Delayed myocardial enhancement is achieved by intravenously injecting a certain amount of magnetic contrast agent and performing an MRI 5 to 20 minutes later, when the active myocardial signal is suppressed and the infarcted area of the myocardium is shown as a high signal.
The mechanism of delayed myocardial enhancement can be categorized into the following two points.
1. Delayed inflow and outflow of contrast in the infarcted area, the reduction of the microvascular bed in the infarcted area of the myocardium will lead to the lengthening of the distance for the contrast to diffuse into the extravascular area, and the diffusion time and the square of the diffusion distance are proportional to the square of the diffusion distance, so the inflow and outflow of the contrast is prolonged, and the infarcted area can be measured according to the area of the high signal from the delayed enhancement image, which will outline the contour of the infarcted area of the myocardium.
2. The increase of extracellular gap in the infarcted area leads to the increase of the contrast agent gap. The edema and cell membrane destruction in the infarcted area can increase the extracellular gap, leading to the increase of the spatial distribution of the contrast agent distribution.
The occurrence of delayed myocardial enhancement requires timely consultation and reasonable treatment in accordance with medical advice.