title: "Molecular" MR imaging at high fields.
abstract: Magnetic resonance imaging (MRI) and spectroscopy (MRS) have contributed considerably to clinical radiology, and a variety of MR techniques have been developed to evaluate pathological processes as well as normal tissue biology at the cellular and molecular level. However, in comparison to nuclear imaging, MRI has relatively poor sensitivity for detecting true molecular changes or for detecting the presence of targeted contrast agents, though these remain under active development. In recent years very high field (7T and above) MRI systems have been developed for human studies and these provide new opportunities and technical challenges for molecular imaging. We identify 5 types of intrinsic contrast mechanisms that do not require the use of exogenous agents but which can provide molecular and cellular information. We can derive information on tissue composition by (i) imaging different nuclei, especially sodium (ii) exploiting chemical shift differences as in MRS (iii) exploiting specific relaxation mechanisms (iv) exploiting tissue differences in the exchange rates of molecular species such as amides or hydroxyls and (v) differences in susceptibility. The increased signal strength at higher fields enables higher resolution images to be acquired, along with increased sensitivity to detecting subtle effects caused by molecular changes in tissues.
authors.affiliation: Vanderbilt University Institute of Imaging Science, 1161 21st Ave South, Nashville, TN 37212, USA. Electronic address: john.gore@vanderbilt.edu.
authors.forename: John C
authors.initials: JC
authors.lastname: Gore
authors.affiliation: Vanderbilt University Institute of Imaging Science, 1161 21st Ave South, Nashville, TN 37212, USA.
authors.forename: Zhongliang
authors.initials: Z
authors.lastname: Zu
authors.affiliation: Vanderbilt University Institute of Imaging Science, 1161 21st Ave South, Nashville, TN 37212, USA.
authors.forename: Ping
authors.initials: P
authors.lastname: Wang
authors.affiliation: Vanderbilt University Institute of Imaging Science, 1161 21st Ave South, Nashville, TN 37212, USA.
authors.forename: Hua
authors.initials: H
authors.lastname: Li
authors.affiliation: Vanderbilt University Institute of Imaging Science, 1161 21st Ave South, Nashville, TN 37212, USA.
authors.forename: Junzhong
authors.initials: J
authors.lastname: Xu
authors.affiliation: Vanderbilt University Institute of Imaging Science, 1161 21st Ave South, Nashville, TN 37212, USA.
authors.forename: Richard
authors.initials: R
authors.lastname: Dortch
authors.affiliation: Vanderbilt University Institute of Imaging Science, 1161 21st Ave South, Nashville, TN 37212, USA.
authors.forename: Daniel F
authors.initials: DF
authors.lastname: Gochberg
mesh_terms: D000577:Amides; D000818:Animals; D001921:Brain / Q000000981:diagnostic imaging; D001931:Brain Mapping; D003287:Contrast Media; D006801:Humans; D017665:Hydroxyl Radical; D008279:Magnetic Resonance Imaging / Q000295:instrumentation*; D009682:Magnetic Resonance Spectroscopy / Q000295:instrumentation*; D057054:Molecular Imaging / Q000295:instrumentation*
chemical_list: D000577:Amides; D003287:Contrast Media; D017665:Hydroxyl Radical
keywords: CEST; Chemical exchange; Endogenous contrast; High field; Magnetization transfer; Molecular imaging