Z Spectral Analysis for the Quantification of Multiple Slow-Exchanging Metabolites

Kejia Cai¹, Anup Singh¹, Mohammad Haris¹, Ravi Prakash Reddy Nanga¹, Ranjit Ittyerah¹, Damodar Reddy¹, Harish Poptani¹, Hari Hariharan¹, Ravinder Reddy¹

This conventional quantification method may be confounded by the intrinsic magnetic transfer ratio (MTR) asymmetry as well as the Nuclear Overhauser Effect (NOE) effect. To decouple these confounding effects, we demonstrate a comprehensive Lorentzian fitting of Z spectra in brain tumor for the quantification of multiple slow-exchanging metabolites contributing to Z spectrum acquired with low RF saturating amplitude. Results show an increased amide proton transfer (APT) integral and a decreased CEST integral at 2ppm in tumor compared to normal brain tissue. The novel Z spectral analysis method may be used for differentiating tumor metabolic profile from normal tissue.