title: Fast T2 gradient-spin-echo (T2-GraSE) mapping for myocardial edema quantification: first in vivo validation in a porcine model of ischemia/reperfusion.
abstract: BACKGROUND
  Several T2-mapping sequences have been recently proposed to quantify myocardial edema by providing T2 relaxation time values. However, no T2-mapping sequence has ever been validated against actual myocardial water content for edema detection. In addition, these T2-mapping sequences are either time-consuming or require specialized software for data acquisition and/or post-processing, factors impeding their routine clinical use. Our objective was to obtain in vivo validation of a sequence for fast and accurate myocardial T2-mapping (T2 gradient-spin-echo [GraSE]) that can be easily integrated in routine protocols.
  
  
  METHODS
  The study population comprised 25 pigs. Closed-chest 40 min ischemia/reperfusion was performed in 20 pigs. Pigs were sacrificed at 120 min (n = 5), 24 h (n = 5), 4 days (n = 5) and 7 days (n = 5) after reperfusion, and heart tissue extracted for quantification of myocardial water content. For the evaluation of T2 relaxation time, cardiovascular magnetic resonance (CMR) scans, including T2 turbo-spin-echo (T2-TSE, reference standard) mapping and T2-GraSE mapping, were performed at baseline and at every follow-up until sacrifice. Five additional pigs were sacrificed after baseline CMR study and served as controls.
  
  
  RESULTS
  Acquisition of T2-GraSE mapping was significantly (3-fold) faster than conventional T2-TSE mapping. Myocardial T2 relaxation measurements performed by T2-TSE and T2-GraSE mapping demonstrated an almost perfect correlation (R(2) = 0.99) and agreement with no systematic error between techniques. The two T2-mapping sequences showed similarly good correlations with myocardial water content: R(2) = 0.75 and R(2) = 0.73 for T2-TSE and T2-GraSE mapping, respectively.
  
  
  CONCLUSIONS
  We present the first in vivo validation of T2-mapping to assess myocardial edema. Given its shorter acquisition time and no requirement for specific software for data acquisition or post-processing, fast T2-GraSE mapping of the myocardium offers an attractive alternative to current CMR sequences for T2 quantification.
authors.affiliation: Centro Nacional de Investigaciones Cardiovasculares Carlos III (CNIC), Madrid, Spain.|Hospital Universitario Clínico San Carlos, Madrid, Spain.
authors.forename: Rodrigo
authors.initials: R
authors.lastname: Fernández-Jiménez
authors.affiliation: Centro Nacional de Investigaciones Cardiovasculares Carlos III (CNIC), Madrid, Spain.|Philips Healthcare, Madrid, Spain.
authors.forename: Javier
authors.initials: J
authors.lastname: Sánchez-González
authors.affiliation: Centro Nacional de Investigaciones Cardiovasculares Carlos III (CNIC), Madrid, Spain.
authors.forename: Jaume
authors.initials: J
authors.lastname: Aguero
authors.affiliation: Centro Nacional de Investigaciones Cardiovasculares Carlos III (CNIC), Madrid, Spain.
authors.forename: María
authors.initials: M
authors.lastname: Del Trigo
authors.affiliation: Centro Nacional de Investigaciones Cardiovasculares Carlos III (CNIC), Madrid, Spain.
authors.forename: Carlos
authors.initials: C
authors.lastname: Galán-Arriola
authors.affiliation: Centro Nacional de Investigaciones Cardiovasculares Carlos III (CNIC), Madrid, Spain.|The Zena and Michael A. Wiener CVI, Mount Sinai School of Medicine, New York, NY, USA.
authors.forename: Valentin
authors.initials: V
authors.lastname: Fuster
authors.affiliation: Centro Nacional de Investigaciones Cardiovasculares Carlos III (CNIC), Madrid, Spain. bibanez@cnic.es.|Department of Cardiology, Instituto de Investigación Sanitaria, Fundación Jiménez Díaz Hospital, Madrid, Spain. bibanez@cnic.es.
authors.forename: Borja
authors.initials: B
authors.lastname: Ibáñez
mesh_terms: D000818:Animals; D001834:Body Water / Q000378:metabolism; D004195:Disease Models, Animal; D004489:Edema, Cardiac / Q000378:metabolism / Q000473:pathology*; D007090:Image Interpretation, Computer-Assisted; D019028:Magnetic Resonance Imaging, Cine / Q000379:methods*; D008297:Male; D009203:Myocardial Infarction / Q000378:metabolism / Q000473:pathology*; D015428:Myocardial Reperfusion Injury / Q000378:metabolism / Q000473:pathology*; D009206:Myocardium / Q000378:metabolism / Q000473:pathology*; D011237:Predictive Value of Tests; D015203:Reproducibility of Results; D013552:Swine; D013997:Time Factors