No abstract available.
Radiopharmaceuticals*

No abstract available.
Radiopharmaceuticals*

There is considerable interest in 188Re due to its favorable properties as a therapeutic radionuclide. 188Re and 99mTc act as a matched pair because of their similar chemical properties, and therefore methods of labeling with 99mTc can be applied to the labeling with 188Re. With appropriately chosen agents as carriers of 188Re, the labeling can be readily carried out using 188ReO4- in the presence of a reducing agent. 188Re radio pharmaceuticals based on 99mTc complexes have been synthesized and are currently being studied for clinical use. Some of them are shown to be suitable for therapeutic use and promising for radiotherapy in nuclear medicine.
Nuclear Medicine ; Radiopharmaceuticals ; Radiotherapy

PURPOSE: N-(3-[18F]Fluoroporpy)-2beta- carbomethoxy-3beta-(4-iodophenyl) nortropane ([18F]FP-CIT) has been shown to be very useful for imaging the dopamine transporter. However, synthesis of this radiotracer is some what troublesome. In this study, we used a new method for the preparation of [18F]FP-CIT to increase radiochemical yield and effective specific activity. MATERIALS AND METHODS: [18F]FP-CIT was prepared by N-alkylation of nor-beta-CIT (2 mg) with 3-bromo-l-[18F]fluoropropane in the presence of Et3N (5-6 drops of DMF/CH3CN, 140 degree C, 20 min). 3-Bromo-l-[18F]fluoropropane was synthesized from 5 microliter of 3-bromo-l-trifluoromethanesulfonyloxypropane (3-bromopropyl -l-triflate) and nBu4N18F at 80 degree C. The final compound was purified by reverse phase HPLC and formulated in 13% ethanol in saline. RESULTS: 3-Bromo-l-[18F]fluoropropane was obtained from 3-bromopropyl-l-triflate and nBu4N18F in 77-80% yield. N-Alkylation of nor-beta-CIT with 3-bromo-l-[18F]fluoropropane was carried out at 140 degree C using acetonitrile containing a small volume of DMF as the solvents. The overall yield of [18F]FP-CIT was 5-10% (decay-corrected) with a radiochemical purity higher than 99% and effective specific activity higher than the one reported in the literature based on their HPLC data. The final [18F]FP-CIT solution had the optimal pH (7.0) and it was pyrogen-free. CONCLUSION:: In this study, 3-bromopropyl-l-triflate was used as the precursor for the [18F]fluorination reaction and new conditions were developed for purification of [18F]FP-CIT by HPLC. We established this new method for the preparation of [18F]FP-CIT, which gave high effective specific activity and relatively good yield.
Chromatography, High Pressure Liquid ; Dopamine Plasma Membrane Transport Proteins* ; Dopamine* ; Ethanol ; Hydrogen-Ion Concentration ; Positron-Emission Tomography ; Solvents

The purpose of this study is to evaluate the diagnostic accuracy of various quantitative indices for the differentiation of benign from malignant primary soft tissue tumors by FDG-PET. A series of 32 patients with a variety of histologically or clinically confirmed benign (20) or malignant (12) soft tissue lesions were evaluated with emission whole body (5min/bed position) PET after injection of [18F]FDG. Regional 20min transmission scan for the attenuation correction and calculation of SUV was performed in 16 patients (10 benign, 6malignant) followed by dynamic acquisition for 56min. Postinjection transmission scan for the attenuation correction and calculation of SUV was executed in the other 16 patients (10 benign, 6 malignant). The following indices were obtained : the peak and average SUV (pSUV, aSUV) of lesions, tumor-to-background ratio acquired at images of 51 min p.i. (TBR51), tumor-to-background ratio of areas under time-activity curves (TBRarea) and the ratio between the activities of tumor ROI at 51 min p.i. and at the time which background ROI reaches maximum activity on the time-activity curves (T51/Tmax). The pSUV, aSUV, TBR51, and TBRarea, in malignant lesions were significantly higher than those in benign lesions. We set the cut-off values of pSUV, aSUV, TBR51, TBRarea and T51/Tmax for the differentiation of benign and malignant lesions at 3.5, 2.8, 5.1, 4.3 and 1.55, respectively. The sensitivity, specificity and accuracy were 91.7%, 80.0%, 84.4% by pSUV and aSUV, 83.3%, 85.0%, 84.4% by TBR51, 83.3%, 100%, 93.8% by TBRarea and 66.7%, 70.0%, 68.8% by Tsl/Tmax. The time-activity curves did not give additional information compared to SUV or TBR. The one false negative was a case with low-grade fibrosarcoma and all four false positives were cases with inflammatory change on histology. The visual analysis of FDG-PET also detected the metastatic lesions in malignant cases with comparable accuracy. In conclusion, all pSUV, aSUV, TBR51, and TBRarea are useful metabolic semi-quantitative indices with good accuracy for the differentiation of benign from malignant soft-tissue lesions.
Fibrosarcoma ; Humans ; Positron-Emission Tomography ; Sensitivity and Specificity

We evaluated the in vivo kinetics, distribution, and pharmacology of N-(4-[F] fluorornethylbenzyl)spiperone ([F]FMBS), a newly developed derivative of spiperone, as a potentially more selective #radiotrar.er for the dopamine (DA) Dz receptors. Mice received 1.9-3.7 MBq (1.8-3.6 nmol/kg) of [F]FMBS by tail vein injectivn. The time course and regional distribution of the tracer in brain were assessed. Blocking studies were carried out by intravenously preinjecting DA Dp receptor blockers (spiperone, butaclamol) as well as drugs with high affinity for DA Dr lSCH 23390), DA transporter (GBR 12909), and serotonin Sp (5-HTz) (ketanserin) sites. After injection of the tracer, the radioactivity in striatum increased steadily over time, resulting in a striatal-to-cerebellar ratio of 4.8 at 120 min postinjection. By contrast, the radioactivity in cerebellum, frontal cortex, and remaining cortex washed out rapidly. Preinjection of unlabe1ed FMBS (1 rng/kg) and spiperone (1 mg/kg) reduced [F] FMBS striatal-to-cerebellar ratio by 41Zo and 80Ya, respectively. (+)-Butaclamol(1 mg/kg) blocked 80Yo of the striatal [F]FMBS binding, while (-)-butaclamol (1 rng/kg) did not. Preinjection of SCH 23390 (1 mg/kg) and GBR 12909 (5 mg/kg) had no significant effect. On [""F]FMBS binding. Ketanserin (1 mg/kg), a ligand for the 5-H1g receptors, did not cause significant inhibition either in striatum, in frontal cortex, or the remaining cortex. The results demonstrate that [F]FMEtS labels DA Dz receptors selectively in vivo in the mouse brain. It may hold promise as a selective radiotracer for studying DA Dz receptors in vivo by PET.
Animals ; Brain ; Cerebellum ; Dopamine* ; Ketanserin ; Kinetics ; Mice ; Pharmacology ; Radioactivity ; Receptors, Dopamine D2* ; Serotonin ; Spiperone* ; Veins

Molecular imaging visualizes cellular processes at a molecular or genetic level in living subjects, and diverse molecular probes are used for this purpose. Radiolabeling methods as well as radioisotopes are very important in preparation of molecular probes, because they can affect the biodistribution in tissues and the excretion route. In this review, the molecular probes are divided into small organic molecules and macromolecules such as peptides and proteins, and their commonly used radiolabeling methods are described.
Molecular Imaging ; Molecular Probes* ; Peptides ; Radioisotopes ; Tomography, Emission-Computed, Single-Photon

No abstract available.
Aging* ; Glucose* ; Metabolism*

No abstract available.
Receptors, Nicotinic*

PURPOSE: The purpose of this study was to assess the diagnostic accuracy of various quantitation methods using F-18-fluorodeoxyglucose (FDG) in patients with malignant or benign lung lesion. MATERIALS AND METHODS: 22 patients (13 malignant including 5 bronchoalverolar cell cancer; 9 benign lesions including 1 hamartoma and 8 active inflammation) were studied after overnight fasting. We performed dynamic PET imaging for 56 min after injection of 370 MBq (10 mCi) of FDG. Standardized uptake values normalized to patients body weight and plasma glucose concentration (SUVglu) were calculated. The uptake rate constant of FDG and glucose metabolic rate were quantified using Patlak graphical analysis (Kpat and Mrpat), three compartment-five parameter model (K5p, MR5p), and six parameter model taking into account heterogeneity of tumor tissue (K6p, MR6p), Areas under receiver operating charac-teristic curves (ROC) were calculated for each method. RESULTS: There was no significant difference of rate constant or glucose metabolic rate measured by various quantitation methods between malignant and benign lesions. The area under ROC curve were 0.73 for SUVglu, 0.66 for Kpat, 0.77 for Mrpat, 0.71 for KSp, 0.73 for MRSp, 0.70 for K6p, and 0.78 for MR6p, No significant difference of area under the ROC curve between these rnethods v;as observed except the area between Kpat vs. Mrpat (p<0.05). CONCLUSION: Quantitative methods did not improve diagnostic accuracy in comparison with nonkinetic methods. However, the clinical utility of these methods needs to be evaluated further in patients with low pretest likelihood of active inflammation or bronchoalveolar cell carcinoma.
Blood Glucose ; Body Weight ; Fasting ; Glucose ; Hamartoma ; Humans ; Inflammation ; Lung Neoplasms ; Lung* ; Population Characteristics ; ROC Curve