# 3D joint T1/T1 ρ/T2 mapping and water‐fat imaging for contrast‐agent free myocardial tissue characterization at 1.5T

## TL;DR

This paper introduces a new MRI technique that maps multiple tissue properties and water-fat content in the heart in about 7 minutes without contrast agents.

## Contribution

A novel 3D joint T1/T1ρ/T2 mapping sequence with water-fat imaging for whole-heart myocardial characterization in a single scan.

## Key findings

- The proposed 3D sequence showed excellent correlation with 2D reference measurements in phantoms.
- Mapping values for healthy subjects were consistent with conventional techniques.
- Promising results were observed in a patient with suspected cardiovascular disease.

## Abstract

To develop a novel, free‐breathing, 3D joint T1/T1ρ/T2 mapping sequence with Dixon encoding to provide co‐registered 3D T1, T1ρ, and T2 maps and water‐fat volumes with isotropic spatial resolution in a single ≈7 min scan for comprehensive contrast‐agent‐free myocardial tissue characterization and simultaneous evaluation of the whole‐heart anatomy.

An interleaving sequence over 5 heartbeats is proposed to provide T1, T1ρ, and T2 encoding, with 3D data acquired with Dixon gradient‐echo readout and 2D image navigators to enable 100% respiratory scan efficiency. Images were reconstructed with a non‐rigid motion‐corrected, low‐rank patch‐based reconstruction, and maps were generated through dictionary matching. The proposed sequence was compared against conventional 2D techniques in phantoms, 10 healthy subjects, and 1 patient.

The proposed 3D T1, T1ρ, and T2 measurements showed excellent correlation with 2D reference measurements in phantoms. For healthy subjects, the mapping values of septal myocardial tissue were T1=1060±48ms, T1ρ=48.1±3.9ms, and T2=44.2±3.2ms for the proposed sequence, against T1=959±15ms, T1ρ=56.4±1.9ms, and T2=47.3±1.5ms for 2D MOLLI, 2D T1ρ‐prep bSSFP and 2D T2‐prep bSSFP, respectively. Promising results were obtained when comparing the proposed mapping to 2D references in 1 patient with active myocarditis.

The proposed approach enables simultaneous 3D whole‐heart joint T1/T1ρ/T2 mapping and water/fat imaging in ≈ 7 min scan time, demonstrating good agreement with conventional mapping techniques in phantoms and healthy subjects and promising results in 1 patient with suspected cardiovascular disease.