title: Dual manganese-enhanced and delayed gadolinium-enhanced MRI detects myocardial border zone injury in a pig ischemia-reperfusion model.
abstract: BACKGROUND
  Gadolinium (Gd)-based delayed-enhancement MRI (DEMRI) identifies nonviable myocardium but is nonspecific and may overestimate nonviable territory. Manganese (Mn(2+))-enhanced MRI (MEMRI) denotes specific Mn(2+) uptake into viable cardiomyocytes. We performed a dual-contrast myocardial assessment in a porcine ischemia-reperfusion (IR) model to test the hypothesis that combined DEMRI and MEMRI identifies viable infarct border zone (BZ) myocardium in vivo.
  
  
  RESULTS
  Sixty-minute left anterior descending coronary artery IR injury was induced in 13 adult swine. Twenty-one days post-IR, 3-T cardiac MRI was performed. MEMRI was obtained after injection of 0.7 mL/kg Mn(2+) contrast agent. DEMRI was then acquired after injection of 0.2 mmol/kg Gd. Left ventricular (LV) mass, infarct, and function were analyzed. Subtraction of MEMRI defect from DEMRI signal identified injured BZ myocardium. Explanted hearts were analyzed by 2,3,5-triphenyltetrazolium chloride stain and tissue electron microscopy to compare infarct, BZ, and remote myocardium. Average LV ejection fraction was reduced (30±7%). MEMRI and DEMRI infarct volumes correlated with 2,3,5-triphenyltetrazolium chloride stain analysis (MEMRI, r=0.78; DEMRI, r=0.75; P<0.004). MEMRI infarct volume percentage was significantly lower than that of DEMRI (14±4% versus 23±4%; P<0.05). BZ MEMRI signal-to-noise ratio (SNR) was intermediate to remote and core infarct SNR (7.5±2.8 versus 13.2±3.4 and 2.9±1.6; P<0.0001), and DEMRI BZ SNR tended to be intermediate to remote and core infarct SNR (8.4±5.4 versus 3.3±0.6 and 14.3±6.6; P>0.05). Tissue electron microscopy analysis exhibited preserved cell structure in BZ cardiomyocytes despite transmural DEMRI enhancement.
  
  
  CONCLUSIONS
  The dual-contrast MEMRI-DEMRI detects BZ viability within DEMRI infarct zones. This approach may identify injured, at-risk myocardium in ischemic cardiomyopathy.
authors: Division of Cardiovascular Medicine, Stanford University Medical Center, Stanford, CA 94305-5233, USA. rdash@cvmed.stanford.edu
authors: Rajesh
authors: R
authors: Dash
authors: Jaehoon
authors: J
authors: Chung
authors: Fumiaki
authors: F
authors: Ikeno
authors: Annett
authors: A
authors: Hahn-Windgassen
authors: Yuka
authors: Y
authors: Matsuura
authors: Mihoko V
authors: MV
authors: Bennett
authors: Jennifer K
authors: JK
authors: Lyons
authors: Tomohiko
authors: T
authors: Teramoto
authors: Robert C
authors: RC
authors: Robbins
authors: Michael V
authors: MV
authors: McConnell
authors: Alan C
authors: AC
authors: Yeung
authors: Todd J
authors: TJ
authors: Brinton
authors: Phillip P
authors: PP
authors: Harnish
authors: Phillip C
authors: PC
authors: Yang
mesh_terms: D000818:Animals; D003287:Contrast Media; D003937:Diagnosis, Differential; D004195:Disease Models, Animal; D019786:Gadolinium DTPA; D007275:Injections, Intravenous; D019028:Magnetic Resonance Imaging, Cine / Q000379:methods*; D008345:Manganese / Q000008:administration & dosage; D015428:Myocardial Reperfusion Injury / Q000175:diagnosis*; D009206:Myocardium / Q000473:pathology*; D011868:Radioisotopes / Q000008:administration & dosage; D015203:Reproducibility of Results; D012720:Severity of Illness Index; D013552:Swine
chemical_list: D003287:Contrast Media; D011868:Radioisotopes; D008345:Manganese; D019786:Gadolinium DTPA