Direct technetium-99m labeling of anti-hepatoma monoclonal antibody fragment:a radioimmunoconjugate for hepatocellular carcinoma imaging

AIM To directly radiolabel an anti-hepatomamAb fragment HAb18 F（ab’）2 with 99mTc bystannous-reduced method,and assess thestability,biodistribution and radioimmun-oimaging（RⅡ）.METHODS Immunoreactive fraction wasdetermined according to Lindmo’s method.Ellman’s reagent was used to determine thenumber of thiols in the reduced F（ab’）2.Labelingefficiency and homogeneity were measured bypaper chromatography,sodium dodecylsulphatepolyacrylamide gel electrophoresis（SDS-PAGE）and autoradiography.Challenge assay involvedthe incubation of aliquots of labeled antibody inethylenediaminetetraacetate（ EDTA ）and L-cysteine（L-cys）solutions with different molarratio at 37℃ for 1h,respectively.Investigationsin vivo utilized nude mice bearing humanhepatocellular carcinoma（HHCC）xenograftswith gamma camera imaging and tissuebiodistribution studies at regular intervals.RESULTS The labeling procedure was finishedwithin 1.5 h compared with the'pretinning'method which would take at least 21h.In vitrostudies demonstrated that the radiolabeled mAbfragment was homogeneous and retained itsimmunoreactivity.Challenge studies indicatedthat 99mTc-labeled HAb18 F（ab’）2 in EDTA is morestable than in L-cys.Imaging and biodistribution showed a significant tumor uptake at 24 h post-injection of 99mTc-labeled HAb18 F（ab’）2.Theblood,kidney,liver and tumor uptakes at 24hwere 0.56±0.09,56.45±11.36,1.43±0.27 and6.57±3.01（%ID/g）,respectively.CONCLUSION 99mTc-HAb18 F（ab’）2 conjugateprepared by this direct method appears to be aneffective way to detect hepatoma in nude micemodel.

Anti-sense oligonucleotide labeled with technetium-99m using hydrazinonictinamide derivative and N-hydroxysuccinimidyl S-acetylmercaptoacetyltriglycline: A comparison of radiochemical behaviors and biological properties

AIM:To explore and compare the radiochemical behavior and biological property of anti-sense oligonuc-leotide (ASON) labeled with technetium-99m using N-hydroxysuccinimidyl S-acetylmercaptoacetyltriglycl ine (NHS-MAG3) and hydrazinonictinamide derivative (HYNIC). METHODS:After HYNIC and NHS-MAG3 were synthesized, ASON was labeled with technetium-99m using HYNIC and NHS-MAG3 as a bifunctional chelator. The in vivo and in vitro stability, binding rates of labeled compounds to serum albumen, biodistribution of 99mTc-MAG3-ASON and 99mTc-HYNIC-ASON in BALB/C mouse and its HT29 tumor cellular uptake were compared. RESULTS:The labeling efficiency and stability of 99mTc-MAG3-ASON were significantly higher than those of 99mTc-HYNIC-ASON (P = 0.02, and P = 0.03, respectively). 99mTc-MAG3-ASON had a significantly lower rate of binding to serum albumen than 99mTc-HYNIC-ASON (P < 0.05). In contrast to 99mTc-HYNIC-ASON, the biodistribution of 99mTc-MAG3-ASON was significantly lower in blood, heart, liver and stomach (P < 0.05), slightly lower in intestines and spleen (P > 0.05) and significantly higher in lung and kidney (P < 0.05). The HT29 tumor cellular uptake rate of 99mTc-MAG3-ASON was significantly higher than that of 99mTc-HYNIC-ASON (P < 0.05). CONCLUSION:99mTc-MAG3-ASON shows superior radiochemical behaviors and biological properties than 99mTc-HYNIC-ASON. 99mTc-MAG3-ASON is a potential radiopharmaceutical agent for in vivo application.

Guava extract (Psidium guajava) alters the labelling of blood constituents with technetium-99m

Psidium guajava (guava) leaf is a phytotherapic used in folk medicine to treat gastrointestinal and respiratory dis-turbances and is used as anti-inflammatory medicine. In nuclear medicine, blood constituents (BC) are labelled with techne-tium-99m (99mTc) and used to image procedures. However, data have demonstrated that synthetic or natural drugs could modify the labelling of BC with 99mTc. The aim of this work was to evaluate the effects of aqueous extract of guava leaves on the labelling of BC with 99mTc. Blood samples of Wistar rats were incubated with different concentrations of guava extract and labelled with 99mTc after the percentage of incorporated radioactivity (%ATI) in BC was determined. The results suggest that aqueous guava extract could present antioxidant action and/or alters the membrane structures involved in ion transport into cells, thus decreasing the radiolabelling of BC with 99mTc. The data showed significant (P<0.05) alteration of ATI in BC from blood incubated with guava extract.

Leukocyte-technetium-99m uptake in Crohn's disease:Does it show subclinical disease?

AIM:To evaluate inflammatory activity in patients with Crohn's disease (CD) using technetium-99m-hexamethylpropyleneamine oxime (99mTc-HMPAO) granulocyte scintigraphy.METHODS: Twenty patients (7 male and 13 female) with CD and five healthy volunteers were selected for 99mTc-HMPAO granulocyte scintigraphy. The Crohn's Disease Activity Index (CDAI), blood tests and C-reactive protein (CRP) of each patient were performed 7 d before the scintigraphic images. The leukocytes were labeled according to the International Society of Radiolabeled Blood Elements (ISORBE) consensus protocol and the scintigraphic images, including single photon emission computed tomography, were obtained 30 min and 2 h after injection of the radiolabeled leukocytes.RESULTS:The labeling yield of the leukocytes with the lipophilic complex 99mTc-HMPAO was 55.0%±10%. Six of the 20 patients (30%) presented congruent results for the three parameters investigated (CDAI, Scintigraphic Index and CRP). On the other hand, 14 patients (70%) did not show congruent results. There was no significant correlation between the indices analyzed according to the Spearman test (P>0.05,n=20).CONCLUSION: The results suggest that 99mTc-HMPAO-labeled leukocyte scintigraphy could be important for determining inflammatory activity in CD even in the absence of clinical symptoms.

Technetium-99m-labeled annexin V imaging for detecting prosthetic joint infection in a rabbit model

Accurate and timely diagnosis of prosthetic joint infection is essential to initiate early treatment and achieve a favorable outcome. In this study, we used a rabbit model to assess the feasibility of technetium-99m-labeled annexin V for detecting prosthetic joint infection. Right knee arthroplasty was performed on 24 New Zealand rabbits. After surgery, methicillin-susceptible Staphylococcus aureus was intra-articularly injected to create a model of prosthetic joint infection （the infected group, n = 12）. Rabbits in the control group were injected with sterile saline （n= 12）. Seven and 21 days after surgery, technetium-99m-labeled annexin V imaging was per- formed in 6 rabbits of each group. Images were acquired 1 and 4 hours after injection of technetium-99m- labeled annexin V （150 MBq）. The operated-to-normal-knee activity ratios were calculated for quantitative ana- lysis. Seven days after surgery, increased technetium-99m-labeled annexin V uptake was observed in all cases. However, at 21 days a notable decrease was found in the control group, but not in the infected group. The operated-to-normal-knee activity ratios of the infected group were 1.84 ±0.29 in the early phase and 2.19 ±0.34 in the delay phase, both of which were significantly higher than those of the control group （P=0.03 and P=0.02）. The receiver operator characteristic curve analysis showed that the operated-to-normal-knee activity ratios of the delay phase at 21 days was the best indicator, with an accuracy of 80%. In conclusion, technetium- 99m-labeled annexin V imaging could effectively distinguish an infected prosthetic joint from an uninfected prosthetic joint in a rabbit model.

Quantitative Analysis of the Tomographic Technetium-99m MIBI (^(99m)Tc-MIBI) Myocardial Bullseye Display: Application to Diagnosis of Coronary Artery Disease

In this study, the 99mTc-MIBI myocardial bullseye display of 31 healthy persons and 34 patients with myocardial ischemia and 17 patients with myocardial infarction were analyzed quantitatively, and compared with the results of myocardial tomography analysis and qualitative bullseye analysis. The sensitivities of the three methods were 88.2%, 91.2 % and 94.1 % respectively (P>0.05),and the specificities were 93. 5%, 83, 9% and 83. 9% respectively (P<0.05).On the other hand, the quantitative analysis obviously outperformed the other two methods in the detection of ischemic segments of myocardium near infarction zone (P<0. 01). The quantitative analysis of 99mTc-MIBI myocardial bullseye (quantitative bullseye) was an objective, specific and sensitive method for diagnosis of coronary artery disease.

A NEW BIFUNCTIONAL CHELATING AGENT α,ε-N,N'-BIS(L-CYSTEINYL)-L-LYSINE FOR RADIOLABELLING OF MONOCLONAL ANTIBODIES WITH TECHNETIUM-99M

α,ε-N,N'-bis(L-cysteinyl)-L-lysine was synthesized and char- acterized for the first time.It was then employed as a bifunctional chelating agent to chelate technetium-99m and subsequently conjugated to fragment F(ab')_2 of anti-gastric tumor monoclonal antibody 3G9.The radiolabelled antibody was satisfactorily stable and immunoreactive.

Is there a role for Tc-99m (V) DMSA scintigraphy in ischemic colitis?

AIM: To evaluate the role of pentavalent Tc-99m dimercaptosuccinic acid [Tc-99m (V) DMSA] in the diagnosis of ischemic colitis. METHODS: Fourteen patients with endoscopically and histologically confirmed ischemic colitis were included in the study. Tc-99m (V) DMSA scintigraphy was performed within 2 d after colonoscopy. Images were considered positive when an area of increased activity was observed in the region of interest and negative when no abnormal tracer uptake was detected. RESULTS: In 3 out of the 14 patients, Tc-99m (V) DMSA images showed moderate activity in the bowel. The scintigraphic results corresponded with the endoscopic findings. In the other 11 patients, no abnormal tracer uptake was detected in the abdomen. CONCLUSION: Besides the limited number of patients, Tc-99m (V) DMSA could not be considered as a useful imaging modality for the evaluation of ischemic colitis.

LABELLING OF METALLOTHIONEIN WITH ^(99m)Tc

99mTc-labelled metallothionein (99mTc-MT) was prepared through both direct and transcomplexation labelling approaches. Buffer systems and a variety of other parameters in the direct labelling procedure were studied in detail. High radiolabelling yields of 93-96% and the specific radioactivity of 3.7 MB/μg were obtained under optimal conditions by the direct labelling method. The prepared 99mTc-MT was stable in vitro. The chelate-exchange kinetics of MT with 99mTc-glucohepatonate and 99mTc-citrate were also studied. Biodistribution and imaging studies showed that 99mTc-MT was accumulated in the animal kidneys at an exceptionally high level, indicating that 99mTc-MT might be a potential renal imaging agent.

Role of scintigraphy in inflammatory bowel disease

The diagnosis of inflammatory bowel disease(IBD) depends on direct endoscopic visualization of the colonic and ileal mucosa and the histological study of the obtained samples.Radiological and scintigraphic methods are mainly used as an adjunct to endoscopy.In this review,we focus on the diagnostic potential of nuclear medicine procedures.The value of all radiotracers is described with special reference to those with greater experience and more satisfactory results.Tc-99m hexamethylpropylene amine oxime white blood cells remain a widely acceptable scintigraphic method for the diagnosis of IBD,as well as for the evaluation of disease extension and severity.Recently,pentavalent Tc-99m dimercaptosuccinic acid has been recommended as an accurate variant and a complementary technique to endoscopy for the follow-up and assessment of disease activity.Positron emission tomography alone or with computed tomography using fluorine-18 fluorodeoxyglucose appears to be a promising method of measuring inflammation in IBD patients.

Simulating the Production of Medical Radioisotopes in a Fast Thorium-Cycle ADS with SERPENT

Radiopharmaceuticals are used in nuclear medicine for diagnostic or therapeutic acts. The short decay half-lives of medical radioisotopes, especially those used for diagnostics, imply that they should be produced continuously and transported as quickly as possible to the medical units where they are used. Neutron-rich medical radioisotopes are generally produced in research reactors, like technetium-99m, lutetium-177, holmium-166 and iodine-131. On the other hand, proton-rich radioisotopes are produced via reactions with charged particles from accelerators like fluorine-18, gallium-67, iodine-123 and thallium-201. Beside this, innovative nuclear reactors are advocated as solutions to the issues of nuclear waste production and proliferation threats. Fast neutron, thorium-cycle and accelerator-driven subcritical (ADS) reactors are some of the most promising of them, proposed as safer fuel breeders and “waste burners”. This article examines the use of a fast thorium-cycle ADS with liquid lead-bismuth eutectic coolant for the production of molybdenum-99/technetium-99m and lutetium-177. Burnup simulation has been made with the Monte-Carlo (MC) code SERPENT. It is demonstrated that MC codes can advantageously be used to determine the optimal irradiation time for a given radioisotope in a realistic reactor core. It is also shown that fast thorium-cycle ADS is an economical option for the production of medical radioisotopes.

Analysis of the successful clinical treatment of 140 patients with parathyroid adenoma:A retrospective study

BACKGROUND Parathyroid adenoma(PA) sometimes recurs after surgery,how to improve the surgical success rate of PA is the key to the treatment of this disease.AIM To investigate the clinical features,diagnosis,and surgical treatment of patients with PA.METHODS Patients who were pathologically confirmed with PA and had undergone surgery for the first time between January 2010 and December 2017 at the Beijing Shijitan Hospital affiliated to Capital Medical University were included in the study.The clinical features,localization diagnosis,and surgical treatment of these patients were analyzed.RESULTS Of the 140 patients,32 were male and 108 were female;132 cases had one adenoma,and 8 had two adenomas.In addition,114 cases had clinical symptoms,among which 51,28,23,8,and 4 had urinary system,skeletal system,digestive system,neuromuscular system,and neuropsychiatric symptoms,respectively,while 26 cases had no obvious symptoms.The median level of preoperative parathyroid hormone(PTH) was 201.0 pg/m L.The positive detection rate of technetium-99m sestamibi(Tc-99m MIBI) single-photon emission computed tomography/computed tomography(SPECT/CT),ultrasound examination,and the combined use of Tc-99m MIBI SPECT/CT and ultrasound examination was 92.9%,85.5%,and 96.4%,respectively.Open surgery was performed in all patients,and PTH was monitored during surgery.The success rate of surgery was 98.6%.After surgery,21 cases developed hypocalcemia,1 case developed temporary hoarseness,and 19 cases had transient hypoparathyroidism but there was no permanent hypoparathyroidism,postoperative hemorrhage,or hematoma in the surgical area.CONCLUSION For patients with clinically unexplained skeletal system,urinary system,and neuropsychiatric symptoms,the possibility of PA should be considered.Imaging examinations such as ultrasound and Tc-99m MIBI SPECT/CT could be integrated before surgery to obtain accurate localization diagnosis.Precise preoperative localization,intraoperative PTH monitoring,and delicate surgery to protect the integrity of the PA capsule ensure a minimally invasive and successful surgery.

Incidental Diagnosis of a Brown Tumor Mimicking Bone and Lung Metastasis during a Parathyroid Scintigraphy

We report herein a case of a 40-year-old male patient with chronic renal failure presenting a severe hyperparathyroidism with an elevation of parathormone level evaluated in nuclear medicine department for MIBI-Technetium-99m parathyroid scintigraphy. The parathyroid scintigraphy revealed the appearance of a preferential fixation of the MIBI-99mTc opposite the lower left pole of the thyroid and opposite the upper part of the right hemi thorax. A subsequent single-photon emission computed tomography-computed tomography focused on the cervico-thoracic region was performed and showed an ectopic parathyroid adenoma associated with an incidental brown tumor mimicking bone and lung metastases. Our case report confirms the usefulness of additional hybrid SPECT-CT imaging in the management of hyperparathyroidism.

Pre-clinical evaluation of a new indirectly labeled 99mTc-6-hydrazinopyridine-3-carboxylic acid （HYNIC）-depreotide with HYNIC as bifunctional chelator

Background Technetium-99m or 99mTC is widely used for labeling peptide in nuclear medicine. Somatostatin and its analog can inhibit tumor cell growth after binding with its receptor. This research was to study the preclinical effect of a new 99rnTc-6-hydrazinopyridine-3-carboxylic acid （HYNIC）-depreotide, indirect 99rnTc labeling of depreotide using HYNIC as a bifunctional chelator. Methods The cyclopeptide, cyclo-[（N-Me） Phe-Tyr-D-Trp-Lys-VaI-Hcy], the linear peptide, and [CICH2-CO.^-Dap-Lys- Cys-Lys-amide] were synthesized by Fmoc solid-phase synthesis. The cyclopeptide and the linear peptide were linked by liquid-phase synthesis. The product depreotide was isolated and purified by high performance liquid chromatography and was confirmed by mass spectrography. Depreotide was labeled with egmTc through a direct labeling method, using HYNIC as a bifunctional chelator. Paper chromatography method was used to calculate the labeling rate, and through the comparative analysis selected the best mark conditions. The new 99mTc-HYNIC-depreotide was tested by high-performance liquid chromatography （HPLC）. The internalization and externalization rates of the new 99mTc-HYNIC-depreotide were studied in A549 cells. Furthermore, biodistribution of the radiopeptide was studied in nude mice, bearing tumors from human lung carcinoma cells SPC-A1. Results The molecular of synthesize depreotide was 1358, and the purity of it was 95.29%. The labeling efficiency of 99mTc-HYNIC-depreotide was highest at pH 6.0 and 15℃, about （70.95±0.84）%. The labeling rate of the new 99mTc-HYNIC-depreotide rose to a peak of （20.75±0.48）% at 60 minutes in A549 cells at 37℃ and decreased slightly later, while it elevated gradually during the time course at 4℃ and 25℃. The internalization rate of the new 99rnTc-HYNIC-depreotide at 37℃ increased gradually and reached the peak of 84.4% in 120 minutes, while the externalization rate of the new 99mTc-HYNIC-depreotide was always less than 20%. In mice bearing the experimental SPC-A1 tumor, the new 99mTc-HYNIC-depreotide demonstrated a high tumor uptake of （4.05±0.04）% ID/g at 1.5 hpi and remained high （（2.51±0.06）% ID/g） at 4 hpi. The tumor-to-lung activity concentration ratio （T/Lu） was very high for the new 99mTc-HYNIC-depreotide at all time points. So did the tumor-to-muscle activity （T/Mu） and tumor-to-blood activity concentration ratios （T/BI）. Conclusion The findings suggested that the new 99mTc-HYNIC-depreotide might be a promising candidate radiopharmaceutical for imaging somatostatin receptor positive lung cancer.

Experimental studies on imaging of infected site with 99m^Tc-labeled ciprofloxacin in mice

Background Bacterial infection can pose a substantial diagnostic dilemma. 99m^Tc-labeled ciprofloxacin （CPF） was developed as a biologically active radiopharmaceutical to diagnose infection. In the present research, we studied the biodistribution and imaging properties of infection tracer 99m^Tc-CPF in a mouse model of infection. Methods CPF was labeled with 99m^Tc and the radiochemical purity and labeling rate were measured. A mouse model of infection was established. We then determined the biodistribution of 99m^Tc-CPF and conducted the whole body scintigraphy of the animal model. Results 99m^Tc-Ciprotech was stable for at least 6 hours at room temperature. The labeling rate of CPF by 99m^Tc was over 90%. Clearance of radioactivity mainly occurred in the liver and kidney, and the clearance from blood was rapid. Both biodistribution and imaging results showed higher uptake of 99m^Tc-CPF at sites of infection. The infectious tissue/normal tissue ratio peak was 4.30 at 4 hours after injection. Conclusions 99m^Tc-CPF is a sensitive radiopharmaceutical for scintigraphy of infectious lesions and it is easy to prepare.