Publications by authors named "Shih-Wei Chiang"

14 Publications

  • Page 1 of 1

Hypoperfusion of the infrapatellar fat pad and its relationship to MRI T2* relaxation time changes in a 5/6 nephrectomy model.

Sci Rep 2021 May 11;11(1):9924. Epub 2021 May 11.

Department and Graduate Institute of Biology and Anatomy, National Defense Medical Center, No.161, Sec. 6, Minquan E. Rd., Neihu Dist., Taipei, 11490, Taiwan.

The purpose of present study was to longitudinally investigate the alterations in infrapatellar fat pad (IPFP) vascularity in 5/6 nephrectomized rats by using dynamic contrast enhanced (DCE) MRI and IPFP degeneration by using MRI T2* relaxation time. Twelve male Sprague-Dawley rats were assigned to a control group and a 5/6 nephrectomy CKD group. The right knees of all rats were longitudinally scanned by 4.7 T MRI, and serial changes in the IPFP were assessed at 0, 8, 16, 30, and 44 weeks by DCE-MRI (parameters A, k and k) and MRI T2* mapping. After MRI measurements, knee specimens were obtained and evaluated histologically. The CKD group had IPFPs with lower blood volume A and lower permeability k values from 16 weeks (p < 0.05), lower venous washout k value from 30 weeks (p < 0.001), and significantly higher T2* values reflecting adipocyte degeneration beginning at 16 weeks (p < 0.05). The histopathological results confirmed the MRI findings. Hypoperfusion and adipocytes degeneration related to CKD were demonstrated in a rodent 5/6 nephrectomy model. DCE parameters and MRI T2* can serve as imaging biomarkers of fat pad degeneration during CKD progression.
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http://dx.doi.org/10.1038/s41598-021-89336-8DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8113578PMC
May 2021

Changes in sensorimotor-related thalamic diffusion properties and cerebrospinal fluid hydrodynamics predict gait responses to tap test in idiopathic normal-pressure hydrocephalus.

Eur Radiol 2018 Nov 7;28(11):4504-4513. Epub 2018 May 7.

Research Center of Translational Imaging, School of Medicine, College of Medicine, Taipei Medical University, Taipei, Taiwan.

Objectives: To compare diffusion tensor (DT)-derived indices from the thalamic nuclei and cerebrospinal fluid (CSF) hydrodynamic parameters for the prediction of gait responsiveness to the CSF tap test in early iNPH patients.

Methods: In this study, 22 patients with iNPH and 16 normal controls were enrolled with the approval of an institutional review board. DT imaging and phase-contrast magnetic resonance imaging were performed in patients and controls to determine DT-related indices of the sensorimotor-related thalamic nuclei and CSF hydrodynamics. Gait performance was assessed in patients using gait scale before and after the tap test. The Mann-Whitney U test and receiver operating characteristic (ROC) curve analysis were applied to compare group differences between patients and controls and assess the predictive performance of gait responsiveness to the tap test in the patients.

Results: Fractional anisotropy (FA) and axial diffusivity showed significant increases in the ventrolateral (VL) and ventroposterolateral (VPL) nuclei of the iNPH group compared with those of the control group (p < 0.05). The predictions of gait responsiveness of ventral thalamic FA alone (area under the ROC curve [AUC] < 0.8) significantly outperformed those of CSF hydrodynamics alone (AUC < 0.6). The AUC curve was elevated to 0.812 when the CSF peak systolic velocity and FA value were combined for the VPL nucleus, yielding the highest sensitivity (0.769) and specificity (0.778) to predict gait responses.

Conclusions: Combined measurements of sensorimotor-related thalamic FA and CSF hydrodynamics can provide potential biomarkers for gait response to the CSF tap test in patients with iNPH.

Key Points: • Ventrolateral and ventroposterolateral thalamic FA may predict gait responsiveness to tap test. • Thalamic neuroplasticity can be assessed through DTI in idiopathic normal-pressure hydrocephalus. • Changes in the CST associated with gait control could trigger thalamic neuroplasticity. • Activities of sensorimotor-related circuits could alter in patients with gait disturbance. • Management of patients with iNPH could be more appropriate.
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http://dx.doi.org/10.1007/s00330-018-5488-xDOI Listing
November 2018

Histogram analysis of T2*-based pharmacokinetic imaging in cerebral glioma grading.

Comput Methods Programs Biomed 2018 Mar 15;155:19-27. Epub 2017 Nov 15.

Research Center of Translational Imaging, College of Medicine, Taipei Medical University, Taipei, Taiwan; Radiogenomic Research Center, Taipei Medical University Hospital, Taipei Medical University, Taipei, Taiwan; Department of Radiology, School of Medicine, College of Medicine, Taipei Medical University, Taipei, Taiwan; Department of Medical Imaging, Taipei Medical University Hospital, Taipei Medical University, Taipei, Taiwan; Department of Medical Research, Taipei Medical University Hospital, Taipei Medical University, Taipei, Taiwan. Electronic address:

Background And Objective: To investigate the feasibility of histogram analysis of the T2*-based permeability parameter volume transfer constant (K) for glioma grading and to explore the diagnostic performance of the histogram analysis of K and blood plasma volume (v).

Methods: We recruited 31 and 11 patients with high- and low-grade gliomas, respectively. The histogram parameters of K and v, derived from the first-pass pharmacokinetic modeling based on the T2* dynamic susceptibility-weighted contrast-enhanced perfusion-weighted magnetic resonance imaging (T2* DSC-PW-MRI) from the entire tumor volume, were evaluated for differentiating glioma grades.

Results: Histogram parameters of K and v showed significant differences between high- and low-grade gliomas and exhibited significant correlations with tumor grades. The mean K derived from the T2* DSC-PW-MRI had the highest sensitivity and specificity for differentiating high-grade gliomas from low-grade gliomas compared with other histogram parameters of K and v.

Conclusions: Histogram analysis of T2*-based pharmacokinetic imaging is useful for cerebral glioma grading. The histogram parameters of the entire tumor K measurement can provide increased accuracy with additional information regarding microvascular permeability changes for identifying high-grade brain tumors.
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http://dx.doi.org/10.1016/j.cmpb.2017.11.011DOI Listing
March 2018

Knee subchondral bone perfusion and its relationship to marrow fat and trabeculation on multi-parametric MRI and micro-CT in experimental CKD.

Sci Rep 2017 06 8;7(1):3073. Epub 2017 Jun 8.

Department of Radiology, Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan.

The pathogenesis of chronic kidney disease (CKD) is multifactorial. In the progression of CKD arthropathy, arteriosclerosis may alter the knee subchondral bone marrow by altering blood flow through the bone vasculature. Herein, multi-parametric MRI assessment, including dynamic contrast enhanced magnetic resonance imaging (DCE-MRI), magnetic resonance spectroscopy (MRS), MRI T2*, contrast enhanced MR angiography (CE-MRA), and micro-CT were applied in a rodent nephrectomy model to: 1) investigate the blood perfusion of subchondral bone marrow and its relationship to fat water content and trabeculation pattern in CKD and 2) demonstrate the feasibility of using multi-parametric MRI parameters as imaging biomarkers to evaluate the disease's progression. Two groups of rats in our study underwent either 1) no intervention or 2) 5/6 nephrectomy. We found that in the CKD group, perfusion amplitude A and elimination constant k values were significantly decreased, and vascular permeability k was significantly increased. MRS showed that fat fraction (FF) was significantly lower, water fraction (WF) was significantly higher in the CKD group. Micro-CT showed a significant loss of trabecular bone. Knee subchondral bone marrow perfusion deficiency in experimental CKD may be associated with decreased fat content, increased water content, and sparse trabeculation.
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http://dx.doi.org/10.1038/s41598-017-03059-3DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5465086PMC
June 2017

Early white matter injuries in patients with acute carbon monoxide intoxication: A tract-specific diffusion kurtosis imaging study and STROBE compliant article.

Medicine (Baltimore) 2017 Feb;96(5):e5982

Department of Radiology, School of Medicine, College of Medicine, Taipei Medical University Translational Imaging Research Center Department of Medical Imaging, Taipei Medical University Hospital, Taipei Medical University, Taipei Department of Medical Imaging and Radiological Sciences, Kaohsiung Medical University, Kaohsiung Department of Radiology, Tri-Service General Hospital and National Defense Medical Center Graduate Institute of Biomedical Electronics and Bioinformatics, National Taiwan University School of Biomedical Engineering, College of Biomedical Engineering, Taipei Medical University, Taipei, Taiwan.

Evaluation of acute white matter injuries caused by carbon monoxide (CO) poisoning can be limited by conventional magnetic resonance (MR) imaging. We aim to evaluate the feasibility of diffusion kurtosis imaging (DKI) for early detection of white matter alterations in patients with acute CO intoxication.A total of 30 subjects including 15 acute CO patients and 15 age- and sex-matched healthy volunteers were enrolled in this study. MR examinations were performed on a 3T MR scanner within 8 days after CO intoxication. DKI data were acquired to derive axial, radial, and mean kurtosis, as well as fractional anisotropy (FA), axial, radial, and mean diffusivity for tract-specific comparisons between the 2 groups.Significant decreases of mean kurtosis were shown in the genu of corpus callosum, cingulum, and motor-related tracts (corticospinal and corticobulbar tracts) in patients with acute CO intoxication as compared with controls. On the contrary, significant differences of FA values were merely shown in the regions of corticospinal tracts.DKI demonstrated comparably stronger potential than diffusion tensor imaging in terms of early detection of white matter changes in patients with acute CO intoxication. This may have implications in therapeutic strategy for managing acute CO intoxication patients.
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http://dx.doi.org/10.1097/MD.0000000000005982DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5293452PMC
February 2017

Early Idiopathic Normal Pressure Hydrocephalus Patients With Neuropsychological Impairment Are Associated With Increased Fractional Anisotropy in the Anterior Thalamic Nucleus.

Medicine (Baltimore) 2016 May;95(19):e3636

From the Department of Biomedical Imaging and Radiological Sciences (Y-CC, Y-TW), National Yang-Ming University; Department of Radiology (S-WC, H-WK, C-YC), Tri-Service General Hospital and National Defense Medical Center; Graduate Institute of Biomedical Electrics and Bioinformatics (S-WC, H-WC), National Taiwan University; Department of Psychiatry (C-HC), Tri-Service General Hospital; Institute of Statistical Science (ML), Academia Sinica, Taipei; Department of Radiology (D-PK), Taoyuan Armed Forces General Hospital, Taoyuan; Department of Neurosurgery (HIM); Department of Neurology (G-SP), Tri-Service General Hospital; Department of Medical Imaging and Imaging Research Center (C-YC), Taipei Medical University Hospital; and Department of Radiology (C-YC), College of Medicine, Taipei Medical University, Taipei, Taiwan.

In this study, we aimed to investigate the reactive changes in diffusion tensor imaging (DTI)-derived diffusion metrics of the anterior thalamic nucleus (AN), a relaying center for the Papez circuit, in early idiopathic normal pressure hydrocephalus (iNPH) patients with memory impairment, as well as its correlation with the patients' neuropsychological performances. In total, 28 probable iNPH patients with symptom onset within 1 year and 17 control subjects were prospectively recruited between 2010 and 2013 for this institutional review board-approved study. Imaging studies including DTI and a neuropsychological assessment battery were performed in all subjects. Diffusion metrics were measured from the region of the AN using tract-deterministic seeding method by reconstructing the mammillo-thalamo-cingulate connections within the Papez circuit. Differences in diffusion metrics and memory assessment scores between the patient and control group were examined via the Mann-Whitney U test. Spearman correlation analyses were performed to examine associations between diffusion metrics of AN and neuropsychological tests within the patient group. We discovered that early iNPH patients exhibited marked elevations in fractional anisotropy, pure diffusion anisotropy, and axial diffusivity (all P < 0.01), as well as lower neuropsychological test scores including verbal and nonverbal memory (all P < 0.05) compared with normal control. Spearman rank correlation analyses did not disclose significant correlations between AN diffusion metrics and neuropsychological test scores in the patient group, whereas ranked scatter plots clearly demonstrated a dichotic sample distribution between patient and control samples. In summary, our study highlighted the potential compensatory role of the AN by increasing thalamocortical connectivity within the Papez circuit because memory function declines in early iNPH when early shunt treatment may potentially reverse the memory deficits.
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http://dx.doi.org/10.1097/MD.0000000000003636DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4902519PMC
May 2016

Middle Cerebral Artery Calcification: Association With Ischemic Stroke.

Medicine (Baltimore) 2015 Dec;94(50):e2311

From the Department of Radiology, Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan (H-WK, H-WC, S-WC, G-SH, H-HH, C-YC); Department of Biomedical Imaging and Radiological Sciences, National Yang-Ming University, Taipei, Taiwan (H-WK); Institute of Statistical Science, Academia, Taipei, Taiwan Sinica (ML); Department of Electrical Engineering, National Taiwan University, Taipei, Taiwan (H-WC, S-WC); Department of Medical Imaging, Taipei Medical University Hospital, Taipei, Taiwan (H-SL, P-HT, C-YC); Imaging Research Center, Taipei Medical University, Taipei, Taiwan (H-SL, P-HT, C-YC); Graduate Institute of Clinical Medicine, Taipei Medical University, Taipei, Taiwan (H-SL, P-HT, C-YC); Department of Medical Imaging and Radiological Sciences, Kaohsiung Medical University, Kaohsiung, Taiwan (M-CC); and Department of Neurology, Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan (G-SP)..

Calcification of the middle cerebral artery (MCA) is uncommon in the healthy elderly. Whether calcification of the MCA is associated with cerebral ischemic stroke remains undetermined. We intended to investigate the association using Agatston calcium scoring of the MCA. This study retrospectively included 354 subjects with ischemic stroke in the MCA territory and 1518 control subjects who underwent computed tomography (CT) of the brain. We recorded major known risk factors for ischemic stroke, including age, gender, hypertension, diabetes mellitus, smoking, hyperlipidemia, and obesity, along with the MCA calcium burden, measured with the Agatston calcium scoring method. Univariate and modified logistic regression analyses were performed to examine the association between the MCA calcification and ischemic stroke. The univariate analyses showed significant associations of ischemic stroke with age, hypertension, diabetes mellitus, smoking, total MCA Agatston score, and the presence of calcification on both or either side of the MCA. Subjects with the presence of MCA calcification on both or either side of the MCA were 8.46 times (95% confidence interval, 4.93-14.53; P < 0.001) more likely to have a cerebral infarct than subjects without MCA calcification after adjustment for the major known risk factors, including age, hypertension, diabetes mellitus, and smoking. However, a higher degree of MCA calcification reflected by the Agatston score was not associated with higher risk of MCA ischemic stroke after adjustment for the confounding factors and presence of MCA calcification. These results suggest that MCA calcification is associated with ischemic stroke in the MCA territory. Further prospective studies are required to verify the clinical implications of the MCA calcification.
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http://dx.doi.org/10.1097/MD.0000000000002311DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5058941PMC
December 2015

High Agatston Calcium Score of Intracranial Carotid Artery: A Significant Risk Factor for Cognitive Impairment.

Medicine (Baltimore) 2015 Sep;94(39):e1546

From the Department of Radiology, Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan (H-WK, H-WC, S-WC, G-SH, H-HH, C-YC); Department of Biomedical Imaging and Radiological Sciences, National Yang-Ming University, Taipei, Taiwan (H-WK); Institute of Statistical Science, Academia Sinica, Taipei, Taiwan (ML); Department of Electrical Engineering, National Taiwan University, Taipei, Taiwan (H-WC, S-WC); Department of Medical Imaging, Taipei Medical University Hospital, Taipei, Taiwan (H-SL, P-HT, C-YC); Imaging Research Center, Taipei Medical University, Taipei, Taiwan (H-SL, P-HT, C-YC); Graduate Institute of Clinical Medicine, Taipei Medical University, Taipei, Taiwan (H-SL, P-HT, C-YC); Department of Medical Imaging and Radiological Sciences, Kaohsiung Medical University, Kaohsiung, Taiwan (M-CC); and Department of Neurology, Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan (G-SP).

The effect of intracranial internal carotid artery (ICA) calcification on cognitive impairment is uncertain. Our objective was to investigate whether intracranial ICA calcification is a significant cognitive predictor for cognitive impairment. Global cognition and degrees of intracranial ICA calcification of 579 subjects were assessed with Mini-Mental State Examination (MMSE) and Agatston calcium scoring method, respectively. Other risk factors for cognitive impairment, including age, education level, hypertension, diabetes mellitus, smoking, hyperlipidemia, and body mass index, were documented and analyzed for their associations with cognitive function. In univariate analyses, older age, lower education level, hypertension, diabetes mellitus, and higher intracranial ICA Agatston scores were significantly associated with cognitive impairment. In ordinal logistic regression, only age and total intracranial ICA Agatston score were significant risk factors for cognitive impairment. After adjustment for the other documented risk factors, subjects were 7% (95% CI: 5-10; P < 0.001) and 6% (95% CI: 0-13; P = 0.04) more likely to have lower cognitive category with every year increment of age and every 100-point increment of the total intracranial ICA Agatston score respectively. These results suggest an important role of the intracranial ICA calcification on cognitive impairment.
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http://dx.doi.org/10.1097/MD.0000000000001546DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4616872PMC
September 2015

Change in T2* relaxation time of Hoffa fat pad correlates with histologic change in a rat anterior cruciate ligament transection model.

J Orthop Res 2015 Sep 18;33(9):1348-55. Epub 2015 May 18.

Department of Radiology, Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan.

The Hoffa fat pad (infrapatellar fat pad) is a source of post-traumatic anterior knee pain, and Hoffa disease is a syndrome leading to chronic inflammation of the fat pad. Herein, change in T2* relaxation time of the fat pad was measured in a rodent anterior cruciate ligament transection (ACLX) model in order to (i) examine the causal relationship of anterior cruciate ligament (ACL) deficiency and Hoffa disease and (ii) demonstrate the feasibility of using T2* as an imaging biomarker to monitor disease progression. Three groups of male Sprague Dawley rats (n = 6 each group), received either (i) no intervention; (ii) sham surgery at the right knee; or (iii) right ACLX. T2* relaxation time was measured and histology was examined in the Hoffa fat pad after surgery. At 13 and 18 weeks after surgery, T2* values were significantly higher in the right fat pad than the left (p < 0.001) and significantly higher in the ACLX group than the control and sham groups (p < 0.001). Histology showed fibrosis and degeneration of adipocytes in the right knees of the ACLX group. We conclude that ACL deficiency and Hoffa disease are causally related and that MRI T2* value can serve as an imaging biomarker of Hoffa disease progression.
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http://dx.doi.org/10.1002/jor.22914DOI Listing
September 2015

Advanced MR imaging of gliomas: an update.

Biomed Res Int 2013 4;2013:970586. Epub 2013 Jun 4.

Department of Biomedical Imaging and Radiological Sciences, National Yang-Ming University, Taipei 112, Taiwan.

Recent advances in the treatment of cerebral gliomas have increased the demands on noninvasive neuroimaging for the diagnosis, therapeutic planning, tumor monitoring, and patient outcome prediction. In the meantime, improved magnetic resonance (MR) imaging techniques have shown much potentials in evaluating the key pathological features of the gliomas, including cellularity, invasiveness, mitotic activity, angiogenesis, and necrosis, hence, further shedding light on glioma grading before treatment. In this paper, an update of advanced MR imaging techniques is reviewed, and their potential roles as biomarkers of tumor grading are discussed.
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http://dx.doi.org/10.1155/2013/970586DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3686060PMC
February 2014

Effects of microvascular permeability changes on contrast-enhanced T1 and pharmacokinetic MR imagings after ischemia.

Stroke 2013 Jul 6;44(7):1872-7. Epub 2013 Jun 6.

Department of Radiology, Tri-Service General Hospital, Taipei, Taiwan.

Background And Purpose: Brain enhancement on contrast-enhanced T1-weighted imaging (CET1-WI) after ischemic stroke is generally accepted as an indicator of the blood-brain barrier disruption. However, this phenomenon usually starts to become visible at the subacute phase. The purpose of this study was to evaluate the time-course profiles of K(trans), cerebral blood volume (vp), and CET1-WI with early detection of blood-brain barrier changes on K(trans) maps and their role for prediction of subsequent hemorrhagic transformation in acute middle cerebral arterial infarct.

Methods: Twenty-six patients with acute middle cerebral arterial stroke and early spontaneous reperfusion, whose MR images were obtained at predetermined stroke stages, were included. T2*-based MR perfusion-weighted images were acquired using the first-pass pharmacokinetic model to derive K(trans) and vp. Parenchymal enhancement observed on maps of K(trans), vp, and CET1-WI at each stage was compared. Association among these measurements and hemorrhagic transformation was analyzed.

Results: K(trans) map showed significantly higher parenchymal enhancement in ischemic parenchyma as compared with that of vp map and CET1-WI at early stroke stages (P<0.05). The increased K(trans) at acute stage was not associated with parenchymal enhancement in CET1-WI at the same stage. Parenchymal enhancement in CET1-WI started to occur at the late subacute stage and tended to be luxury reperfusion-dependent. Patients with hemorrhagic transformation showed higher mean K(trans) values as compared with patients without hemorrhagic transformation (P=0.02).

Conclusions: Postischemic brain enhancement on routine CET1-WI seems to be closely related to the luxury reperfusion at the late subacute stage and is not dependent on microvascular permeability changes at the acute stage.
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http://dx.doi.org/10.1161/STROKEAHA.113.001558DOI Listing
July 2013

T2 values of posterior horns of knee menisci in asymptomatic subjects.

PLoS One 2013 28;8(3):e59769. Epub 2013 Mar 28.

Graduate Institute of Biomedical Electronics and Bioinformatics, National Taiwan University, Taipei, Taiwan, ROC.

Purpose: The magnetic resonance (MR) T2 value of cartilage is a reliable indicator of tissue properties and therefore may be used as an objective diagnostic tool in early meniscal degeneration. The purpose of this study was to investigate age, gender, location, and zonal differences in MR T2 value of the posterior horns of knee menisci in asymptomatic subjects.

Methods: Sixty asymptomatic volunteers (30 men and 30 women) were enrolled and divided into three different age groups: 20-34, 35-49 and 50-70 years. The inclusion criteria were BMI<30 kg/cm(2), normalized Western Ontario and McMaster Universities (WOMAC) pain score of zero, and no evidence of meniscal and ligamentous abnormalities on routine knee MR imaging. The T2 values were measured on images acquired with a T2-weighted fat-suppressed turbo spin-echo sequence at 3T.

Results: The mean T2 values in both medial and lateral menisci for the 20-34, 35-49, and 50-70 age groups were 9.94 msec±0.94, 10.73 msec±1.55, and 12.36 msec±2.27, respectively, for women and 9.17 msec±0.74, 9.64 msec±0.67, and 10.95 msec±1.33, respectively, for men. The T2 values were significantly higher in the 50-70 age group than the 20-34 age group (P<0.001) and in women than in men (P = 0.001, 0.004, and 0.049 for each respective age group). T2 values were significantly higher in medial menisci than in lateral menisci only in women age 50-70 (3.33 msec, P = 0.006) and in the white zone and red/white zone of the 50-70 and 35-49 age groups than that of the 20-34 age group (2.47, 1.02; 2.77, 1.16 msec, respectively, all P<0.01).

Conclusion: The MR T2 values of the posterior meniscal horns increase with increasing age in women and are higher in women than in men. The age-related rise of T2 values appears to be more severe in medial menisci than in lateral menisci. Differences exist in the white zone and red/white zone.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0059769PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3610938PMC
January 2014

Delayed parkinsonism after CO intoxication: evaluation of the substantia nigra with inversion-recovery MR imaging.

Radiology 2012 Oct 24;265(1):215-21. Epub 2012 Jul 24.

Department of Radiology, Tri-Service General Hospital, National Defense Medical Center, Institute of Biomedical Engineering, National Yang-Ming University, Taipei, Taiwan.

Purpose: To quantitatively investigate signal alterations of the substantia nigra in patients with delayed parkinsonism following CO intoxication, as seen on gray matter (GM)-suppressed inversion-recovery (IR) magnetic resonance (MR) images.

Materials And Methods: This prospective study was approved by the local institutional review board, and written informed consent was obtained from all subjects. Thirteen patients with delayed onset of CO-induced parkinsonism (nine men and four women; mean age, 40.3 years), 13 age-matched CO-intoxicated patients without parkinsonism, and 13 age-matched healthy volunteers were examined with GM-suppressed IR MR imaging. The signal intensity of the substantia nigra was normalized to the adjacent normal-appearing white matter in the temporal lobe, followed by semiautomatic segmentation into medial, middle, and lateral parts by using a skeleton-based algorithm. Multivariate and univariate analyses and Spearman rank correlation test were performed to examine the relationships between variables. Clinical severity was assessed with the modified Hoehn and Yahr rating scale.

Results: The normalized signal ratios in the middle and lateral segments of the substantia nigra were significantly higher in those with CO-induced parkinsonism, compared with those with CO intoxication without parkinsonism or normal volunteers (P=.02). For the medial segments, the ratios showed no significant differences among the groups. The normalized signal ratios of substantia nigra were correlated with the severity of parkinsonism, particularly in the lateral segments (ρ=0.927, P<.001).

Conclusion: CO toxicity to the substantia nigra plays a role in pathophysiologic mechanisms of CO-induced parkinsonism. GM-suppressed IR MR imaging is a useful tool in depicting substantia nigra injury following CO intoxication.
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http://dx.doi.org/10.1148/radiol.12112714DOI Listing
October 2012

Potential long-term effects of MDMA on the basal ganglia-thalamocortical circuit: a proton MR spectroscopy and diffusion-tensor imaging study.

Radiology 2011 Aug 1;260(2):531-40. Epub 2011 Jun 1.

Department of Radiology, Tri-Service General Hospital and National Defense Medical Center, 325 Cheng-Kung Rd, NeiHu, Taipei, Taiwan 114, Republic of China.

Purpose: To investigate the effects of 3,4-methylenedioxymethamphetamine (MDMA, commonly known as "ecstasy") on the alterations of brain metabolites and anatomic tissue integrity related to the function of the basal ganglia-thalamocortical circuit by using proton magnetic resonance (MR) spectroscopy and diffusion-tensor MR imaging.

Materials And Methods: This study was approved by a local institutional review board, and written informed consent was obtained from all subjects. Thirty-one long-term (>1 year) MDMA users and 33 healthy subjects were enrolled. Proton MR spectroscopy from the middle frontal cortex and bilateral basal ganglia and whole-brain diffusion-tensor MR imaging were performed with a 3.0-T system. Absolute concentrations of metabolites were computed, and diffusion-tensor data were registered to the International Consortium for Brain Mapping template to facilitate voxel-based group comparison.

Results: The mean myo-inositol level in the basal ganglia of MDMA users (left: 4.55 mmol/L ± 2.01 [standard deviation], right: 4.48 mmol/L ± 1.33) was significantly higher than that in control subjects (left: 3.25 mmol/L ± 1.30, right: 3.31 mmol/L ± 1.19) (P < .001). Cumulative lifetime MDMA dose showed a positive correlation with the levels of choline-containing compounds (Cho) in the right basal ganglia (r = 0.47, P = .02). MDMA users also showed a significant increase in fractional anisotropy (FA) in the bilateral thalami and significant changes in water diffusion in several regions related to the basal ganglia-thalamocortical circuit as compared with control subjects (P < .05; cluster size, >50 voxels).

Conclusion: Increased myo-inositol and Cho concentrations in the basal ganglia of MDMA users are suggestive of glial response to degenerating serotonergic functions. The abnormal metabolic changes in the basal ganglia may consequently affect the inhibitory effect of the basal ganglia to the thalamus, as suggested by the increased FA in the thalamus and abnormal changes in water diffusion in the corresponding basal ganglia-thalamocortical circuit.
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http://dx.doi.org/10.1148/radiol.11101918DOI Listing
August 2011
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