Introduction Thymidylate synthase (TSase) and folate receptors (FRs) are well developed targets of cancer therapy. Discovery of a simple and fast method for the conversion of 11CH3I to [11C]-formaldehyde (11CH2O) encouraged us to label the co-factor of this enzyme. Preliminary studies conducted on cell lines have demonstrated a preferential uptake of [11-14C]-(R)-N5,N10-methylene-5,6,7,8-tetrahydrofolate (14CH2H4folate) by cancerous cell vs. normal cells from the same organ [1] pointing out 11CH2H4folate as a PET tracer for cancer imaging. Herein we report the synthesis of 11CH2H4folate, which may serve as a potential positron emission tomography (PET) tracer. Methods In a remotely controlled module, 11CH3I was bubbled into a reaction vial containing trimethylamine N-oxide (TMAO) in DMF and heated to 70 °C for 2 min. 11CH2O formed after the completion of reaction was then mixed with a solution of freshly prepared tetrahydrofolate (H4folate) by using a fast chemo-enzymatic approach to accomplish synthesis of 11CH2H4folate. Purification of the product was carried out by loading the crude reaction mixture on a SAX cartridge, washing with water to remove unbound impurities and finally eluting with a saline solution. Results The synthesis and purification of 11CH2H4folate was completed within 5 min. HPLC analysis of the product after SAX purification indicate more than 90% of the radioactivity that was retained on the SAX cartridge was in 11CH2H4folate with minor (<10%) radioactivity due to unreacted 11CH2O. Conclusion We present a fast (~5 min) synthesis and purification of 11CH2H4folate, as a potential PET tracer. The final product is received in physiological compatible buffer (100 mM sodium phosphate, pH 7.0 containing 500 mM NaCl) and ready for use in vivo.

In this paper, a new adaptive bolus-chasing control scheme is proposed to synchronize the bolus peak in a patient's vascular system and the imaging aperture of a computed tomography (CT) scanner. The proposed control scheme is theoretically evaluated and experimentally tested on a modified Siemens SOMATOM Volume Zoom CT scanner. The first set of experimental results are reported on bolus-chasing CT angiography using realistic bolus dynamics, real-time CT imaging and adaptive table control with physical vasculature phantoms. The data demonstrate that the proposed control approach tracks the bolus propagation well, and clearly outperforms the constant-speed scheme that is the current clinical standard.

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In this paper, an interactive term identification approach is proposed for identification of non-parametric nonlinear systems. The idea is to make a high-dimensional nonlinear identification problem into a number of low-dimensional problems and thus to effectively combat the problem of the curse of dimensionality. Convergence results are established in the paper and numerical results support the theoretical analysis and demonstrate that the proposed approach is an attractive alternative to existing nonlinear identification methods.