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

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*

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

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

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

Previous single-photon emission computed tomography (SPECT) studies have demonstrated decreased (1231)beta-CIT (2beta-carbomethoxy-3beta(4-iodophenyl) tropane) striatal binding in Parkinson's disease (PD) patients. The present study extends our previous work by examining SPECT measures of (1231) beta-CIT binding in a larger group of PD patients with varying disease severity. Forty-six L-dopa-responsive PD patients(Hoehn-Yahr stage 1-3) had either a total of 15 SPECT scans over a 24 hr period or two scans at 12 hr and 24 hr after injection of (1231) beta-CIT. (1231) beta-CIT binding in the striatum was estimated using two indices: the specific-to nonspecific binding ratio, calculated as (striatal-cerebellar)/cerebellar radioactivity (specific binding ratio: SBR) at 24 hr postinjection as well as at its peak, which occurred at 12-24 hr postinjection; and the binding potential, the ratio of the rate constant of binding to the dopamine (DA) transporters (k3) to that of dissociation from the DA transporters (K4), as calculated by tracer kinetic modeling. The mean SBR at 24 hr postinjection, the mean peak SDR, and the mean binding potential in the striatum were all significantly correlated with Hoehn-Yahr stage, total store of UPDRS, motor score of UPDRS, and activities of daily living score of UPDRS. There were significant correlations between the sum of lateralizing UPDRS subscales (tremor, rigidity, bradykinesia) calculated for each individual limb and the SPECT measures of [123I]beta-CIT binding in the contralateral striatum. There were excellent correlations among the peak striatal SBR, the stiiatal SBR at 24 hr postinjection, and the binding potential. The results indicate that [123I]beta-CIT may be a useful marker of disease severity in PD. Additionally, the simple tissue ratio at 24 hr postinjection may be acceptable for the assessment of [123I]beta-CIT binding in PD, making repeated scanning and complicated modeling procedures less necessary. [123I]beta-CIT SPECT may be clinically useful for the early diagnosis and serial monitoring of PD.
Activities of Daily Living ; Dopamine ; Early Diagnosis ; Extremities ; Humans ; Parkinson Disease* ; Radioactivity ; Tomography, Emission-Computed* ; Tomography, Emission-Computed, Single-Photon

The goals of developments in nuclear medicine instrumentation are to offer a higher-quality image and to aid diagnosis, prognosis assessment or treatment planning and monitoring. It is necessary for physicists and engineers to improve or design new instrumentation and technique, and to implement, validate, and apply these new approaches in the practice of nuclear medicine. The researches in physical properties of detectors and crystal materials and advance in image analysis technology have improved quantitative and diagnostic accuracy of nuclear medicine images. This review article presents recent developments in nuclear medicine instrumentation, including scatter and attenuation correction, new detector technology, tomographic image reconstruction methods, 511 keV imaging, dual modality imaging device, small gamma camera, PET developments, image display and analysis methods.
Diagnosis ; Gamma Cameras ; Image Processing, Computer-Assisted ; Nuclear Medicine* ; Prognosis