Poster Session - Pediatric Brain MR Imaging: no. 2090We use DTI to detect and quantify Wallerian degeneration (WD) in pediatric MCA strokes. Fractional anisotropy (FA) and mean diffusivity (MD)of the
infarction, ipsilateral internal capsule (PLIC) and cerebral peduncle (CP) were measured in nine children and compared to the matched contralateral side. WD
was characterized by statistically significant differences in FA, but not MD, of the ipsilateral PLIC and CP compared to normal side. FA was reduced in all
children, whilst corresponding hyperintense signals on T2W were seen in five children. DTI is more sensitive than conventional MRI and can be used to detect
and quantify WD.published_or_final_versio

Cao, G

Chan, FL

Chung, BHY

Khong, PL

Ooi, CGC

Wong, VCN

Zhou, LJ

HKU Scholars Hub

Title Diffusion tensor MR imaging in the evaluation of Walleriandegeneration in pediatric strokes: work-in-progressAuthor(s) Khong, PL; Zhou, LJ; Wong, VCN; Chung, BHY; Ooi, CGC; Cao,G; Chan, FLCitationThe 11th Annual Meeting of the International Society of MagneticResonance Imaging in Medicine (ISMRM 2003), Toronto, ON.,Canada, 10-16 July 2003. In Conference Proceedings, 2003, v. 11,no. 2090Issued Date 2003URL http://hdl.handle.net/10722/98683Rights This work is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License.Diffusion tensor MR imaging in the evaluation of Wallerian degeneration in pediatric strokes: work-in-progress  P. Khong1, L. Zhou1, V. C. Wong1, B. H. Chung1, C. G. Ooi1, C. Guang2, F. Chan1 1Queen Mary Hospital, The University of Hong Kong, Hong Kong, Hong Kong, Hong Kong, 2GE Medical Systems, China, China, China, People's Republic of Synopsis: We use DTI to detect and quantify Wallerian degeneration (WD) in pediatric MCA strokes. Fractional anisotropy (FA) and mean diffusivity (MD) of the infarction, ipsilateral internal capsule (PLIC) and cerebral peduncle (CP) were measured in nine children and compared to the matched contralateral side.  WD was characterized by statistically significant differences in FA, but not MD, of the ipsilateral PLIC and CP compared to the normal side.  FA was reduced in all children, whilst corresponding hyperintense signals on T2-weighted images were seen in five children.  DTI is more sensitive than conventional MRI and can be used to detect and quantify WD.    Purpose: Wallerian degeneration (WD), the anterograde degeneration of axons and myelin sheaths after proximal axonal or cell body injury, is known to occur after cerebral infarction (1). In this preliminary study, we aim to evaluate if DTI, using the indices fractional anisotropy (FA) and mean diffusivity (MD), can detect and quantify Wallerian degeneration in pediatric middle cerebral artery (MCA) strokes and to compare the findings with conventional MR imaging. As the prognostic indicators of neuromotor outcome in pediatric strokes are multifactorial and not well defined (2), our future goal is to determine its relationship with neuromotor outcome.  Materials and Methods: Patients between one year and 18 years of age with evidence of a unilateral infarction in the MCA territory by CT scan or MRI were recruited.  Those with congenital structural anomalies, mitochondrial disease, traumatic hemorrhage, Moya Moya disease were excluded.   MRI was performed using a Signa 1.5 Tesla imager (GE Medical Systems, Milwaukee, WI, USA) with a standard head coil. Axial spin-echo T1-weighted (500/10/23/256 X 224 [TR/TE/FOV/acquisition matrix]), fast spin-echo proton density (2400/10 [TR/TE]) and T2-weighted images (4000/ 100/ 23/ 320 x 224 [TR/TE/FOV/acquisition matrix]) were performed. DTI was performed using single-shot spin-echo echo-planar imaging (10000/ minimum/28/128 x 128[TR/TE/FOV/acquisition matrix]). Diffusion-sensitizing gradient encoding was applied in 25 directions by using a diffusion-weighted factor b=1200s/mm2.   Quantitative values of FA and MD were obtained by manually placing regions-of-interest (ROI) within the infarction, and in selected areas along the ipsilateral corticospinal tract, i.e. the posterior limb of the internal capsule at the level of the globus pallidus (PLIC) and cerebral peduncle (CP). Identical ROIs were placed in the matched contralateral regions. Student’s t-test was used to detect any statistically significant differences in FA and MD between the infarction hemisphere and the contralateral normal region.  The corticospinal tract FA was derived from the mean value of PLIC FA and CP FA.  The patients were further divided into two groups, those with corticospinal tract FA ratio (infarct hemisphere/normal hemisphere) of < 0.8 and ≥0.8, and compared with brain-stem area asymmetry (cross-sectional area of the CP) and the largest cross-sectional area of the infarction on T2-weighted axial image, using student’s t-test.  P<0.05 was considered statistically significant.   The presence of signal intensity changes in the internal capsule and cerebral peduncles on T2-weighted images were recorded.  Results: There were nine children aged between 14 months and 17 years of age (mean: 92.5 months) who presented with hemiplegia between birth and 10 years of age (mean: 20 months).  The cause of stroke was congenital heart disease (n=5), perinatal (n=1), severe dehydration (n=1) and indeterminate (n=2).  The infarction was right sided in five children and left sided in four children. Area of infarction ranged between 212mm2 and 2997mm2 (mean: 1075mm2).   WD was detected on conventional T2-weighted image by hyperintense signals in the PLIC in four children and CP in one child. The area of CP was smaller on the infarct hemisphere compared to the normal hemisphere in all children, with the reduction in area ranging between 6% and 28% (mean: 15%).    The FA of the infarction, PLIC and CP were reduced, and the MD of the infarction and PLIC were increased on the infarct hemisphere compared to the normal hemisphere in all children, whilst the MD of the CP was increased in six children only.  The mean FA ratios of the infarct hemisphere to the normal hemisphere in the infarction, PLIC and CP were 0.45, 0.77 and 0.79 respectively and the differences were statistically significant in all sites (p=0.029, p=0.014 and 0.008 respectively).  The mean MD ratio of the infarction to the contralateral normal side was 2.55 (p<0.001).  The differences in MD in the other sites were not statistically significant.         FA MD (x10-3mm2s-1)  Infarction Side Normal Side Infarction Side Normal Side Infarction 0.069(0.014)* 0.194(0.147) 2.945(0.577) *** 1.168(0.160) PLIC 0.367(0.108)* 0.475(0.041) 1.23(0.205) 1.041(0.116) CP 0.337(0.082) ** 0.426(0.055) 1.419(0.124) 1.347(0.099) Corticospinal Tract  0.352(0.087)** 0.451(0.046) 1.307(0.101) 1.194(0.087)  For the groups with corticospinal tract FA ratio of <0.8 (n=4) and ≥0.8 (n=5), the reduction in area of the CP in the infarct hemisphere was 17% and 13% respectively, and the area of infarction was 1268.5mm2 and 919.4mm2 respectively. These differences were not statistically significant (p=0.378 and p=0.622)  Conclusion: We have shown that in pediatric strokes, there is significant loss of anisotropy in Wallerian degeneration and reduction is less severe than in the infarction site.  Also, DTI, using the index FA, is more sensitive than conventional MR imaging for the detection of Wallerian degeneration.  This is in agreement with findings in adult stroke patients (3). DTI is therefore useful for monitoring the evolution of pediatric strokes and quantifying the severity of Wallerian degeneration.  Further studies are required to determine if the measurement of FA in Wallerian degeneration can be used as an indicator of neuromotor outcome.    References: 1. Kuhn MJ, Johnson KA, Davis KR.  Radiology 1988;168:199-202.    2.     Golomb MR, MacGregor DL, Domi T et al.  Ann Neurol 2001;50:163-168. 3. Werring DJ, Toosy AT, Clark CA et al.  J Neurol Neurosurg Physchiatry 2000;69:269-272. Table showing the mean FA and MD values of nine children with unilateral MCA stroke. *p<0.05, **p<0.01, ***p<0.001(student t-test).  2090Proc. Intl. Soc. Mag. Reson. Med. 11 (2003)

Diffusion tensor MR imaging in the evaluation of Wallerian degeneration in pediatric strokes: work-in-progress

Zhou, L

Guang, C

Chan, F

INTRODUCTION: Wallerian degeneration, the anterograde degeneration of axons and myelin sheaths after proximal axonal or cell body injury, is known to occur after cerebral infarction. In this pilot study, we aim to evaluate if diffusion tensor imaging (DTI), using the indices of fractional anisotropy (FA) and mean diffusivity (MD), can detect and quantify Wallerian degeneration in paediatric middle cerebral artery (MCA) strokes and to compare the findings with conventional MR imaging. METHODS: Nine children with unilateral MCA infarctions were studied. Axial T1-weighted, proton density and T2-weighted images, as well as DTI were performed using a Signa 1.5 Tesla imager. Quantitative values of FA …published_or_final_versio

Cheung, RTF

Title Diffusion tensor imaging in the evaluation of Walleriandegeneration in paediatric stroke: work-in-progressAuthor(s) Zhou, LJ; Wong, VCN; Chung, BHY; Ooi, CGC; Cheung, RTF;Khong, PLCitationThe 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/10722/54028Rights 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

Hong Kong Medical Journal

Diffusion tensor imaging in the evaluation of Wallerian degeneration in paediatric stroke: work-in-progress

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Diffusion tensor MR imaging in the evaluation of Wallerian degeneration in pediatric strokes: work-in-progress

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