Edward K. Wong

IMAGING OF OSTEOMYELITIS IN THE MATURE SKELETON

Diagnosis of acute osteomyelitis is often challenging but can be made by plain radiograph, bone scan, or MR imaging. This diagnosis may be more problematic in small bones, in diabetic or immunocompromised patients, those partially treated, post-traumatic, previous surgery, or with pre-existing marrow conditions and associated soft tissue infections. CT is the modality of choice for revealing sequestra and cortical erosions in chronic osteomyelitis. Nonenhanced and enhanced STIR or fat-saturated sequences are essential to reveal the marrow abnormality and its extension for diagnosis of subtle cases with neuropathic or other associated conditions. Combined radionuclide scintigraphy becomes necessary in complicated situations.

Lumbar spine imaging. Normal variants, imaging pitfalls, and artifacts.

Accurate recognition and reporting of spine abnormalities on MRI requires knowledge of normal anatomy and its variants. This article deals with common normal variants, points out pitfalls which may be sources of errors in interpretation and describes imaging artifacts which are essential to be recognized and not mistaken for true pathologies.

Quantification and standardized description of color vision deficiency caused by anomalous trichromats-part I: simulation and measurement

The MPEG-21 Multimedia Framework allows visually impaired users to have an improved access to visual content by enabling content adaptation techniques such as color compensation. However, one important issue is the method to create and interpret the standardized CVD descriptions when making the use of generic color vision tests. In Part I of our study to tackle the issue, we present a novel computerized hue test (CHT) to examine and quantify CVD, which allows reproducing and manipulating test colors for the purposes of computer simulation and analysis of CVD. Both objective evaluation via color difference measurement and subjective evaluation via clinical experiment showed that the CHT works well as a color vision test: it is highly correlated with the Farnsworth-Munsell 100 Hue (FM100H) test and allows for a more elaborate and correct color reproduction than the FM100H test.

Absorption of Fluorescein Given under the Upper Lid

BACKGROUND The need for a more efficacious approach to administer topical ocular medications prompted the authors to consider applying conventional eye drops under the upper lid rather than beneath the lower lid. Preliminary observations on patients with glaucoma using a beta-blocker beneath the upper lid suggested a drop in intraocular pressure into the normal range in some previously refractory patients being treated with the same medications. To test this clinical observation, the authors observed if there were any physiologic differences in topical fluorescein absorption into the anterior chamber when given beneath the upper lid versus the lower lid. METHODS A 5-microliters drop of fluorescein solution was placed under the upper-lid fornix of one eye and under the lower-lid fornix of the other eye in human volunteers, and absorption into the anterior chamber was measured at hourly intervals, for a total of 3 hours. RESULTS Hotelling T2 multivariate analysis for all 3 hours demonstrates that upper-lid administration of fluorescein results in significantly higher absorption of fluorescein into the anterior chamber than does lower-lid administration (P = 0.0088; for hours 2 and 3, the statistical differences is even more dramatic: P < 0.0044). CONCLUSION Using conventional eye drops beneath the upper lid, the authors observed increased absorption of fluorescein into the anterior chamber when compared with lower-lid administration. Profuse tearing, especially by younger subjects, significantly and rapidly diminished anterior chamber absorption of fluorescein. It is reasonable to consider further clinical studies to test this new approach to drug delivery.

Quantification and standardized description of color vision deficiency caused by anomalous trichromats-part II: modeling and color compensation

A color compensation scheme has been developed to enhance the perception of people with color vision deficiency (CVD) and for people suffering from anomalous trichromacy. It is operated within the MPEG-21 Multimedia Framework, which provides a standardized description of CVD. The basic idea behind the proposed color compensation consists of simulating the path of human color perception. As such, compensated color is realized by relying on the spectral cone sensitivities of the human eye and the spectral emission functions of the display device. For quantified color compensation, the spectral sensitivity of anomalous cones has been modeled according to the deficiency degree of the standardized CVD description. The latter is based on the error score of a computerized hue test (CHT), developed in Part I of our study. Given the anomalous cone spectra, the reduction of error score on the CHT after color compensation was measured in each deficiency degree. The quantitative relationship of color compensation with the error score is linearly regressed, based on the deficiency degree with the least error score after color compensation as well as the error score before color compensation.

Media Accessibility for Low-Vision Users in the MPEG-21 Multimedia Framework

Ethical and legal requirements have made accessibility a crucial feature in any information systems. This paper presents a content adaptation framework, based on the MPEG-21 standard, to help low-vision users have better accessibility to visual contents. We first present an overview of MPEG-21 Digital Item Adaptation (DIA) and the low-vision description tool which enables interoperable content adaptation. This description tool lists seven low-vision symptoms, namely loss of fine detail, lack of contrast, central vision loss, peripheral vision loss, hemianopia, light sensitivity, and need of light. Then we propose a systematic contrast-enhancement method to improve the content visibility for low-vision users, focusing on the first two symptoms. The effectiveness of the low-vision description tool and our adaptation framework is verified by some experiments with an adaptation test-bed. The major advantages of the proposed approach include 1) support of a wide range of low-vision conditions, and 2) customized content adaptation to specific characteristics of each user.

Color Compensation for Anomalous Trichromats Based on Error Score of FM-100 Hue Test

In this paper, we propose novel color compensation for anomalous trichromat. The proposed method is to compensate colors defected due to anomalous trichromacy. The proposed color compensation is performed with color deficiency degree measured by total error score of FM-100 Hue test. The relationship between the deficiency degree and color variation is modeled for accurate compensation. Clinical experiments were performed and the results verified the proposed compensation method

First-order Wiener kernel visually evoked potentials obtained from multiple sclerosis patients

Visually evoked potentials (VEP) were measured in multiple sclerosis patients with five sizes of reversing check stimuli. The VEPs were obtained using random binary sequence triggered check reversals. The random binary sequence was cross-correlated with scalp potential responses to obtain the estimates of the linear response of the system.For each evaluation a series of five VEPs, one for each of five check sizes, was done. A correlation coefficient was calculated to evaluate check size versus amplitude of the major negative wave. A tabulation was made to compare Snellen chart visual acuity with these correlation coefficients. For the eyes with a Snellen acuity of 20/20, 63% of the VEP amplitudes increased as the check size was decreased with correlation coefficients of -0.6 to -1. For the eyes with a Snellen acuity of 20/70 or less the amplitude decreased with the check size decrease, showing a correlation coefficient of +0.6 to +1 in 45% of the evaluations. The check size giving the largest amplitude was also tabulated with respect to the visual acuity, but did not appear to have as strong a relationship to visual acuity.

User description and media adaptation for low vision accessibility

Ethical and legal requirements have made accessibility a cruciat feature for any information systems. However, the current accessible technologies are just suitable for either mild impairments or total impairments. This paper deals with visual content adaptation, in the context of the MPEG-21 standard, to help low vision users have better accessibility to the contents. The proposed approach includes descriptions for the low vision impairment and content adaptation techniques that meet the characteristics of users. The major advantages o f the proposed approach include I ) support of a wide range of low vision conditions, 2) customized content adaptation to specific characteristics of each user.