Contrast-Enhanced Magnetic Resonance Imaging for Detection and Quantification of Fibrosis in Human Myocardium
OHSU # 1182
Myocardial fibrosis is a morphologic change common to multiple cardiac disease conditions. In addition to replacement (scar) fibrosis, there is increasing recognition of interstitial (reactive) fibrosis acting as an important player in structural remodeling of the diseased heart, as well as the genesis of fatal arrhythmia leading to sudden cardiac death.
OHSU has developed a novel, non-invasive, imaging-based test to analyze diffuse fibrosis to determine the global fibrosis burden on the heart. OHSU’s unique software techniques, in combination with DCE-MRI, can obtain a quantitative measure of the extracellular volume fraction as a marker of fibrosis in viable and nonviable myocardium.
Currently, fibrosis is quantified by histochemical analysis of tissue samples obtained by surgical biopsy. Biopsies are simply localized samples that do not provide a reliable indication of the overall fibrosis burden on the whole heart. The availability of a non-invasive test to quantify replacement and interstitial fibrosis shown to be correlated with the current gold standard and most widely used measure for quantification of myocardial fibrosis (collagen volume fraction (CVF)):
• Reduces the need for endocardial biopsies
• Provides a significant advancement for improving patient care, treatment planning and patient risk determination.
MRI of delayed contrast enhancement (DCE) with an extracellular contrast agent has become a desirable method to depict non-viable myocardium with high spatial resolution. DCE MRI relies on the detection of contrast enhancement relative to other remote areas in the heart, as following acute myocardial infarction. MRI of delayed contrast enhancement reflects the breakdown of the cell-membrane, which increases the volume of distribution of the contrast relative to viable myocardium.
In cardiac diseases such as non-ischemic dilated cardiomyopathies with evidence from histology of diffuse fibrosis, current non-invasive tests, including those based on cardiac MRI, may fail in detecting diffuse, generalized fibrosis. Focal areas of delayed contrast enhancement may be either absent, or only provide a partial measure of fibrosis extent and burden.
This is achieved by measuring the myocardial partition coefficient for an extracellular contrast agent, showing the relative distribution volume of the contrast agent which are used to quantify diffuse, reactive, interstitial, or replacement fibrosis, conditions that may be inadequately detected by current methods. Such determined amounts and/or locations of myocardial fibrosis may be correlated to the risk of heart disease or failure and in such a way a risk factor, such as a numeric or textual risk factor, may be assigned and be helpful in risk stratification for sudden cardiac death as well as disease severity, thereby providing important information for treatment planning.
PCT Publication No. WO/2008/128033
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