Fig 1.
Z-spectra of LGG (A), HGG (C), and corresponding NAWM (B, D). Z-spectra of tumor was steeper than that of NAWM, presumably because of less MT effect in tumor compared with NAWM. Prolongation of saturation pulses results in larger MT effect and thus wider Z-spectra in both tumor and NAWM.
Fig 2.
MTRasym of tumor (A) and NAWM (B) and ΔMTRasym (C) in LGG. MTRasym (A) of tumor was decreased with the saturation length in lower frequency range (1–2 ppm), but equivalent at 3.5 ppm. MTRasym of NAWM (B) is decreased with the saturation length in the entire frequency range. ΔMTRasym (C) was increased with the saturation length at higher frequency offsets (>2 ppm).
Fig 3.
MTRasym of tumor and NAWM and ΔMTRasym in HGG.
MTRasym of tumor (A) was decreased with the saturation length in lower frequency range (<2 ppm), but was increased at 3.5 ppm. MTRasym of NAWM (B) was decreased with the saturation length in entire frequency range. ΔMTRasym (C) was increased with the saturation length at higher frequency (>2 ppm). ΔMTRasym (3.5 ppm) with the 2 s saturation reached maximum at around 3.5 ppm (specific frequency of amide protons).
Fig 4.
MTRasym (3.5 ppm) and ΔMTRasym (3.5 ppm) of LGG and HGG.
No significant differences were observed in MTRasym (3.5 ppm) among the three saturation lengths in LGG, while MTRasym (3.5 ppm) with the 1 s and 2 s saturation was significantly higher than that with the 0.5 s saturation in HGG (A). ΔMTRasym (3.5 ppm) with the 1 s and 2 s saturation length was significantly higher than that with the 0.5 s saturation in LGG, and ΔMTRasym (3.5ppm) of HGG significantly increased with the saturation length (B). Both MTRasym (3.5ppm) and ΔMTRasym (3.5ppm) were significantly higher in HGG than in LGG at any saturation pulse lengths.
Fig 5.
A case of diffuse astrocytoma (Grade II, LGG).
The APT-weighted signal of the tumor in the left frontal lobe is almost comparable in all the saturation pulse lengths, but the contrast between tumor and normal brain tissue is slightly increased at longer saturation pulses due to decreased signal in NAWM.
Fig 6.
A case of glioblastoma multiforme (Grade IV, HGG).
The APT-weighted signal of the tumor in the left temporal lobe is increased with the saturation length, and the contrast between tumor and normal brain tissue becomes larger at longer saturation pulses.