title: Molecular imaging: challenges of bringing imaging of intracellular targets into common clinical use.
abstract: Molecular imaging (MI) takes advantage of several new techniques to detect biomarkers or biochemical and cellular processes, with the goal of obtaining high sensitivity, specificity and signal-to-noise ratio imaging of disease. The imaging modalities bearing the most promise for MI are positron emission tomography (PET), single photon emission computer tomography (SPECT) and different optical imaging techniques with high sensitivity. Also magnetic resonance imaging (MRI) with contrast agents like ultra-small superparamagnetic iron oxide particles (USPIO), magnetic resonance spectroscopy and ultrasound imaging with contrast agents may be useful approaches. MI techniques have been used in the clinic for many years, i.e. PET imaging using (18)  F-labeled fluorodeoxyglucose. Animal studies have during the last years revealed great potential for MI also with several other agents. The focus of the present article is the challenges of clinical imaging of intracellular targets following intravenous injection of the agents. Thus, the great challenge of getting enough contrast agent into the cytosol and at the same time obtaining a low signal from tissue just outside the diseased area is discussed.
authors.affiliation: Centre for Cancer Biomedicine, Faculty Division, Norwegian Radium Hospital, University of Oslo, Montebello, Olso, Norway. tore.skotland@rr-research.no
authors.forename: Tore
authors.initials: T
authors.lastname: Skotland
mesh_terms: D000818:Animals; D001692:Biological Transport; D003287:Contrast Media / Q000008:administration & dosage / Q000493:pharmacokinetics*; D003600:Cytosol / Q000378:metabolism; D011992:Endosomes / Q000378:metabolism; D005462:Fluorine Radioisotopes / Q000008:administration & dosage / Q000493:pharmacokinetics; D019788:Fluorodeoxyglucose F18 / Q000008:administration & dosage / Q000493:pharmacokinetics; D006801:Humans; D007275:Injections, Intravenous; D017613:Iodine Compounds / Q000008:administration & dosage / Q000493:pharmacokinetics; D007473:Ion Channels / Q000378:metabolism; D008279:Magnetic Resonance Imaging; D045423:Microbubbles; D057054:Molecular Imaging / Q000379:methods* / Q000639:trends; D049268:Positron-Emission Tomography / Q000379:methods; D019275:Radiopharmaceuticals / Q000008:administration & dosage / Q000493:pharmacokinetics; D012680:Sensitivity and Specificity; D017556:Technetium Compounds / Q000008:administration & dosage / Q000493:pharmacokinetics; D015899:Tomography, Emission-Computed, Single-Photon / Q000379:methods; D014057:Tomography, X-Ray Computed; D014463:Ultrasonography / Q000379:methods
chemical_list: D003287:Contrast Media; D005462:Fluorine Radioisotopes; D017613:Iodine Compounds; D007473:Ion Channels; D019275:Radiopharmaceuticals; D017556:Technetium Compounds; D019788:Fluorodeoxyglucose F18