Digitech Ophthalmologist

Product Overview

Digitech Ophthalmologist

What is Digitech Ophthalmologist ? Software tool for OphthalmologistIts like a smart assistance who will carry out the routine tasks with ease freeing more time for the important work.

AdvantagesThis software operates on the images taken by Fundus Camera Leaves more time for the doctor to actually focus on the important diagnostic part rather than menial work.Presents information and statistics in such a way to help doctor take the best decision Improves patient care at reduced prices as telemedicine is possible due to this innovation

Digitech Ophthalmologist

Features: The major features are illustrated as below.

Patient Database ManagementDistortion CorrectionPanorama Image ConstructionCup to Disk Ration (CDR ) AnalysisRetina 3D Reconstruction Blood Vessel Analysis Glaucoma Detection Retinopathy

Each Feature is discussed at a greater length in the following slides.

Digitech Ophthalmologist Features

Patient Database Management

Archiving and maintaining the medical data is one of the most important tasks A tool for sophisticated archival and easy retrieval of the data is necessary when dealing with the large databasesTechlead Patient Database system avails doctors the following facilities

Store the database per patient basis for keeping track of historyAccess the database for a particular clinical manifestation Allow Multiple doctors to comment on the single case and all visible to the userA portable format of database which can be shared among doctors with simpler means such as cell phones Simple User Interface

Patient Database Management Cntd…

Patient Database Management Cntd…

Distortion Correction

Images are distorted due to the deviation of the light from direct Path. The distortion is induced by

EYE LensCamera Lens Figure shows example

of Camera Lens Distortion

Distortion CorrectionAchieved by applying Polynomial Correction on the input imageCorrection is applied on radial axis with the coefficients based on camera lensComplete removal is impossible as eye lens characteristics of individual are not known

Panorama Construction

Complete retina surface is segmented in 7-9 virtual overlapping parts and individually photographed Retina is photographed in such a way to compensate the distortion caused by the Eye lens and the curvature of retina. Figure shows the method of photography of retina

Panorama Construction Cntd..

Panorama Construction Features

Image Distortion is not 100% correctable making the alignment difficult

Manually Stitching Images is a tedious Job Panorama construction utility performs this

operation in no time

Testing Tested on more than 100 datasets Stitching time is < 40 seconds for 7 images (Each Image 9MPixel)Time varies depending on the features in a image.

Panorama Image is constructed from the 7 images 6 out of which are shown in the above slide taken at different positions (as shown with purple circles)

CDR Analysis

What is CDR ? It’s the ratio between surface area occupied by Optic Cup to Surface area occupied by Optic Disc.

What’s its Clinical Significance When Cup surface area increases, CDR increases. This is indication of variation of intra ocular pressure and sometimes can indicate progress of glaucoma

Current Method Manual marking – Ambiguous

Optic Cup Contour

Optic Disc Contour

CDR Analysis Cntd…

Accurate Extraction of the contours will result in the accurate prediction of clinical manifestationHow to increase the accuracy of detected contours

Active Contours or SNAKE algorithmLike the snake , when put near the object, it fits the object contour with minimum error distance i.e. maximally touches the actual boundary

Example Video of Snake Operation

CDR Analysis Reports

CDR Analysis is used to monitor the intra ocular and dilation of Cup surface area CDR is measured from the centre of the optic disk and traversing axially at a particular angle towards the disc contour. The distance where it cuts cup contour is marked as CUP while the distance at which it cuts the disc contour is marked as disc.

This procedure is repeated for0 -360 degrees and is plot as a graph

Centre point

Angle 0 Degree

Cup Intercept Distance @ 0 Degree

Disc Intercept Distance @ 0 Degree

CDR Analysis Reports

Figure shows the graph of CDR plot for two different dates for chronological studies

Blood Vessel Analysis

Tracing the blood vessels accurately is the backbone of the entire application

Blood vessels are used as the markers of information for panorama Image construction AV Ratio gives vital information about Arterial narrowing and hence the systemic hypertension as well as Diabetics and optic atrophyALR or arterial reflex is a measure of thinning of the artery walls which in turn alarm about arteriosclerosis and atherosclerosis

AV Ratio, Artery width to Vain Width

Development of the Blood Vessel Analysis Algorithm

• Development of a robust algorithm for vessel tracing (Vessel Strokes algorithm )

• Development of Adaptive Vessel tracing algorithm (Accurate boundary detection for exact calculation of AV ratio and ALR are essential for Clinical manifestation)

• Vessel classification and Tree formation (with some domain knowledge and fine tuning)

• Fine tuning of the algorithm is required so that the best results are obtained for most of the images– The most important challenge still remains is to identify the

algorithm which works for almost all the input images. Even the best algorithm needs to be fine tuned for the performance on a given dataset.

Robust Algorithm Development

• Many algorithms were tried and tested for reliable extraction of the blood vessels from background in variety of images

• Vessel Stroke algorithm performed the best in all kinds of input image conditions

• Following figure shows example of vessel extraction

Adaptive Vessel Tracing Algorithm

Adaptive Vessel Tracing Algorithm Drawing the centre line of the vessel Drawing the boundaries of the vesselIdentifying the branch points Identifying the crossover points Identifying the end of the vessel Accurately adjusting the boundaries as per local statistics Identify and Join the broken vessels without addition of errors Identify Blood vessel type: Artery / Vein Build the Vessel Tree Data structure

For each of the above parameters, the algorithm has been tested for more than 300 images at a time. This dataset consists of input images of various kinds.

Blood Vessel tracing Utility

The blood vessel tracing utility allows user to calculate the following

Traced Vessels Vessel Classification- Artery and Veins TreeVessel Tree – Connected tree starts from Optic DiscAV ratio at the selected region ALR Ratio at the selected regionFollowing figure shows the snapshot of the utility

Vessel Analysis Utility

3D Retina Reconstruction

3D analysis is a powerful tool for in biomedical applications and already popular in radiology Retina Can be viewed as a 2D image as well as a 3D structure 3D visualization is possible if the stereo view of the Retina is available Once the stereo imaging data is in hand getting the 3D output is a two step job

Generation of 3D data from 2D Images using stereo algorithmsVisualizing the 3D data with some viewer

Generation of 3D Data from 2D images

Stereo imaging takes 2 images with a lateral shift, preferably from two different cameras. The two images are processed to identify the disparity between the matching structures to calculate the depth of the feature.

Figure below shows one such example

Features of Techlead Stereo Algorithm

• Robust algorithm even works for images taken by single camera. Ideal if the input is provided from a standard stereo imaging setup with 2 cameras

• Automatic Y shift correction • Automatic Disparity range calculation• Automatic Cropping of the Area of Interest • Automatic correction of rotation • Auto Identification of left and right images • Facility to fine tune parameters (defaults are stored)• View the output in a interactive 3D viewer

Snapshot of the 3D Viewer

Glaucoma Detection

What is Glaucoma?Glaucoma is a disease which can result in loss of vision.It’s early detection and treatment is of prime importance.

Physiological Appearance:

Fan-like pattern near Optic Cup Extended Optic

Cup

Glaucoma Detection (Contd..)

Evaluation of Nerve Fiber layer(NFL) is essential for early detection of Glaucoma.Physiological Appearance of NFL:

Methods of Glaucoma DetectionMedian Radial TransformFourier Series DescriptorsHough Transform

Striated Parabolic Arcs

Glaucoma Detection Results

Glaucoma Detection NFL Detection

Retinopathy

Retinopathy refers to a group of diseases which can cause severe vision loss or blindness.This retinal damage can be a result of ruptured blood vessels, swelling in optic nerve etc.Digital Retinopathy identifies these symptoms by the abnormal coloring as shown below:

Retinopathy (Contd..)

Retinopathy Algorithm

Detected Abnormal Patch

Retinopathy : Screening

Screening If the input image is normal or abnormal

User can train the software with

Selecting and deleting the reference Images.Accepting / rejecting the outcome of the softwareAdjusting thresholds Internal Algorithm will tune itself to give best results

Retinopathy: Training

Salient Features:Training – the doctor can train this software to classify what are normal and abnormal images.

Input Algorithm Output

FeedbackTraining

Retinopathy (Contd..)

Salient Features:Intelligent Disease Locator

Uses biological domain knowledge to extract the diseased areasTrain the algorithm to separate a particular pattern of data Use this knowledge for future reference with systematic classification

Retinopathy (Contd..)

Retinopathy Disease Tracker Tool:Analyze large dataView Patient HistoryPatient’s ResponseGraphical representation

Retinopathy (Contd..)

Retinopathy Disease Tracker Tool(Contd..)Shows statistics along with data sets.Finds similar patient history.Software will present analysis and hypothesis to doctors to be accepted or rejected.Content based image retrieval used to identify similar cases.Doctor can share the data of a particular patient case with another in a standard format like DICOM including all the analysis and expert comments.

Retinopathy (Contd..)

Multiple ExaminationsWhen one patient comes more than one timeThe current analysis is checked with history and the results are shown under multiple examinations

Newly identified area Marked with Blue Circle

Thank You