To measure and assess the significance of myocardial extracellular volume (ECV), determined non-invasively by equilibrium contrast cardiovascular magnetic resonance, as a clinical biomarker in health and a number of cardiac diseases of varying pathophysiology.
Tertiary referral cardiology centre in London, UK.
192 patients were mainly recruited from specialist clinics. We studied patients with Anderson-Fabry disease (AFD, n=17), dilated cardiomyopathy (DCM, n=31), hypertrophic cardiomyopathy (HCM, n=31), severe aortic stenosis (AS, n=66), cardiac AL amyloidosis (n=27) and myocardial infarction (MI, n=20). The results were compared with those for 81 normal subjects.
In normal subjects, ECV (mean (95% CI), measured in the septum) was slightly higher in women than men (0.273 (0.264 to 0.282 vs 0.233 (0.225 to 0.244), p<0.001), with no change with age. In disease, the ECV of AFD was the same as in normal subjects but higher in all other diseases (p<0.001). Mean ECV was the same in DCM, HCM and AS (0.280, 0.291, 0.276 respectively), but higher in cardiac AL amyloidosis and higher again in MI (0.466 and 0.585 respectively, each p<0.001). Where ECV was elevated, correlations were found with indexed left ventricular mass, end systolic volume, ejection fraction and left atrial area in apparent disease-specific patterns.
Myocardial ECV, assessed non-invasively in the septum with equilibrium contrast cardiovascular magnetic resonance, shows gender differences in normal individuals and disease-specific variability. Therefore, ECV shows early potential to be a useful biomarker in health and disease.
"In a single breath-hold, using various approaches, a T1 colour relaxation map is made [11–13]. Within the map, each given pixel value directly corresponds its underlying relaxation time that can be seen (in colour) or more formally measured, standardized, calibrated to histology [14••, 15, 16], compared across diseases and with normal reference ranges . There are two key ways of using T1 mapping: without or before contrast (native T1 mapping); and with contrast, typically by subtracting the pre and post maps with hematocrit correction to generate the extracellular volume fraction (ECV) (Fig. 1). "
[Show abstract][Hide abstract] ABSTRACT: Heart failure (HF) is a major and growing cause of morbidity and mortality. Despite initial successes, there have been few recent therapeutic advances. A better understanding of HF pathophysiology is needed with renewed focus on the myocardium itself. A new imaging technique is now available that holds promise. T1 mapping is a cardiovascular magnetic resonance (CMR) technique for non-invasive myocardial tissue characterization. T1 alters with disease. Pre-contrast (native) T1 changes with a number of processes such as fibrosis, edema and infiltrations. If a post contrast scan is also done, the extracellular volume fraction (ECV) can be measured, a direct measure of the interstitium and its reciprocal, the cell volume. This dichotomy is fundamental - and now measurable promising more targeted therapy and new insights into disease biology.
Current Cardiovascular Imaging Reports 09/2014; 7(9):9287. DOI:10.1007/s12410-014-9287-8
"It must be noted however that the majority of these segments were located at the septum, which also showed highest ECV values in healthy control subjects (Table 2). The ECV value observed in our control group was similar to values reported in earlier studies using a similar MOLLI-sequence for T1 mapping before and after contrast administration, and the standard deviation was rather small [18,19]. "
[Show abstract][Hide abstract] ABSTRACT: In hypertrophic cardiomyopathy (HCM), autopsy studies revealed both increased focal and diffuse deposition of collagen fibers. Late gadolinium enhancement imaging (LGE) detects focal fibrosis, but is unable to depict interstitial fibrosis. We hypothesized that with T1 mapping, which is employed to determine the myocardial extracellular volume fraction (ECV), can detect diffuse interstitial fibrosis in HCM patients.
T1 mapping with a modified Look-Locker Inversion Recovery (MOLLI) pulse sequence was used to calculate ECV in manifest HCM (n = 16) patients and in healthy controls (n = 14). ECV was determined in areas where focal fibrosis was excluded with LGE.
The total group of HCM patients showed no significant changes in mean ECV values with respect to controls (0.26 +/- 0.03 vs 0.26 +/- 0.02, p = 0.83). Besides, ECV in LGE positive HCM patients was comparable with LGE negative HCM patients (0.27 +/- 0.03 vs 0.25 +/- 0.03, p = 0.12).
This study showed that HCM patients have a similar ECV (e.g. interstitial fibrosis) in myocardium without LGE as healthy controls. Therefore, the additional clinical value of T1 mapping in HCM seems limited, but future larger studies are needed to establish the clinical and prognostic potential of this new technique within HCM.
Journal of Cardiovascular Magnetic Resonance 04/2014; 16(1):28. DOI:10.1186/1532-429X-16-28 · 4.56 Impact Factor
"Newer refinements include shorter breath-holds, better sequence design, and lately, ECV maps with pixel-by-pixel representation of ECV for a simplified detection and quantitative display of focal and diffuse fibrosis (see Fig. 1) [57••]. There is an apparent spectrum of interstitial expansion with cardiac amyloid, aortic stenosis and cardiomyopathy having large changes in ECV; but age and gender have much smaller or possibly no contributions  once partial volume issues are accounted for. The ratio of pathophysiological signal to measurement error is a key determinant of test performance. "
[Show abstract][Hide abstract] ABSTRACT: Cardiovascular magnetic resonance imaging (CMR) has become the gold standard not only for cardiac volume and function quantification, but for a key unique strength: non-invasive myocardial tissue characterization. Several different techniques, separately or in combination, can detect and quantify early and established myocardial pathological processes permitting better diagnosis, prognostication and tracking of therapy. The authors will focus on the histological and pathophysiological evidence of these imaging parameters in the characterization of edema, infarction, scar and fibrosis. In addition to laying out the strengths and weaknesses of each modality, the reader will be introduced to rapid developments in T1 and T2 mapping as well as the use of contrast-derived extracellular volume for quantification of diffuse fibrosis.
Current Cardiovascular Imaging Reports 03/2014; 7(3). DOI:10.1007/s12410-013-9254-9
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