Identification, segmentation, and image property study of acute infarcts in diffusion-weighted images by using a probabilistic neural network and adaptive Gaussian mixture model.
OBJECTIVE
Accurate identification of infarcted regions of the brain is critical in management of stroke patients. An efficient and fast method for identification and segmentation of infarcts in the diffusion-weighted images (DWI) is proposed.


METHODS
Thirteen stroke patients were studied. DWI scans were acquired with a slice thickness of 5 mm. We have used a probabilistic neural network for selecting infarct slices and an adaptive (two-level) Gaussian mixture model for segmentation of the infarcts. Statistical analysis, such as identification of distribution, first-order statistics calculation, and receiver operating characteristic curve analysis, was performed.


RESULTS
The average dice index is about 0.6, and average sensitivity and specificity are about 81% and 99%, respectively. The value of sensitivity and dice index are influenced by the number of false positives and false negatives. Because artifacts and infarcts have similar imaging characteristics, it is difficult to completely eliminate the artifacts. The accuracy of localization is nearly 100% as there were only two false-positive and three false-negative slices of all 381 slices. The algorithm takes about 1 minute in the Matlab computing environment to process a volume.


CONCLUSIONS
A method to localize and segment the acute brain infarcts is proposed. The method aids the clinician in reducing the time needed to localize and segment the infarcts. The speed of localization and segmentation can be enhanced further by implementing the algorithm in VC++ and using fast algorithms for selection of Gaussian mixture model parameters.
Prakash K N
Bhanu
B
Biomedical Imaging Lab, Singapore Bioimaging Consortium, Agency for Science Technology and Research, 30 Biopolis Street, #07-01 Matrix Singapore 138671. bhanu@sbic.a-star.edu.sg
Gupta
Varsha
V
Bilello
Michel
M
Beauchamp
Norman J
NJ
Nowinski
Wieslaw L
WL
D000465:Algorithms; D016477:Artifacts; D002544:Cerebral Infarction / Q000000981:diagnostic imaging*; D005188:False Negative Reactions; D005189:False Positive Reactions; D006801:Humans; D007091:Image Processing, Computer-Assisted; D016571:Neural Networks, Computer; D016011:Normal Distribution; D012372:ROC Curve; D014057:Tomography, X-Ray Computed