Progress of the segmentation methods of magnetic resonance image and its application / 国际生物医学工程杂志

Magnetic resonance imaging (MRI) plays a more and more important role in medical image area for its advantages of nonradiative,multiple imaging and high spatial resolution.This review gives a systematic discussion over a couple of MRI segmentation algorithms that are used widely to help people have an entire knowledge of MRI segmentation methods.On the base of classification and summary of MRI segmentation,the MRI segmentation algorithms have been classified into 5 different categories after preliminary investigation and survey.Based on threshold,pattern recognition,active contours,Markov random field (MRF) and graph cut,separately.After further investigation and survey we summarize the characters and field of applications of the 5 different algorithms,then take a few segment experiments among these algorithms on abdomen MRI and present their distinct characteristics.At last,we take a prospect at the future of the MRI segmentation.

Ultrasonographic Segmentation of Cervical Lymph Nodes Based on the Graph Cut with Elliptical Shape Constraint / 航天医学与医学工程

Objective To propose a modified graph cut algorithm under the elliptical shape constraint to segment the ultrasonogram of cervical lymph nodes. Methods Since cervical lymph nodes were usually oval-shaped, the prior of the elliptical shape information, which was expressed as a distance function, was used to constrain the cut cost of the graph cut algorithm. The initially segmented contour was fitted with an ellipse to get the constraint. Then a certain segmentation was obtained by minimizing the cut cost function constrained with the elliptical prior. This procedure was iterated until it to be convergent. Results Under the same user input, this algorithm successfully segmented nodes on the low contrast ultrasonograms, while the traditional graph cut approach failed. For 20 ultrasonograms, with the average minimum Euclidean distance (AMINDIST) measure and the Hausdorff distance measure, these two distances between contours manually delineated by the radiologist and those segmented by this algorithm were far less than the distances resulted from the traditional graph cut algorithm. Conclusion It is indicated that utilizing the elliptical shape constraint prior can obviously improve the graph cut algorithm for segmenting cervical nodes on ultrasonograms.