Preclinical MR fingerprinting (MRF) at 7 T: effective quantitative imaging for rodent disease models

Abstract

High field, preclinical magnetic resonance imaging (MRI) scanners are now commonly used to quantitatively assess disease status and efficacy of novel therapies in a wide variety of rodent models. Unfortunately, conventional MRI methods are highly susceptible to respiratory and cardiac motion artifacts resulting in potentially inaccurate and misleading data. We have developed an initial preclinical, 7.0 T MRI implementation of the highly novel Magnetic Resonance Fingerprinting (MRF) methodology that has been previously described for clinical imaging applications. The MRF technology combines a priori variation in the MRI acquisition parameters with dictionary-based matching of acquired signal evolution profiles to simultaneously generate quantitative maps of T1 and T2 relaxation times and proton density. This preclinical MRF acquisition was constructed from a Fast Imaging with Steady-state Free Precession (FISP) MRI pulse sequence to acquire 600 MRF images with both evolving T1 and T2 weighting in approximately 30 minutes. This initial high field preclinical MRF investigation demonstrated reproducible and differentiated estimates of in vitro phantoms with different relaxation times. In vivo preclinical MRF results in mouse kidneys and brain tumor models demonstrated an inherent resistance to respiratory motion artifacts as well as sensitivity to known pathology. These results suggest that MRF methodology may offer the opportunity for quantification of numerous MRI parameters for a wide variety of preclinical imaging applications.

Rapid T2 mapping of mouse heart using the carr–purcell–meiboom–gill sequence and compressed sensing reconstruction

“…A novel MR imaging and post-processing method, termed MR fingerprinting, has been proposed recently, which can provide simultaneous T 1 and T 2 quantification in spite of field inhomogeneities (19). The application of this novel technique for mouse brain and body imaging has been recently reported (20), but its application for T 2 mapping in fast-beating mouse heart remains to be demonstrated.…”

MR Fingerprinting for Rapid Quantitative Abdominal Imaging

“…To retrieve tissue properties (T1, T2, and M 0 ) from the FISP MR fingerprinting experiment, a dictionary that included the signal evolutions from all possible combinations of parameters for a T1 range of 100-3000 msec, a T2 range of 5-500 msec, and a B 1 range of 10%-200% of the nominal value was calculated by using Bloch simulations (14). B 1 was simulated as a ratio of obtained flip angle divided by the nominal (expected) flip angle and thus was unitless.…”

Dual Contrast - Magnetic Resonance Fingerprinting (DC-MRF): A Platform for Simultaneous Quantification of Multiple MRI Contrast Agents

“…The MRF method acquired 3000 images with time-varying contrast generated by the FA and TR variation. This FISP-MRF implementation included a non-selective inversion preparation (inversion time = 21 ms) immediately prior to the FISP-MRF image acquisitions to increase the sensitivity of the MRF signal evolution profiles to T1 relaxation times 22 . The MRF acquisition also incorporated undersampled spiral trajectories as described previously 25 .…”

“…This important factor limits the capability of MRI to independently assess simultaneously-administered contrast agents (e.g., a Gd-based T1 agent and an iron-based T2 agent). The Magnetic Resonance Fingerprinting (MRF) methodology has recently been developed to simultaneously generate inherently co-registered T1 and T2 relaxation time maps in both patients [19][20][21] and animal models 22,23 . MRF uses a unique acquisition and quantification strategy that combines a priori acquisition parameter variation with a dictionary-based pattern matching algorithm to obtain quantitative assessments of multiple imaging parameters simultaneously.…”