Clinical importance of microvascular obstruction on contrast-enhanced MRI in reperfused acute myocardial infarction.
BACKGROUND
The aim of the present study was to investigate the clinical importance of microvascular obstruction (MO) on contrast-enhanced magnetic resonance imaging (MRI), comparing it with the myocardial perfusion index (MPI) assessed using first-pass MRI.


RESULTS
Cardiac MRI was performed in 33 patients within 7 days after reperfusion of a myocardial infarction (MI). Using a bolus injection of Gd-DPTA, first-pass images were obtained with the Turbo-FLASH sequence. Time-intensity curves in the left ventricular cavity and in myocardial sections were generated and then the MPI was assessed by the maximum slope method. Late enhancement (LE) was assessed using the true-FISP sequence. According to the transmurality of LE, the patients were classified into 3 groups: Group 1 included patients with localized endocardial enhancement; Group 2, patients with transmural enhancement; Group 3, patients having LE with MO. In cases of anterior infarction, the MPI for the anterior wall and parts of the inferior wall in Group 3 was significantly lower than that for Group 1 and 2. For inferior infarction, the MPI for parts of the inferior wall in Group 3 was significantly lower than that for Group 1 and 2.


CONCLUSIONS
MO is related to lower MPI, indicating severe microvascular damage. LE with or without MO is an important marker of perfusion status after reperfused MI.
Nagao
Michinobu
M
Department of Radiology, Prefectural Ehime Imabari Hospital, Imabari, Japan. i-minagao@epnh.pref.ehime.jp
Higashino
Hiroshi
H
Matsuoka
Hiroshi
H
Kawakami
Hideo
H
Mochizuki
Teruhito
T
Murase
Kenya
K
Uemura
Masahiko
M
Kouno
Tamami
T
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D003287:Contrast Media / Q000008:administration & dosage; D003326:Coronary Circulation; D005260:Female; D019786:Gadolinium DTPA / Q000008:administration & dosage; D006352:Heart Ventricles / Q000000981:diagnostic imaging / Q000503:physiopathology; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008833:Microcirculation / Q000000981:diagnostic imaging / Q000503:physiopathology; D008875:Middle Aged; D009203:Myocardial Infarction / Q000000981:diagnostic imaging* / Q000209:etiology / Q000503:physiopathology; D015428:Myocardial Reperfusion Injury / Q000150:complications / Q000000981:diagnostic imaging* / Q000503:physiopathology; D011446:Prospective Studies; D011859:Radiography
D003287:Contrast Media; D019786:Gadolinium DTPA