The HIV-1 genetic variation in 60 infected Malaysian intravenous drug users (IDU) was studied by comparison of the nucleotide sequences and their predicted amino acid sequences in the V3 loop of the external glycoprotein gp120. In this study, HIV-1 B, C and E subtypes were identified among Malaysian IDU, with HIV-1 B being the predominant subtype (91.7%). HIV-1 C and HIV-1 E were minority subtypes among Malaysian IDU. Analysis of the amino acid alignment of the C2-V3 region of the env gene suggests a genetic relationship between Thai and Malaysian B and E subtype strains. This study serves as a baseline for monitoring HIV-1 genetic diversity and spread in Malaysia.
For broad-beam soft X-ray sources, assessment of the quality of image produced by such units is made complex by the low penetration capabilities of the radiation. In the present study we have tested the utility of several types of test tool, some of which have been fabricated by us, as part of an effort to evaluate several key image defining parameters. These include the film characteristic, focal-spot size, image resolution and detail detectability. The two sources of X-rays used in present studies were the University of Malaya flash X-ray device (UMFX1) and a more conventional soft X-ray tube (Softex, Tokyo), the latter operating at peak accelerating potentials of 20 kVp. We have established, for thin objects, that both systems produce images of comparable quality and, in particular, objects can be resolved down to better than 45 microm.
The medical radiation usage for diagnostic radiology in Malaysia (a Level II country) for 1990-1994 is reported, enabling a comparison to be made for the first time with the United Nations Scientific Committee on the Effects of Atomic Radiation Report. In 1994, the number of physicians, radiologists, x-ray units, and x-ray examinations per 1,000 population was 0.45, 0.005, 0.065, and 183, respectively. (Level I countries had averages of 2.6, 0.072, 0.35, and 860, respectively). In 1994, a total of 3.6 million x-ray examinations were performed; the annual effective dose per capita to the population was 0.05 mSv, and the collective effective dose was 1,000 person-Sv. Chest examinations contributed 63% of the total. Almost all examinations experienced increasing frequency from 1990 to 1994 except for barium studies, cholecystography, and intravenous urography (-23%, -36%, -51%). These decreases are related to the increasing use of ultrasound and greater availability of fiberoptic endoscopy. Notable increases during the same period were observed in computed tomography (161%), cardiac procedures (190%), and mammography (240%). In order to progress from Level II to Level I status Malaysia needs to expand and upgrade radiological service in tandem with the health care development of the country.
Wavelet-based image coding algorithms (lossy and lossless) use a fixed perfect reconstruction filter-bank built into the algorithm for coding and decoding of images. However, no systematic study has been performed to evaluate the coding performance of wavelet filters on medical images. We evaluated the best types of filters suitable for medical images in providing low bit rate and low computational complexity. In this study a variety of wavelet filters are used to compress and decompress computed tomography (CT) brain and abdomen images. We applied two-dimensional wavelet decomposition, quantization and reconstruction using several families of filter banks to a set of CT images. Discreet Wavelet Transform (DWT), which provides efficient framework of multi-resolution frequency was used. Compression was accomplished by applying threshold values to the wavelet coefficients. The statistical indices such as mean square error (MSE), maximum absolute error (MAE) and peak signal-to-noise ratio (PSNR) were used to quantify the effect of wavelet compression of selected images. The code was written using the wavelet and image processing toolbox of the MATLAB (version 6.1). This results show that no specific wavelet filter performs uniformly better than others except for the case of Daubechies and bi-orthogonal filters which are the best among all. MAE values achieved by these filters were 5 x 10(-14) to 12 x 10(-14) for both CT brain and abdomen images at different decomposition levels. This indicated that using these filters a very small error (approximately 7 x 10(-14)) can be achieved between original and the filtered image. The PSNR values obtained were higher for the brain than the abdomen images. For both the lossy and lossless compression, the 'most appropriate' wavelet filter should be chosen adaptively depending on the statistical properties of the image being coded to achieve higher compression ratio.
Generally there is a significant delay before optimized performance of mammography is fully realized in the developing countries. To evaluate the status of mammographic performance, a survey of mammographic image quality and exposure was performed in nine hospitals from four selected South East Asian countries. The entrance exposure on the surface of the American College of Radiology (ACR) mammographic phantom (ACR-RMI model 156) was made using both thermoluminescent dosimeters (TLDs) and an ionization chamber. The TLDs were mailed from the University of Wisconsin Radiation Calibration Laboratory (UWRCL) to the cooperating hospitals. The surveyed hospitals processed the images and returned them to the UWRCL for subsequent evaluation of the image quality of the mammographic phantom. Machine-specific data, technique factors and sensitometric data were also obtained. At 28 kVp, the mean entrance exposure is 0.91 R (0.46 to 2.6 R), mean glandular dose is 1.61 mGy (0.90 to 4.15 mGy), mean optical density is 1.37 (0.66 to 2.30), mean total phantom image score is 9.1(4-12). Only three of the nine hospitals tested achieved an acceptable score above the minimum 10. Results for 25 and 30 kVp showed similar trend. The variation between the ion chamber measurements and TLD measurements ranged from 4 to 24%. There is a wide variation in the image quality and entrance exposure among hospitals in South East Asia. There is a need for a quality assurance program. The factors that cause low score in the phantom images must be corrected. Calibration and the use of appropriate ionization chambers for mammography is important.
Teleradiology is the most mature and rapidly evolving specialty in telemedicine. The use of teleradiology has grown tremendously during the past few years. This article describes the role of teleradiology in health care along with a brief history of its development in tandem with advances in telecommunications and computer technologies. Teleradiology standards, image acquisition, data compression, transmission and image interpretation are summarised. The impact of teleradiology in the practice of radiology, traces the evolution of the modality especially in the Malaysian perspective and its current and future role are discussed.
X-ray based radiological procedure statistics and trend in Malaysia for 1990-1994 is reported; this information allows comparisons to be made with the United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR) Report. Additionally it is essential information for health care planners and providers. Malaysia is categorised as a health care level II country based on the UNSCEAR definition. In 1994, the number of physicians, radiologists, x-ray units and x-ray examinations per 1000 population was 0.45, 0.005, 0.065 and 183 respectively. 3.6 million x-ray examinations were performed in 1994, with chest radiography being the commonest study (63%). Information on x-ray examinations, number of hospitals and x-ray units is reported for the Ministry of Health, private practice and teaching hospitals. Examination frequency increased in computed tomography (161%), cardiac procedures (190%), and mammography (240%); while a decrease in barium studies (-23%), cholecystography (-36%), and intravenous urography (-51%) was noted. There is a potential and need to expand and upgrade radiological services.
Diagnosis of ectopic pregnancy prior to rupture is an arduous task even with the availability of many new investigative methods and imaging modalities. Above all, a high index of suspicion is necessary when dealing with women who present in early pregnancy with abdominal pain and vaginal bleeding. With the increased use of ovulation induction agents, the probability of heterotropic pregnancy should be kept in mind. The use of transvaginal ultrasonography (TVS) will help in earlier diagnosis because of its advantages over transabdominal ultrasonography (TAS).
We report two cases of body piercing as a religious practice that subsequently led to the development of granulomatous nodules at previously punctured sites of the skin and oral mucosa. These lesions were diagnosed as sarcoid-like foreign body reaction after other possible causes including sarcoidosis, tuberculosis, tuberculoid leprosy, fungal infections, viral infections, and Crohn's disease were excluded.
We reviewed the deliveries in a teaching hospital in a multiracial community over the period of one year (1988), and investigated the relationship between maternal height, ethnic origin, and the extremes of birth weight with the likelihood of emergency lower segment caesarean section (LSCS). After excluding patients with obvious indications for LSCS, 5,050 patients were entered in the study. Chi-square analysis showed that the risk of emergency LSCS is significantly higher in the Indians compared to Chinese and Malays, but does not differ significantly between the latter two groups. Logistic regression analysis showed that birth weight of less than 2,500 g or greater than 3,500 g is the most significant association with emergency LSCS rate. Conditional logistic regression showed that, provided the individuals conformed to the characteristics of the cohort in this study, risk of emergency LSCS for a 150 cm (25th centile) tall Indian pregnant lady is almost twice that of a 158 cm (75th centile) tall non-Indian).
A case of denture hyperplasia of the upper labial sulcus with concomitant oncocytic metaplastic changes is described. The patient concerned is an elderly male wearing an ill-fitting upper full denture.
Leiomyomas are benign neoplasms of smooth muscle origin. They represent rare entities in the oral cavity. A case arising from the incisive papilla region of a 3-month-old infant is described and the histogenesis as well as the biologic potential of this tumor are discussed.
X-ray microradiography of surgically excised breast specimens offers the possibility of morphological characterization of calcifications. When combined with digital imaging techniques there exists added potential for obtaining valuable basic quantitative morphometric information regarding differences between microcalcifications in tissues exhibiting evidence of fibrocystic change, benign and malignant tumours. A total of 157 excised breast specimens from 84 patients were microradiographed using a Softex Super Soft X-ray unit and Kodak AA high resolution industrial film. A Quantimet 570C image analysis system was used to digitize and analyse the microradiographs. Of the 157 microradiographs, 51 (from 30 patients) revealed microcalcification clusters. The existence of significant differences between the three identified categories of tissue were indicated by clustering parameters. These included the number of particles per cluster, area of clusters, maximum distance to nearest neighbour, and geometric mean distance to nearest neighbour. The distribution pattern index (DPI), another of the clustering parameters used in this study, has been observed to be a particularly powerful discriminator. The value for fibrocystic change was found to be significantly smaller (0.514) than that for benign tumour (0.796) whilst that for benign tumour was observed to be significantly larger than that for malignant tumour (0.604) at a p-value of less than 0.05 (Kruskal-Wallis one-way analysis of variance).
Eighty-nine patients who had hydatidiform moles evacuated at the General Hospital, Kuala Lumpur, were followed with serum beta hCG determinations from October 1988 to June 1991. A regression curve for serum beta hCG, as measured by RIA, was derived from the results of 47 of the patients who demonstrated spontaneous regression of serum beta hCG titres. All 47 patients had normal serum titres at 135 days after evacuation. The mean time taken to reach normal level was 82.6 days, while the range was 39 to 135 days (5 to 19 weeks).
An AIDS patient with multiple opportunistic infections (Candida, Pneumocystis carinii and Isospora belli) was identified at the University Hospital, Kuala Lumpur. The patient presented with profuse diarrhoea associated with lethargy, anorexia and weight loss. Routine stool examination showed Isospora belli oocysts. The infection responded to treatment with trimethroprim-sulfamethoxazole but relapse occurred 8 weeks later. This represents the first documented case of isosporiasis to occur in an AIDS patient in Malaysia.
We report a 39-year-old male who presented with tuberculous meningitis and was found also to be HIV-infected. In the course of his illness, he developed multiple opportunistic infections such as herpes genitalis, oesophageal candidiasis, CMV retinitis and finally succumbed to Penicillium marneffei septicaemia.
Adenomatoid odontogenic tumours (AOT) are benign, hamartomatous odontogenic lesions that not uncommonly mimic a dentigerous cyst radiographically. Such a case as found involving an unerupted left maxillary canine in a 19-year-old Chinese female is described. The differential diagnosis of some common odontogenic cysts and neoplasms occurring in Malaysians, that may present in a dentigerous relationship to an unerupted tooth is discussed. A brief review of the radiographic literature on AOT is also included.