Assessment of intramyocardial hemorrhage with dark-blood T2*-weighted cardiovascular magnetic resonance

Xingmin Guan,Hui Han,Jane Sykes,Hsin-Jung Yang,Yinyin Chen,Daoyuan Ren,Mengsu Zeng,Frank S Prato,Rohan Dharmakumar,Xinheng Zhang,John Butler

doi:10.1186/s12968-021-00787-4

Abstract

BackgroundIntramyocardial hemorrhage (IMH) within myocardial infarction (MI) is associated with major adverse cardiovascular events. Bright-blood T2*-based cardiovascular magnetic resonance (CMR) has emerged as the reference standard for non-invasive IMH detection. Despite this, the dark-blood T2*-based CMR is becoming interchangeably used with bright-blood T2*-weighted CMR in both clinical and preclinical settings for IMH detection. To date however, the relative merits of dark-blood T2*-weighted with respect to bright-blood T2*-weighted CMR for IMH characterization has not been studied. We investigated the diagnostic capacity of dark-blood T2*-weighted CMR against bright-blood T2*-weighted CMR for IMH characterization in clinical and preclinical settings.Materials and methodsHemorrhagic MI patients (n = 20) and canines (n = 11) were imaged in the acute and chronic phases at 1.5 and 3 T with dark- and bright-blood T2*-weighted CMR. Imaging characteristics (Relative signal-to-noise (SNR), Relative contrast-to-noise (CNR), IMH Extent) and diagnostic performance (sensitivity, specificity, accuracy, area-under-the-curve, and inter-observer variability) of dark-blood T2*-weighted CMR for IMH characterization were assessed relative to bright-blood T2*-weighted CMR.ResultsAt both clinical and preclinical settings, compared to bright-blood T2*-weighted CMR, dark-blood T2*-weighted images had significantly lower SNR, CNR and reduced IMH extent (all p < 0.05). Dark-blood T2*-weighted CMR also demonstrated weaker sensitivity, specificity, accuracy, and inter-observer variability compared to bright-blood T2*-weighted CMR (all p < 0.05). These observations were consistent across infarct age and imaging field strengths.ConclusionWhile IMH can be visible on dark-blood T2*-weighted CMR, the overall conspicuity of IMH is significantly reduced compared to that observed in bright-blood T2*-weighted images, across infarct age in clinical and preclinical settings at 1.5 and 3 T. Hence, bright-blood T2*-weighted CMR would be preferable for clinical use since dark-blood T2*-weighted CMR carries the potential to misclassify hemorrhagic MIs as non-hemorrhagic MIs.

Highlights

Intramyocardial hemorrhage (IMH) within myocardial infarction (MI) is associated with major adverse cardiovascular events
While IMH can be visible on dark-blood T2*-weighted cardiovascular magnetic resonance (CMR), the overall conspicuity of IMH is significantly reduced compared to that observed in bright-blood T2*-weighted images, across infarct age in clinical and preclinical settings at 1.5 and 3 T
From the 29 patients undergoing CMR following acute ST-elevation MI (STEMI), a total of 20 patients (17 male, 34–65 years, 58 to 92 kg) were identified to be positive for IMH and 10 patients were assigned to the 1.5 T group and the remaining 10 were assigned to the 3 T group

Summary

Introduction

Intramyocardial hemorrhage (IMH) within myocardial infarction (MI) is associated with major adverse cardiovascular events. Well before the strengths of T2*-based CMR was recognized for IMH detection, T2*-based CMR had become important in the standard of care in patients with global myocardial iron overload diseases such as thalassemia [14] In this setting, T2*-based CMR was originally performed with bright-blood approaches (with blood in LV chamber appearing bright), but later magnetizationprepared dark-blood T2*-based CMR became common as it offered greater immunity to image artifacts [15,16,17]. The tissue environment of global iron loading and hemorrhagic MI are very different—unlike global iron overloading disorder, in hemorrhagic MI, there is gross increase in edema, localized wall motion abnormalities and only spatially localized increases in iron concentration Given these differences, it is unclear whether dark-blood T2*based CMR can yield equivalent diagnostic information as bright-blood T2*-based CMR in the detection and characterization of IMH. We tested our hypothesis by performing a head-to-head comparison between bright- and dark-blood T2*-weighted CMR in ST-elevation MI patients and validated large animal models with IMH in the acute and chronic phases of MI at 1.5 and 3 T

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Discussion

Conclusion