Chien-Hung Chang

Differentiation of Primary Central Nervous System Lymphomas and Glioblastomas: Comparisons of Diagnostic Performance of Dynamic Susceptibility Contrast-Enhanced Perfusion MR Imaging without and with Contrast-Leakage Correction

BACKGROUND AND PURPOSE: Contrast leakage results in underestimation of the CBV of brain tumors. Our aim was to compare the diagnostic performance of DSC perfusion MR imaging without and with mathematic contrast-leakage correction in differentiating PCNSLs and glioblastomas. MATERIALS AND METHODS: Perfusion parameters—CBV, corrected CBV, and leakage coefficient—were measured in enhancing tumor portions and contralateral NAWM of 15 PCNSLs and 20 glioblastomas, respectively. The ratios of CBV and corrected CBV were calculated by dividing the tumor values by those obtained from contralateral NAWM. A paired t test was used to compare tumor K2 and NAWM K2, as well as tumor CBV ratios without and with leakage correction. Comparisons of CBV, corrected CBV, and K2 between PCNSLs and glioblastomas were done by using a 2-sample t test. The diagnostic performance of DSC perfusion MR imaging without and with contrast-leakage correction was assessed with receiver operating characteristic curve analysis. RESULTS: PCNSLs and glioblastomas demonstrated higher K2 than those in their contralateral NAWM. Corrected CBV ratios were significantly higher than the uncorrected ones for both tumors. PCNSLs had lower CBV ratios (P < .001), lower corrected CBV ratios (P < .001), and higher K2 (P = .001) compared with glioblastomas. In differentiating between PCNSLs and glioblastomas, the area under the curve of the CBV ratio, corrected CBV ratio, and K2 were 0.984, 0.940, and 0.788, respectively. CONCLUSIONS: PCNSL can be differentiated from glioblastoma with CBV ratios, corrected CBV ratios, and K2. CBV without contrast-leakage correction seems to have the best diagnostic performance in differentiating the 2 tumors.

Differentiation of Pyogenic Brain Abscesses from Necrotic Glioblastomas with Use of Susceptibility-Weighted Imaging

In this article the authors used SWI to evaluate the hypointense peripheral rim seen in both glioblastomas and pyogenic abscesses. Studying 12 abscesses and 20 glioblastomas, they discovered the rims were complete and had smooth contours more commonly in the former. An unexpected sign that was only seen in abscesses was that of a dual rim of hypointensity surrounding the lesions. They concluded that SWI is helpful in separating these 2 entities and the most specific sign was the dual rim. BACKGROUND AND PURPOSE: A common imaging finding in brain abscess and necrotic glioblastoma is a T2 hypointense margin. The features of this hypointense rim on SWI have not been previously described, to our knowledge. We aimed to differentiate abscesses from glioblastomas by assessing the morphology of their lesion margin by using SWI. MATERIALS AND METHODS: T2WI and SWI were performed in 12 abscesses and 20 rim-enhancing glioblastomas. On T2WI and SWI, the prevalence and the border types (complete versus incomplete) of hypointense rims were qualitatively assessed. On SWI, the contour (smooth versus irregular) and the location of hypointense rims relative to the contrast-enhancing rims as well as the prevalence of the “dual rim sign,” defined as 2 concentric rims at lesion margins with the outer one being hypointense and the inner one hyperintense relative to cavity contents, were also analyzed. RESULTS: Prevalence and the border types of the hypointense rims on T2WI were not different between abscesses and glioblastomas. On SWI, there were significantly more hypointense rims that were complete (P < .001) and smooth (P < .001), having the same location as the contrast-enhancing rims (P < .001) for abscesses. A dual rim sign was present in 9 of 12 abscesses but absent in all glioblastomas (P < .001). CONCLUSIONS: SWI may be helpful in differentiating pyogenic abscesses from necrotic glioblastomas. The dual rim sign is the most specific imaging feature distinguishing the 2.

Amyloid deposition after cerebral hypoperfusion: Evidenced on [18F]AV-45 positron emission tomography

Animal studies have shown that cerebral hypoperfusion may be associated with amyloid plaque accumulation. Amyloid plaque is known to be associated with dementia and [(18)F]AV-45 is a positron emission tomography (PET) ligand that binds to extracelluar plaques. We hypothesized that demented patients with cerebral hypoperfusion may have increased [(18)F]AV-45 uptake. Five demented patients with cerebral hypoperfusion due to unilateral carotid artery stenosis (CAS) were examined with [(18)F]AV-45 PET, and the results were compared with six elderly controls. The standard uptake value ratio (SUVR) of each region of interest (ROI) was created using whole cerebellum as the reference region. All subjects underwent magnetic resonance imaging (MRI) for obtaining structural information. Patients with dementia and unilateral CAS had a higher global [(18)F]AV-45 SUVR (1.34 ± 0.06) as compared with controls (1.10 ± 0.04, p=0.0043), especially over the frontal, temporal, precuneus, anterior cingulate and occipital regions. The statistical distribution maps revealed a significantly increased [(18)F]AV-45 SUVR in the medial frontal, caudate, thalamus, posterior cingulate, occipital and middle and superior temporal regions ipsilateral to the side of CAS (p<0.01). The present study found that cerebral [(18)F]AV-45 binding is increased in demented patients with CAS, and its distribution is lateralized to the CAS side, suggesting that amyloid-related dementia may occur under cerebral hypoperfusion.

Rapid progression and brain atrophy in anti-AMPA receptor encephalitis

Anti-α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptor encephalitis is an anti-neuronal surface antigen autoimmune encephalitis that is rarely reported. Our study evaluated the first known patient who developed anti-AMPA receptor encephalitis during pregnancy. Initial brain MRI revealed bilateral limbic encephalitis. However, rapid brain atrophy on MRI with extensive hypometabolism of cerebral cortices, caudate nuclei and brain stem hypoperfusion on (18)F-FDG PET developed when clinically progressed. IgG index of serial CSF studies reflected the clinical improvements after plasmapheresis and plasma exchange. The clinical spectrum of anti-AMPA receptor encephalitis may be expanded from limited limbic involvement to extended central nervous system.

Establishment of Electronic Chart-based Stroke Registry System in a Medical System in Taiwan

To establish a prospective, real-time, self-sustainable stroke registry system, we incorporated a registry with an electronic chart to create an electronic chart-based stroke registry system in November 2006. The International Classification of Diseases Ninth Revision code (430-437) was used to auto-enroll stroke patients admitted to neurology departments. Clinical information was written by doctors, nursing information was recorded by nurses, and basic patient information was entered by administrative departments. Numerical data and the date and time of any studies were auto-downloaded from the hospital computer. In total, 212 items were auto-downloaded, including basic patient information, laboratory blood test and examination results, and the date and time of imaging and special intervention. The stroke scales (121 items, National Institutes of Health Stroke Scale, Barthel index, and modified Rankin scale) were designed to be auto-adjusted to reduce incompatibility. The 95 items with pull-down options were used to specify the contents. This registry system can be time-, labor- and money-saving with secured data accuracy.

Plasticity of Circle of Willis: A Longitudinal Observation of Flow Patterns in the Circle of Willis One Week after Stenting for Severe Internal Carotid Artery Stenosis

Background and Purpose: The purpose of the present study was to assess whether the direction of flow via the circle of Willis (CoW) changed after stenting for severe internal carotid artery (ICA) stenosis. Methods: 65 patients (38 men, mean age 63.2 ± 8.4 years, range 44–82) with a symptomatic ICA occlusion were investigated. Magnetic resonance angiography was performed prior to and 1 week after carotid artery stenting (CAS). The pattern in the CoW was assessed. Results: One third of the subjects (35.38%) had a significantly altered flow pattern in the CoW after unilateral CAS, including blocked ipsilateral A1 segment collateral (n = 4), blocked contralateral A1 segment collateral (n = 5), blocked ipsilateral posterior communicating artery (PCoA) segment collateral (n = 4), blocked ipsilateral A1 segment and P1 segment collateral (n = 1), opening of ipsilateral A1 segment collateral (n = 5), opening of ipsilateral PCoA segment collateral (n = 3) and opening of ipsilateral P1 segment collateral (n = 1). Conclusions: CoW segmental hypoplasia is not a static feature. Willisian collateralization with recruitment of the CoW segment (A1, P1 and PCoA) may be blocked after CAS. CAS also leads to the opening of new willisian collateralization, either for relief of reperfusion pressure or for other hypoperfused areas.

Impact of silent ischemic lesions on cognition following carotid artery stenting.

Objective: The occurrence of silent ischemic lesions (SILs) is a common finding after carotid artery stenting (CAS). This study aimed to evaluate the impact of SILs on cognitive functioning following CAS. Methods: The retrospective study separated 131 patients with unilateral carotid stenosis into three groups: medication only, MRI-evaluated CAS and CT-evaluated CAS, and compared the sociodemographic factors, post-CAS images and Mini-Mental State Examination scores performed before and 6–12 months after enrollment. Results: Seven minor strokes occurred in the 99 patients receiving CAS. SILs were detected in 12 of 55 patients with diffusion-weighted MR imaging (DWI) and in 3 of 37 patients with CT 1 week after CAS. In patients with DWI follow-up, the frequency of SILs was 8, 24, 43 and 60% in patients with 0-, 1-, 2- and 3-vessel coronary artery disease (p = 0.006). The frequency of SILs on DWI was 0, 32 and 33% in patients with improved, unchanged, or deteriorated cognitive functioning (p = 0.02). Such an association was not observed if based on SILs on CT or manifesting stroke. Conclusion: The presence of coronary artery disease increases the risk for having post-CAS SILs, and the occurrence of SILs may be associated with cognitive changes after CAS.

Predictors of Clinical Deterioration during Hospitalization following Acute Ischemic Stroke

Background/Aims: A number of risk factors for early worsening of neurological symptoms have been identified. We aimed to evaluate the influence of hemorheologic, biochemical, and metabolic factors on neurological deterioration during hospitalization following acute ischemic stroke and develop a model of neurological deterioration. Methods: Worsening of stroke was defined as a deleterious increase in NIH Stroke Scale (NIHSS) score of ≧4 points during hospitalization. We performed multivariate logistic regression analysis and constructed a prediction model based on chart data of 2,398 patients admitted at five medical centers; 203 of the patients had worsening of stroke and 2,186 had not. Results: The results of multivariate logistic regression analysis showed that hemoglobin (odds ratio: 0.529) and albumin (odds ratio: 0.024) were significantly associated with stroke deterioration, as were the modified Rankin Scale on emergency department admission (odds ratio: 4.956) and length of hospitalization (odds ratio: 1.201). After adjusting for age, gender and NIHSS on emergency department admission, only hemoglobin (odds ratio: 0.894, 95% confidence interval: 0.814–0.981, p = 0.018) was associated with worsening. Conclusion: Hemoglobin and albumin were found to be risk factors for persistent neurological deterioration during hospitalization following acute ischemic stroke, suggesting that blood viscosity may be related to neurological deterioration.

Coexisting Diseases of Moyamoya Vasculopathy

BACKGROUND Several coexisting diseases have been reported in patients with moyamoya vasculopathy (MMV), but studies of quasi-moyamoya disease (quasi-MMD) are rare. This study aims to investigate the frequency of known coexisting diseases in patients with quasi-MMD and to compare quasi-MMD with moyamoya disease (MMD). METHODS Between 2000 and 2011, we retrospectively screened patients with International Classification of Diseases, Ninth Revision, code of 4375 (MMD) in the Health Information System of our hospital. The vascular images of each patient were confirmed by 2 neurologists and 1 neuroradiologist based on the diagnostic criteria of Japan Ministry of Health and Welfare. We excluded the patients with missing images and erroneous diagnosis. Demographics, coexisting diseases, laboratory data, treatment, and recurrent strokes were recorded. The eligible patients were divided into quasi-MMD and MMD groups according to the presence or absence of coexisting diseases. RESULTS MMV was found in 90 patients including 37 (41.1%) quasi-MMD and 53 (58.9%) MMD. Atherosclerosis (32.4%) and thyroid disease (29.7%) were the leading coexisting diseases in quasi-MMD. Patients with MMD became symptomatic in a bimodal age distribution, whereas patients with quasi-MMD became symptomatic in a single-peak distribution. The prognosis of recurrent strokes was similar between quasi-MMD and MMD based on Kaplan-Meier analysis. CONCLUSIONS A bimodal distribution of onset age was noted in MMD, whereas a single-peak distribution was found in quasi-MMD. Coexisting diseases were usually underevaluated but were more common than expected in patients with MMV. Atherosclerosis and thyroid diseases were the leading coexisting diseases in different preferential age.

ALOX5AP genetic variants and risk of atherothrombotic stroke in the Taiwanese population

We explored the role of variants of the arachidonate 5-lipoxygenase-activating protein (ALOX5AP) gene as factors for atherothrombotic stroke (ATS). A HapMap-based haplotype-tagging single nucleotide polymorphism (htSNP) association study was conducted in an isolated Taiwanese population. Multivariate logistic regression analyses revealed that patients with the GG/CG genotype of rs4293222 and the AA/AG genotype of rs4360791 had a 1.61-fold (odds ratio [OR]=1.61; 95% confidence interval [CI]=1.02-2.56, p=0.042) and a 1.69-fold (OR=1.69; 95% CI=1.00-2.86, p=0.047) increased risk of ATS, compared with patients with the CC/GG genotype, respectively. The most common haplotype allele, GTA, was used as a reference when analyzing the association between the haplotypes related to rs4293222, rs10507391, rs12429692 and ATS. The combined frequencies of all minor variant alleles of the three selected htSNP were associated with a 44% decreased risk of ATS (OR=0.56; 95% CI=0.37-0.84, p=0.005). This study provides preliminary evidence suggesting that genetic polymorphisms of ALOX5AP are associated with ATS.