title: Gradient Spin Echo (GraSE) imaging for fast myocardial T2 mapping.
abstract: BACKGROUND
  Quantitative Cardiovascular Magnetic Resonance (CMR) techniques have gained high interest in CMR research. Myocardial T2 mapping is thought to be helpful in diagnosis of acute myocardial conditions associated with myocardial edema. In this study we aimed to establish a technique for myocardial T2 mapping based on gradient-spin-echo (GraSE) imaging.
  
  
  METHODS
  The local ethics committee approved this prospective study. Written informed consent was obtained from all subjects prior to CMR. A modified GraSE sequence allowing for myocardial T2 mapping in a single breath-hold per slice using ECG-triggered acquisition of a black blood multi-echo series was developed at 1.5 Tesla. Myocardial T2 relaxation time (T2-RT) was determined by maximum likelihood estimation from magnitude phased-array multi-echo data. Four GraSE sequence variants with varying number of acquired echoes and resolution were evaluated in-vitro and in 20 healthy volunteers. Inter-study reproducibility was assessed in a subset of five volunteers. The sequence with the best overall performance was further evaluated by assessment of intra- and inter-observer agreement in all volunteers, and then implemented into the clinical CMR protocol of five patients with acute myocardial injury (myocarditis, takotsubo cardiomyopathy and myocardial infarction).
  
  
  RESULTS
  In-vitro studies revealed the need for well defined sequence settings to obtain accurate T2-RT measurements with GraSE. An optimized 6-echo GraSE sequence yielded an excellent agreement with the gold standard Carr-Purcell-Meiboom-Gill sequence. Global myocardial T2 relaxation times in healthy volunteers was 52.2 ± 2.0 ms (mean ± standard deviation). Mean difference between repeated examinations (n = 5) was -0.02 ms with 95% limits of agreement (LoA) of [-4.7; 4.7] ms. Intra-reader and inter-reader agreement was excellent with mean differences of -0.1 ms, 95% LoA = [-1.3; 1.2] ms and 0.1 ms, 95% LoA = [-1.5; 1.6] ms, respectively (n = 20). In patients with acute myocardial injury global myocardial T2-RTs were prolonged (mean: 61.3 ± 6.7 ms).
  
  
  CONCLUSIONS
  Using an optimized GraSE sequence CMR allows for robust, reliable, fast myocardial T2 mapping and quantitative tissue characterization. Clinically, the GraSE-based T2-mapping has the potential to complement qualitative CMR in patients with acute myocardial injuries.
authors.affiliation: Department of Radiology, University of Bonn, Sigmund-Freud-Straße 25, 53127, Bonn, Germany. martin.sprinkart@ukb.uni-bonn.de.|Institute of Medical Engineering, Ruhr-University Bochum, Universitätsstraße, Bochum, Germany. martin.sprinkart@ukb.uni-bonn.de.
authors.forename: Alois M
authors.initials: AM
authors.lastname: Sprinkart
authors.affiliation: Department of Radiology, University of Bonn, Sigmund-Freud-Straße 25, 53127, Bonn, Germany. julian.luetkens@ukb.uni-bonn.de.
authors.forename: Julian A
authors.initials: JA
authors.lastname: Luetkens
authors.affiliation: Department of Radiology, University of Bonn, Sigmund-Freud-Straße 25, 53127, Bonn, Germany. frank.traeber@ukb.uni-bonn.de.
authors.forename: Frank
authors.initials: F
authors.lastname: Träber
authors.affiliation: Department of Radiology, University of Bonn, Sigmund-Freud-Straße 25, 53127, Bonn, Germany. jonas.doerner@ukb.uni-bonn.de.
authors.forename: Jonas
authors.initials: J
authors.lastname: Doerner
authors.affiliation: Department of Radiology, University of Bonn, Sigmund-Freud-Straße 25, 53127, Bonn, Germany. juergen.gieseke@philips.com.|Philips Healthcare Germany, Lübeckertordamm, Hamburg, Germany. juergen.gieseke@philips.com.
authors.forename: Jürgen
authors.initials: J
authors.lastname: Gieseke
authors.affiliation: Philips Healthcare Germany, Lübeckertordamm, Hamburg, Germany. bernhard.schnackenburg@philips.com.
authors.forename: Bernhard
authors.initials: B
authors.lastname: Schnackenburg
authors.affiliation: Institute of Medical Engineering, Ruhr-University Bochum, Universitätsstraße, Bochum, Germany. georg.schmitz@rub.de.
authors.forename: Georg
authors.initials: G
authors.lastname: Schmitz
authors.affiliation: Department of Radiology, University of Bonn, Sigmund-Freud-Straße 25, 53127, Bonn, Germany. daniel.thomas@ukb.uni-bonn.de.
authors.forename: Daniel
authors.initials: D
authors.lastname: Thomas
authors.affiliation: Department of Radiology, University of Bonn, Sigmund-Freud-Straße 25, 53127, Bonn, Germany. rami.homsi@ukb.uni-bonn.de.
authors.forename: Rami
authors.initials: R
authors.lastname: Homsi
authors.affiliation: Department of Radiology, University of Bonn, Sigmund-Freud-Straße 25, 53127, Bonn, Germany. wolfgang.block@ukb.uni-bonn.de.
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Block
authors.affiliation: Department of Radiology, University of Bonn, Sigmund-Freud-Straße 25, 53127, Bonn, Germany. hans.schild@ukb.uni-bonn.de.
authors.forename: Hans
authors.initials: H
authors.lastname: Schild
authors.affiliation: Department of Radiology, University of Bonn, Sigmund-Freud-Straße 25, 53127, Bonn, Germany. cp@naehle.net.
authors.forename: Claas P
authors.initials: CP
authors.lastname: Naehle
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D005260:Female; D064368:Healthy Volunteers; D006801:Humans; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D008279:Magnetic Resonance Imaging / Q000295:instrumentation / Q000379:methods*; D008297:Male; D008875:Middle Aged; D009200:Myocardial Contraction; D009203:Myocardial Infarction / Q000175:diagnosis* / Q000503:physiopathology; D009205:Myocarditis / Q000175:diagnosis* / Q000503:physiopathology; D015588:Observer Variation; D019047:Phantoms, Imaging; D011237:Predictive Value of Tests; D011446:Prospective Studies; D015203:Reproducibility of Results; D054549:Takotsubo Cardiomyopathy / Q000175:diagnosis* / Q000503:physiopathology; D055815:Young Adult