Cardiac MR elastography: comparison with left ventricular pressure measurement.
OBJECTIVE
To compare magnetic resonance elastography (MRE) with ventricular pressure changes in an animal model.


METHODS
Three pigs of different cardiac physiology (weight, 25 to 53 kg; heart rate, 61 to 93 bpm; left ventricular [LV] end-diastolic volume, 35 to 70 ml) were subjected to invasive LV pressure measurement by catheter and noninvasive cardiac MRE. Cardiac MRE was performed in a short-axis view of the heart and applying a 48.3-Hz shear-wave stimulus. Relative changes in LV-shear wave amplitudes during the cardiac cycle were analyzed. Correlation coefficients between wave amplitudes and LV pressure as well as between wave amplitudes and LV diameter were determined.


RESULTS
A relationship between MRE and LV pressure was observed in all three animals (R2 >or= 0.76). No correlation was observed between MRE and LV diameter (R2 <or= 0.15). Instead, shear wave amplitudes decreased 102 +/- 58 ms earlier than LV diameters at systole and amplitudes increased 175 +/- 40 ms before LV dilatation at diastole. Amplitude ratios between diastole and systole ranged from 2.0 to 2.8, corresponding to LV pressure differences of 60 to 73 mmHg.


CONCLUSIONS
Externally induced shear waves provide information reflecting intraventricular pressure changes which, if substantiated in further experiments, has potential to make cardiac MRE a unique noninvasive imaging modality for measuring pressure-volume function of the heart.
Elgeti
Thomas
T
Department of Radiology, Charité - Universitätsmedizin Berlin, Campus Mitte, Charitéplatz 1, 10117 Berlin, Germany. thomas.elgeti@charite.de
Laule
Michael
M
Kaufels
Nikola
N
Schnorr
Jörg
J
Hamm
Bernd
B
Samani
Abbas
A
Braun
Jürgen
J
Sack
Ingolf
I
D000818:Animals; D006328:Cardiac Catheterization; D054459:Elasticity Imaging Techniques; D019028:Magnetic Resonance Imaging, Cine; D023421:Models, Animal; D011237:Predictive Value of Tests; D013552:Swine; D013556:Swine, Miniature; D013997:Time Factors; D016277:Ventricular Function, Left; D017725:Ventricular Pressure