3D simultaneous quantification of SPIO and Gadolinium Contrast Agents In Vivo using MR Fingerprinting

Abstract

Molecular imaging is a powerful asset to a range of disciplines, allowing for precise, noninvasive, longitudinal imaging of a myriad of biological processes. Magnetic resonance molecular imaging offers the ability to perform longitudinal studies of molecular interactions with excellent contrast, high resolution deep within tissue, without the use of radionuclides. With the emergence of molecular imaging, the number of contrast agents targeting specific molecular or cellular processes has dramatically expanded. However, molecular imaging studies are still limited to qualitative analysis of a single agent, either requiring multiple imaging sessions, or expensive multi-modal equipment to image more than one agent. Simultaneous quantification of multiple contrast agents on a single modality would dramatically improve the research potential of molecular imaging studies.

Magnetic resonance fingerprinting (MRF) offers a novel MR imaging methodology that can generate multiple parameter maps simultaneously while allowing for greatly accelerated acquisition times. While previous studies have shown that information gathered using MRF can separate two contrast agents administered simultaneously in vitro, it has not yet been demonstrated that MRF can quantify the two agents most commonly used in molecular imaging studies: Gadolinium and SPIO, the latter of which imposes the additional requirement of T2* mapping. The objective of this project is to develop and apply an implementation of MRF which includes sufficient T2* mapping to quantify SPIO labelled cells and a Gadolinium contrast agent in vivo, in 3D, within a preclinically acceptable scan time of approximately 20 mins. Dual quantification of these two agents in vivo would allow for studies mapping complex molecular interactions, such as immunotherapy drug location and cell death maps, simultaneously.