Amide Proton Transfer Imaging for Brain Tumors: Initial Experience and Current Status

(Educational Exhibit, RSNA 2018) V Mahajan, MBBS, MBA; R Bhattacharjee, MENG; I Saha, PhD; H Mahajan, MD; S Panwar, MD; V Venugopal, MD TEACHING POINTS • Amide Proton Transfer (APT) Images contain quantitative colour maps that show protein / peptide content. • APT imaging is able to accurately predict tumour grade in pre-surgical cases. • APT imaging is showing promise in differentiating tumour recurrence from radiation necrosis. • APT imaging can be used in combination with Susceptibility Weighted Imaging (SWI) based ITSS (Intra-Tumoral Susceptibility Score) to predict tumour grade when compared to Contrast-Enhanced Perfusion MRI. • Some fundamental problems with the APT acquisition need to be addressed for it to come into day-to-day clinical practice, especially with respect to quantification and artefacts. TABLE OF CONTENTS/OUTLINE • Review of current brain tumour MR imaging protocols • Mechanism behind APT imaging • Review of current clinical literature on APT imaging for brain tumors • APT for tumour recurrence vs radiation necrosis • APT in glioma grading • APT with SWI-based ITSS as a non-contrast replacement for CE-Perfusion MR • Limitations and future directions for APT imaging in the brain