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1.  Initial in vivo PET imaging of 5-HT1A receptors with 3-[18F]mefway 
4-trans-[18F]Mefway is a PET radiotracer with high affinity for 5-HT1A receptors. Our preliminary work indicated the positional isomer, 3-[18F]mefway, would be suitable for PET imaging of 5-HT1A receptors. We now compare the in vivo behaviour of 3-mefway with 4-mefway to evaluate 3-[18F]mefway as a potential 5-HT1A PET radiotracer. Two male rhesus macaques were given bolus injections of both 3- and 4-trans-[18F]mefway in separate experiments. 90 minute dynamic PET scans were acquired. TACs were extracted in the mesial temporal lobe (MTL) and caudal anterior cingulate gyrus (cACg). The cerebellum (CB) was used as a reference region. In vivo behavior of the radiotracers in the CB was compared based upon the ratio of normalized PET uptake for 3- and 4-trans-[18F]mefway. Specific binding was compared by examining MTL/CB and cACg/CB ratios. The subject-averaged ratio of 3-[18F]mefway to 4-trans-[18F]mefway in the cerebellum was 0.96 for 60-90 minutes. MTL/CB reached plateaus of ~2.7 and ~6 by 40 minutes and 90 minutes for 3- and 4-trans-[18F]mefway, respectively. cACg/CB reached plateaus of ~2.5 and ~6 by 40 minutes and 70 minutes for 3- and 4-trans-[18F]mefway, respectively. The short pseudoequilibration times and sufficient uptake of 3-[18F]mefway may be useful in studies requiring short scan times. Furthermore, the similar nondisplaceable clearance in the CB to 4-trans-[18F]mefway suggests the lower BPND of 3-[18F]mefway is due to a lower affinity. The lower affinity of 3-[18F]mefway may make it useful for measuring changes in endogenous 5-HT levels, however, this remains to be ascertained.
PMCID: PMC4138142  PMID: 25143866
5-HT1A; PET; serotonin; mefway
2.  Positron emission tomography and near-infrared fluorescence imaging of vascular endothelial growth factor with dual-labeled bevacizumab 
The pivotal role of vascular endothelial growth factor (VEGF) in cancer is underscored by the approval of bevacizumab (Bev, a humanized anti-VEGF monoclonal antibody) for first line treatment of cancer patients. The aim of this study was to develop a dual-labeled Bev for both positron emission tomography (PET) and near-infrared fluorescence (NIRF) imaging of VEGF. Bev was conjugated to a NIRF dye (i.e. 800CW) and 2-S-(4-isothiocyanatobenzyl)-1,4,7-triazacyclononane-1,4,7-triacetic acid (p-SCN-Bn-NOTA) before 64Cu-labeling. Flow cytometry analysis of U87MG human glioblastoma cells revealed no difference in VEGF binding affinity/specificity between Bev and NOTA-Bev-800CW. 64Cu-labeling of NOTA-Bev-800CW was achieved with high yield. Serial PET imaging of U87MG tumor-bearing female nude mice revealed that tumor uptake of 64Cu-NOTA-Bev-800CW was 4.6 ± 0.7, 16.3 ± 1.6, 18.1 ± 1.4 and 20.7 ± 3.7 %ID/g at 4, 24, 48 and 72 h post-injection respectively (n = 4), corroborated by in vivo/ex vivo NIRF imaging and biodistribution studies. Tumor uptake as measured by ex vivo NIRF imaging had a good linear correlation with the % ID/g values obtained from PET (R2 = 0.93). Blocking experiments and histology both confirmed the VEGF specificity of 64Cu-NOTA-Bev-800CW. The persistent, prominent, and VEGF-specific uptake of 64Cu-NOTA-Bev-800CW in the tumor, observed by both PET and NIRF imaging, warrants further investigation and future clinical translation of such Bev-based imaging agents.
PMCID: PMC3249831  PMID: 22229128
Positron emission tomography (PET); Near-infrared fluorescence (NIRF) Imaging; Vascular endothelial growth factor (VEGF); 64Cu; Tumor angiogenesis; Cancer

Results 1-2 (2)