Search results for "positron"
showing 10 items of 1346 documents
Radiomics and artificial intelligence in prostate cancer: new tools for molecular hybrid imaging and theragnostics
2022
AbstractIn prostate cancer (PCa), the use of new radiopharmaceuticals has improved the accuracy of diagnosis and staging, refined surveillance strategies, and introduced specific and personalized radioreceptor therapies. Nuclear medicine, therefore, holds great promise for improving the quality of life of PCa patients, through managing and processing a vast amount of molecular imaging data and beyond, using a multi-omics approach and improving patients’ risk-stratification for tailored medicine. Artificial intelligence (AI) and radiomics may allow clinicians to improve the overall efficiency and accuracy of using these “big data” in both the diagnostic and theragnostic field: from technical…
[11C]-DASB microPET imaging in the aged rat: Frontal and meso-thalamic increases in serotonin transporter binding
2011
Whereas molecular imaging studies in the aging human brain have predominantly demonstrated reductions in serotonin transporter (5-HTT) availability, the majority of the rodent studies, using autoradiographic methods, report increases in neural 5-HTT levels with age. To our knowledge, however, no previous rodent studies have assessed this topic in vivo, and therefore it remains unclear whether this discrepancy arises from methodological or inter-species differences. We performed an [(11)C]-DASB microPET study to evaluate the effects of aging on 5-HTT availability in the rat brain. To generate binding potential estimates, quantitative tracer kinetic modeling was applied using the simplified r…
Synthesis and evaluation in rats of the dopamine D2/3 receptor agonist 18F-AMC20 as a potential radioligand for PET
2015
Dopamine D2/3 receptor (D2/3R) agonist PET tracers are better suited for the imaging of synaptic dopaminergic neurotransmission than D2/3R antagonists and may also offer the opportunity to study in vivo the high-affinity state of D2/3R (D2/3RHigh). With the aim to develop 18F-labeled D2/3R agonists suitable for widespread clinical application, we report here on the synthesis and in vitro and in vivo evaluation of a D2/3R agonist ligand from the aminomethyl chromane (AMC) class-(R)-2-[(4- 18Fluorobenzylamino)methyl]chroman-7-ol (18F-AMC20). Methods: In vitro affinities of AMC20 toward dopaminergic receptor subtypes were measured in membrane homogenates prepared from HEK293 cells expressing h…
PEGylation of HPMA-based block copolymers enhances tumor accumulation in vivo: a quantitative study using radiolabeling and positron emission tomogra…
2013
Abstract This paper reports the body distribution of block copolymers (made by controlled radical polymerization) with N-(2-hydroxypropyl)methacrylamide (HPMA) as hydrophilic block and lauryl methacrylate (LMA) as hydrophobic block. They form micellar aggregates in aqueous solution. For this study the hydrophilic/hydrophobic balance was varied by incorporation of differing amounts of poly(ethylene glycol) (PEG) side chains into the hydrophilic block, while keeping the degree of polymerization of both blocks constant. PEGylation reduced the size of the micellar aggregates (Rh = 113 to 38 nm) and led to a minimum size of 7% PEG side chains. Polymers were labeled with the positron emitter 18F,…
[(11)C]PR04.MZ, a promising DAT ligand for low concentration imaging: Synthesis, efficient (11)C-O-methylation and initial small animal PET studies.
2009
PR04.MZ was designed as a highly selective dopamine transporter inhibitor, derived from natural cocaine. Its binding profile indicates that [{sup 11}C]PR04.MZ may be suited as a PET radioligand for the non-invasive exploration of striatal and extrastriatal DAT populations. As a key feature, its structural design facilitates both, labelling with fluorine-18 at its terminally fluorinated butynyl moiety and carbon-11 at its methyl ester function. The present report concerns the efficient [{sup 11}C]MeI mediated synthesis of [{sup 11}C]PR04.MZ from an O-desmethyl precursor trifluoroacetic acid salt with Rb{sub 2}CO{sub 3} in DMF in up to 95 {+-} 5% labelling yield. A preliminary {mu}PET-experim…
HPMA-LMA copolymer drug carriers in oncology: an in vivo PET study to assess the tumor line-specific polymer uptake and body distribution.
2013
Polymeric drug carriers aim to selectively target tumors in combination with protecting normal tissue. In this regard polymer structure and molecular weight are key factors considering organ distribution and tumor accumulation of the polymeric drug delivery system. Four different HPMA based copolymer structures (random as well as block copolymers with lauryl methacrylate as hydrophobic block) varying in molecular weight, size and resulting architecture were analyzed in two different tumor models (AT1 prostate carcinoma and Walker-256 mammary carcinoma) in vivo. Polymers were labeled with (18)F and organ/tumor uptake was followed by μPET imaging and ex vivo biodistribution. Vascular permeabi…
44Sc-DOTA-BN[2-14]NH2 in comparison to 68Ga-DOTA-BN[2-14]NH2 in pre-clinical investigation. Is 44Sc a potential radionuclide for PET?
2011
In the present study we demonstrate the in vitro and in vivo comparison of the (44)Sc and (68)Ga labeled DOTA-BN[2-14]NH(2). (44)Sc is a positron emitter with a half life of 3.92 h. Hence it could be used for PET imaging with ligands requiring longer observation time than in the case of (68)Ga.The binding affinity of (nat)Sc-DOTA-BN[2-14]NH(2) and (nat)Ga-DOTA-BN[2-14]NH(2) to GRP receptors was studied in competition to [(125)I-Tyr(4)]-Bombesin in the human prostate cancer cell line PC-3. A preliminary biodistribution in normal rats was performed, while first microPET images were assessed in male Copenhagen rats bearing the androgen-independent Dunning R-3327-AT-1 prostate cancer tumor.The …
Ileal Melanoma, A Rare Cause of Small Bowel Obstruction: Report of a Case, and Short Literature Review.
2020
Background: Malignant melanoma frequently spreads to the gastrointestinal tract, with 60% of patients with advanced metastatic disease showing digestive involvement; however, primary MM of the small intestine is a controversial diagnosis. In fact, whether these lesions arise as true small bowel primary neoplasms or represent metastases from unidentified cutaneous melanomas remains debatable. The most common complications are intestinal obstruction, massive gastrointestinal bleeding, and perforation. Objective & Methods: We report a case of a 64-year-old patient, with an unremarkable medical history, in which a late diagnosis of primary ileal malignant melanoma in the setting of an emer…
Preliminary in vivo and ex vivo evaluation of the 5-HT2A imaging probe [18F]MH.MZ
2009
Abstract Introduction The 5-HT 2A receptor is one of the most interesting targets within the serotonergic system because it is involved in a number of important physiological processes and diseases. Methods [ 18 F]MH.MZ, a 5-HT 2A antagonistic receptor ligand, is labeled by 18 F-fluoroalkylation of the corresponding desmethyl analogue MDL 105725 with 2-[ 18 F]fluoroethyltosylate ([ 18 F]FETos). In vitro binding experiments were performed to test selectivity toward a broad spectrum of neuroreceptors by radioligand binding assays. Moreover, first micro-positron emission tomography (μPET) experiments, ex vivo organ biodistribution, blood cell and protein binding and brain metabolism studies of…
18F-labeling and evaluation of novel MDL 100907 derivatives as potential 5-HT2A antagonists for molecular imaging.
2009
Abstract Introduction The serotonergic system, especially the 5-HT2A receptor, is involved in various diseases and conditions. It is a very interesting target for medicinal applications. Methods Two novel 5-HT2A tracers, namely, [ 18 F]DD-1 and the enantiomeric pure ( R )-[ 18 F]MH.MZ, were radiolabeled by 18 F-fluoroalkylation of the corresponding desmethyl analogue. In vitro binding autoradiography on rat brain slices was performed to test the affinity and selectivity of these tracers. Moreover, first μPET experiments of ( R )-[ 18 F]MH.MZ were carried out in Sprague-Dawley rats. Results [ 18 F]DD-1 ( K i =3.23 nM) and ( R )-[ 18 F]MH.MZ ( K i =0.72 nM) were 18 F-fluoroalkylated by the se…