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.
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.
Analysis of case records of 46 patients with peripheral odontogenic fibroma (1967-95) diagnosed in the Division of Stomatology, Institute for Medical Research, Kuala Lumpur, disclosed a relatively young age of onset (mean, 32.2 years; range 5 months-64 years; peak incidence second decade of life), a slight female preponderance (M:F ratio 1:1.3), no racial predilection, a slight bias towards location in the mandible (52%) and a wide histomorphological range. All cases were treated by simple excision. Follow-up records were generally not available, so we do not know what the recurrence rate is.
The lining epithelium of 15 cases of odontogenic keratocyst (OKC) was evaluated immunohistochemically. The peroxidase-antiperoxidase technique was applied to study the distribution of polyclonal keratin and S-100 protein while the indirect method was used to examine monoclonal vimentin and desmin reactivity. Consistent positive keratin staining was revealed in the lining epithelium of all 15 OKCs with additional intense staining in the stratum corneum. None of the cases showed vimentin or desmin reactivity within the lining epithelium elements. One of the 15 cysts studied showed positive S-100 protein staining in the nuclei of the lining epithelial cells. The pertinent literature on the immunophenotyping of the lining epithelium of OKC is reviewed.
Four cases of either combined occurrence of ameloblastoma and odontogenic keratocyst or a rare keratinising variant of ameloblastoma are presented. The cardinal histomorphologic characteristics are simultaneous occurrence of ameloblastomatous epithelial islands with central keratinisation and multiple keratinising cysts. Immunohistochemically the tumour elements were keratin positive and occasionally S-100 protein and desmin positive. Major differential diagnosis of these neoplasms are discussed.
Granular cell ameloblastoma (GCA) is a well recognized variant of follicular ameloblastoma with extensive granular cell change. In contrast, plexiform granular cell odontogenic tumor (PGCOT) is a rare and recently described lesion characterized histologically by a monophasic plexiform pattern of granular cells. In this paper, two cases of an unusual granular cell odontogenic tumor exhibiting combined features of these two entities are described along with their immunohistochemical characteristics. The granular cells of both the GCA and PGCOT areas showed similar patterns of expression for keratin and S-100, which differed from those of typical ameloblastoma. No reactivity for desmin or vimentin was noted. The histomorphologic and immunohistochemical features of these hybrid tumors suggest that the granular cells present have a common origin, most probably the odontogenic epithelium.
Seventeen cases of desmoplastic ameloblastoma were examined immunohistochemically. Immunoperoxidase techniques were applied for detection of keratin, desmin, vimentin and S-100 protein expression in these tumors. The tumor epithelium of desmoplastic ameloblastoma exhibited weak, focal, inconstant keratin staining, weak, variable expression of S-100 protein, desmin immunoreactivity of mild to moderate intensity and vimentin non-reactivity. The pertinent literature on the immunohistochemistry of ameloblastomas is briefly reviewed.
Four hundred and one cases of ameloblastoma of the jaw diagnosed in the Division of Stomatology, Institute for Medical Research, Kuala Lumpur, between 1967 and 1991 have been analysed. There were 214 males and 187 females. Of these, 50.1% were Malays, 34.7% Chinese, 8.2% Indians and 7.0% other races. Seventy-two percent of patients were in the second, third and fourth decades of life (mean age: 30.8 years). Ninety-three percent of tumours occurred in the mandible and 6.5% in the maxilla. There were 337 cases of conventional ameloblastoma, 49 cases of the unicystic variant and four cases of peripheral ameloblastoma. The predominant histologic patterns were plexiform (34.2%), follicular (16.5%) and mixture of both (17.7%). Majority of the cases were conservatively treated by enucleation. Fifty-nine cases presented with recurrences. Present findings were generally compatible with regional serial studies reported from Thailand, Singapore and Japan.
A case is described of ameloblastoma of the mandible presenting with multiple recurrences and subsequent extension to the maxilla with resultant transformation into an aggressive (malignant?) epithelial odontogenic ghost cell tumour. The latter is a rare, biologically virulent entity that affects mainly males, exhibits a preference for the maxilla and is histologically characterized by atypical malignant odontogenic epithelium associated with areas of ghost cell formation and varying amounts of dentinoid.
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.
Twelve pleomorphic adenomas of minor salivary gland origin were examined for the distribution of S-100 protein, detected using the peroxidase-antiperoxidase (PAP) method. Strong S-100 protein immunoreactivity was noted in areas containing plasmacytoid cells, stellate and spindle cells against a myxochondroid or hyalinous stroma, and solid epithelial areas. Tubular and duct-like structures showed variable stainability. Stromal tissue and normal salivary glands were generally negative for S-100 protein. These findings were compared with those reported elsewhere.
The records of the Division of Stomatology, Institute for Medical Research, Kuala Lumpur, Malaysia, were reviewed for the incidence of odontogenic keratocysts of the orthokeratinised variety, during the 20-year-period, 1967 to 1986. Nine cases were found. The clinical, histological and radiological features of these cases are reported. Many features were similar to previous reports of this entity but a peak incidence in the second decade of life, an almost even distribution in the maxilla and mandible, and a distinct predilection for the Chinese were observed. It is suggested that these features may be peculiar to Malaysians.
The combined epithelial odontogenic tumour represents a hybrid lesion comprising primarily areas of adenomatoid odontogenic tumour intermixed with foci of calcifying epithelial odontogenic tumour. Five such cases retrieved from the files of the Division of Stomatology, Institute for Medical Research, Kuala Lumpur, and four others from the existing literature were analysed. A mean age of 18.8 years, a female preponderance (66.7%) with a male to female ratio of 1:2 and predilection for the mandible (55.6%) were observed. All cases were treated by conservative surgery and the lack of recurrence confirmed the innocuous nature of this lesion.
The early Malaysian experience of laparoscopic sterilisation with the Fallope tubal rings, as undertaken at the Obstetrical and Gynaecological Unit of the University Hospital, University of Malaya in Kuala Lumpur, Malaysia is reported in a study of 291 consecutive females that had had the procedure undertaken during the one year period, May 1975 to April 1976. Of the 291 cases, 247 women were sterilised in the "interval" period, 43 after "menstrual regulation" procedure and one after a spontaneous abortion. General anaesthesia was used in all except one case. The salient socio-demographic, contraceptive and reproductive characteristics of study cases are presented and discussed. The technical problems, the early complications and morbidity encountered in this study are presented and discussed in the light of other similar studies, and in relation to sterilisation by laparoscopic tubal electrocoagulation. The overall impression is that laparoscopic sterilisation with the Fallope tubal rings is preferred to that by tubal electrocoagulation, in view of the possible inadvertent serious electrical burns of other structures during the use of the latter procedure.
A case is described of ameloblastoma of maxilla presenting with numerous calcified keratin pearls. The significance of cellular variation in relation to the behavioural potential of the ameloblastoma in general is briefly discussed.
Uniformity of electric field intensity of microwaves within the microwave oven cavity is necessary to ensure even load-heating, and is particularly important in pathology procedures where small volume irradiation is carried out. A simple and rapid method for mapping electric field distribution, using reversible thermographic paint, is described. Spatial heating patterns for various positions, and the effects of introducing dummy loads to modify heating distributions, have been obtained for a dedicated microwave processor, and comparison made with a domestic microwave oven.
One of the important functions of the Coronary Care Unit (CCU) is the continuous and intensive monitoring of cardiac function. To date, many monitoring techniques have been developed and tested. In this paper, both the conventional and computerised monitoring techniques are reviewed and evaluated. It is shown that a computerised system has several defirute advantages over the conventional system, e.g. lower false alarm rate, accurate and fast data processing, retrospective studies. However one also ought to be aware of the limitations,
Osteoma is a benign tumour consisting of mature bone tissue. It is an uncommon lesion that occurs mainly in the bones of the craniofacial complex. Only a few cases involving the condylar process have been reported. An osteoma of the left condyle causing limited mouth-opening in a 32-year-old Malaysian Chinese female is reported here to alert the practitioner to consider this lesion as a diagnostic possibility in instances of trismus or limited-mouth opening.