Acute myocardial ischemia and reperfusion: MR imaging with albumin-Gd-DTPA.

Abstract

The utility of a macromolecular, intravascular contrast agent, albumin-gadolinium diethylenetriaminepentaacetic acid (DTPA), for the differentiation of acutely ischemic and reperfused myocardium on magnetic resonance (MR) images was investigated. Regional, reversible myocardial ischemia was produced in rats and confirmed. After reperfusion, flow to the compromised myocardial segment returned to baseline. Normal myocardium could not be differentiated from ischemic myocardium on nonenhanced MR images (n = 12). After 5 minutes of myocardial ischemia and after administration of albumin-Gd-DTPA, the ischemic zone involving the free wall of the left ventricle was characterized by the absence of significant enhancement. Normal myocardium appeared homogeneously enhanced (by 145%). This pattern persisted for up to 1 hour of myocardial ischemia. In six rats that underwent myocardial reperfusion after 5 minutes of ischemia, the normal and reperfused myocardium became isointense. Radiotracer studies with albumin-Gd-153-DTPA confirmed the decreased distribution of contrast agent to the ischemic myocardium, possibly due to decreased blood pool or a blocked primary delivery system in the ischemic myocardium.

Assessment of myocardial salvage after ischemia and reperfusion using magnetic resonance imaging and spectroscopy.

“…However, on reperfusion, the distribution of albumin-"'Gd-DTPA returned to normal in the previously ischemic region ( Figure 6B). These findings correlate with the MRI data using albuminGd-DTPA, in which decreased contrast enhancement was observed within ischemic myocardium after 16 minutes of coronary occlusion. After repertissue T, and increased contrast enhancement in fusion, the signal intensity of the ischemic region normalized (Figures 2A, 2B, and 3C).…”

“…24,25 The myocardial distribution of albumin-"53Gd-DTPA after short periods of ischemia and reflow suggest that this macromolecular contrast agent may serve as a perfusion agent. As noted in Figure 6A, there was significant reduction in the myocardial distribution of radiolabeled albumin in the ischemic region compared with normally perfused myocardium after 16 minutes of coronary occlusion. However, on reperfusion, the distribution of albumin-"'Gd-DTPA returned to normal in the previously ischemic region ( Figure 6B).…”

“…15 This marker allows for the identification of myocardial ischemia and may also allow for the assessment of reperfusion. 16 The present study was designed to assess the ability of MRI with albuminGd-DTPA 1) to identify ischemic myocardium early after coronary occlusion in an animal model of ischemia and reperfusion, 2) to differentiate irreversibly damaged from salvaged myocardium after reperfusion, and 3) to correlate contrast-enhanced MRI changes with those observed in 31phosphorus (31P) magnetic resonance spectroscopy (MRS).…”

Regional myocardial blood volume and flow: First‐pass MR imaging with polylysine‐Gd‐DTPA

“…Convolving the actual input C LV (t) with R MVi (t) and weighting by the relative flow f i and fractional mass w i gives the content q i (t). For the entire ROI, the content q(t) is obtained by summing over the paths: (4) The ROI is thereby defined as that excluding any signal originating outside the region due to imperfect spatial resolution.…”

“…A variety of intravascular and extracellular MR contrast agents have been studied for delineation of infarcted myocardium (1)(2)(3) and for identification of acutely ischemic and reperfused cardiac muscle (4,5). The first-pass MR imaging technique with the extracellular contrast agent gadolinium diethylenetriaminepentaacetic acid (DTPA) has been used to assess myocardial perfusion in patients at rest (6,7) and during pharmacologic stress (8,9).…”