MRI evaluation of microvascular obstruction in experimental reperfused acute myocardial infarction using a T1 and T2 preparation pulse sequence

J Magn Reson Imaging. 2007 Dec;26(6):1486-92. doi: 10.1002/jmri.21063.

Abstract

Purpose: To investigate a T1 and T2 preparation pulse sequence to evaluate microvascular obstruction (MO) in a porcine model of reperfused acute myocardial infarction (AMI).

Materials and methods: A total of 14 pigs with reperfused AMI underwent MRI examinations at baseline and three to four hours after reperfusion. MRI scans included a left ventricular functional study, T1 and T2 measurement on a 1.5T MRI system. At reperfusion, first-pass myocardial perfusion (FPMP) images were obtained after bolus injection of gadopentetate dimeglumine followed by an intravenous drip. Delayed contrast-enhanced MRI (DE-MRI) and T1 measurements were performed 30 and 45 minutes, respectively, after the bolus, during a constant infusion of gadopentetate dimeglumine.

Results: In 11 pigs MO was hypoenhanced in FPMP and DE-MRI. In later T1 preparation difference images postcontrast, MO was hyperenhanced while delayed hyperenhanced (DHE) regions appeared dark. MO areas on DE-MRI and T1 images were comparable. T1 reduction (%) postcontrast in MO was small compared to measurements from DHE regions (P < 0.0001) and similar to those from control segments (P = 0.66). Precontrast T1 and T2 values at reperfusion from MO and DHE regions were larger than in control regions.

Conclusion: Using T1 preparation under a constant gadopentetate dimeglumine (Gd-DTPA) infusion, delayed imaging at 30 to 45 minutes demonstrates MO as a positive contrast with larger T1 values. Elevated T1 and T2 values in MO precontrast may also help to differentiate them from both control and DHE regions.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Contrast Media / administration & dosage
  • Coronary Stenosis / physiopathology*
  • Disease Models, Animal
  • Gadolinium DTPA / administration & dosage
  • Image Enhancement / methods
  • Image Processing, Computer-Assisted / methods
  • Magnetic Resonance Imaging / methods*
  • Microcirculation / physiopathology
  • Myocardial Infarction / physiopathology*
  • Myocardial Reperfusion*
  • Swine
  • Time Factors

Substances

  • Contrast Media
  • Gadolinium DTPA