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Biomedical subjects

Yih Yian Sitoh

Publications and source records attributed to Yih Yian Sitoh.

8 recordsLinked to original sources

Clinical significance of cerebral white matter lesions in older Asians with suspected dementia.

BACKGROUND: cerebral white matter lesions are commonly seen on neuroimaging in older people and have been associated with clinical features such as gait abnormalities, urinary incontinence and depression. The significance of cerebral white matter lesions in older people with dementia remains uncertain. OBJECTIVES: to study the association between cerebral white matter lesions and the presence or absence of dementia in a group of elderly Asian patients; and to determine the clinical significance of cerebral white matter lesions in patients who are diagnosed to have dementia in terms of associated clinical features and the impact of cerebral white matter lesions on cognitive status. METHODS: for the first objective, the records of 141 older people of Asian ethnicity presenting to a memory clinic for the evaluation of suspected dementia were reviewed to compare the prevalence of cerebral white matter lesions in patients who did not fulfil the criteria for dementia, patients diagnosed to have Alzheimer's disease and patients diagnosed to have vascular dementia. For the second objective, 115 of these patients who were diagnosed to have dementia were studied to determine if demented patients with cerebral white matter lesions were more likely to have urinary incontinence, Parkinsonism, depression and greater severity of dementia. In addition, a comparison was made between demented patients with cerebral white matter lesions and those without cerebral white matter lesions in terms of psychometric assessment scores. RESULTS: cerebral white matter lesions were more common in Asian patients with vascular dementia. Demented patients with cerebral white matter lesions were also found to have more severe dementia and greater functional disability. CONCLUSION: cerebral white matter lesions are common, and are associated with greater functional disability in elderly Asian patients with dementia.

Aged↗

Providing optimal radiology service in the severe acute respiratory syndrome outbreak: use of mobile CT.

OBJECTIVE: Severe acute respiratory syndrome (SARS) is a serious atypical pneumonia caused by a novel pathogen. We describe our experience using a mobile CT scanner in an improvised isolation ward with life-support systems, portable lead shielding, and strict barrier nursing. This scanner was used exclusively for patients with SARS and patients with other illnesses who were also thought to have SARS. This arrangement freed the other CT scanners in the main department for non-SARS patients. In 5 weeks, 90 studies were performed; no cases of cross infection of health care workers were reported. CONCLUSION: Mobile CT may be used to provide dedicated radiology services to seriously ill patients requiring strict isolation during an infectious disease outbreak.

Adult↗

MR imaging features of pigmented villonodular synovitis of the cervical spine.

Pigmented villonodular synovitis (PVNS) is a benign proliferative disorder primarily occurring in the large joints of the appendicular skeleton such as the knee and hip joints. We present an unusual case of PVNS involving the cervical spine in an adult. MR imaging showed an enhancing mass lesion arising from the posterior elements of the cervical spine and hyperintensity on the T2-weighted images, without evidence of T2 susceptibility effects. Gross total excision of the tumor was performed, and the diagnosis was established by histopathology.

Adult↗

Nipah virus encephalitis: serial MR study of an emerging disease.

PURPOSE: To report the serial magnetic resonance (MR) imaging findings of the Nipah virus. MATERIALS AND METHODS: Twelve patients underwent serial MR imaging. Eight patients were examined at the outbreak; 11, at 1 month; and seven, at 6 months. Contrast material-enhanced MR images, diffusion-weighted images, and single-voxel proton MR spectroscopic images were reviewed. Clinical and neurologic assessment, as well as analysis of the size, location, and appearance of brain lesions on MR images, were performed. RESULTS: During the outbreak, all eight patients had multiple small foci of high signal intensity within the white matter on T2-weighted images. In six patients, cortical and brain stem lesions were also detected, and five patients had diffusion-weighted MR imaging-depicted hyperintensities. One month after the outbreak, five patients had widespread tiny foci of high signal intensity on T1-weighted images, particularly in the cerebral cortex. Diffusion-weighted images showed decreased prominence or disappearance of lesions over time. There was no evidence of progression or relapse of the lesions at 6-month follow-up. MR spectroscopy depicted reduction in N-acetylaspartate-to-creatine ratio and elevation of choline-to-creatine ratios. CONCLUSION: The Nipah virus has findings unlike other viral encephalitides: small lesions that are primarily within the white matter, with transient punctate cortical hyperintensities on T1-weighted images.

Adult↗

Maple syrup urine disease: diffusion-weighted and diffusion-tensor magnetic resonance imaging findings.

We present conventional magnetic resonance (MR) imaging with diffusion-weighted and diffusion-tensor imaging findings in a 10-day-old neonate with maple syrup urine disease (MSUD). On conventional MR imaging, signal abnormalities were noted in the affected white matter of cerebellum, dorsal brainstem, thalami, posterior limbs of internal capsules, and the corona radiata. These regions showed marked hyperintensity on diffusion-weighted images with decreased apparent diffusion coefficient values (average 68% reduction). Diffusion-tensor imaging showed decreased anisotropy (average 57% reduction) in the corresponding areas. Both diffusion-weighted and diffusion-tensor imaging are valuable in the diagnosis and understanding of the pathogenesis of MSUD, with findings that suggest cytotoxic edema and damaged oligodendro-axonal units within the affected white matter.

Brain↗