John H. Chan

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Myelinated axons of white matter demonstrate prominent directional differences in water diffusion. We performed diffusion-weighted imaging on ten patients with head injury to explore the feasibility of using water diffusion anisotropy for quantitating diffuse axonal injury. We showed significant decrease in diffusion anisotropy indices in areas with or(More)
The term jing-shen-fen-lie-zheng (mind-split-disease) has been used to denote schizophrenia in Chinese societies. Many Asian countries, where the Chinese writing system is used, adopt a similar translation. This study examined whether a less pejorative name si-jue-shi-diao (dys-regulation of thought and perception) as a diagnostic label for symptoms of(More)
We examined nine patients with histologically proven nasopharyngeal carcinoma (NPC), treated with radiotherapy, using dynamic susceptibility contrast MRI (DSC-MRI). In eight there was clinical evidence of radionecrosis of the temporal lobe, and one was examined for local recurrence in the nasopharynx. All patients had either high-signal finger-like or(More)
A large number of artifacts occur in magnetic resonance (MR) imaging of the musculoskeletal system. These artifacts may potentially affect the quality of MR images, and may also simulate pathologic conditions and produce pitfalls in interpretation. Motion artifacts may be periodic or random. Protocol-error artifacts include saturation, wraparound,(More)
Increased signal intensity on magnetic resonance (MR) imaging of tendons arising from the magic angle phenomenon is well recognized. This study aimed to evaluate the effect of varying the echo time (TE) upon tendon signal intensity, and to determine if a modified TE value produces acceptable T1 and proton density (PD) weighted images. Fresh bovine tendons(More)
STUDY DESIGN A study to test the ability of an additional cervicothoracic localizer scan to decrease interobserver discrepancy in the identification of vertebral segments in magnetic resonance imaging of the lumbar spine. OBJECTIVES To investigate whether lumbar vertebral segments can be identified correctly from lumbosacral magnetic resonance localizer(More)
OBJECTIVE Increasingly shorter TEs are being used for T1-weighted and proton density-weighted sequences in MR imaging of the knee. This study aims to evaluate the effect of a short TE on meniscal signal intensity. MATERIALS AND METHODS Thirty porcine knees were imaged with a 1.5-T MR scanner using spin-echo T1-weighted and proton density-weighted(More)
Hypertrophic olivary degeneration (HOD) is a rare type of neuronal degeneration involving the dento-rubo-olivary pathway. It is distinguished from other types of neuronal degeneration in that hypertrophy, rather than atrophy, takes place in the neurons in the inferior olivary nucleus. Prior to the invention of Magnetic Resonance Imaging (MRI), HOD was(More)
The aim of the study was to investigate the feasibility of using digital subtraction in contrast-enhanced MR imaging of the brain to reduce the MR contrast dosage without jeopardizing patient care. Fifty-two patients with intracranial lesions, either intra-axial or extra-axial, detected by computerized tomography were selected for contrast-enhanced MR(More)