Biomedical subjects

Po-nin Chan

Publications and source records attributed to Po-nin Chan.

2 recordsLinked to original sources

PubMedDate not supplied

Diffusion-weighted magnetic resonance imaging in radiation-induced cerebral necrosis. Apparent diffusion coefficient in lesion components.

OBJECTIVE: The objective of this retrospective study was to investigate the diffusivity of different components of radiation-induced cerebral necrosis with the hypothesis that the diffusivity of the various components is elevated to different degrees. METHODS: Twenty-two patients (18 men, 4 women, aged 34-72 years) with radiation injury to the temporal lobes after radiation therapy (RT) for nasopharyngeal carcinoma with diagnosis confirmed on serial magnetic resonance imaging (MRI) were studied with coronal T2-weighted, diffusion-weighted, and gadolinium-enhanced MRI. Using three diffusion directions for diffusion-weighted MRI, the apparent diffusion coefficients (ADCs) of the enhanced component, the cystic or liquefied component, and the edema component were measured. RESULTS: ADCs of all components of RT-induced cerebral necrosis (154 +/- 21.6 x 10(-5) mm2/s for contrast-enhanced component; 188 +/- 47.4 x 10(-5) mm2/s for cystic/liquefied component; 177 +/- 35.4 x 10(-5) mm2/s for edema component) were all significantly higher (P<0.00001) than ADC of the normal frontal lobe white matter (82 +/- 12.4 x 10(-5) mm2/s). The ADC of the enhanced component was significantly lower than that of the cystic/liquefied component (P=0.0096) and the edema component (P=0.003). A significantly lower ADC was shown in the enhanced component in temporal lobes showing both short-term morphologic deterioration (P=0.024) and occurrence of deterioration on long-term follow-up (P=0.04) compared with the temporal lobes that showed improvement or stable morphology. CONCLUSIONS: ADCs of the contrast-enhanced component, cystic/liquefied component, and edema in RT-induced cerebral necrosis was significantly higher than in normal brain parenchyma. There is association between a lower ADC in the contrast-enhanced component and morphologic deterioration.

Brain↗

PubMedDate not supplied

Severe acute respiratory syndrome: thin-section computed tomography features, temporal changes, and clinicoradiologic correlation during the convalescent period.

OBJECTIVE: To evaluate thin-section computed tomography findings of patients with severe acute respiratory syndrome (SARS) in the convalescent period and to correlate the results with clinical parameters and lung function tests. METHODS: Ninety-nine severe acute respiratory syndrome patients with persistent changes on follow-up chest radiography were included. One hundred seventy computed tomography examinations at baseline (n=70), 3 months (n=56), and 6 months (n=44) were retrospectively evaluated to determine the extent of ground-glass opacification, reticulation, and total parenchymal involvement. Patients' demographic information, clinical information during treatment, and results of lung function tests at 3 and 6 months were correlated with computed tomography findings. RESULTS: A significant serial improvement in the extent of overall ground-glass opacification, overall reticulation, and total parenchymal involvement was observed (P <0.01). Advanced age, previous intensive care unit admission, mechanical ventilation, alternative treatment, higher peak lactate dehydrogenase, and peak radiographic involvement during treatment showed a positive correlation with overall reticulation and total parenchymal involvement at 6 months. There was a significant negative correlation between overall reticulation and total parenchymal involvement with diffusion capacity adjusted for hemoglobin at 3 and 6 months (P <0.01). CONCLUSION: Lung changes on thin-section computed tomography of severe acute respiratory syndrome patients improved with time during the convalescent period and showed a significant correlation with advanced age, parameters indicating severe illness, and diffusion capacity adjusted for hemoglobin on follow-up.

Adult↗