Elsevier

JACC: Cardiovascular Imaging

Volume 5, Issue 9, September 2012, Pages 897-907
JACC: Cardiovascular Imaging

Original Research
Quantification of Extracellular Matrix Expansion by CMR in Infiltrative Heart Disease

https://doi.org/10.1016/j.jcmg.2012.04.006Get rights and content
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Objectives

The aim of this study was to perform direct quantification of myocardial extracellular volume fraction (ECF) with T1-weighted cardiac magnetic resonance (CMR) imaging in patients suspected to have infiltrative heart disease.

Background

Infiltrative heart disease refers to accumulation of abnormal substances within the myocardium. Qualitative assessment of late gadolinium enhancement (LGE) remains the most commonly used method for CMR evaluation of patients suspected with myocardial infiltration. This technique is widely available and can be performed in a reproducible and standardized manner. However, the degree of extracellular matrix expansion due to myocardial infiltration in the intercellular space has, to date, not been amenable to noninvasive quantification with LGE.

Methods

We performed 3-T CMR in 38 patients (mean age 68 ± 15 years) who were referred for assessment of infiltrative heart disease and also in 9 healthy volunteers as control subjects. The T1 quantification by Look-Locker gradient-echo before and after contrast determined segmental myocardial partition coefficients. The ECF was obtained by referencing the tissue partition coefficient for gadolinium to the plasma volume fraction in blood, derived from serum hematocrit. Cine CMR and LGE imaging in matching locations were also performed.

Results

Seventeen patients (45%) had cardiac amyloidosis (CA) (biopsy-confirmed or clinically highly probable), 20 (53%) had a non-amyloid cardiomyopathy, and 1 had lysosomal storage disease. Median global ECF was substantially higher in CA patients (0.49) compared with non-amyloid cardiomyopathy patients (0.33, p < 0.0001) and volunteers (0.24, p = 0.0001). The ECF strongly correlated with visually assessed segmental LGE (r = 0.80, p < 0.0001) and LV mass index (r = 0.69, p < 0.0001), reflecting severity of myocardial infiltration. In patients with CA, ECF was highest in segments with LGE, although it remained elevated in segments without qualitative LGE.

Conclusions

The CMR ECF quantification identified substantial expansion of the interstitial space in patients with CA compared with volunteers. Further studies using this technique for diagnosis and assessment of the severity of myocardial infiltration are warranted.

Key Words

amyloid
infiltrative cardiomyopathy
left ventricular mass
myocardial delayed enhancement
T1 mapping

Abbreviations and Acronyms

λGd
partition coefficient for gadolinium
CA
cardiac amyloidosis
CMR
cardiac magnetic resonance
ECF
myocardial extracellular fraction
ECG
electrocardiogram
LGE
late gadolinium enhancement
LV
left ventricular
LVEF
left ventricular ejection fraction

Cited by (0)

Dr. Mongeon is supported by the Bourse du Coeur 2009 scholarship and receives research funding from Montreal Heart Institute Foundation, Montreal, Canada. Dr. Jerosch-Herold is supported in part by a research grant from the National Institutes of Health (R01HL090634-01A1). Dr. Kwong receives salary support from a research grant from the National Institutes of Health (NIH R01HL091157). All other authors have reported that they have no relationships relevant to the contents of this paper to disclose.