Evaluating the Systemic Right Ventricle by Cardiovascular Magnetic Resonance: Short Axis or Axial Slices?

ObjectiveTo evaluate differences in functional parameters and reproducibility between short axis and axial slice orientation in the quantitative evaluation of the systemic right ventricle by cardiovascular magnetic resonance. DesignCross-sectional evaluation comparing two methods (Bland-Altman). SettingTertiary care outpatients. InterventionsQuantitative cardiovascular magnetic resonance evaluation using short axis or axial slice orientation. Main Outcome MeasuresIntraobserver variance, interobserver variance and systematic differences in systemic right ventricular volumes, ejection fraction, and mass between both methods. PatientsTwenty-two patients (mean age 33 7 years) with systemic right ventricle (three with congenitally corrected transposition of the great arteries and 19 with atrially switched transposition of the great arteries). ResultsCompared with short axis slices, analysis of axial slices resulted in higher end systolic volume (6.6%, P <.01), while mass (-10.8%, P <.01) and ejection fraction (-8.9%, P <.01) turned out lower. Intraobserver and interobserver reproducibility were similar for both methods when measuring end-diastolic and end-systolic volumes. However, ejection fraction and stroke volume were measured more consistently in axial orientation, while ventricular mass was measured more consistently in short axis orientation. ConclusionThere are significant differences in volume, mass, and function between measurements in axial and short axis orientation. Ejection fraction and stroke volume, which have a high clinical relevance, were measured more consistently in axial slice orientation. Consequently, we recommend using axial slice orientation in patients with a systemic right ventricle