Fat-corrected rNOE-CEST contrast for breast cancer imaging

Motivation: Application of quantitative CEST contrasts for breast imaging is limited due to pronounced fat-induced artifacts. The most prominent fat artifact appears in the Z-spectrum between [-2,-4] ppm, directly overlapping the rNOE signal at around -3.5 ppm, making accurate rNOE evaluation extremely challenging. Goal(s): To investigate fat-corrected rNOE-CEST contrast (MTRRex) in breast cancer. Approach: We retrospectively apply a novel postprocessing fat correction procedure on CEST data of patients with breast cancer. Results: Fat-corrected MTRRex rNOE values showed 140% increase in tumor as compared to normal-appearing glandular tissue. Furthermore, a strong correlation (R2=0.71) between MTRRex rNOE and the tumor proliferation marker Ki-67 was found. Impact: The significant elevation in fat-corrected MTRRex rNOE contrast along with the strong correlation with a tumor proliferation marker indicate the potential to use rNOE imaging as a valuable non-invasive imaging biomarker for breast cancer diagnosis, treatment planning, and monitoring.