Article

Three-dimensional plus time biventricular strain from tagged MR images by phase-unwrapped harmonic phase

Electrical and Computer Engineering Department, Auburn University, Auburn, Alabama 36849-5201, USA.
Journal of Magnetic Resonance Imaging (Impact Factor: 2.79). 10/2011; 34(4):799-810. DOI: 10.1002/jmri.22665
Source: PubMed

ABSTRACT To validate a method called bi-ventricular strain unwrapped phase (BiSUP) for reconstructing three-dimensional plus time (3D+t) biventricular strain maps from phase-unwrapped harmonic phase (HARP) images derived from tagged cardiac magnetic resonance imaging (MRI).
A set of 30 human subjects were imaged with tagged MRI. In each study, 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. The 3D strain maps were computed independently in each imaged time frame through systole and mid diastole in each study. The BiSUP strain and displacements were compared with those estimated by a 3D feature-based (FB) technique and a 2D+t HARP technique.
The standard deviation of the difference between strains measured by the FB and the BiSUP methods was less than 4% of the average of the strains from the two methods. The correlation between peak minimum principal strain measured using the BiSUP and HARP techniques was over 83%.
The BiSUP technique can reconstruct full 3D+t strain maps from tagged MR images through the cardiac cycle in a reasonable amount of time and user interaction compared with other 3D analysis methods.

Download full-text

Full-text

Available from: Thomas Denney, Aug 12, 2014
0 Followers
 · 
116 Views
  • [Show abstract] [Hide abstract]
    ABSTRACT: In this article, we describe a three-dimensional shape reconstruction system based on the Mach–Zehnder interferometer structure and Young's double pinhole interference principle, while utilizing Fresnel reflection on fiber end face and interference at the fourth port of 3-dB coupler to achieve closed-loop precise control of fringe phase. A root-mean-square phase stability of 4 mrad is measured with the system. The shape of the object is determined by analyzing the fringe pattern. A new algorithm called rotating rectangular window autoselection is used as the band-pass filter. The measuring time of the whole system is less than 200 ms, and the error of system is 0.27 mm. Meanwhile, the overall complexity of the measuring algorithm is O(nlogn). © 2012 Wiley Periodicals, Inc. Int J Imaging Syst Technol, 22, 208–213, 2012 © 2012 Wiley Periodicals, Inc.
    International Journal of Imaging Systems and Technology 11/2012; 22(4):208-213. DOI:10.1002/ima.22024 · 0.77 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: A novel B-Spline based approach to phase unwrapping in tagged magnetic resonance images is proposed for cardiac motion tracking. A bicubic B-spline surface is used to model the absolute phase. The phase unwrapping problem is formulated as a mixed integer optimization problem that minimizes the sum of the difference between the spatial gradients of absolute and wrapped phases, and the difference between the rewrapped and wrapped phases. In contrast to the existing techniques for motion tracking, the proposed approach can overcome the limitation of interframe half-tag displacement and increase the robustness of motion tracking. The article further presents a hybrid harmonic phase imaging-B-spline method to take the advantage of the harmonic phase imaging method for small motion and the efficiency of the B-Spline approach for large motion. The proposed approach has been successively applied to a full set of cardiac MRI scans in both long and short axis slices with superior performance when compared with the harmonic phase imaging and quality guided path-following methods. Magn Reson Med, 2012. © 2012 Wiley Periodicals, Inc.
    Magnetic Resonance in Medicine 05/2013; DOI:10.1002/mrm.24359 · 3.40 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: To compare the acute changes in circumferential and longitudinal strain after exposing a coronary artery to various interventions in swine. Percutaneous balloon angioplasty catheter was guided to location aid device (LAD) under X-ray fluoroscopy to create different patterns of ischemic insults. Pigs (n = 32) were equally divided into 4 groups: controls, 90 min LAD occlusion/reperfusion, LAD microembolization, and combined LAD occlusion/microembolization/reperfusion. Three days after interventions, cine, tagged and viability magnetic resonance imaging (MRI) were acquired to measure and compare left and right circumferential strain, longitudinal strain and myocardial viability, respectively. Measurements were obtained using HARP and semi-automated threshold method and statistically analyzed using unpaired t-test. Myocardial and vascular damage was characterized microscopically. Coronary microemboli caused greater impairment in l left ventricular (LV) circumferential strain and dyssynchrony than LAD occlusion/reperfusion despite the significant difference in the extent of myocardial damage. Microemboli also caused significant decrease in peak systolic strain rate of remote myocardium and LV dyssynchrony. Cine MRI demonstrated the interaction between LV and right ventricular (RV) at 3 d after interventions. Compensatory increase in RV free wall longitudinal strain was seen in response to all interventions. Viability MRI, histochemical staining and microscopy revealed different patterns of myocardial damage and microvascular obstruction. Cine MRI revealed subtle changes in LV strain caused by various ischemic insults. It also demonstrated the interaction between the right and left ventricles after coronary interventions. Coronary microemboli with and without acute myocardial infarction (AMI) cause complex myocardial injury and ventricular dysfunction that is not replicated in solely AMI.
    12/2013; 5(12):472-83. DOI:10.4329/wjr.v5.i12.472
Show more