Initial experiences with Amide Proton Transfer Imaging – Correlation between quantitative MTRasym ratio, rCBV and rCBF values in brain tumours
Poster Presentation at the European Congress of Radiology, Vienna, 2019
Amide proton transfer (APT) imaging is a new molecular MRI technique based on chemical exchange saturation transfer mechanism with proposed use as an imaging biomarker in brain tumours. We evaluated the correlation between Asymmetric magnetization transfer ratio (MTRasym) measured on APT scans with relative cerebral blood volume (rCBV) and relative CBF (rCBF) values measured on Dynamic susceptibility contrast (DSC) MR perfusion in patients with brain tumours.
Methods and Materials
Eleven patients underwent the clinical MRI protocol on 3.0 T MRI (Ingenia, Philips), followed by Perfusion and APT scans. Perfusion scans were performed using first-pass dynamic susceptibility-weighted contrast-enhanced (DSC) perfusion-weighted images and APT scans were performed by using a 2-dimensional single-slice radiofrequency-spoiled GRE protocol, with 21 frequency offsets from +5 to −5 ppm. ROIs were placed in solid parts of tumours on both perfusion and APT maps and the corresponding MTRasym, rCBV and rCBF values were measured.
The MTRasym, rCBV and rCBF values were plotted in each case and compared. The Pearson product-moment correlation coefficients were calculated between MTRasym and rCBV as well as MTRasym and rCBF were 0.3022 and 0.1158 suggesting a very weak correlation.
This study revealed a very weak correlation between quantitative values of APT scans and rCBV values measured on DSC perfusion scans. Although technically a positive correlation, the relationship between them is weak. Further prospective evaluation of APT is needed to corroborate our early observations.