Biomedical subjects

Pek Lan Khong

Publications and source records attributed to Pek Lan Khong.

5 recordsLinked to original sources

PubMed2004

White-matter diffusion anisotropy after chemo-irradiation: a statistical parametric mapping study and histogram analysis.

The aim of the study was to evaluate white-matter (WM) diffusion anisotropy in medulloblastoma survivors after cranial irradiation and chemotherapy using voxel-based analysis with SPM99 and fractional anisotropy (FA) histogram-derived indices, and to identify quantitative indices for detecting and monitoring children with treatment-induced white-matter injury. Familywise error rate (FWE) that corrects for multiple comparisons was used to locate statistically significant regions of P < 0.05 in voxel-based analysis. Subsequently, the false discovery rate (FDR) controlling procedure (corrected P < 0.05) was used. FA map histogram analysis of histogram-derived indices, mean FA, mean FA peak height, and peak location was performed. Two-sample t test was used in all analyses. Using FWE-corrected P < 0.05, there was a cluster of reduced anisotropy in the periventricular white matter lateral to the left ventricular atrium. When FDR-corrected P < 0.05 was used, there were multiple clusters of reduced anisotropy in the periventricular white matter, the corpus callosum, and corona radiata. Simplified voxel-based morphometry (VBM)-like analysis of cerebrospinal fluid (CSF) did not show significant differences between patient and control subjects. 'White-matter FA map' histogram showed significant reduction in mean FA and mean FA peak location and significant increase in mean FA peak height in the patient group compared to control subjects (P = 0.003, P = 0.003, and P = 0.014, respectively). This approach of quantifying FA can be applied to characterize anisotropy in the white matter after cranial irradiation and chemotherapy and can potentially be used to detect and monitor treatment-induced neurotoxicity.

Adolescent↗

PubMed2004

High-resolution CT findings of severe acute respiratory syndrome at presentation and after admission.

OBJECTIVE: The aim of this study was to assess the high-resolution CT (HRCT) findings at presentation and after hospital admission in patients with severe acute respiratory syndrome (SARS). MATERIALS AND METHODS: We reviewed the HRCT findings at presentation (n = 12) and after hospital admission (n = 25) of 29 patients with SARS and compared the HRCT findings with the radiographic findings. HRCT scans were obtained using 1-mm (n = 28) or 2-mm (n = 1) collimation. The radiographs and HRCT scans were reviewed independently by two observers who reached a decision by consensus. RESULTS: All patients had abnormal findings on HRCT at presentation. Eight of these 12 patients had normal findings on radiographs. The predominant HRCT findings at presentation consisted of unilateral (n = 6) or bilateral (n = 2) ground-glass opacities or focal unilateral (n = 2) or bilateral (n = 2) areas of consolidation. All patients showed progression of disease on follow-up. The predominant HRCT findings on follow-up CT scans consisted of unilateral (n = 2) or bilateral ground-glass opacities (n = 13), unilateral (n = 2) or bilateral consolidation (n = 5), or a mixed bilateral pattern of ground-glass attenuation, consolidation, and reticulation (n = 3). Reticulation with associated architectural distortion and mild traction bronchiectasis was present in eight patients. CONCLUSION: HRCT can show parenchymal abnormalities in patients with SARS who have normal findings on radiographs at presentation. Follow-up CT scans obtained in hospitalized patients show findings consistent with fibrosis in a small percentage of patients.

Adult↗

PubMed2003

Severe acute respiratory syndrome: radiographic and CT findings.

OBJECTIVE: We review the radiographic and CT findings in the lungs of 12 patients with severe acute respiratory syndrome (SARS) in an effort to describe the most common radiologic findings for this disease. CONCLUSION: The most common radiographic findings of SARS patients at presentation are unilateral or bilateral ground-glass opacities or focal unilateral or bilateral areas of consolidation. In hospitalized SARS patients, the abnormalities tend to progress to bilateral air-space consolidation. CT may reveal parenchymal disease in patients whose radiographs show normal results.

Adult↗

PubMed2002

Sonographic features of ileal duplication cyst at 12 weeks.

Enteric duplication cyst is a congenital abnormality that is believed to arise from abnormal recanalization of the bowel during embryogenesis. Previous reports suggest that the condition may be suspected prenatally by sonographic demonstration of an intra-abdominal cystic mass in the second and third trimesters. We present the sonographic features of a fetus with ileal duplication cyst at 12 weeks of gestation, which show that the condition may present in the first trimester of pregnancy.

Adult↗

PubMed2002

Magnetic resonance spectroscopy and analysis of MECP2 in Rett syndrome.

We studied the in vivo cerebral metabolites and documented the presence of MECP2 gene mutations in six Chinese females with Rett syndrome. Magnetic resonance spectroscopy spectra from the frontal lobe (gray and white matter) and deep gray nuclei (basal ganglia and thalamus) of either side were obtained. N-acetylaspartate/total creatine, choline/total creatine, and N-acetylaspartate/choline ratios were analyzed and compared with six healthy age-matched female control subjects. MECP2 gene mutation was identified in four patients; one patient had polymorphism and one patient did not have gene mutation. N-acetylaspartate/total creatine of the frontal lobe of all patients (mean: 2.63, S.D. = 0.33) was decreased compared with age-matched control subjects (mean: 3.15, S.D. = 0.27), and the difference was statistically significant (P = 0.017) with a mean difference of 0.52 (95% CI = 0.68-0.36). The difference in all other metabolite ratios in the frontal lobe and deep gray nuclei were not statistically significant compared with age-matched control subjects. Mild frontal lobe and anterior temporal lobe atrophy was present in three patients. Proton-magnetic resonance spectroscopy is a sensitive method capable of detecting the biochemical changes in Rett syndrome and is able to detect changes before conventional magnetic resonance imaging. Our preliminary results suggest that reduction in N-acetylaspartate/total creatine ratio may not be related to the MECP2 mutation.

Adolescent↗