Stress T1 mapping and quantitative perfusion cardiovascular magnetic resonance in patients with suspected obstructive coronary artery disease

Abstract

Aims: T1 mapping reactivity (ΔT1) has been proposed as a novel contrast-free technique to detect obstructive coronary artery disease (CAD). The aims of the study are: (i) to compare the cardiovascular magnetic resonance (CMR)-derived ΔT1 with quantitative perfusion (QP CMR) measures; (ii) to assess the influence of sex and comorbidities on ΔT1; and (iii) to assess the diagnostic accuracy of ΔT1 to detect obstructive CAD diagnosed with the invasive coronary angiography (ICA) and/or fractional flow reserve.

Methods and results: This study retrospectively analysed 51 patients with suspected obstructive CAD who underwent CMR including rest and adenosine stress first-pass perfusion and native T1 mapping (MOLLI). A moderate correlation was found between pooled rest and stress native T1 mapping and myocardial blood flow (Pearson's r = 0.476; P < 0.001). When stratified by myocardial perfusion reserve (MPR), ischaemic myocardium had significantly lower stress T1 mapping values (P < 0.001) and ΔT1 (P = 0.005) vs. nonischaemic myocardium. Male sex and history of diabetes were independently associated with lower ΔT1. The optimal cut-off value of ΔT1 to detect impaired MPR on a per-vessel basis was ≤5.4%, with an area under the curve of 0.662 (95% CI: 0.563-0.752, P = 0.003), sensitivity of 84% (95% CI: 67-95), and specificity of 46% (95% CI: 34-58). When validated against ICA, stress T1 and ΔT1 did not reach statistical significance in detecting obstructive CAD.

Conclusion: ΔT1 is significantly influenced by sex and comorbidities and has poor diagnostic accuracy for detecting myocardial ischaemia. Therefore, the clinical utility of ΔT1 in a real-world cohort of patients to detect obstructive CAD is limited.

Keywords: T1 mapping; cardiovascular magnetic resonance; coronary artery disease; myocardial ischaemia; quantitative perfusion.

Graphical Abstract

This study compared CMR-derived ΔT1 and QP measures, evaluated the influence of sex and comorbidities on ΔT1, and assessed the diagnostic accuracy of ΔT1 to detect oCAD, as diagnosed by ICA and/or fractional flow reserve, in a real-world cohort of patients with suspected oCAD. Pooled rest and stress native T1 mapping correlated moderately with MBF (Pearson’s r = 0.476; P < 0.001). The optimal cut-off value of ΔT1 to detect impaired MPR on a per-vessel basis was ≤5.4%, with an AUC of 0.662 (95% CI: 0.563–0.752, P = 0.003), sensitivity of 84% (95% CI: 67–95), and specificity of 46% (95% CI: 34–58). When validated against ICA, stress T1 and ΔT1 did not reach statistical significance for detecting oCAD. In contrast, stress MBF and MPR demonstrated good diagnostic accuracy for detecting oCAD with AUCs of 0.834 and 0.745, respectively. In the presented case example, myocardial ischaemia with reduced stress MBF and MPR in all coronary territories was associated with reduced ΔT1 values in the respective territories. ΔT1, T1 mapping reactivity; AUC, area under the curve; CI, confidence interval; CMR, cardiovascular magnetic resonance; ICA, invasive coronary angiography; MBF, myocardial blood flow; MPR, myocardial perfusion reserve; oCAD, obstructive coronary artery disease; QP, quantitative perfusion.

Figure 1

Adenosine stress perfusion CMR scanning protocol. AIF, arterial input function; LAX, long axis; LGE, late gadolinium enhancement; SAX, short axis.

Figure 2

Correlation between T1 mapping and quantitative perfusion measures. MBF, myocardial blood flow.

Figure 3

Native T1 mapping in ischaemic myocardium. Panel A shows rest and stress T1 mapping and ΔT1 in ischaemic and nonischaemic myocardium when stratified by MBF, while panel B shows stratification according to MPR. MBF, myocardial blood flow; MPR, myocardial perfusion reserve; ΔT1, T1 mapping reactivity.

Figure 4

Diagnostic performance of stress T1 mapping and ΔT1 to detect myocardial ischaemia (defined as reduced MPR) on a per-coronary territory analysis. AUC, area under the curve; MPR, myocardial perfusion reserve; ΔT1, T1 mapping reactivity.

Figure 5

Diagnostic performance of T1 mapping and quantitative perfusion measures to detect obstructed coronary artery on a per-coronary territory analysis. AUC, area under the curve; MBF, myocardial blood flow; MPR, myocardial perfusion reserve; ΔT1, T1 mapping reactivity.