title: A dual propagation contours technique for semi-automated assessment of systolic and diastolic cardiac function by CMR.
abstract: BACKGROUND
  Although cardiovascular magnetic resonance (CMR) is frequently performed to measure accurate LV volumes and ejection fractions, LV volume-time curves (VTC) derived ejection and filling rates are not routinely calculated due to lack of robust LV segmentation techniques. VTC derived peak filling rates can be used to accurately assess LV diastolic function, an important clinical parameter. We developed a novel geometry-independent dual-contour propagation technique, making use of LV endocardial contours manually drawn at end systole and end diastole, to compute VTC and measured LV ejection and filling rates in hypertensive patients and normal volunteers.
  
  
  METHODS
  39 normal volunteers and 49 hypertensive patients underwent CMR. LV contours were manually drawn on all time frames in 18 normal volunteers. The dual-contour propagation algorithm was used to propagate contours throughout the cardiac cycle. The results were compared to those obtained with single-contour propagation (using either end-diastolic or end-systolic contours) and commercially available software. We then used the dual-contour propagation technique to measure peak ejection rate (PER) and peak early diastolic and late diastolic filling rates (ePFR and aPFR) in all normal volunteers and hypertensive patients.
  
  
  RESULTS
  Compared to single-contour propagation methods and the commercial method, VTC by dual-contour propagation showed significantly better agreement with manually-derived VTC. Ejection and filling rates by dual-contour propagation agreed with manual (dual-contour - manual PER: -0.12 +/- 0.08; ePFR: -0.07 +/- 0.07; aPFR: 0.06 +/- 0.03 EDV/s, all P = NS). However, the time for the manual method was approximately 4 hours per study versus approximately 7 minutes for dual-contour propagation. LV systolic function measured by LVEF and PER did not differ between normal volunteers and hypertensive patients. However, ePFR was lower in hypertensive patients vs. normal volunteers, while aPFR was higher, indicative of altered diastolic filling rates in hypertensive patients.
  
  
  CONCLUSIONS
  Dual-propagated contours can accurately measure both systolic and diastolic volumetric indices that can be applied in a routine clinical CMR environment. With dual-contour propagation, the user interaction that is routinely performed to measure LVEF is leveraged to obtain additional clinically relevant parameters.
authors.affiliation: Electrical and Computer Engineering Department, Auburn University, Auburn, AL 36849, USA. fengwe1@auburn.edu
authors.forename: Wei
authors.initials: W
authors.lastname: Feng
authors.forename: Hosakote
authors.initials: H
authors.lastname: Nagaraj
authors.forename: Himanshu
authors.initials: H
authors.lastname: Gupta
authors.forename: Steven G
authors.initials: SG
authors.lastname: Lloyd
authors.forename: Inmaculada
authors.initials: I
authors.lastname: Aban
authors.forename: Gilbert J
authors.initials: GJ
authors.lastname: Perry
authors.forename: David A
authors.initials: DA
authors.lastname: Calhoun
authors.forename: Louis J
authors.initials: LJ
authors.lastname: Dell'Italia
authors.forename: Thomas S
authors.initials: TS
authors.lastname: Denney
mesh_terms: D000465:Algorithms; D016022:Case-Control Studies; D003971:Diastole; D006801:Humans; D006973:Hypertension / Q000175:diagnosis* / Q000503:physiopathology; D007090:Image Interpretation, Computer-Assisted; D008279:Magnetic Resonance Imaging; D009200:Myocardial Contraction; D015588:Observer Variation; D011237:Predictive Value of Tests; D015203:Reproducibility of Results; D012984:Software; D013318:Stroke Volume; D013599:Systole; D013997:Time Factors; D016277:Ventricular Function, Left
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