A robust automated left ventricle region of interest localization technique using a cardiac cine MRI atlas

Abstract

Region of interest detection is a precursor to many medical image processing and analysis applications, including segmentation, registration and other image manipulation techniques. The optimal region of interest is often selected manually, based on empirical knowledge and features of the image dataset. However, if inconsistently identified, the selected region of interest may greatly affect the subsequent image analysis or interpretation steps, in turn leading to incomplete assessment during computer-aided diagnosis or incomplete visualization or identification of the surgical targets, if employed in the context of pre-procedural planning or image-guided interventions. Therefore, the need for robust, accurate and computationally efficient region of interest localization techniques is prevalent in many modern computer-assisted diagnosis and therapy applications. Here we propose a fully automated, robust, a priori learning-based approach that provides reliable estimates of the left and right ventricle features from cine cardiac MR images. The proposed approach leverages the temporal frame-to-frame motion extracted across a range of short axis left ventricle slice images with small training set generated from les than 10% of the population. This approach is based on histogram of oriented gradients features weighted by local intensities to first identify an initial region of interest depicting the left and right ventricles that exhibits the greatest extent of cardiac motion. This region is correlated with the homologous region that belongs to the training dataset that best matches the test image using feature vector correlation techniques. Lastly, the optimal left ventricle region of interest of the test image is identified based on the correlation of known ground truth segmentations associated with the training dataset deemed closest to the test image. The proposed approach was tested on a population of 100 patient datasets and was validated against the ground truth region of interest of the test images manually annotated by experts. This tool successfully identified a mask around the LV and RV and furthermore the minimal region of interest around the LV that fully enclosed the left ventricle from all testing datasets, yielding a 98% overlap with their corresponding ground truth. The achieved mean absolute distance error between the two contours that normalized by the radius of the ground truth is 0.20 ± 0.09.

Integrating Atlas and Graph Cut Methods for Left Ventricle Segmentation from Cardiac Cine MRI

“…All patient volumes are rotated about the z-axis (i.e., slice-encoding direction) to roughly align their orientation with that of the reference patient using the DICOM Image Orientation Patient (IPP) field. The region of interest (ROI) (in the xy-plane) enclosing the left and right ventricles is extracted using the method described in [11] by correlating the 2D motion images generated from the 3D volumes across the cardiac cycle. The only manual input required by our algorithm is the start and end slices of the LV, such that the ROI is restricted in the z-direction, preventing over/under segmentation of slices that do not belong to the desired anatomy.…”