Evaluating the systemic right ventricle by cardiovascular magnetic resonance: Short axis or axial slices?

Objective: To 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. Design: Cross-sectional evaluation comparing two methods (Bland-Altman). Setting: Tertiary care outpatients. Interventions: Quantitative cardiovascular magnetic resonance evaluation using short axis or axial slice orientation. Main Outcome Measures: Intraobserver variance, interobserver variance and systematic differences in systemic right ventricular volumes, ejection fraction, and mass between both methods. Patients: Twenty-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). Results: Compared 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. Conclusion: There 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.

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