title: Papillary muscle involvement in myocardial infarction: initial results using multicontrast late-enhancement MRI.
abstract: We hypothesized that multicontrast late-enhancement (MCLE) MRI would improve the identification of papillary muscle involvement (PM-MI) in patients with myocardial infarction (MI), compared with conventional late gadolinium enhancement (LGE) MRI using the inversion recovery fast gradient echo (IR-FGRE) technique. Cardiac LGE-MRI studies using both MCLE and IR-FGRE pulse sequences were performed on a 1.5 Tesla (T) MRI system in 23 patients following MI. In all patients, PM-MI was confirmed by the diagnostic criteria as outlined below: (a) the increased signal intensity of PM was the same or similar to that of adjacent hyper-enhanced left ventricular (LV) infarct segments; and (b) the hyper-enhanced PM region was limited to the PM area defined by precontrast cine images of steady-state free precession (SSFP). Visual contrast score was rated according to the differentiation between LV blood pool and hyper-enhanced infarct myocardium. Quantitative contrast-noise ratios (CNR) of infarct relative to blood pool and viable myocardium were also measured on MCLE and IR-FGRE images. Of these 23 patients, 13 studies demonstrated primarily involvement of the territories of the right coronary (RCA, 8 patients) and/or left circumflex (LCX, 5 patients) arteries and 10 involved the territories of left anterior descending artery (LAD) with some LCX involvement. Although both IR-FGRE and MCLE determined the presence and extent of LV MI, better visual contrast scores were achieved in MCLE (2.9 ± 0.3) compared with IR-FGRE (1.6 ± 0.8, P < 0.001). The CNRs of infarct relative to LV blood pool showed a significant statistical difference (n = 23, P < 0.00001) between MCLE (16.2 ± 7.2) and IR-FGRE images (4.8 ± 4.1), which is consistent with the result of visual contrast scores between infarct and LV blood pool. The CNRs of infarct versus viable myocardium did not demonstrate a significant statistical difference (n = 23, P = 0.61) between MCLE (14.4 ± 7.0) and IR-FGRE images (13.6 ± 6.1). MCLE clearly demonstrated PM-MI in all cases (100%, 23/23) while only 39% (9/23) could be visualized on the corresponding IR-FGRE images. In conclusion, MCLE imaging provides better contrast between blood pool and infarct myocardium, thus improving the determination of PM-MI.
authors.affiliation: Imaging Research and Cardiology, Sunnybrook Health Sciences Centre, University of Toronto, Toronto, Ontario, Canada. ysyang@sri.utoronto.ca
authors.forename: Yuesong
authors.initials: Y
authors.lastname: Yang
authors.forename: Kim
authors.initials: K
authors.lastname: Connelly
authors.forename: John J
authors.initials: JJ
authors.lastname: Graham
authors.forename: Jay
authors.initials: J
authors.lastname: Detsky
authors.forename: Tony
authors.initials: T
authors.lastname: Lee
authors.forename: Rhonda
authors.initials: R
authors.lastname: Walcarius
authors.forename: Gideon
authors.initials: G
authors.lastname: Paul
authors.forename: Graham A
authors.initials: GA
authors.lastname: Wright
authors.forename: Alexander J
authors.initials: AJ
authors.lastname: Dick
mesh_terms: D003287:Contrast Media / Q000008:administration & dosage; D005260:Female; D019786:Gadolinium DTPA / Q000008:administration & dosage*; D006801:Humans; D007089:Image Enhancement / Q000379:methods*; D019028:Magnetic Resonance Imaging, Cine / Q000379:methods*; D008297:Male; D008875:Middle Aged; D009203:Myocardial Infarction / Q000473:pathology*; D010210:Papillary Muscles / Q000473:pathology*; D010865:Pilot Projects; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
chemical_list: D003287:Contrast Media; D019786:Gadolinium DTPA