Biomedical subjects

Tchoyoson C C Lim

Publications and source records attributed to Tchoyoson C C Lim.

5 recordsLinked to original sources

PubMed2006

Disseminated spread of recurrent oligodendroglioma (WHO grade II).

Oligodendroglioma is a relatively uncommon primary brain tumour. The occurrence of metastatic dissemination of oligodendroglioma is rare and usually occurs in patients with anaplastic oligodendroglioma. The dissemination of WHO Grade II oligodendroglioma can occur and we report a patient with an initial diagnosis of a left temporal oligodendroglioma who presented with disseminated disease in the left temporal lobe, sellar region, medulla oblongata, both frontal lobes and ventricles more than 8 years later. Histology at dissemination showed anaplastic oligodendroglioma. Similar reports of metastatic dissemination of oligodendrogliomas reveal that the tumours may remain as WHO Grade II or may progress to anaplastic oligodendroglioma at metastasis. However, regardless of the histological grade at metastasis, the prognosis of metastatic oligodendroglioma is poor.

Humans↗

PubMed2005

Multi-voxel MR spectroscopic imaging of the brain: utility in clinical setting-initial results.

BACKGROUND AND PURPOSE: Compared to single voxel methods, MR spectroscopic imaging (MRSI) of the brain provides metabolic information with improved anatomical coverage and spectral resolution, but may be difficult to perform in the clinical setting. We evaluate the factors influencing spectral quality in MRSI using a semi-automated method, focussing on lipid contamination, and phase correction errors related to magnetic field inhomogeneity. METHODS: We retrospectively analysed MRSI studies planned by radiologists and radiographers. Two-dimensional MRSI studies using point-resolved spectroscopy (PRESS) localisation, at long echo time (135 or 144 ms) were acquired on a 1.5 T scanner. Studies that contained lipid contamination and abnormally inverted spectra were reviewed and the latter correlated with anatomic location at the base of skull, and with the area of the region of interest (ROI) studied. RESULTS: Of 128 consecutive MRSI studies, six showed abnormal inverted spectra, of which four were acquired at the base of skull. Multivariate logistic regression analysis showed that study location at the base of skull, but not larger ROI, was a significant predictor for the risk of being affected by inverted spectra (RR for base of skull: 11.76, 95% CI: 1.86-74.18, P=0.009. RR for area of ROI: 3.68, 95% CI: 0.57-23.67, P=0.170). Seven studies showed lipid contamination; all were in close proximity to the overlying scalp. CONCLUSION: Using a semi-automated acquisition and post-processing method, MRSI can be successfully applied in the clinical setting. However, care should be taken to avoid regions of high magnetic field inhomogeneity at the base of skull, and lipid contamination in voxels prescribed near the scalp.

Brain Chemistry↗

PubMed2004

Perfusion imaging using arterial spin labeling.

Arterial spin labeling is a magnetic resonance method for the measurement of cerebral blood flow. In its simplest form, the perfusion contrast in the images gathered by this technique comes from the subtraction of two successively acquired images: one with, and one without, proximal labeling of arterial water spins after a small delay time. Over the last decade, the method has moved from the experimental laboratory to the clinical environment. Furthermore, numerous improvements, ranging from new pulse sequence implementations to extensive theoretical studies, have broadened its reach and extended its potential applications. In this review, the multiple facets of this powerful yet difficult technique are discussed. Different implementations are compared, the theoretical background is summarized, and potential applications of various implementations in research as well as in the daily clinical routine are proposed. Finally, a summary of the new developments and emerging techniques in this field is provided.

Animals↗

PubMed2004

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↗

PubMed2003

Serial diffusion-weighted magnetic resonance imaging in adult-onset citrullinaemia.

A 25-year-old Chinese man presented with a 2-year history of recurrent coma. His plasma ammonia level was extremely elevated, with raised citrulline level and absence of argininosuccinic acid. Adult-onset citrullinaemia, a condition rarely reported outside the Japanese population, was diagnosed. Serial magnetic resonance (MR) imaging, including diffusion-weighted (DW) studies, showed initial involvement of the insula cortex and cingulate gyrus, changing to a pattern of multiple small lesions in the depths of the cortical sulci. This changing pattern of lesions over time on DW MR imaging has not previously been described in adult-onset citrullinaemia.

Adult↗