Free‐breathing, non‐ECG, continuous myocardial T₁ mapping with cardiovascular magnetic resonance multitasking

Abstract

Purpose To evaluate the accuracy and repeatability of a free‐breathing, non‐electrocardiogram (ECG), continuous myocardial T1 and extracellular volume (ECV) mapping technique adapted from the Multitasking framework. Methods The Multitasking framework is adapted to quantify both myocardial native T1 and ECV with a free‐breathing, non‐ECG, continuous acquisition T1 mapping method. We acquire interleaved high–spatial resolution image data and high–temporal resolution auxiliary data following inversion‐recovery pulses at set intervals and perform low‐rank tensor imaging to reconstruct images at 344 inversion times, 20 cardiac phases, and 6 respiratory phases. The accuracy and repeatability of Multitasking T1 mapping in generating native T1 and ECV maps are compared with conventional techniques in a phantom, a simulation, 12 healthy subjects, and 10 acute myocardial infarction patients. Results In phantoms, Multitasking T1 mapping correlated strongly with the gold‐standard spin‐echo inversion recovery (R2 = 0.99). A simulation study demonstrated that Multitasking T1 mapping has similar myocardial sharpness to the fully sampled ground truth. In vivo native T1 and ECV values from Multitasking T1 mapping agree well with conventional MOLLI values and show good repeatability for native T1 and ECV mapping for 60 seconds, 30 seconds, or 15 seconds of data. Multitasking native T1 and ECV in myocardial infarction patients correlate positively with values from MOLLI. Conclusion Multitasking T1 mapping can quantify native T1 and ECV in the myocardium with free‐breathing, non‐ECG, continuous scans with good image quality and good repeatability in vivo in healthy subjects, and correlation with MOLLI T1 and ECV in acute myocardial infarction patients.

High‐dimensionality undersampled patch‐based reconstruction (HD‐PROST) for accelerated multi‐contrast MRI

“…The average reconstruction time for 2D MRF with HD‐PROST was ~10 min per data set. Additional comparisons with single‐contrast PROST reconstruction (i.e., reconstructing each singular image independently) and with a global low‐rank tensor decomposition (in the spirit of cardiac multitasking) are provided in Supporting Information Figure .…”

“…These types of reconstruction techniques, also known as the globally (GLR) or locally low‐rank (LLR) methods, have been efficiently used in many applications such as T 2 mapping or dynamic contrast enhanced MRI . More recently, high‐order tensor decomposition techniques, exploiting global correlation, have been efficiently used to allow for highly accelerated multi‐dimensional cardiac MRI acquisitions . Although those techniques have shown promise for motion‐resolved quantitative cardiac imaging by efficiently solving a global low‐rank tensor decomposition, they do not exploit the strong non‐local correlations between neighboring patches.…”

Cardiac T1 mapping: Techniques and applications

“…The magnetization evolution during the acquisition is characteristic of a specific combination of T 1 and T 2 , and thus the T 1 and T 2 values can be simultaneously determined by pattern matching. CMR multitasking is another computational approach to parametric mapping, where continuous golden‐angle radial data are acquired following an inversion pulse without ECG gating or breath‐holding . Low‐rank tensor modeling is used to resolve both cardiac and respiratory motion during reconstruction, yielding dynamic T 1 maps as a function of cardiac or respiratory phase.…”

Free‐running 3D whole heart myocardial T1 mapping with isotropic spatial resolution

“…Recently, the magnetic resonance multitasking technique using 2D radial acquisition has been proposed for motionresolved quantitative myocardial T 1 and T 2 imaging without breath-holding or ECG triggering. 15,16 2D myocardial mapping is typically performed with thick slices to avoid the influence of through-plane motion 13 and low SNR. 3D acquisitions can overcome these limitations and provide whole heart coverage for comprehensive characterization of diffuse diseases of myocardium.…”