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Session: Poster session I
Session starts: Thursday 24 January, 15:00

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Savine Minderhoud (Erasmus Medisch Centrum)

Abstract:
Background – Phase contrast (PC) CMR flow measurements are widely used for blood flow assessment, but they suffer from phase offset errors (POE). It is crucial to correct for them and the most reliable method is to additionally scan a stationary phantom. An alternative is to use stationary tissue (ST) in the body. The aim of this study was to evaluate the impact of POE in daily practice by comparing the difference of the flow measurements with and without correction using the stationary phantom and the stationary tissue. Furthermore, the interscanner variation was assessed. Methods – We included 166 patients in which both aorta and main pulmonary artery flow measurements were acquired including a static phantom. Subjects were scanned on three different 1.5T scanners: GE Signa Artist (MRI 1, n=63), GE Discovery MR450 (MRI 2, n=51), and GE Signa Explorer (MRI 3, n=52). Breath-hold PC images were acquired perpendicular to the vessel using fast cine PC pulse sequence with the same parameters on all scanners. Medis Q-flow was used to obtain uncorrected and ST corrected flow measurements, which were compared with phantom corrected measurements and corrected for BSA. A difference of >10% in net flow was defined as clinically relevant. POE influences on regurgitation fraction were assessed by Bland-Altman plots. Results - Of the 166 cases included, with a median age was 27 (5-74) years. In all scanners the median difference in flow between no correction and phantom correction was ≤3%, however, with a wide range of over- and underestimation. ST correction resulted in larger differences compared to no correction (p<0.01). Clinically significant differences were seen in 19% of all measurements with no correction and in 30% with ST correction (p<0.01). Furthermore, there were significant differences between scanners (no correction, p<0.01; ST correction, p<0.01). Differences in regurgitation fraction with ST correction and no correction are shown (figure). Conclusion - Background POE have a significant impact on flow quantification in many patients. Unexpectedly, background phase correction using ST correction worsens accuracy compared to no correction. POE vary greatly between scanners.