Comparison between cardiac magnetic resonance stress T1 mapping and [15O]H2O positron emission tomography in patients with suspected obstructive coronary artery disease

Aims To compare cardiac magnetic resonance (CMR) measurement of T1 reactivity (DT1) with [¹⁵O]H₂O positron emission tomography (PET) measurements of quantitative myocardial perfusion. ................................................................................................................................................................................................... Methods Forty-three patients with suspected obstructed coronary artery disease underwent [¹⁵O]H₂O PET and CMR at and results 1.5-T, including rest and adenosine stress T1 mapping (ShMOLLI) and late gadolinium enhancement to rule out presence of scar tissue. DT1 was determined for the three main vascular territories and compared with [¹⁵O]H₂O PET-derived regional stress myocardial blood flow (MBF) and myocardial flow reserve (MFR). DT1 showed a significant but poor correlation with stress MBF (R² = 0.04, P = 0.03) and MFR (R² = 0.07, P = 0.004). Vascular territories with impaired stress MBF (i.e. <_2.30 mL/min/g) demonstrated attenuated DT1 compared with vascular territories with preserved stress MBF (2.9 ± 2.2% vs. 4.1 ± 2.2%, P = 0.008). In contrast, DT1 did not differ between vascular territories with impaired (i.e. <2.50) and preserved MFR (3.2 ± 2.6% vs. 4.0 ± 2.1%, P = 0.25). Receiver operating curve analysis of DT1 resulted in an area under the curve of 0.66 [95% confidence interval (CI): 0.57–0.75, P = 0.009] for diagnosing impaired stress MBF and 0.62 (95% CI: 0.53–0.71, P = 0.07) for diagnosing impaired MFR. ................................................................................................................................................................................................... Conclusions CMR stress T1 mapping has poor agreement with [¹⁵O]H₂O PET measurements of absolute myocardial perfusion. Stress T1 and DT1 are lower in vascular territories with reduced stress MBF but have poor accuracy for detecting impaired myocardial perfusion.