Cardiac magnetic resonance: is phonocardiogram gating reliable in velocity-encoded phase contrast imaging?
OBJECTIVE
To assess the diagnostic accuracy of phonocardiogram (PCG) gated velocity-encoded phase contrast magnetic resonance imaging (MRI).


METHODS
Flow quantification above the aortic valve was performed in 68 patients by acquiring a retrospectively PCG- and a retrospectively ECG-gated velocity-encoded GE-sequence at 1.5 T. Peak velocity (PV), average velocity (AV), forward volume (FV), reverse volume (RV), net forward volume (NFV), as well as the regurgitant fraction (RF) were assessed for both datasets, as well as for the PCG-gated datasets after compensation for the PCG trigger delay.


RESULTS
PCG-gated image acquisition was feasible in 64 patients, ECG-gated in all patients. PCG-gated flow quantification overestimated PV (Δ 3.8 ± 14.1 cm/s; P = 0.037) and underestimated FV (Δ -4.9 ± 15.7 ml; P = 0.015) and NFV (Δ -4.5 ± 16.5 ml; P = 0.033) compared with ECG-gated imaging. After compensation for the PCG trigger delay, differences were only observed for PV (Δ 3.8 ± 14.1 cm/s; P = 0.037). Wide limits of agreement between PCG- and ECG-gated flow quantification were observed for all variables (PV: -23.9 to 31.4 cm/s; AV: -4.5 to 3.9 cm/s; FV: -35.6 to 25.9 ml; RV: -8.0 to 7.2 ml; NFV: -36.8 to 27.8 ml; RF: -10.4 to 10.2 %).


CONCLUSIONS
The present study demonstrates that PCG gating in its current form is not reliable enough for flow quantification based on velocity-encoded phase contrast gradient echo (GE) sequences.


CONCLUSIONS
Phonocardiogram gating is an alternative to ECG-gating in cardiac MRI. Phonocardiogram gating shows only limited reliability for velocity-encoded cardiac MRI. Further refinements of the post-processing algorithm are necessary.
Department of Diagnostic and Interventional Radiology and Neuroradiology, University Hospital Essen, Hufelandstrasse 55, 45122, Essen, Germany. Kai.Nassenstein@uni-due.de
Kai
K
Nassenstein
Stephan
S
Orzada
Lars
L
Haering
Andreas
A
Czylwik
Christoph
C
Jensen
Thomas
T
Schlosser
Oliver
O
Bruder
Mark E
ME
Ladd
Stefan
S
Maderwald
D000368:Aged; D000369:Aged, 80 and over; D001783:Blood Flow Velocity; D055424:Cardiac-Gated Imaging Techniques / Q000379:methods*; D016009:Chi-Square Distribution; D003326:Coronary Circulation; D005260:Female; D006801:Humans; D007090:Image Interpretation, Computer-Assisted; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D010701:Phonocardiography / Q000379:methods*; D012189:Retrospective Studies; D018709:Statistics, Nonparametric