title: Cardiac MRI: a new gold standard for ventricular volume quantification during high-intensity exercise.
abstract: BACKGROUND
  Accurate measures are critical when attempting to distinguish normal from pathological changes in cardiac function during exercise, yet imaging modalities have seldom been assessed against invasive exercise standards. We sought to validate a novel method of biventricular volume quantification by cardiac MRI (CMR) during maximal exercise.
  
  
  RESULTS
  CMR was performed on 34 subjects during exercise and free-breathing with the use of an ungated real-time (RT-ungated) CMR sequence. ECG and respiratory movements were retrospectively synchronized, enabling compensation for cardiac cycle and respiratory phase. Feasibility of RT-ungated imaging was compared with standard exercise CMR imaging with ECG gating (gated); accuracy of RT-ungated CMR was assessed against an invasive standard (direct Fick); and reproducibility was determined after a second bout of maximal exercise. Ventricular volumes were analyzed more frequently during high-intensity exercise with RT-ungated compared with gated CMR (100% versus 47%; P<0.0001) and with better interobserver variability for RT-ungated (coefficient of variation=1.9% and 2.0% for left and right ventricular stroke volumes, respectively) than gated (coefficient of variation=15.2% and 13.6%; P<0.01). Cardiac output determined by RT-ungated CMR proved accurate against the direct Fick method with excellent agreement (intraclass correlation coefficient, R=0.96), which was highly reproducible during a second bout of maximal exercise (R=0.98).
  
  
  CONCLUSIONS
  When RT-ungated CMR is combined with post hoc analysis incorporating compensation for respiratory motion, highly reproducible and accurate biventricular volumes can be measured during maximal exercise.
authors.affiliation: Department of Cardiovascular Medicine, University Hospital of Leuven, Leuven, Belgium. andre.lagerche@med.kuleuven.be
authors.forename: Andre
authors.initials: A
authors.lastname: La Gerche
authors.forename: Guido
authors.initials: G
authors.lastname: Claessen
authors.forename: Alexander
authors.initials: A
authors.lastname: Van de Bruaene
authors.forename: Nele
authors.initials: N
authors.lastname: Pattyn
authors.forename: Johan
authors.initials: J
authors.lastname: Van Cleemput
authors.forename: Marc
authors.initials: M
authors.lastname: Gewillig
authors.forename: Jan
authors.initials: J
authors.lastname: Bogaert
authors.forename: Steven
authors.initials: S
authors.lastname: Dymarkowski
authors.forename: Piet
authors.initials: P
authors.lastname: Claus
authors.forename: Hein
authors.initials: H
authors.lastname: Heidbuchel
mesh_terms: D000293:Adolescent; D000328:Adult; D000704:Analysis of Variance; D001145:Arrhythmias, Cardiac / Q000175:diagnosis* / Q000473:pathology / Q000503:physiopathology; D055424:Cardiac-Gated Imaging Techniques / Q000592:standards*; D002648:Child; D004562:Electrocardiography; D005080:Exercise Test / Q000592:standards*; D005240:Feasibility Studies; D006333:Heart Failure / Q000175:diagnosis* / Q000473:pathology / Q000503:physiopathology; D006339:Heart Rate; D006352:Heart Ventricles / Q000473:pathology / Q000503:physiopathology*; D006801:Humans; D019028:Magnetic Resonance Imaging, Cine / Q000592:standards*; D008875:Middle Aged; D015588:Observer Variation; D011237:Predictive Value of Tests; D012015:Reference Standards; D015203:Reproducibility of Results; D012119:Respiration; D013318:Stroke Volume; D013997:Time Factors; D016277:Ventricular Function, Left; D016278:Ventricular Function, Right; D055815:Young Adult