Native T1-rho mapping for myocardial scar detection in patients with probable or confirmed coronary artery disease

T1rho cardiac mapping is an emerging, non-contrast magnetic resonance imaging (MRI) technique sensitive to myocardial biochemical and microstructural changes, whereas late gadolinium enhancement (LGE) remains the reference standard for scar visualization, though its reliance on contrast agent limits its applications and raises safety and environmental concerns. This study aimed to evaluate native T1-rho (T1ρ) mapping in detecting myocardial scars, compared with the gold standard LGE method.

A prospective study was conducted, including patients with suspected or known coronary artery disease (CAD). In addition to adenosine stress cardiac magnetic resonance (CMR) and LGE, native T1ρ mapping was performed. T1ρ-weighted images were acquired at the mid-left ventricular level using a spin-lock preparation pulse with varying durations (0, 20, 30, 40 ms) and a maximum amplitude of 500 Hz. Subsequently, a T1ρ map was generated and compared to LGE for visual assessment, scar quantification, and diagnostic performance.

Of the 250 participants, 75 (30%) were categorized as positive scar based on LGE findings. The sensitivity and specificity (with 95% confidence interval) for scar detection using T1ρ mapping alone were 39% (29-50%) and 88% (83-93%), respectively, which increased to 71% (60-80%) and 99% (96-100%), respectively, by combining with steady-state free precession (SSFP) cine. T1ρ relaxation time in the scarred area was significantly higher than the average T1ρ at the septum of the negative scar group (77.9±7.2 vs. 43.3±4.5 ms, P<0.001). A T1ρ value cut-off of 49.2 ms can detect myocardial scar with a sensitivity and specificity of 81% (74-87%) and 72% (69-74%), respectively.

Native T1ρ mapping can serve as an alternative method to standard LGE method for detecting myocardial scar with good reproducibility and high specificity, though sensitivity was low when only using T1ρ maps.