Craig Kenneth Jones1,2, Alan J. Huang1,3, Peter C. M. van Zijl1,2
1FM Kirby Center, Kennedy Krieger Institute, Baltimore, MD, United States; 2Department of Radiology & Radiological Sciences, Johns Hopkins Medical Institutes, Baltimore, MD, United States; 3Department of Biomedical Engineering, Johns Hopkins University, Baltimore, MD, United States
Recently, chemical exchange saturation transfer (CEST) MRI has been used to detect the signals of mobile proteins and peptides in vivo through the exchange between amide protons and water protons. It is well known that mid to large size mobile macromolecules should experience cross-relaxation effects called Nuclear Overhauser Enhancements (NOEs), the build-up of which should be slower than exchange effects. In this work, exchange-relayed NOEs of mobile proteins are shown to be visible in CEST images in vivo. This is possible because a small B1 irradiation field was used to avoid competing effects from exchange and semi-solid magnetization transfer effects.