Watershed segmentation of basal left ventricle for quantitation of cine cardiac MRI function
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Watershed segmentation of basal left ventricle for quantitation of cine cardiac MRI function Yingli Lu1*, Kim A Connelly2, Alexander J Dick3, Graham A Wright1, Perry E Radau1 From 2011 SCMR/Euro CMR Joint Scientific Sessions Nice, France. 3-6 February 2011 Introduction To quantitatively analyze global and regional cardiac function from MR, clinical parameters such as ejection fraction (EF) and volumes are required. These depend upon accurate delineation of endo- and epicardial contours of the left ventricle (LV). Previous work [1] has demonstrated the difficulty of accurate LV segmentation, especially in basal slices where the LV outflow tract (LVOT) interrupts continuous myocardial contours. A novel method for the robust, accurate and fully automatic LV segmentation from short axis (SA) cine MR images is presented in this study that applies watershed technique to solve basal slice segmentation. Materials and methods Imaging data (N=146, 40 ischemic heart failure, 32 nonischemic heart failure, 35 LV hypertrophy and 39
normals; 37 female, 109 male; age: 59.815.8) were acquired from a 1.5T scanner (GE CV/i Excite) with IR-SSFP SA cine MR. The basal slice with LVOT is identified by the following steps (Fig. 1a): 1. Choose the middle slice image as the start image, and process each image sequentially in the basal direction. 2. Apply the optimal threshold method [1] to convert the ROI to a binary image (Fig.1b). 3. Identify the binary object with blood pool and LVOT (Fig.1b). 4. Calculate the length of the major axis L of the ellipse that has the same normalized second central moments as the binary object. 5. If the ratio of current L to preceding L larger than a predefined threshold (In this work, threshold = 1.2), basal slice with LVOT is identified. The blood pool is separated from the LVOT by the following steps: 1. Calculate the Euclidean distance transform of the binary object, i.e., the distance between
Figure 1 a) Detection procedure of the basal slice with LVOT. b) Basal slice with LVOT. c) Blood pool binary image. d) Watershed results, with detected LV blood pool (orange).
1 Imaging Research, Sunnybrook Health Sciences Centre, Toronto, ON, Canada Full list of author information is available at the end of the article
© 2011 Lu et al; licensee BioMed Central Ltd. This is an open access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
Lu et al. Journal of Cardiovascular Magnetic Resonance 2011, 13(Suppl 1):P4 http://jcmr-online.com/content/13/S1/P4
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Table 1 Evaluation of contours Patient Group
LV located (%)
APD (mm)
DM
endo
epi
endo
epi
HFI
97.5 (39/40)
1.83
1.86
0.92
0.94
HFNI
96.9 (31/32)
1.91
1.93
0.92
0.94
HYP
94.3 (33/35)
2.70
2.14
0.85
0.93
HEA
89.7 (35/39)
1.88
1.87
0.90
0.93
endo: endocardial, epi: epicardial, APD: average
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