Chan, GCF

Khong, PL

Kwong, DLW

Leung, LHT

Ooi, CGC

Zhou, LJ

Hong Kong Medical Journal

HKU Scholars Hub

Title Diffusion tensor imaging for the evaluation of treatment-inducedneurotoxicity in childhood medulloblastomaAuthor(s) Khong, PL; Leung, LHT; Chan, GCF; Kwong, DLW; Zhou, LJ;Ooi, CGCCitationThe 8th Medical Research Conference, Medical Science Group,The University of Hong Kong, Queen Mary Hospital, Hong Kong,25-26 January 2003, v. 9 n. 1 Suppl, p. 74Issued Date 2003URL http://hdl.handle.net/10722/54195Rights Creative Commons: Attribution 3.0 Hong Kong License74      HKMJ Vol 9 No 1 February 2003 SupplementDiffusion tensor imaging for the evaluation of treatment-induced neurotoxicity inchildhood medulloblastomaPL Khong1, LHT Leung1, GCF Chan2, DLW Kwong3, LJ Zhou1, CGC Ooi1. Department of Diagnostic Radiology1, Paediatrics2and Oncology3, The University of Hong Kong, Queen Mary Hospital, Hong KongIntroduction: We propose the use of diffusion tensor MR imaging (DTI) to evaluate treatment-induced white matter (WM) injury inchildhood medulloblastoma survivors and also aim to determine if fractional anisotropy(FA) can be used as an index for evaluation oftreatment-induced neurotoxicity.Methods: 13 medulloblastoma survivors who were treated with surgery, cranial irradiation and chemotherapy were evaluated. Con-ventional MR imaging and DTI were performed using a 1.5 Tesla imager. FA maps were generated using the FUNCTOOL software. Voxel-based comparison between the patient and control groups was performed with SPM99. Contrasts (1 –1) and (–1 1) were employed for thedetection of positive and negative activations. FA of selected supratentorial WM sites (frontal periventricular WM, parietal periventricularWM and corona radiata) were also measured by placement of regions-of-interest (ROI). ROIs of similar size were placed on identical sitesas far possible in the healthy age-matched controls. FA (sum of frontal and parietal WM and corona radiata FA) was compared with age attreatment, time interval after treatment and intellectual outcome (deterioration of school performance). Two-tailed paired t-test was usedfor detection of statistical significance.Results: Patients were between 3 -17 yrs of age at treatment (mean: 8.2 yrs) and time-interval between treatment and MR imagingranged between 1–11 yrs (mean: 3.7 yrs). Voxel-based comparison showed areas of activation in the periventricular WM, especiallyparietal WM, and corona radiata. Using ROIs, mean FA of patients was reduced in all sites compared to controls, with a reduction ofbetween 15.6% and 19.2%. The reduction was statistically significant in the parietal WM and corona radiata (p=0.011 and p=0.040respectively) FA reduction of the groups £ 5 years (n=5) and >5 years of age (n=8) at treatment was 61.1% and 34.8% respectively andFA reduction in the group with < 5 years (n=8) and ≥ 5 years interval (n=5) since treatment was 35.4% and 60.3% respectively. Thesedifferences were however, not statistically significant. Comparing school performance, FA reduction of those with mild deterioration (n=5)and those with moderate/severe deterioration (n=8) was 19.9% and 60.6 % respectively and this difference was statistically significant(p=0.041).Conclusion: Loss of anisotropy occurs in the periventricular white matter of post-treatment medulloblastoma survivors and this loss issignificantly greater in those with poor intellectual outcome. DTI is therefore useful in detection and monitoring of treatment-inducedneurotoxicity.Diffusion tensor imaging in the evaluation of Wallerian degeneration in paediatricstroke: work-in-progressLJ Zhou1, VCN Wong2, BHY Chung2, CGC Ooi1, RTF Cheung3, PL Khong1. Departments of Diagnostic Radiology1,Paediatrics2 and Medicine3, The University of Hong Kong, Queen Mary Hospital, Hong KongIntroduction: Wallerian degeneration, the anterograde degeneration of axons and myelin sheaths after proximalaxonal or cell body injury, is known to occur after cerebral infarction. In this pilot study, we aim to evaluate ifdiffusion tensor imaging (DTI), using the indices of fractional anisotropy (FA) and mean diffusivity (MD), candetect and quantify Wallerian degeneration in paediatric middle cerebral artery (MCA) strokes and to compare thefindings with conventional MR imaging.Methods: Nine children with unilateral MCA infarctions were studied. Axial T1-weighted, proton densityand T2-weighted images, as well as DTI were performed using a Signa 1.5 Tesla imager. Quantitative values of FAand MD were obtained by manually placing regions-of-interest (ROI) in the infarction, and selected areas along theipsilateral corticospinal tract, i.e. the posterior limb of the internal capsule (PLIC) and cerebral peduncle (CP).Identical ROIs were placed in the matched contralateral regions. The corticospinal tract FA was derived by themean value of PLIC FA and CP FA. The presence of signal intensity changes in the internal capsule and cerebralpeduncles on T2-weighted images were recorded. Statistical comparisons between two sides were performed usingthe Student’s t-test.Results: WD was detected on conventional T2-weighted imaging by hyperintense signal in the PLIC in 4 childrenand CP in 1 child. The FA of the infarction, PLIC and CP were reduced, and the MD of the infarction and PLICwere increased on the ipsilateral side compared to the contralateral side in all children, whilst the MD of the CP wasincreased in six children. The mean FA ratio of the ipsilateral to the contralateral side in the infarction, PLIC, CPwas 0.45, 0.77 and 0.79 respectively and the differences were statistically significant in all sites (p=0.029, p=0.014and 0.008 respectively). The mean MD ratio of the ipsilateral to the contralateral side in the infarction was 2.55 andthis difference was statistically significant (p<0.001). The differences in MD in the other sites were not statisticallysignificant.Conclusion: DTI is more sensitive than conventional MRI and can be used to detect and quantify WD. Furtherstudies are required to determine if the measurement of FA in Wallerian degeneration can be used as an indicator ofneuromotor outcome.NUS-05NUS-06

Diffusion tensor imaging for the evaluation of treatment-induced neurotoxicity in childhood medulloblastoma

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Diffusion tensor imaging for the evaluation of treatment-induced neurotoxicity in childhood medulloblastoma

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