title: Amide proton transfer imaging of adult diffuse gliomas: correlation with histopathological grades.
abstract: BACKGROUND
  Amide proton transfer (APT) imaging is a novel molecular MRI technique to detect endogenous mobile proteins and peptides through chemical exchange saturation transfer. We prospectively assessed the usefulness of APT imaging in predicting the histological grade of adult diffuse gliomas.
  
  
  METHODS
  Thirty-six consecutive patients with histopathologically proven diffuse glioma (48.1 ± 14.7 y old, 16 males and 20 females) were included in the study. APT MRI was conducted on a 3T clinical scanner and was obtained with 2 s saturation at 25 saturation frequency offsets ω = -6 to +6 ppm (step 0.5 ppm). δB0 maps were acquired separately for a point-by-point δB0 correction. APT signal intensity (SI) was defined as magnetization transfer asymmetry at 3.5 ppm: magnetization transfer ratio (MTR)asym = (S[-3.5 ppm] - S[+3.5 ppm])/S0. Regions of interest were carefully placed by 2 neuroradiologists in solid parts within brain tumors. The APT SI was compared with World Health Organization grade, Ki-67 labeling index (LI), and cell density.
  
  
  RESULTS
  The mean APT SI values were 2.1 ± 0.4% in grade II gliomas (n = 8), 3.2 ± 0.9% in grade III gliomas (n = 10), and 4.1 ± 1.0% in grade IV gliomas (n = 18). Significant differences in APT intensity were observed between grades II and III (P < .05) and grades III and IV (P < .05), as well as between grades II and IV (P < .001). There were positive correlations between APT SI and Ki-67 LI (P = .01, R = 0.43) and between APT SI and cell density (P < .05, R = 0.38). The gliomas with microscopic necrosis showed higher APT SI than those without necrosis (P < .001).
  
  
  CONCLUSIONS
  APT imaging can predict the histopathological grades of adult diffuse gliomas.
authors.affiliation: Department of Molecular Imaging and Diagnosis, Graduate School of Medical Science, Kyushu University, Fukuoka, Japan (O.T.); Department of Clinical Radiology, Graduate School of Medical Science, Kyushu University, Fukuoka, Japan (O.T., T.Y., A.H., K.Y., K.K., H.H.); Philips Research, Hamburg, Germany (J.K.); Philips Electronics Japan, Tokyo, Japan (Y.S.); Department of Neuropathology, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan (S.O.S., T.I.); Department of Neurosurgery, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan (N.H., M.M., K.Y.); Advanced Imaging Research Center, UT Southwestern Medical Center, Dallas, Texas (K.S., M.T.).
authors.forename: Osamu
authors.initials: O
authors.lastname: Togao
authors.forename: Takashi
authors.initials: T
authors.lastname: Yoshiura
authors.forename: Jochen
authors.initials: J
authors.lastname: Keupp
authors.forename: Akio
authors.initials: A
authors.lastname: Hiwatashi
authors.forename: Koji
authors.initials: K
authors.lastname: Yamashita
authors.forename: Kazufumi
authors.initials: K
authors.lastname: Kikuchi
authors.forename: Yuriko
authors.initials: Y
authors.lastname: Suzuki
authors.forename: Satoshi O
authors.initials: SO
authors.lastname: Suzuki
authors.forename: Toru
authors.initials: T
authors.lastname: Iwaki
authors.forename: Nobuhiro
authors.initials: N
authors.lastname: Hata
authors.forename: Masahiro
authors.initials: M
authors.lastname: Mizoguchi
authors.forename: Koji
authors.initials: K
authors.lastname: Yoshimoto
authors.forename: Koji
authors.initials: K
authors.lastname: Sagiyama
authors.forename: Masaya
authors.initials: M
authors.lastname: Takahashi
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Honda
mesh_terms: D000328:Adult; D000577:Amides / Q000737:chemistry; D001932:Brain Neoplasms / Q000473:pathology*; D005260:Female; D005909:Glioblastoma / Q000473:pathology*; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D060787:Neoplasm Grading; D011522:Protons
chemical_list: D000577:Amides; D011522:Protons
keywords: amide proton transfer (APT) imaging; chemical exchange saturation transfer (CEST); glioma.