Elsevier

JACC: Cardiovascular Imaging

Volume 15, Issue 12, December 2022, Pages 2069-2079
JACC: Cardiovascular Imaging

Original Research
Native T1 Mapping for the Diagnosis of Myocardial Fibrosis in Patients With Chronic Myocardial Infarction

https://doi.org/10.1016/j.jcmg.2022.09.011Get rights and content
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Abstract

Background

Myocardial fibrosis is a fundamental process in cardiac injury. Cardiac magnetic resonance native T1 mapping has been proposed for diagnosing myocardial fibrosis without the need for gadolinium contrast. However, recent studies suggest that T1 measurements can be erroneous in the presence of intramyocardial fat.

Objectives

The purpose of this study was to investigate whether the presence of fatty metaplasia affects the accuracy of native T1 maps for the diagnosis of myocardial replacement fibrosis in patients with chronic myocardial infarction (MI).

Methods

Consecutive patients (n = 312) with documented chronic MI (>6 months old) and controls without MI (n = 50) were prospectively enrolled. Presence and size of regions with elevated native T1 and infarction were quantitatively determined (mean + 5SD) on modified look-locker inversion-recovery and delayed-enhancement images, respectively, at 3.0-T. The presence of fatty metaplasia was determined using an out-of-phase steady-state free-precession cine technique and further verified with standard fat-water Dixon methods.

Results

Native T1 mapping detected chronic MI with markedly higher sensitivity in patients with fatty metaplasia than those without fatty metaplasia (85.6% vs 13.3%) with similar specificity (100% vs 98.9%). In patients with fatty metaplasia, the size of regions with elevated T1 significantly underestimated infarct size and there was a better correlation with fatty metaplasia size than infarct size (r = 0.76 vs r = 0.49). In patients without fatty metaplasia, most of the modest elevation in T1 appeared to be secondary to subchronic infarcts that were 6 to 12 months old; the T1 of infarcts >12 months old was not different from noninfarcted myocardium.

Conclusions

Native T1 mapping is poor at detecting replacement fibrosis but may indirectly detect chronic MI if there is associated fatty metaplasia. Native T1 mapping for the diagnosis and characterization of myocardial fibrosis is unreliable.

Key Words

chronic myocardial infarction
fatty metaplasia
fibrosis
cardiac magnetic resonance
MRI
T1 mapping

Abbreviations and Acronyms

CMR
cardiac magnetic resonance
DE-CMR
delayed-enhancement cardiac magnetic resonance
GBCA
gadolinium-based contrast agent
GRE
gradient-recalled echo
LV
left ventricular
MI
myocardial infarction
OOP
out-of-phase
ROI
region of interest
SSFP
steady-state free-precession

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