Radioiodinated paroxetine, a novel potential radiopharmaceutical for lung perfusion scan

Paroxetine (a selective serotonin reuptake inhibitor) was successfully labeled with ¹²⁵I via direct electrophilic substitution reaction at ambient temperature. The reaction parameters studied were paroxetine amount, CAT amount, pH of the reaction mixture, reaction temperature, reaction time and in vitro stability of ¹²⁵I-paroxetine. ¹²⁵I-paroxetine was obtained with a maximum labeling yield of 94 ± 0.23% and in vitro stability up to 24 h. Biodistribution studies showed that maximum in vivo uptake of ¹²⁵I-paroxetine in lungs was 27.89 ± 1.03% injected activity/g tissue at 15 min post-injection and retention in lungs remained high up to 1 h, whereas the clearance from mice appeared to proceed mainly via the hepatobiliary pathway. ¹²⁵I-paroxetine is not a blood product and so it is more safe than the currently available ^99mTc-macroaggregated albumin (^99mTc-MAA), and its lung uptake is higher than that of the recently discovered ^99mTc(CO)₅I and ^99mTc-DHPM. As a conclusion, radioiodinated paroxetine could be used as a novel radiopharmaceutical for lung perfusion scan safer than the currently available ^99mTc-MAA and more potential than the recently discovered ^99mTc(CO)₅I and ^99mTc-DHPM.     

Preparation of radioiodinated ritodrine as a potential agent for lung imaging

Ritodrine (a beta-2 adrenergic receptor agonist) was successfully labeled with ¹²⁵I via direct electrophilic substitution reaction at ambient temperature. ¹²⁵I-ritodrine was obtained with a maximum labeling yield of 97 ± 0.163 % and in vitro stability up to 24 h. Biodistribution studies showed that maximum in vivo uptake of ¹²⁵I-ritodrine in lungs was 20.4 ± 0.22 % injected activity/g tissue at 1 h post-injection, whereas the clearance from mice appeared to proceed mainly via the renal pathway. ¹²⁵I-ritodrine is not a blood product and so it is more safe than the currently available ^99mTc-MAA, and its lung uptake is higher than that of the recently discovered ^99mTc(CO)₅I and ^99mTc-DHPM. As a conclusion, radioiodinated ritodrine could be used as a novel radiopharmaceutical for lung perfusion scan safer than the currently available ^99mTc-MAA and more potential than the recently discovered ^99mTc(CO)₅I and ^99mTc-DHPM.     

Chemical and Physical Characterisation of Macroaggregated Human Serum Albumin: Strength and Specificity of Bonds with 99mTc and 68Ga

Background: Macroaggregated human serum albumin (MAA) properties are widely used in nuclear medicine, labelled with ^99mTc. The aim of this study is to improve the knowledge about the morphology, size, dimension and physical–chemical characteristics of MAA and their bond with ^99mTc and ⁶⁸Ga. Methods: Commercial kits of MAA (Pulmocis^®) were used. Characterisation through experiments based on SEM, DLS and Stokes’ Law were carried out. In vitro experiments for Langmuir isotherms and pH studies on radiolabelling were performed and the stability of the radiometal complex was verified through competition reactions. Results: The study settles the MAA dimension within the range 43–51 μm. The Langmuir isotherm reveals for [^99mTc]MAA: Bmax (46.32), h (2.36); for [⁶⁸Ga]MAA: Bmax (44.54), h (0.893). Dual labelling reveals that MAA does not discriminate different radioisotopes. Experiments on pH placed the optimal pH for labelling with ^99mTc at 6. Conclusion: Radiolabelling of MAA is possible with high efficiency. The nondiscriminatory MAA bonds make this drug suitable for radiolabelling with different radioisotopes or for dual labelling. This finding illustrates the need to continue investigating MAA chemical and physical characteristics to allow for secure labelling with different isotopes.     

Technetium-99m Radiopharmaceuticals for Ideal Myocardial Perfusion Imaging: Lost and Found Opportunities

The favorable nuclear properties in combination with the rich coordination chemistry make technetium-99m the radioisotope of choice for the development of myocardial perfusion tracers. In the early 1980s, [^99mTc]Tc-Sestamibi, [^99mTc]Tc-Tetrofosmin, and [^99mTc]Tc-Teboroxime were approved as commercial radiopharmaceuticals for myocardial perfusion imaging in nuclear cardiology. Despite its peculiar properties, the clinical use of [^99mTc]Tc-Teboroxime was quickly abandoned due to its rapid myocardial washout. Despite their widespread clinical applications, both [^99mTc]Tc-Sestamibi and [^99mTc]Tc-Tetrofosmin do not meet the requirements of an ideal perfusion imaging agent due to their relatively low first-pass extraction fraction and high liver absorption. An ideal radiotracer for myocardial perfusion imaging should have a high myocardial uptake; a high and stable target-to-background ratio with low uptake in the lungs, liver, stomach during the image acquisition period; a high first-pass myocardial extraction fraction and very rapid blood clearance; and a linear relationship between radiotracer myocardial uptake and coronary blood flow. Although it is difficult to reconcile all these properties in a single tracer, scientific research in the field has always channeled its efforts in the development of molecules that are able to meet the characteristics of ideality as much as possible. This short review summarizes the developments in ^99mTc myocardial perfusion tracers, which are able to fulfill hitherto unmet medical needs and serve a large population of patients with heart disease, and underlines their strengths and weaknesses, the lost and found opportunities thanks to the developments of the new ultrafast SPECT technologies.     

Synthesis and biological evaluation of <Superscript>99m</Superscript>Tc-DHPM complex: a potential new radiopharmaceutical for lung imaging studies

In the recent years interests on dihydropyrimidinone and their analogues have increased potentially due to their wide range of pharmacological/biological activities. Synthesis, radiolabeling with technetium-99 m (^99mTc) and biological evaluation of 5-etoxycarbonyl-4-phenyl-6-methyl-3,4-dihydro-(1H)-pyrimidine-2-one (DHPM) were studied in this present work. After synthesis complexation of DHPM with ^99mTc was carried out using stannous chloride as the reducing agent. The complex (^99mTc-DHPM) was characterized by thin layer chromatography, radio-HPLC technique and determination of partition co-efficient. Radiochemical stability and particle size distribution of the complex were also measured. Biodistribution/scintigraphy studies were performed in rats and rabbits to evaluate the pharmacological characteristics of this complex. The radiochemical purity of the complex was over 95% as studied by thin layer chromatography and radio-HPLC. It was stable over 24 h at room temperature. Its partition coefficient indicated that it was a lipophilic complex. According to the European Pharmacopeia, >80% of ^99mTc labeled radiopharmaceutical (^99mTc-MAA) in the size range 10–50 μm, must be accumulated in the lungs 15 min after intravenous administration. In this study >85% of the ^99mTc-DHPM complex in the average size of 40 μm. Biodistribution studies of ^99mTc-DHPM in rat revealed that the complex accumulated in the lung with high uptake and good retention after intravenous administration. Scintigraphic studies in rabbit also revealed that most of the administered radiolabeled complex was accumulated in the lungs and after 1 h slowly excreted through the renal system. The lung uptake (ID%/g) was 10.12, 9.67, 8.60 and 5.01 and the lung/liver ratio was 7.49, 2.88, 2.62 and 1.87 at 2, 15, 30 and 60 min post-injection, respectively. These results suggested that ^99mTc-DHPM could be suitable as a potential lung perfusion imaging agent. Further studies with ^99mTc-DHPM and its derivatives are warranted to develop new ^99mTc-labeled imaging agents for clinical applications.     

Preparation and Evaluation of Novel Folate Isonitrile 99mTc Complexes as Potential Tumor Imaging Agents to Target Folate Receptors

In order to seek novel technetium-99m folate receptor-targeting agents, two folate derivatives (CN5FA and CNPFA) were synthesized and radiolabeled to obtain [^99mTc]Tc-CN5FA and [^99mTc]Tc-CNPFA complexes, which exhibited high radiochemical purity (>95%) without purification, hydrophilicity, and good stability in vitro. The KB cell competitive binding experiments indicated that [^99mTc]Tc-CN5FA and [^99mTc]Tc-CNPFA had specificity to folate receptor. Biodistribution studies in KB tumor-bearing mice illustrated that [^99mTc]Tc-CN5FA and [^99mTc]Tc-CNPFA had specific tumor uptake. Compared with [^99mTc]Tc-CN5FA, the tumor/muscle ratios of [^99mTc]Tc-CNPFA were higher, resulting in a better SPECT/CT imaging background. According to the results, the two ^99mTc complexes have potential as tumor imaging agents to target folate receptors.     

Imaging Hydrogen Sulfide in Hypoxic Tissue with [99mTc]Tc-Gluconate

Hydrogen sulfide (H₂S) is the third gasotransmitter and is generated endogenously in hypoxic or inflammatory tissues and various cancers. We have recently demonstrated that endogenous H₂S can be imaged with [^99mTc]Tc-gluconate. In the present study, we detected H₂S generated in hypoxic tissue, both in vitro and in vivo, using [^99mTc]Tc-gluconate. In vitro uptake of [^99mTc]Tc-gluconate was measured under hypoxic and normoxic conditions, using the colon carcinoma cell line CT26, and was higher in hypoxic cells than that in normoxic cells. An acute hindlimb ischemia-reperfusion model was established in BALB/c mice by exposing the animals to 3 h of ischemia and 3 h of reperfusion prior to in vivo imaging. [^99mTc]Tc-gluconate (12.5 MBq) was intravenously injected through the tail vein, and uptake in the lower limb was analyzed by single-photon emission computed tomography/computed tomography (SPECT/CT). SPECT/CT images showed five times higher uptake in the ischemic limb than that in the normal limb. The standard uptake value (SUVmean) of the ischemic limb was 0.39 ± 0.03, while that of the normal limb was 0.07 ± 0.01. [^99mTc]Tc-gluconate is a novel imaging agent that can be used both in vitro and in vivo for the detection of endogenous H₂S generated in hypoxic tissue.     

Preparation and Biological Evaluation of [99mTc]Tc-CNGU as a PSMA-Targeted Radiotracer for the Imaging of Prostate Cancer

Prostate-specific membrane antigen (PSMA) is a well-established biological target that is overexpressed on the surface of prostate cancer lesions. Radionuclide-labeled small-molecule PSMA inhibitors have been shown to be promising PSMA-specific agents for the diagnosis and therapy of prostate cancer. In this study, a glutamate-urea-based PSMA-targeted ligand containing an isonitrile (CNGU) was synthesized and labeled with ^99mTc to prepare [^99mTc]Tc-CNGU with a high radiochemical purity (RCP). The CNGU ligand showed a high affinity toward PSMA (K_i value is 8.79 nM) in LNCaP cells. The [^99mTc]Tc-CNGU exhibited a good stability in vitro and hydrophilicity (log P = −1.97 ± 0.03). In biodistribution studies, BALB/c nude mice bearing LNCaP xenografts showed that the complex had a high tumor uptake with 4.86 ± 1.19% ID/g, which decreased to 1.74 ± 0.90% ID/g after a pre-injection of the selective PSMA inhibitor ZJ-43, suggesting that it was a PSMA-specific agent. Micro-SPECT imaging demonstrated that the [^99mTc]Tc-CNGU had a tumor uptake and that the uptake was reduced in the image after blocking with ZJ-43, further confirming its PSMA specificity. All of the results in this work indicated that [^99mTc]Tc-CNGU is a promising PSMA-specific tracer for the imaging of prostate cancer.     

Effective synthesis of Tc tricarbonyl complexes by microwave heating

Technetium-99m (^99mTc) is one of the most frequently used nuclides for single-photon emission computed tomography (SPECT) imaging because of its radiochemical characteristics, such as gamma emission of suitable energy (141 keV) and adequate half-life (6.01 h). Although triaquatricarbonyl ^99mTc cation ([^99mTc(CO)₃(H₂O)₃]⁺) has several advantages as a ^99mTc-labeling agent, e.g., compact chelate size, chelate stability, and simplicity of preparation, its synthetic protocols should be improved. Because microwave heating is a convenient method for synthetic reactions, we studied the effect of microwave irradiation on the synthesis of ^99mTc tricarbonyl complexes. We found several factors beneficial for the preparation of nuclear medicines. In particular, microwave heating promoted one-pot syntheses of ^99mTc tricarbonyl chelates in a short time. In addition, the ^99mTc tricarbonyl complex could be obtained using low concentrations of ligands.     

Novel 99mTc labeled σ receptor ligand as a potential tumor imaging agent

A novel ^99mTc labeled complex, [N-[2-((2-oxo-2-(4-(3-phenylpropyl)piperazin-1-yl)ethyl) (2-mercaptoethyl)amino)acetyl]-2-aminoethanethiolato]Technetium(V) oxide (PPPE-MAMA’-^99mTcO) ([ ^99m Tc]-2) has been designed and prepared based on the integrated approach. The corresponding rhenium complex (PPPE-MAMA’-ReO)(Re-2) has been prepared and characterized. In vitro competition binding assays show moderate affinity of Re-2 towards σ₁ and σ₂ receptors with K _i values of 8.67 ± 0.07 and 5.71 ± 1.88 μmol, respectively. Planar images obtained at 0.5 h, 4 h, 20 h after i.v. injection indicate the accumulation of [ ^99m Tc]-2 in MCF-7 human breast tumor bearing mice at 20 h. Furthermore, the accumulation of [ ^99m Tc]-2 has been inhibited at 20 h after co-injection of [ ^99m Tc]-2 plus haloperidol (1 mg/kg). Biodistribution studies of [ ^99m Tc]-2 display an in vivo tumor uptake of 0.14% ± 0.01% ID/g at 24 h post i.v. injection with a tumor/muscle ratio of 6.02 ± 0.87. The above results suggest that [ ^99m Tc]-2, derived from a previously published lead compound, retains certain tumor uptake and affinity for σ receptors. [ ^99m Tc]-2 may be used as a basis for further structural modifications to develop tumor imaging agents with high affinity for σ receptors.     

Radiosynthesis and evaluation of novel [99mTc(I)]+ and [99mTc(I)(CO)3]+ complexes with a 4-nitroimidazole isocyanide for imaging tumor hypoxia

[^99mTc(I)]⁺ and [^99mTc(I)(CO)₃]⁺ complexes with isocyanide exhibit high stability, which makes them suitable platforms to develop novel ^99mTc radiopharmaceuticals. To develop novel ^99mTc radiotracers for imaging hypoxia, in this study, a novel L ligand (4-nitroimidazole isocyanide derivative) was synthesized and labelled using [^99mTc(I)]⁺ core and [^99mTc(I)(CO)₃]⁺ core to produce [^99mTc(L)₆]⁺ and [^99mTc(CO)₃(L)₃]⁺ with high yields. To verify the structure of the ^99mTc complexes, corresponding rhenium analogues were synthesized and characterized. Both of the ^99mTc complexes were stable and hydrophilic. in vitro cellular uptake results showed they could exhibit good hypoxic selectivity. The evaluation of biodistribution in mice bearing S180 tumors indicated both of them could accumulate in tumor. Between them, [^99mTc(L)₆]⁺ exhibited higher tumor uptake and tumor/non-target ratio than [^99mTc(CO)₃(L)₃]⁺. Further, single photon emission computed tomography (SPECT) imaging studies of [^99mTc(L)₆]⁺ indicated an obvious accumulation in tumor and the value of the region-of-interest (ROI) ratio of the uptake for the tumor site to the corresponding non-tumor region was 5.64 ± 0.52. The above results suggested [^99mTc(L)₆]⁺ would be a potential tracer for imaging tumor hypoxia.     

Novel tetradentate diamine dioxime ligands: synthesis,characterization and in vivo behavior of their 99mTc‐complexes

Two novel diamine dioxime ligands, 4,7‐diaza‐3,8‐diethyldecane‐2,9‐dione bis oxime (3) and 4,9‐diaza‐3,10‐diethyldodecane‐2,11‐dione bis oxime (5), were synthesized in order to develop new brain perfusion imaging agents, based on ^99mTc(V)‐complexes. The synthesis involved condensation of 2‐hydroxyimino‐3‐pentanone with appropriate diamine in protic solvent which afforded the bis imine adducts. Subsequent reduction of imine functional groups yielded a diastereoisomeric mixture of 3 and 5. UV–visible, IR, ¹H NMR, ¹³C NMR and elemental analysis were used to characterize the structures of the synthesized compounds. ^99mTc‐complexes of both diamine dioximes were prepared and radiolabeling conditions optimized to give the maximum yield. Physicochemical parameters of the labeled complexes as well as and their biodistribution in rats were investigated. Both compounds (3 and 5) formed ^99mTc‐complexes with a net charge of zero, determined by electrophoresis. The resultant lipophilic ^99mTc‐complexes of 3 and 5 were readily formed at pH ~9.0 within 10 min at room temperature with yields of 90% and 95%, respectively. The ^99mTc‐3 complex was found to be stable within 1 h, while ^99mTc‐5 was stable for a few hours. A significant brain uptake of ^99mTc‐3 (2.1% injected dose) and ^99mTc‐5 (1.8% injected dose) complexes, 2 min after injection, is in accordance with their lipophilicity. The present study suggests that both ligands are promising candidates as new ^99mTc‐based brain‐imaging agents. Copyright © 2012 John Wiley & Sons, Ltd.     

Development of electrochemical labelling procedures using MEK extracted99mTc

Electrolytic labelling procedures have been reported for various^99mTc radiopharmaceuticals which differ widely in the choice of the electrodes, working pH, applied voltage and the quantity of current passed. The authors have studied the electrolytic labelling of^99mTc EHDP, gluconate and glucoheptonate with MEK extracted^99mTc using tin electrodes under different experimental conditions. The results have, shown that these compounds can be efficiently labelled with^99mTc in a single step procedure avoiding multiple pH adjustments. Labelling of human serum albumin microspheres suitable for lung imaging with^99mTc by the electrolytic method is also reported.     

Synthesis of techentium-99m labeled clinafloxacin (99mTc�CCNN) complex and biological evaluation as a potential Staphylococcus aureus infection imaging agent

In the present study synthesis of the ^99mTc?CCNN complex and its efficacy as a prospective Staphylococcus aureus (S. aureus) infection imaging agent was assessed. The ^99mTc?CCNN complex was characterized in terms of stability in saline, serum, in vitro binding with S. aureus and in vivo percent absorption in male Wister rats (MWR) infected with live and heat killed S. aureus. Radiochemically the ^99mTc?CCNN complex showed stable behavior in saline and serum at different intervals. At 30 min after reconstitution the complex showed maximum radiochemical purity (RCP) yield of 97.55 ± 0.22%. The RCP yield decreased to 90.50 ± 0.18% within 240 min. In serum, 18.15% unwanted side product was appeared within 16 h of the incubation. In vitro saturated binding with S. aureus was observed at different intervals with a 62.00% maximum at 90 min. Normal percent in vivo uptake was observed in MWR artificially infected with live S. aureus with a five times higher in the infected muscle as compared to the inflamed and normal muscles. No difference in the percent uptake of the complex in MWR infected with heat killed S. aureus in the infected, inflamed and normal muscles were observed. Based on the promising in vitro and in vivo radiochemical and biological characteristics, we recommend the ^99mTc?CCNN complex for in vivo localization of the S. aureus infectious foci.     

In vitro incorporation studies of 99mTc–alendronate sodium at different bone cell lines

Bisphosphonates can be labeled with Technetium-99m (^99mTc) and are used for bone imaging because of their good localization in the skeleton and rapid clearance from soft tissues. Over the last decades bone scintigraphy has been used extensively in the evaluation of oncological patients to provide information about the sites of bone lesions, their prognosis and the effectiveness of therapy by showing the sequential changes in tracer uptake. Since the lesion visualization and lesion/bone ratio are important utilities for a bone scanning radiopharmaceutic; in this study incorporation of ^99mTc labeled alendronate sodium (^99mTc–ALD) was evaluated in U₂OS (human bone osteosarcoma) and NCI-H209 (human bone carcinoma) cell lines. ALD was directly labeled by ^99mTc, radiochemical purity and stability of the complex were analyzed by radioactive thin layer chromatography and radioactive high performance liquid chromatography studies. For cell incorporation study, NCI-H209 and U₂OS cell lines were used with standard cell culture methods. The six well plates were used for all experiments and the integrity of each cell monolayer was checked by measuring its transepithelial electrical resistance (TEER) with an epithelial voltammeter. Results confirmed that ALD was successfully radiolabeled with ^99mTc. ^99mTc–ALD incorporated with NCI-H209 and U₂OS cells. The uptake percentages of ^99mTc–ALD in NCI-H209 and U₂OS cell lines were found significantly different. Since ^99mTc–ALD highly uptake in cancer cell line, the results demonstrated that radiolabeled ALD may be a promising agent for bone cancer diagnosis.     

Impact of Different [Tc(N)PNP]-Scaffolds on the Biological Properties of the Small cRGDfK Peptide: Synthesis,In Vitro and In Vivo Evaluations

Background: The [^99mTc][Tc(N)(PNP)] system, where PNP is a bisphosphinoamine, is an interesting platform for the development of tumor ‘receptor-specific’ agents. Here, we compared the reactivity and impact of three [Tc(N)(PNP)] frameworks on the stability, receptor targeting properties, biodistribution, and metabolism of the corresponding [^99mTc][Tc(N)(PNP)]-tagged cRGDfK peptide to determine the best performing agent and to select the framework useful for the preparation of [^99mTc][Tc(N)(PNP)]-housing molecular targeting agents. Methods: cRGDfK pentapeptide was conjugated to Cys and labeled with each [Tc(N)(PNP)] framework. Radioconjugates were assessed for their lipophilicity, stability, in vitro and in vivo targeting properties, and performance. Results: All compounds were equally synthetically accessible and easy to purify (RCY ≥ 95%). The main influences of the synthon on the targeting peptide were observed in in vitro cell binding and in vivo. Conclusions: The variation in the substituents on the phosphorus atoms of the PNP enables a fine tuning of the biological features of the radioconjugates. ws[^99mTc][Tc(N)(PNP3OH)]– and [^99mTc][Tc(N)(PNP3)]– are better performing synthons in terms of labeling efficiency and in vivo performance than the [^99mTc][Tc(N)(PNP43)] framework and are therefore more suitable for further radiopharmaceutical purposes. Furthermore, the good labeling properties of the ws[^99mTc][Tc(N)(PNP3OH)]– framework can be exploited to extend this technology to the labeling of temperature-sensitive biomolecules suitable for SPECT imaging.     

Design,Preparation, and Evaluation of a Novel 99mTcN Complex of Ciprofloxacin Xanthate as a Potential Bacterial Infection Imaging Agent

In order to seek novel technetium-99m bacterial infection imaging agents, a ciprofloxacin xanthate (CPF2XT) was synthesized and radiolabeled with [^99mTcN]²⁺ core to obtain the ^99mTcN-CPF2XT complex, which exhibited high radiochemical purity, hydrophilicity, and good stability in vitro. The bacteria binding assay indicated that ^99mTcN-CPF2XT had specificity to bacteria. A study of biodistribution in mice showed that ^99mTcN-CPF2XT had a higher uptake in bacterial infection tissues than in turpentine-induced abscesses, indicating that it could distinguish bacterial infection from sterile inflammation. Compared to ^99mTcN-CPFXDTC, the abscess/blood and abscess/muscle ratios of ^99mTcN-CPF2XT were higher and the uptakes of ^99mTcN-CPF2XT in the liver and lung were obviously decreased. The results suggested that ^99mTcN-CPF2XT would be a potential bacterial infection imaging agent.     

Synthesis and biological evaluation of 99mTc tricarbonyl complex of O,O′‐diethylethylenediamine‐N,N′‐di‐3‐propanoate as potential tumour diagnostic agent

The extensive development of radiopharmaceuticals towards early tumour detection and treatment has increased the demand for new ligands with higher tumour selectivity. Research has been done on the potential of the novel O,O′‐diethylethylenediamine‐N,N′‐di‐3‐propanoate ( L ) ligand as a radionuclide vehicle for tumour targeting. Under alkaline conditions, L hydrolyses and produces half ester ligand ( L' ) and diacid ligand ( L'' ), with characteristic donor atom array N,N,O. Ligand L was successfully labelled with ^99mTc at pH = 9 by coordination with the octahedral fac‐[^99mTc(CO)₃(H₂O)₃]⁺ intermediate, forming the main radioproduct fac‐[^99mTcL′(CO)₃] (Tc1). The ^99mTc complex showed a low lipophilic character (log P = 0.48) and low binding affinity to human serum albumin (2.51 ± 0.48%). In vitro stability studies in saline and human plasma, as well as challenge studies with cysteine and histidine, revealed high stability of the complex during 24 h. Biodistribution studies of Tc1 in female C57BL/6 mice bearing B16/F1 melanoma metastases showed significant tumour uptake: 9.81 ± 1.19%ID g^?1 in the liver, 5.87 ± 0.54%ID g^?1 in the lungs and 3.17 ± 0.33%ID g^?1 in the ovary at 30 min post‐injection. Favourable physicochemical properties, satisfactory in vitro/in vivo stability and biodistribution profile in the experimental metastatic melanoma model indicate the possible application of the radiolabelled ligand in tumour diagnosis. Copyright © 2015 John Wiley & Sons, Ltd.     

Preparation of186Re labeled immunoglobulins: Direct and indirect methods

Kits were developed for labeling sulphur microcolloids with^99mTc. The microcolloids were prepared to get the desired particle size. The stannous chloride was treated with sulphide ions released from thioacetamide in the presence of carboxymethyl cellulose and the pH of the reaction was adjusted to 3.0. The contents of single reaction vial were reacted with^99mTc, the radiochemical yield was higher than 95%. Sulphur-microcolloid kits were stable and the stability was followed for 6 hours. The freeze-dried kits were followed more than three months after production and were found stable. Bone marrow uptake in rabbits was determined to be about 36%. The preparation of^99mTc-sulphur microcolloid is performed in single step process and axellent node scintigraphy was obtained using experimental animal.     

Evaluation of Traumatic Spinal Cord Injury in a Rat Model Using 99mTc-GA-5 as a Potential In Vivo Tracer

Spinal cord injury (SCI) refers to the damage suffered in the spinal cord by any trauma or pathology. The purpose of this work was to determine whether ^99mTc-GA-5, a radiotracer targeting Glial Fibrillary Acidic Protein (GFAP), can reveal in vivo the reactivation of astrocytes in a murine model with SCI. A method for the ^99mTc radiolabeling of the mouse anti-GFAP monoclonal antibody GA-5 was implemented. Radiochemical characterization was performed, and radioimmunohistochemistry assays were used to evaluate the integrity of ^99mTc-GA-5. MicroSPECT/CT was used for in vivo imaging to trace SCI in the rats. No alterations in the GA-5’s recognition/specificity ability were observed after the radiolabeling. The GA-5’s radiolabeling procedure implemented in this work offers a practical method to allow the in vivo following of this monoclonal antibody to evaluate its biodistribution and specificity for GFAP receptors using SPECT/CT molecular imaging.