2(α) were 5.47 +- 2.13 and 8.45 +- 4.50 min and T_1/2(β) were 96.15 +- 22.29 and 58.78 +- 32.79 min for the two dose groups. AUC were 0.895 +- 0.455 and 38.36 +- 5.181 μg·min·mL^-1. There were no marked differences of T_1/2(α) and T_1/2(β) between the two dose groups (P > 0.05), but the AUC increased markedly with the dose increasing (P < 0.05). The biodistribution of ¹²⁵I-r-Sak was wide in rats. Radioactivity wa highest in kidney, followed in order by plasma, liver, lung, spleen, heart and brain. Excretion experiment showed that the sum of the accumulative excretion of the ratio-material plus the enrichment of the ratio-material in thyroid was approximately 80% in 96 h

[en] Objective: To study the preparation of ¹⁸⁸Re (V)-dimercaptosuccinic acid (DMSA) and to evaluate the quality of ¹⁸⁸Re (V)-DMSA kit. Methods: The complex was prepared by reducing ¹⁸⁸Re in the presence of DMSA with stannous chloride in acid medium at pH=1.5. Excess stannous chloride was required and the presence of hydrochloric acid didn' t reduce the yield from 100%. A large dose of ascorbic acid was used to minimize auto-radiolysis. The labeled rate and stability of the kit and the labeled compound stability in vitro were analyzed by high-performance liquid chromatograms (HPLC). Finally the biodistribution of ¹⁸⁸Re (V)-DMSA and ⁹⁹Tc^m (V)-DMSA in mice was compared. Results: The labeled rate was 100% and yield was steady in vitro after the compound was kept in room temperature as long as 24 h (>97%). Keeping the kit at -20 degree C and 4 degree C for 3 months the labeled rate was still >95%. Compared with ⁹⁹Tc^m (V)-DMSA, the biodistribution of ¹⁸⁸Re (V)-DMSA was similar. Both of them accumulated highest in bone and excreted from kidney. Conclusion: The quality of ¹⁸⁸Re(V)-DMSA kit is satisfactory. (authors)

[en] The aim of this study was to evaluate magnetic resonance (MR) signal variations of transplanted human gastric adenocarcinoma cells (SGC-7901) in athymic mice after the administration of folate-receptor-targeted MR contrast agent gadolinium-diethylenetriaminepentaacetic acid-folate (Gd-DTPA-Folate). A paramagnetic contrast agent, Gd-DTPA-Folate was synthesized by conjugating folic acid to diethylenetriaminepentaacetic acid (DTPA), then reacting with GdCl₃. The athymic mice with a human tumor cell implant were divided into either the study group or the control group. The 0.4 mL Gd-DTPA-Folate was injected into the abdominal cavity of the mice in the study group, while the control group received Gd-DTPA with equivalent Gd³⁺. The signal features of the tumor precontrast and postcontrast were observed on T₁W_IMR scanning was carried out at 0, 1, 2, 3, 4, 6, 12 and 24 hour post-injection. The tumor signal intensity at 0, 1, 2 and 3h postcontrast in the study group was significantly higher than that of precontrast. The biggest difference appeared at one hour and the difference was retained about 3 hours. In the control group, there was no statistical difference between the tumor signal intensity at any time point post injection and that of prior to injection except 0 and 1h postcontrast. Gd-DTPA-Folate can produce a sustained increase in the signal intensity of the transplanted human gastric adenocarcinoma cells in athymic mice, thus, it may become a promising folate-receptor-specific magnetic resonance contrast media. (authors)