Nile Univerity Mohamed Kilany Supervisors : Dr. Nael F. Osman

The decrease of blood supply to a section of the heart muscle will cause it to hibernate or die Dead tissue is called an infarct, which is important to identify and measure Delayed enhancement is and MR imaging technique that uses contrast agents to mark the infarcted tissue Delayed enhancement can reveal the existence of: 1- Myocardial infarction; 2- Infectious pathology; 3- Fibrosis; or 4- A tumorous lesion 2

Cardiac MRI is the gold standard for Delayed Enhancement Imaging The Concept: The rate the contrast agent leaves the infarcted region is much slower than that of a healthy tissue Note: The combination of perfusion imaging and Myocardial Delayed Enhancement can help evaluate areas of the myocardium that are still viable 3

4 Figure (A) short-axis slice in cardiac muscle shows RV, LV and hyper enhanced region in the epicardium wall of LV. Figure (B) long-axis slice in cardiac muscle shows hyper enhanced region in the epicardium wall of LA.

5 (A)subendocardial (B)transmural (C)Mid-wall or central enhancement is often seen in late stages of heart failure or dilated cardiomyopathy. (D) No hyper-enhancement is seen in both healthy tissue and diffuse fibrosis. (A)subendocardial (B)transmural (C)Mid-wall or central enhancement is often seen in late stages of heart failure or dilated cardiomyopathy. (D) No hyper-enhancement is seen in both healthy tissue and diffuse fibrosis.

We aim to mark (segment) hyper enhanced regions in delayed enhancement images, automatically 6

MR images Measurements 1- Area of infarction 2- Ratio between area of infarction and area of normal tissue Measurements 1- Area of infarction 2- Ratio between area of infarction and area of normal tissue

1- segmentation based on tissue mean intensity+2*standard deviation. 2- k-mean using 2 features (intensity & distance). 3- k-mean on histogram.

The Segmentation is based on Thresholding Threshold =mean intensity of tissue+2* Standard Deviation of tissues intensity.

The idea is: points which are close to each other belong to the same group

Blue curve represents the histogram of simulated delayed enhancement image. The Red line represents cluster.

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14 Simulator Methods Under Testing True Data Compare Error in Area of segmented region Inner Radius= 1.5 cm Outer Radius= 2.4 cm Depth of Infarcted region=0.4 cm Inner Radius= 1.5 cm Outer Radius= 2.4 cm Depth of Infarcted region=0.4 cm Noise Variance=0.01

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The DE Simulator controls: 1- Noise level 2- The 3D size of infarcted region 3- The 3D size of the LV of the heart 4- The ratio between the infarcted region to the healthy myocardium region, per slice

Results on images with the following specs: FeatureValue Noise variance0.09 Inner radius2.5 cm Outer radius5.6 cm Tissue intensity80 Blood intensity110 Core intensity190 Hyper zone intensity 200 Depth of infarction 1 cm Start angle45 degree End angle135 degree AccuracySensitivityPrecession K-mean in 3D K-mean on histogram Thresholding AccuracySensitivityPrecession K-mean in 3D K-mean on histogram Thresholding

The dead region in delayed enhancement images appears brighter than its surrounding. There are 3 methods to segment the dead tissue. Applying k-mean on 3D representation of DE image is trusted technique because it has the highest precision (the segmented region always doesnt contain noise)

MR images Measurements 1- Area of infarction 2- Ratio between area of infarction and area of normal tissue Measurements 1- Area of infarction 2- Ratio between area of infarction and area of normal tissue Detection

Thanks

Heart is supplied with blood by coronary artery and arteriols. 21