title: A polymer-based magnetic resonance tracer for visualization of solid tumors by 13C spectroscopic imaging.
abstract: Morphological imaging precedes lesion-specific visualization in magnetic resonance imaging (MRI) because of the superior ability of this technique to depict tissue morphology with excellent spatial and temporal resolutions. To achieve lesion-specific visualization of tumors by MRI, we investigated the availability of a novel polymer-based tracer. Although the 13C nucleus is a candidate for a detection nucleus because of its low background signal in the body, the low magnetic resonance sensitivity of the nucleus needs to be resolved before developing a 13C-based tracer. In order to overcome this problem, we enriched polyethylene glycol (PEG), a biocompatible polymer, with 13C atoms. 13C-PEG40,000 (13C-PEG with an average molecular weight of 40 kDa) emitted a single 13C signal with a high signal-to-noise ratio due to its ability to maintain signal sharpness, as was confirmed by in vivo investigation, and displayed a chemical shift sufficiently distinct from that of endogenous fat. 13C-PEG40,000 intravenously injected into mice showed long retention in circulation, leading to its effective accumulation in tumors reflecting the well-known phenomenon that macromolecules accumulate in tumors because of leaky tumor capillaries. These properties of 13C-PEG40,000 allowed visualization of tumors in mice by 13C spectroscopic imaging. These findings suggest that a technique based on 13C-PEG is a promising strategy for tumor detection.
authors.affiliation: Diagnostic Division, Otsuka Pharmaceutical Co., Ltd., Tokushima, Tokushima, Japan.
authors.forename: Yoshikazu
authors.initials: Y
authors.lastname: Suzuki
authors.affiliation: Diagnostic Division, Otsuka Pharmaceutical Co., Ltd., Tokushima, Tokushima, Japan.
authors.forename: Mitsuru
authors.initials: M
authors.lastname: Iida
authors.affiliation: Pharmaceutical Division, Otsuka Pharmaceutical Co., Ltd., Tokushima, Tokushima, Japan.
authors.forename: Iwao
authors.initials: I
authors.lastname: Miura
authors.affiliation: Biomedical MR Science Research Center, Shiga University of Medical Science, Otsu, Shiga, Japan.
authors.forename: Toshiro
authors.initials: T
authors.lastname: Inubushi
authors.affiliation: Biomedical MR Science Research Center, Shiga University of Medical Science, Otsu, Shiga, Japan.
authors.forename: Shigehiro
authors.initials: S
authors.lastname: Morikawa
mesh_terms: D000818:Animals; D001672:Biocompatible Materials / Q000008:administration & dosage* / Q000737:chemistry / Q000378:metabolism; D002247:Carbon Isotopes / Q000378:metabolism*; D045744:Cell Line, Tumor; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods*; D051379:Mice; D009368:Neoplasm Transplantation; D009369:Neoplasms / Q000473:pathology*; D011092:Polyethylene Glycols / Q000737:chemistry*; D059629:Signal-To-Noise Ratio
chemical_list: D001672:Biocompatible Materials; D002247:Carbon Isotopes; D011092:Polyethylene Glycols