Nile UniverityMohamed 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

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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

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

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(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

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MR images

Measurements1- Area of infarction

2- Ratio between area of infarction

and area of normal tissue

Measurements1- 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.

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1- Threshold =mean intensity of tissue+2* Standard Deviation of tissue’s 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.

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

Red line represents cluster.

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Simulator

Methods Under Testing

True Data

CompareError in Area of

segmented region

Inner Radius= 1.5 cmOuter Radius= 2.4 cm

Depth of Infarcted region=0.4 cm

Inner Radius= 1.5 cmOuter Radius= 2.4 cm

Depth of Infarcted region=0.4 cm

Noise Variance=0.01Noise Variance=0.01

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The DE Simulator controls:1- Noise level2- The 3D size of infarcted region3- The 3D size of the LV of the heart4- The ratio between the infarcted region to the healthy myocardium region, per slice

Results on images with the following specs: Feature Value

Noise variance

0.09

Inner radius 2.5 cm

Outer radius 5.6 cm

Tissue intensity

80

Blood intensity

110

Core intensity 190

Hyper zone intensity

200

Depth of infarction

1 cm

Start angle 45 degree

End angle 135 degree

Accuracy Sensitivity PrecessionK-mean in 3D 98.066 83.133 81

K-mean on histogram 99.152 99.17467 64.526

Thresholding 96.4 99.26 53.86

Accuracy Sensitivity PrecessionK-mean in 3D 98.066 83.133 81

K-mean on histogram 99.152 99.17467 64.526

Thresholding 96.4 99.26 53.86

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 doesn’t contain noise)

MR images

Measurements1- Area of infarction

2- Ratio between area of infarction

and area of normal tissue

Measurements1- Area of infarction

2- Ratio between area of infarction

and area of normal tissue

DetectionDetection

Thanks

Heart is supplied with blood by coronary artery and arteriols.

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