Tao Jin1, Seong-Gi Kim1, 2
1Department of Radiology, University of Pittsburgh, Pittsburgh, PA, United States; 2Department of Neurobiology, University of Pittsburgh, Pittsburgh, PA, United States
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.