3D left ventricular strain from unwrapped harmonic phase measurements.
OBJECTIVE
To validate a method for measuring 3D left ventricular (LV) strain from phase-unwrapped harmonic phase (HARP) images derived from tagged cardiac magnetic resonance imaging (MRI).


METHODS
A set of 40 human subjects were imaged with tagged MRI. In each study the HARP phase was computed and unwrapped in each short-axis and long-axis image. Inconsistencies in unwrapped phase were resolved using branch cuts manually placed with a graphical user interface. 3D strain maps were computed for all imaged timeframes in each study. The strain from unwrapped phase (SUP) and displacements were compared to those estimated by a feature-based (FB) technique and a HARP technique.


RESULTS
3D strain was computed in each timeframe through systole and mid-diastole in approximately 30 minutes per study. The standard deviation of the difference between strains measured by the FB and the SUP methods was less than 5% of the average of the strains from the two methods. The correlation between peak circumferential strain measured using the SUP and HARP techniques was over 83%.


CONCLUSIONS
The SUP technique can reconstruct full 3D strain maps from tagged MR images through the cardiac cycle in a reasonable amount of time and user interaction compared to other 3D analysis methods.
Venkatesh
Bharath Ambale
BA
Electrical and Computer Engineering Department, Auburn University, Auburn, Alabama 36849-5201, USA.
Gupta
Himanshu
H
Lloyd
Steven G
SG
Dell 'Italia
Louis
L
Denney
Thomas S
TS
D000465:Algorithms; D016022:Case-Control Studies; D015331:Cohort Studies; D006352:Heart Ventricles / Q000473:pathology*; D006801:Humans; D006973:Hypertension / Q000473:pathology; D007091:Image Processing, Computer-Assisted; D021621:Imaging, Three-Dimensional / Q000379:methods*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008944:Mitral Valve Insufficiency / Q000473:pathology; D015233:Models, Statistical; D009203:Myocardial Infarction / Q000473:pathology; D013997:Time Factors; D016277:Ventricular Function, Left