Hasballah Zakaria

A Parametric Model for Studies of Flow in Arterial Bifurcations

Regional differences in hemodynamic loads on arterial walls have been associated with localized vascular disease such as atherosclerosis and cerebral aneurysms. Due to their intrinsic geometric relevance, three-dimensional (3D) reconstructions of arterial segments are frequently used in hemodynamic studies of these diseases. However, it is not possible to use them to systematically vary geometric features for parametric studies. Idealized vascular models are inherently suited for parametric studies, but are limited by their tendency to oversimplify the vessel geometry. In this work, a hierarchy of three parametric bifurcation models is introduced. The models are relatively simple, yet capture all geometric features identified as common to cerebral bifurcations in the complex transition from parent to daughter branches. While these models were initially designed for parametric studies, we also evaluate the possibility of using them for 3D reconstruction of cerebral arteries, with the future goal of improving reconstruction of poor quality clinical data. The lumen surface and vessel hemodynamics are compared between two reconstructed cerebral bifurcations and matched parametric models. Good agreement is found. The average and maximum geometric differences are less than 3.1 and 10%, respectively for all three parametric models. The maximum difference in wall shear stress is less than 8% for the most complex parametric model.

Wearable gait measurement system based on accelerometer and pressure sensor

This paper presents the development of wearable instrument that can be used to study the dynamics of human lower limb. Camera-based gait analysis and force plate system are expensive devices. It also requires time-consuming calibration and setup. The wearable system is much cheaper. This system uses gyroscopes and two-axis accelerometers to measure angle of patients leg and ground while the patient walks. Ground reaction forces during human walking are measured using flexible force sensors placed beneath insoles of the shoes. Communication between the wearable system and computer monitor can be performed using the wireless data communication.

Vessel enhancement algorithm in digital retinal fundus microaneurysms filter for nonproliferative diabetic retinopathy classification

Diabetic Retinopathy is one of a complication of diabetes which can cause blindness. There are two levels of diabetic retinopathy which are nonproliferative diabetic retinopathy (NPDR) and proliferative diabetic retinopathy (PDR). The presence of microaneurysms in the eye is one of the early signs of diabetic retinopathy. Automated detection of microaneurysms in digital color fundus photographs is developed to help opthalmologist to detect the emergence of its early symptoms and determine the next action step for the patient. In this study we developed microaneurysms filter algorithm with the concept of vessel enhancement in order to extract the structure of microaneurysms in medical imagery, especially in the retinal image. Microaneurysms filter algorithm has been able to extract part of microaneurysms in the retinal image and detect pretty well. In addition, microaneurysms filters can also be developed to detect the next symptoms of diabetic retinopathy-hemorraghes (bleeding) that has features in common with microaneurysms which are larger and have irregular shape. Furthermore, the nonproliferative diabetic retinopathy (NPDR) classification system was developed based on the microaneurysms and hemorraghes detection. The system was tested against the patient data. Microanuerisyms detection results on DiaRetDB data has sensitivity value by 57,4% to ophthalmlogist 1, 35,37% for opthalmologist 2 and 62,68% for opthalmologist 3.

Detection of cerebral aneurysms by using time based parametric color coded of cerebral angiogram

Cerebral aneurysm is a cerebrovascular disorder in which weakening in the walls of brain blood vessels causing a swelling or dilation of blood vessels. The disease is also called intracranial aneurysms and usually occurs around the arteries at the base of the brain called the Circle of Willis.

Nailfold capillaroscopy image processing for morphological parameters measurement

Nailfold capillaroscopy is a non-invasive imaging technique employed to assess the microcirculation of blood capillaries. In this paper, image processing will be designed to measure morphological parameters for each capillary. The processes are pre-processing, binarization, skeleton extraction and skeleton segmentation. The morphological parameters are width of capillary, height of capillary, loop morphology, width of terminal loop, caliber and tortuosity. After the implementation, all the parameters can be measured automatically and the binarization process has accuracy up to 96% based on groundtruth image.

Extracting blood flow parameters from Photoplethysmograph signals: A review

Infrared sensors are used in Photoplethysmography measurements (PPG) to get blood flow parameters in the vascular system. It is a simple, low-cost non-invasive optical technique that is commonly placed on a finger or toe, to detect blood volume changes in the micro-vascular bed of tissue. The sensor use an infrared source and a photo detector to detect the infrared wave which is not absorbed. The recorded infrared waveform at the detector side is called the PPG signal. This paper reviews the various blood flow parameters that can be extracted from this PPG signal including the existence of an endothelial disfunction as an early detection tool of vascular diseases.

Detection method of cerebral aneurysm based on curvature analysis from 3D medical images

Cerebral aneurysm is a weak spot in a blood vessel that usually enlarges. Nowadays, cerebral aneurysm detection method is still being done manually by visually observing 2D or 3D medical images (CTA). The main purpose of this paper is to design a method of cerebral aneurysm detection and classify different vascular geometry with color indicator. The method developed was based on curvature analysis of wall vasculatures model that were reconstructed from 3D CTA images. The curvature shape index defined as I=(K1+K2)/K1 where K1 and K2 are the main curvature of vascular model then used as the base of vascular coloring system. Results showed that the shape index is able to differentiate different parts of vasculature model and detect the present of an aneurysm.

Indonesian text-to-speech using syllable concatenation for PC-based low vision aid

Severe low vision patient cannot read a text clearly. Thus, an instrument engineered for them should have an extra function to read aloud the text. Nowadays, Bahasa Indonesia is still not supported properly in any text to speech modul. This ongoing research is trying to develop an Indonesian text to speech with syllable concatenation. The input of the system comes from a plain text file or manually typed input. This text is then truncated until we get a list of words. The word is then analyzed using brute force algorithm to get proper combination of syllable according to the sound library, which has been recorded previously. Arranged sound then came out from speaker. Test of the system shows that this method works well for any text in Bahasa Indonesia.

Noninvasive blood glucose detection using near infrared sensor

The development of noninvasive blood glucose detector is desired to replace invasive method which is costly and uncomfortable. Near Infrared (NIR) spectroscopy is used to detect blood glucose noninvasively since glucose has specific absorbance spectrum in NIR range, 850nm-2500nm. LED is utilized as incoherent infrared source to irradiate body surface in wavelength 1550 nm. Penetrated light is then detected by InGaAs photodiode, sensitive for wavelength 850-1700 nm. As the measurement sites, earlobe is chosen since it is thin. Photodiodes current is converted into voltage using transimpedance amplifier circuit. In order to minimize high frequency noise, low pass filter is applied consecutively. Early testing is conducted by measuring penetrated light in various concentration of glucose solution with wavelength 1300nm, 1450nm, and 1550nm. Measurement indicates correlation between voltage and glucose concentration. In earlobe testing, light can penetrate tissue with detected voltage, 300mV-4V depend on the wavelength. Linear approximation and two point equation is applied to the data. This two approach extracts formula that can estimate blood glucose concentration with maximum 30% error. By using two point equation, a specific formula for each person can be obtained.

Design of ECG Homecare:12-lead ECG acquisition using single channel ECG device developed on AD8232 analog front end

Electrocardiogram (ECG) devices measure electrical activity of the heart muscle to determine heart conditions. ECG signal quality is the key factor in determining the diseases of the heart. However, the availability of ECG devices is causing ECG diagnosis slow and difficult. This paper presents the design of single channel portable ECG device developed on AD8232 chip platform. To extend the capability of an ECG portable device, a 12-lead ECG acquistion technique is also tested out. The results showed the single channel ECG module with additional 12-lead ECG acquisition technique can serve the function of ECG Homecare device, thus making the ECG diagnosis much more accessible.