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.
A chromatographic immunoassay cholera antigen detection kit, the Cholera Spot test, was evaluated. The test was found to be specific with a sensitivity of 10(6) cfu/ml for the direct detection of V. cholerae in simulated stool specimens and 10 cfu/ml in simulated cotton-tipped swab specimens after overnight incubation in alkaline peptone water. This enables early recognition of cholera cases and their contacts so that prevention and control measures can be promptly instituted.
A xanthan gum matrix controlled release tablet formulation containing diclofenac sodium was evaluated in vitro and was found to release the drug at a uniform rate. The gastrointestinal transit behaviour of the formulation as determined by gamma scintigraphy, using healthy male volunteers under fasted and fed conditions, indicated that gastric emptying was delayed with food intake. In contrast, the small intestinal transit remained practically unchanged under both food statuses. Therefore, the delay in caecal arrival observed in the fed state can be attributed to the delay in gastric emptying. Rate of diclofenac sodium absorption was generally higher in the fed state compared to the fasted state, however the total amount absorbed under both food statuses remained practically the same. The rate of in vivo dissolution of the drug in the fed state was faster compared to that in the fasted state. Thus, at the time of caecal arrival, in vivo dissolution was complete in the fed state, unlike in the fasted state, where almost 60% of the drug was delivered to the colon.
A single dose study was conducted to evaluate the bioavailability of a novel self-emulsifying vitamin E preparation, in comparison with that of a commercial product, Natopherol, available as soft gelatin capsules under fasted condition. The self-emulsifying preparation achieved a faster rate and higher extent of absorption. A statistically significant difference was observed between the values of the two preparations in the parameters AUC, Cmax and Tmax. Moreover, the 90% confidence interval of the logarithmic transformed AUC values of the self-emulsifying preparation over those of the soft gelatin capsule product was found to be between 2.1 and 4.1, suggesting an increase in bioavailability of between 210 and 410%. As for Cmax, the 90% confidence interval was between 2.1 and 3.0. However, no statistically significant difference was observed between the t(1/2) values estimated from the plasma concentration versus time data of the two preparations. The values are also comparable to those reported in the literature.
A simple, sensitive and reproducible high-performance liquid chromatography (HPLC) method was developed for the determination of terazosin in human plasma. The method involves a one-step single solvent extraction procedure using dichloromethane with a 0.25 ml plasma sample. Recovery values were all greater than 90% over the concentration range 0.25-100 ng/ml. Terazosin was found to adsorb to glass or plastic tubes, but this could be circumvented by using disposable plastic tubes. Also, rinsing the injector port with methanol after each injection helped to prevent any carry-over effect. The internal standard, prazosin, did not exhibit this problem. The method has a quantification limit of 0.25 ng/ml. The within- and between-day coefficient of variation and accuracy values were all less than 7% over the concentration range 0.25-100 ng/ml and hence the method is suitable for use in pharmacokinetic studies of terazosin.
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.
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.
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.
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).
One hundred and eighty-three patients undergoing surgery were interviewed twenty-four hours following surgery to assess the quality of pain relief they received in the immediate postoperative period. Interviews were conducted using a standard questionnaire for all patients. They were asked to (1) rate the quality of pain relief they obtained on a Visual Pain Analogue Scale (VPAS-0 being no pain and 10 being the worst imaginable pain); (2) state whether they were happy and satisfied with the pain relief they received; (3) if dissatisfied, they were asked to give their reasons. 37.7% (69 patients) had moderate to severe pain--pain score greater than 6 on the VPAS. Most of these patients had undergone abdominal or major orthopaedic surgery. 32.7% (60 patients) were unhappy with their postoperative pain control. The main reasons for complaint from the patients were that analgesic injections were either not given promptly or were not given at all. The survey also highlighted the inadequate under-administration of narcotic injections in the postoperative period despite orders being written up. It showed there is an urgent need for setting up an Acute Pain Service for better postoperative pain control. An anaesthesiology based Acute Pain Service was started in October 1992.
Aim: To explore the safety and feasibility of coronary angioplasty and stenting via the radial artery in a heterogenous group of patients and to report the immediate and 3-month clinical follow-up.
Background: The use of the transradial approach for coronary angiography was first described by Lucien Campeau in 1989. Based on the favorable initial results, this technique has gained widespread acceptance worldwide. Ferdinand Kiemeneij’s work in transradial angioplasty and stenting has taken invasive cardiology into the exciting new era of “minimally invasive coronary intervention”.
Methods and results: Fifty consecutive patients underwent Transradial Percutaneous Transluminal Coronary Angioplasty (PTCA) with or without stenting from mid March 98 – December 98. The right radial approach was utilized in 41 patients (80%) while the left in 9 patients. Ninety percent of the procedures was done on an adhoc basis. Diabetes mellitus was present in 38% of patients. Eighty percent of the patients had unstable angina pectoris and 60% had a prior history of acute myocardial infarction. The commonest vessel involved was the LAD (41%) and type B lesions predominated (54%). PTCA was successful in 96%. One patient had a total LAD occlusion, which could not be wired, and another developed severe spasm during catheter manipulation. The latter ad successful PTCA via the right femoral route Stents were utilized in 57% of patients. The commonest indication for stenting was suboptimal PTCA results (89%) and dissection (14%). There was no stent embolization and all stents were successfully deployed (100%). One patient developed acute stent thrombosis necessitating repeat PTCA and another patient sustained an acute anteroseptal myocardial infarction 5 days post procedure as a result of subacute stent thrombosis and died. Two patients had successful primary PTCA. There was no bleeding or vascular complications. 60% of patients were treated on an outpatient basis. At 3-months follow up 1 patient required CABG’s for disease progression. Three patients had absent radial pulses without adverse consequence. No patient required repeat PTCA at follow up.
Conclusion: In summary, adhoc PTCA and stenting is safe and feasible in our patient population. A study on the cost effectiveness of the procedure compared to conventional femoral PTCA is warranted.
We have investigated the pharmacokinetics and bioavailability of alpha-, gamma- and delta-tocotrienols under fed and fasted conditions in eight healthy volunteers. The volunteers were administered a single oral dose of mixed tocotrienols (300 mg) under fed or fasted conditions. The bioavailability of tocotrienols under the two conditions was compared using the parameters peak plasma concentration (Cmax), time to reach peak plasma concentration (Tmax) and total area under the plasma concentration-time curve (AUC(o-infinity)). A statistically significant difference was observed between the fed and fasted logarithmic transformed values of Cmax (P < 0.01) and AUC(0-infinity) (P < 0.01) for all three tocotrienols. In addition, the 90% confidence intervals for the ratio of the logarithmic transformed AUC(0-infinity) values of alpha-, gamma- and delta-tocotrienols under the fed state over those of the fasted state were found to lie between 2.24-3.40, 2.05-4.09 and 1.59-3.81, respectively, while those of the Cmax were between 2.28-4.39, 2.31-5.87 and 1.52-4.05, respectively. However, no statistically significant difference was observed between the fed and fasted Tmax values of the three homologues. The mean apparent elimination half-life (t(1/2)) of alpha-, gamma- and delta-tocotrienols was estimated to be 4.4, 4.3 and 2.3 h, respectively, being between 4.5- to 8.7-fold shorter than that reported for alpha-tocopherol. No statistically significant difference was observed between the fed and fasted t(1/2) values. The mean apparent volume of distribution (Vd/f) values under the fed state were significantly smaller than those of the fasted state, which could be attributed to increased absorption of the tocotrienols in the fed state.
This study aimed to evaluate dry powder inhaler naive asthmatic patients' perception and preference of the Accuhaler, a multidose dry powder inhaler and the pressurized metered dose inhaler (pMDI). After the first instruction, 66.7% of 48 patients enrolled in the study could demonstrate the correct use of the Accuhaler. When the patients were asked to compare the pMDI and the Accuhaler after using the Accuhaler to administer salmeterol for 4 weeks, the Accuhaler scored significantly better than the pMDI for the following features: knowing how many doses are left, presence of an attached cover, taste, instruction for use, attractiveness, ease of use, ease of holding, shape, and comfortable mouthpiece. The pMDI scored better to the Accuhaler in terms of size. More patients preferred the Accuhaler than the pMDI; the presence of a dose counter and perceived ease of use were the main reasons cited for their preference for the Accuhaler.
Study site: Asthma Clinic, University of Malaya Medical Centre (UMMC), Kuala Lumpur, Malaysia
Thirty-one chevron osteotomies for hallux valgus performed over a period of four years were reviewed. Their follow-up period ranged from one to five years. All the patients had pain over the bunion prior to operation. After operation, there was marked decrease of pain over the first matatarsophalangeal joint. The preoperative hallux valgus angle average 27 degrees and the postoperative angle averaged 12 degrees. The preoperative intermetatarsal angle averaged 13 degrees and the postoperative angle, 8 degrees. Ninety-one per cent of the patients were satisfied with the result of the procedure.
A simple liquid chromatographic method using amperometric detection was developed for the determination of naltrexone in human plasma. Prior to analysis, naltrexone and the internal standard (naloxone) were extracted from plasma samples using a 9:1 mixture of chloroform and isopropyl alcohol. The mobile phase comprised 0.1 M disodium hydrogen orthophosphate (pH 3.5) and acetonitrile (85.5:14.5, v/v). Analysis was run at a flow-rate of 0.8 ml/min with the detector operating under oxidative mode at an applied potential of +0.95 V. The method is specific and sensitive with a detection limit of approximately 1 ng/ml at a signal-to-noise ratio of 3:1. Mean recovery value of the extraction procedure was about 93%, while the within day and between day coefficient of variation and percent error values of the assay method were all less than 10%. The calibration curve was linear over a concentration range of 1.5-100 ng/ml.
A simple high-performance liquid chromatographic method was developed for the determination of ranitidine in human plasma. Prior to analysis, ranitidine and the internal standard (metoprolol) were extracted from alkalinized plasma samples using dichloromethane. The mobile phase was 0.05 M potassium dihydrogenphosphate-acetonitrile (88:12, v/v) adjusted to pH 6.5. Analysis was run at a flow-rate of 1.3 ml/min and at a detection wavelength of 229 nm. The method is sensitive with a detection limit of 1 ng/ml at a signal-to-noise ratio of 3:1, while the quantification limit was set at 15 ng/ml. The calibration curve was linear over a concentration range of 15-2000 ng/ml. Mean recovery value of the extraction procedure was about 90%, while the within-day and between-day coefficients of variation and percent error values of the assay method were all less than 15%.
Aminoacylase I (E.C.3.5.1.14) was immobilized by entrapment in calcium alginate beads coated with polyethyleneimine for the production of L-phenylalanine by the hydrolysis of a racemic mixture of N-acetyl-DL-phenylalanine. The operational stability in terms of batch operation and continuous reaction in packed-bed bioreactor were studied. Kinetic constants, Km and Vmax values of free and immobilized enzymes were studied. Polyethyleneimine treatment was found to enhance the operational stability of the enzyme though its activity was substantially reduced. When polyethyleneimine-coated calcium alginate beads were packed into packed bed bioreactor, it was stable for at least 25 days under continuous operation without appreciable loss of activity.