Diffusion-weighted imaging findings in central skull base osteomyelitis with pharyngeal abscess formation.
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Abscess↗
Biomedical subjects
Yih-Yian Sitoh
Publications and source records attributed to Yih-Yian Sitoh.
Facial fat volume in HIV-infected patients with lipoatrophy.
BACKGROUND: The volume and anatomical distribution of facial fat depletion in HIV related lipoatrophy have not been properly quantified. We aimed to determine the extent and distribution of facial fat loss in HIV-infected patients with lipoatrophy and whether this differs from wasting. DESIGN: We studied HIV-infected patients with clinically defined moderate to severe lipoatrophy without wasting (n = 15), clinically defined wasting (> 10% weight loss and recent opportunistic infection) with no previous reported lipodystrophy (n = 15), and controls without lipodystrophy or wasting (n = 15). Facial MRI scans were performed, and areas of fat were manually traced bilaterally in all individual image slices and summed to calculate volume in anatomically defined regions of interest. RESULTS: Patients with lipoatrophy had lower fat volumes in the temporal region (8.9 +/- 9.4 vs 20.5 +/- 7.2 ml; P < 0.001), cheek region (25.6 +/- 24.9 vs 55.5 +/- 15.0 ml; P < 0.001), periorbital region (1.9 +/- 1.0 vs 2.7 +/- 1.0 ml; P = 0.09) and buccal fat pad (13.4 +/- 9.4 vs 21.8 +/- 9.8 ml; P = 0.030) compared with controls. Patients with wasting had temporal, cheek, periorbital and buccal fat pad volumes (10.4 +/- 6.7 ml, 34.0 +/- 14.8 ml, 1.4 +/- 1.1 ml and 13.1 +/- 4.6 ml respectively) that were lower than controls (all P < 0.01) but similar to lipoatrophy patients (all P > 0.5). CONCLUSIONS: Facial fat depletion in lipoatrophy is substantial (approximately 50% volume loss) and involves superficial and deep fat (buccal fat pad). The distribution and volume of fat change is similar to that seen in wasting. Given the extent of the changes, complete surgical correction is unlikely to be possible and hence emphasis should be placed on prevention of lipoatrophy [corrected]
Adipose Tissue↗
Parallel imaging techniques in functional MRI.
Originally developed for increased scanning velocity in cardiac imaging, parallel imaging (PI) techniques have recently also been applied for the reduction of artifacts in single-shot techniques. In functional brain imaging (fMRI) techniques, PI has been used for several purposes. It has been applied to reduce the distortions caused by the length of the echo-planar imaging readout, diminution of the gradient-related acoustic noise, as a means to increase acquisition speed or to increase the achievable brain coverage per unit time. In this article, the different applications of PI techniques in fMRI are reviewed, together with the basic theoretical background and the recently developed hardware necessary to achieve rapid, high signal-to-noise ratio PI-fMRI.
Artifacts↗
Combined magnetic resonance tractography and functional magnetic resonance imaging in evaluation of brain tumors involving the motor system.
The goal of neuro-oncologic surgery is to maximize tumor resection while preserving vital brain functions. Identification of the relation between the tumor and adjacent functional cortical areas as well as efferent subcortical white matter tracts is important for preservation of function. Combined diffusion tensor imaging with magnetic resonance (MR) tractography and functional blood oxygen level-dependent MR imaging were applied successfully for preoperative planning and guidance in 2 patients with tumors near the motor cortex. The combination of these novel functional imaging techniques can provide new information for presurgical planning.
Adult↗