in vivo Saturation Transfer Imaging of Nuclear Overhauser Effect from Aromatic and Aliphatic Protons: Implication to APT Quantification

Tao Jin¹, Seong-Gi Kim¹, ²

Recent <I>in vivo</I> saturation transfer MRI studies have showed significant signals from the Nuclear Overhauser effect (NOE) from aliphatic protons of macromolecules. In this preliminary study, we found that the aromatic protons, with frequency range downfield of water and close to the amide frequencies, can also affect the water signal in a saturation transfer experiment through the NOE, and the effect is significant <I>in vivo</I>. Both aromatic and aliphatic NOE signals are not sensitive to tissue pH, while they impose difficulties to the quantification of amide proton transfer contrast, they may provide novel MRI contrast complementary to CEST.