Abstract
Summary Transcytolemal water exchange and its effect on myocardial T1 relaxation can, if neglected, lead to a significant underestimate of the myocardial extracellular volume fraction, a novel marker of diffuse fibrosis. Background LGE may fail to detect diffuse fibrosis in several cardiac conditions. A novel approach uses the myocardial extracellular volume-fraction (MECVF), measured as distribution volume of a gadolinium constrast, as a marker of extracellular expansion. Previous studies have assumed the fast-exchange (FX) limit for the transcytolemal waterexchange, yet the administration of an extracellular-agent can create significant transcytolemal T1-differences, and cause an underestimation of extracellular volume fraction under the FX assumption. We hypothesized that the quantitative measure of MECVF with using a 2-site H-exchange model (2SX-model) correlates positively with the extracellular volume fraction, while the FX approach underestimates extra-cellular matrix expansion in a rodent model of hypertensive heart disease and diffuse myocardial fibrosis created by administration of L-NAME. Methods L-NAME(3mg/ml) or placebo was administered respectively to 22(bw=36.9±2.3g) and 15(bw=37.6±2.5g) wildtype mice. Animals were imaged at baseline and 7weeks after treatment on a 4.7T small-animal MRI-system. T1(#of T1’s>5/mouse) was quantified with a modified Look-Locker gradient-echo-cine technique, before and after fractionated Gd-DPTA administration (mean max. R1 in blood post-contrast=5.0±2.26 1/s). MECVF obtained from the T1 measurements with the 2SX and FX-models, and by using blood hematocrit to adjust the partition coefficient. Connective tissue volume fraction (CTVF) was measured using Masson’s trichrome.
Highlights
LGE may fail to detect diffuse fibrosis in several cardiac conditions
We hypothesized that the quantitative measure of myocardial extracellular volume-fraction (MECVF) with using a 2-site H-exchange model (2SX-model) correlates positively with the extracellular volume fraction, while the FX approach underestimates extra-cellular matrix expansion in a rodent model of hypertensive heart disease and diffuse myocardial fibrosis created by administration of L-NAME
MECVF was substantially higher in L-NAME-treated animals (0.43±0.09 vs, 0.26±0.03, p
Summary
Novel magnetic resonance imaging marker of diffuse myocardial fibrosis in hypertensive heart disease: the role of transcytolemmal waterexchange. Summary Transcytolemal water exchange and its effect on myocardial T1 relaxation can, if neglected, lead to a significant underestimate of the myocardial extracellular volume fraction, a novel marker of diffuse fibrosis
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have