MR fingerprinting for rapid quantification of myocardial T₁, T₂, and proton spin density

Abstract

Purpose To introduce a 2D MR Fingerprinting technique for quantification of T1, T2, and M0 in myocardium. Methods An ECG-triggered MR Fingerprinting (MRF) method is introduced for mapping myocardial T1, T2, and M0 during a single breathhold in as short as four heartbeats. The pulse sequence employs variable flip angles, repetition times, inversion recovery times, and T2 preparation dephasing times. A dictionary of possible signal evolutions is simulated for each scan that incorporates the subject’s unique variations in heart rate. Aspects of the sequence design were explored in simulations, and the accuracy and precision of cardiac MRF were assessed in a phantom study. In vivo imaging was performed at 3T in eleven volunteers to generate native parametric maps. Results T1 and T2 measurements from the proposed cardiac MRF sequence correlated well with standard spin echo measurements in the phantom study (R2>0.99). A Bland-Altman analysis revealed good agreement for myocardial T1 measurements between MRF and MOLLI (bias 1ms, 95% limits of agreement −72 to 72ms) and T2 measurements between MRF and T2-prepared bSSFP (bias −2.6ms, 95% limits of agreement −8.5 to 3.3ms). Conclusions MRF can provide quantitative single slice T1, T2, and M0 maps in the heart within a single breathhold.

MR Fingerprinting of Adult Brain Tumors: Initial Experience

“…Given its multiparametric capabilities and repeatability, this technique holds the capability to become a useful MR imaging biomarker 29, 30 . Although the clinical applications and utility of this technique have not been assessed so far, the in-vivo quantitation data in healthy volunteers and in patients are emerging 31–33 .…”

Magnetic resonance fingerprinting – An overview

“…For example, Ma, et al [2] used a sequential reordering strategy with spiral trajectory for balanced steady state free precession (bSSFP) based MRF for brain imaging. Hamilton, et al [15] used a golden angle based rotational reordering strategy with spiral trajectory for steady state free precession (SSFP) based MRF for cardiac imaging. Cloos, et al [7] used a uniform rotational reordering strategy with radial trajectory for Plug-n-Play based MRF (PnP-MRF) for musculoskeletal imaging.…”

“…Depending on the organ being evaluated or the physiological properties being measured through the MRF acquisition, the collection of fingerprints may either be generated only once for each sequence and applied to all patients[2,14] or may have to be generated individually for each patient[10,15]. For example in cardiac MRF as described by Hamilton, et al [15], the simulation was repeated individually for each new scan to accommodate the differences in heart rate for each person.…”

“…For example in cardiac MRF as described by Hamilton, et al [15], the simulation was repeated individually for each new scan to accommodate the differences in heart rate for each person. However, this process took only 12 seconds, so there was no major time-penalty.…”

“…Cardiac MRF as described by Hamilton, et al [15] provided simultaneous estimation of T1, T2 and M 0 values with a resolution of 1.6 × 1.6 × 8 mm 3 using a breath-hold acquisition of 16 heartbeats. While there are no patient data available yet, comparison of T1 and T2 MRF values from normal volunteers show good concordance with conventional mapping methods[15]. Further technical development involves reducing the scan time, volumetric acquisition for whole heart coverage and optimizing the M 0 values obtained.…”