The ECV in the myocardium may be estimated from the concentration of extracellular contrast agent in the myocardium relative to the blood in a dynamic steady state [7 (link),9 (link),13 (link)].
since the change in relaxation rate ΔR1 (where R1 = 1/T1) between pre and post contrast is directly proportional to the Gd-DTPA concentration, ΔR1 = γ [Gd-DTPA] (γ = 4.5 L mmol-1 sec-1). A dynamic steady state exists for tissues which have a contrast exchange rate with the blood which is faster than the net clearance of contrast from the blood [7 (link)]. A dynamic steady state between the plasma and interstitium may be achieved by slow intravenous infusion [3 (link),9 (link)], or by imaging 15 min following an intravenous bolus administration [12 (link),13 (link)] for normally perfused myocardium, although 15 min may not be adequate for recently infarcted myocardium [16 (link)]. The bolus method was used in this study since it fits well with clinical workflow and permits conventional late enhancement imaging at the desired dose. The ECV formula (Eq [1 ]) implies that our myocardial ECV measurements include both the intra- and extravascular space, and is related to the estimate of extracellular extravascular volume fraction (Ve) [8 (link),12 (link)] which includes additional constant factors. The factor (1-hematocrit), which varies between individuals, represents the blood volume of distribution (blood ECV) and converts the equation from a partition coefficient calculation to a myocardial ECV.
since the change in relaxation rate ΔR1 (where R1 = 1/T1) between pre and post contrast is directly proportional to the Gd-DTPA concentration, ΔR1 = γ [Gd-DTPA] (γ = 4.5 L mmol-1 sec-1). A dynamic steady state exists for tissues which have a contrast exchange rate with the blood which is faster than the net clearance of contrast from the blood [7 (link)]. A dynamic steady state between the plasma and interstitium may be achieved by slow intravenous infusion [3 (link),9 (link)], or by imaging 15 min following an intravenous bolus administration [12 (link),13 (link)] for normally perfused myocardium, although 15 min may not be adequate for recently infarcted myocardium [16 (link)]. The bolus method was used in this study since it fits well with clinical workflow and permits conventional late enhancement imaging at the desired dose. The ECV formula (Eq [1 ]) implies that our myocardial ECV measurements include both the intra- and extravascular space, and is related to the estimate of extracellular extravascular volume fraction (Ve) [8 (link),12 (link)] which includes additional constant factors. The factor (1-hematocrit), which varies between individuals, represents the blood volume of distribution (blood ECV) and converts the equation from a partition coefficient calculation to a myocardial ECV.
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