title: Quantitative assessment of amide proton transfer (APT) and nuclear overhauser enhancement (NOE) imaging with extrapolated semisolid magnetization transfer reference (EMR) signals: II. Comparison of three EMR models and application to human brain glioma at 3 Tesla.
abstract: OBJECTIVE
  To evaluate the use of three extrapolated semisolid magnetization transfer reference (EMR) methods to quantify amide proton transfer (APT) and nuclear Overhauser enhancement (NOE) signals in human glioma.
  
  
  METHODS
  Eleven patients with high-grade glioma were scanned at 3 Tesla. aEMR(2) (asymmetric magnetization-transfer or MT model to fit two-sided, wide-offset data), sEMR(2) (symmetric MT model to fit two-sided, wide-offset data), and sEMR(1) (symmetric MT model to fit one-sided, wide-offset data) were assessed. ZEMR and experimental data at 3.5 ppm and -3.5 ppm were subtracted to calculate the APT and NOE signals (APT(#) and NOE(#)), respectively.
  
  
  RESULTS
  The aEMR(2) and sEMR(1) models provided quite similar APT(#) signals, while the sEMR(2) provided somewhat lower APT(#) signals. The aEMR(2) had an erroneous NOE(#) quantification. Calculated APT(#) signal intensities of glioma (∼4%), much larger than the values reported previously, were significantly higher than those of edema and normal tissue. Compared with normal tissue, gadolinium-enhancing tumor cores were consistently hyperintense on the APT(#) maps and slightly hypointense on the NOE(#) maps.
  
  
  CONCLUSIONS
  The sEMR(1) model is the best choice for accurately quantifying APT and NOE signals. The APT-weighted hyperintensity in the tumor was dominated by the APT effect, and the MT asymmetry at 3.5 ppm is a reliable and valid metric for APT imaging of gliomas at 3T.
authors.affiliation: Divison of MR Research, Department of Radiology, Johns Hopkins University, Baltimore, Maryland, USA.
authors.forename: Hye-Young
authors.initials: HY
authors.lastname: Heo
authors.affiliation: Divison of MR Research, Department of Radiology, Johns Hopkins University, Baltimore, Maryland, USA.
authors.forename: Yi
authors.initials: Y
authors.lastname: Zhang
authors.affiliation: Divison of MR Research, Department of Radiology, Johns Hopkins University, Baltimore, Maryland, USA.
authors.forename: Shanshan
authors.initials: S
authors.lastname: Jiang
authors.affiliation: Divison of MR Research, Department of Radiology, Johns Hopkins University, Baltimore, Maryland, USA.
authors.forename: Dong-Hoon
authors.initials: DH
authors.lastname: Lee
authors.affiliation: Divison of MR Research, Department of Radiology, Johns Hopkins University, Baltimore, Maryland, USA.|F.M. Kirby Research Center for Functional Brain Imaging, Kennedy Krieger Institute, Baltimore, Maryland, USA.
authors.forename: Jinyuan
authors.initials: J
authors.lastname: Zhou
mesh_terms: D000328:Adult; D000368:Aged; D001932:Brain Neoplasms / Q000000981:diagnostic imaging*; D005260:Female; D005910:Glioma / Q000000981:diagnostic imaging*; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods* / Q000592:standards; D008297:Male; D008875:Middle Aged; D012815:Signal Processing, Computer-Assisted
keywords: APT; CEST; MT; NOE; brain glioma