3 research outputs found
Effects of heart valve prostheses on phase contrast flow measurements in Cardiovascular Magnetic Resonance - a phantom study
Background: Cardiovascular Magnetic Resonance is often used to evaluate patients after heart valve replacement. This study systematically analyses the influence of heart valve prostheses on phase contrast measurements in a phantom trial. Methods: Two biological and one mechanical aortic valve prostheses were integrated in a flow phantom. B-0 maps and phase contrast measurements were acquired at a 1.5 T MR scanner using conventional gradient-echo sequences in predefined distances to the prostheses. Results were compared to measurements with a synthetic metal-free aortic valve. Results: The flow results at the level of the prosthesis differed significantly from the reference flow acquired before the level of the prosthesis. The maximum flow miscalculation was 154 ml/s for one of the biological prostheses and 140 ml/s for the mechanical prosthesis. Measurements with the synthetic aortic valve did not show significant deviations. Flow values measured approximately 20 mm distal to the level of the prosthesis agreed with the reference flow for all tested all prostheses. Conclusions: The tested heart valve prostheses lead to a significant deviation of the measured flow rates compared to a reference. A distance of 20 mm was effective in our setting to avoid this influence
Effects of heart valve prostheses on phase contrast flow measurements in Cardiovascular Magnetic Resonance – a phantom study
Effects of heart valve prostheses on phase contrast flow measurements in Cardiovascular Magnetic Resonance
Die Kardiovaskuläre Magnetresonanztomographie (CMR) ist eine etablierte
Methode zur Evaluation von Patienten mit Herzklappenerkrankungen und nach
Herzklappenersatz. Diese Studie analysiert systematisch den Einfluss von
Herzklappenprothesen auf Phasenkontrast (PC)- Flussmessungen in der CMR im
Flussmodell [1]. Zwei biologische und eine mechanische Aortenklappenprothese
wurden in ein Flussphantom eingesetzt. B0-Maps und Phasenkontrast-
Flussmessungen wurden am 1.5 und 3 Tesla (T) CMR in definierten Abständen von
der Prothese durchgefĂĽhrt. Die Resultate wurden mit Messungen eines
Kunststoff-Inlays verglichen. Zudem wurde exemplarisch fĂĽr jede Prothese
jeweils ein Patient untersucht und die Resultate mit einem herzgesunden
Probanden verglichen [1]. Die Resultate der Flussmessungen in Höhe der
Prothese unterschieden sich signifikant von Referenzmessungen proximal der
Prothese. Die maximale Fehlkalkulation sowohl im 1.5T als auch im 3T CMR
betrug etwa 150 ml/s in einer der beiden biologischen Prothesen und 140 ml/s
in der mechanischen Prothese im 1.5T CMR. Messungen mit eingesetztem
Kunststoff-Inlay zeigten demgegenĂĽber keine signifikanten Abweichungen. Die
Ergebnisse der Flussmessungen circa 20 mm in-vitro und 30 mm in-vivo distal
der Prothese entsprachen den Referenzflussmessungen in allen getesteten
Prothesen und Feldstärken [1]. Die untersuchten Herzklappenprothesen zeigten
eine signifikante Abweichung der gemessenen Flussraten verglichen mit einem
Referenzpunkt. Mit einem Abstand 20 mm in-vitro und 30 mm in-vivo distal zur
Prothese war diese Abweichung nicht mehr zu verzeichnen [1].Cardiovascular Magnetic Resonance is established in patients with heart valve
diseases before and after surgery. This study analyses systematically the
influence of heart valve prostheses on phase contrast measurements in a
phantom [1]. Two biological and one mechanical aortic valve prostheses were
placed in a flow phantom. B0 maps and phase contrast flow measurements were
acquired at a 1.5T and 3T CMR scanner using in predefined distances to the
prostheses. Results were compared to measurements with a synthetic metal-free
aortic valve. Additionally for each prosthesis a patient was examined and the
results were compared to a hearth- healthy volunteer [1]. The flow results at
the level of the prosthesis differed significantly from the reference flow
acquired before the level of the prosthesis. The maximum flow miscalculation
was around 150 ml/s in 1.5.T and 3T CMR for one of the biological prostheses
and 140 ml/s in 1.5T CMR for the mechanical prosthesis. Measurements with the
synthetic aortic valve did not show significant deviations. Flow values
measured approximately 20 mm in-vitro and 30 mm in-vivo distal to the level of
the prosthesis agreed with the reference flow for all tested all prostheses
[1]. The tested heart valve prostheses lead to a significant deviation of the
measured flow rates compared to a reference. A distance of 20 mm in-vitro and
30mm in-vivo was effective in our setting to avoid this influence [1]