Open AccessAmide Proton Transfer Imaging of Diffuse Gliomas: Effect of Saturation Pulse Length in Parallel Transmission-Based Technique
Author(s) -
Osamu Togao,
Akio Hiwatashi,
Jochen Keupp,
Koji Yamashita,
Kazufumi Kikuchi,
Takashi Yamada,
Masami Yoneyama,
Marijn J. Kruiskamp,
Koji Sagiyama,
Masaya Takahashi,
Hiroshi Honda
Publication year - 2016
Publication title -
plos one
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.99
H-Index - 332
ISSN - 1932-6203
DOI - 10.1371/journal.pone.0155925
Subject(s) - magnetization transfer , saturation (graph theory) , glioma , nuclear magnetic resonance , nuclear medicine , homogeneous , pulse sequence , materials science , magnetic resonance imaging , analytical chemistry (journal) , medicine , chemistry , physics , radiology , cancer research , mathematics , chromatography , combinatorics , thermodynamics
In this study, we evaluated the dependence of saturation pulse length on APT imaging of diffuse gliomas using a parallel transmission-based technique. Twenty-two patients with diffuse gliomas (9 low-grade gliomas, LGGs, and 13 high-grade gliomas, HGGs) were included in the study. APT imaging was conducted at 3T with a 2-channel parallel transmission scheme using three different saturation pulse lengths (0.5 s, 1.0 s, 2.0 s). The 2D fast spin-echo sequence was used for imaging. Z-spectrum was obtained at 25 frequency offsets from -6 to +6 ppm (step 0.5 ppm). A point-by-point B0 correction was performed with a B0 map. Magnetization transfer ratio (MTR asym ) and ΔMTR asym (contrast between tumor and normal white matter) at 3.5 ppm were compared among different saturation lengths. A significant increase in MTR asym (3.5 ppm) of HGG was found when the length of saturation pulse became longer (3.09 ± 0.54% at 0.5 s, 3.83 ± 0.67% at 1 s, 4.12 ± 0.97% at 2 s), but MTR asym (3.5 ppm) was not different among the saturation lengths in LGG. ΔMTR asym (3.5 ppm) increased with the length of saturation pulse in both LGG (0.48 ± 0.56% at 0.5 s, 1.28 ± 0.56% at 1 s, 1.88 ± 0.56% at 2 s and HGG (1.72 ± 0.54% at 0.5 s, 2.90 ± 0.49% at 1 s, 3.83 ± 0.88% at 2 s). In both LGG and HGG, APT-weighted contrast was enhanced with the use of longer saturation pulses.