Characterization of carotid plaques using chemical exchange saturation transfer imaging.

PURPOSE: The preoperative assessment of carotid plaques is necessary to render revascularization safe and effective. The aim of this study is to evaluate the usefulness of chemical exchange saturation transfer (CEST)-MRI, particularly amide proton transfer (APT) imaging as a preoperative carotid plaque diagnostic tool. METHODS: We recorded the APT signal intensity on concentration maps of 34 patients scheduled for carotid endarterectomy. Plaques were categorized into group A (APT signal intensity ≥ 1.90 E-04; n = 12) and group B (APT signal intensity < 1.90 E-04; n = 22). Excised plaques were subjected to histopathological assessment and, using the classification promulgated by the American Heart Association, they were classified as intraplaque hemorrhage-positive [type VI-positive (tVI+)] and -negative [no intraplaque hemorrhage (tVI-)]. RESULTS: Of the 34 patients, 22 (64.7%) harbored tVI+- and 12 (35.3%) had tVI- plaques. The median APT signals were significantly higher in tVI+- than tIVI- patients (2.43 E-04 (IQR = 0.98-4.00 E-04) vs 0.54 E-04 (IQR = 0.14-1.09 E-04), p < .001). Histopathologically, the number of patients with tVI+ plaques was significantly greater in group A (100%, n = 12) than group B (45%, n = 22) (p < .01). The number of symptomatic patients or asymptomatic patients with worsening stenosis was also significantly greater in group A than group B (75% vs 36%, p < .01). CONCLUSION: In unstable plaques with intraplaque hemorrhage and in patients with symptoms or progressive stenosis, the ATP signals were significantly elevated. CEST-MRI studies has the potential for the preoperative assessment of the plaques' characteristics.

Conversion map from quantitative parameter mapping to myelin water fraction: comparison with R1·R2* and myelin water fraction in white matter.

OBJECTIVE: To clarify the relationship between myelin water fraction (MWF) and R1⋅R2* and to develop a method to calculate MWF directly from parameters derived from QPM, i.e., MWF converted from QPM (MWFQPM). MATERIALS AND METHODS: Subjects were 12 healthy volunteers. On a 3 T MR scanner, dataset was acquired using spoiled gradient-echo sequence for QPM. MWF and R1⋅R2* maps were derived from the multi-gradient-echo (mGRE) dataset. Volume-of-interest (VOI) analysis using the JHU-white matter (WM) atlas was performed. All the data in the 48 WM regions measured VOI were plotted, and quadratic polynomial approximations of each region were derived from the relationship between R1·R2* and the two-pool model-MWF. The R1·R2* map was converted to MWFQPM map. MWF atlas template was generated using converted to MWF from R1·R2* per WM region. RESULTS: The mean MWF and R1·R2* values for the 48 WM regions were 11.96 ± 6.63%, and 19.94 ± 4.59 s-2, respectively. A non-linear relationship in 48 regions of the WM between MWF and R1·R2* values was observed by quadratic polynomial approximation (R2 ≥ 0.963, P < 0.0001). DISCUSSION: MWFQPM map improved image quality compared to the mGRE-MWF map. Myelin water atlas template derived from MWFQPM may be generated with combined multiple WM regions.

Determination of Alzheimer's disease based on morphology and atrophy using machine learning combined with automated segmentation.

BACKGROUND: To evaluate the degree of cerebral atrophy for Alzheimer's disease (AD), voxel-based morphometry has been performed with magnetic resonance imaging. Detailed morphological changes in a specific tissue area having the most evidence of atrophy were not considered by the machine-learning technique. PURPOSE: To develop a machine-learning system that can capture morphology features for determination of atrophy of brain tissue in early-stage AD and classification of healthy participants or patients. MATERIAL AND METHODS: Three-dimensional T1-weighted (3D-T1W) data were obtained from AD Neuroimaging Initiative (200 healthy controls and 200 patients with early-stage AD). Automated segmentation of 3D-T1W data was performed. Deep learning (DL) and support vector machine (SVM) were trained using 66-segmented volume values as input and AD diagnosis as output. DL was performed using 66 volume values or gray matter (GM) and white matter (WM) volume values. SVM learning was performed using 66 volume values and six regions with high variable importance. 3D convolutional neural network (3D-CNN) was trained using the segmented images. Accuracy and area under curve (AUC) were obtained. Variable importance was evaluated from logistic regression analysis. RESULTS: DL for GM and WM volume values, accuracy 0.6; SVM for all volume values, accuracy 0.82 and AUC 0.81; DL for all volume values, accuracy 0.82 and AUC 0.8; 3D-CNN using segmental images of the whole brain, accuracy 0.5 and AUC 0.51. SVM using volume values of six regions, accuracy 0.82; image-based 3D-CNN, highest accuracy 0.69. CONCLUSION: Our results show that atrophic features are more considerable than morphological features in the early detection of AD.

Influence of Pitch on Surface Dose Distribution and Image Noise of Computed Tomography Scans.

This study evaluated the effect of pitch on 256-slice helical computed tomography (CT) scans. Cylindrical water phantoms (CWP) were measured using axial and helical scans with various pitch values. The surface dose distributions of CWP were measured, and reconstructed images were obtained using filtered back-projection (FBP) and iterative model reconstruction (IMR). The image noise in each reconstructed image was decomposed into a baseline component and another component that varied along the z-axis. The baseline component of the image noise was highest at the center of the reconstructed image and decreased toward the edges. The normalized 2D power spectra for each pitch were almost identically distributed. Furthermore, the ratios of the 2D power spectra for IMR and FBP at different pitch values were obtained. The magnitudes of the components varying along the z-axis were smallest at the center of the reconstructed image and increased toward the edge. The ratios of the 3D power spectra on the fx axis for IMR and FBP at different pitch values were obtained. The results showed that the effect of the pitch was related to the component that varied along the z-axis. Furthermore, the pitch had a smaller effect on IMR than on FBP.

A diagnostic index based on quantitative susceptibility mapping and voxel-based morphometry may improve early diagnosis of Alzheimer's disease.

OBJECTIVES: Voxel-based morphometry (VBM) is widely used to quantify the progression of Alzheimer's disease (AD), but improvement is still needed for accurate early diagnosis. We evaluated the feasibility of a novel diagnosis index for early diagnosis of AD based on quantitative susceptibility mapping (QSM) and VBM. METHODS: Thirty-seven patients with AD, 24 patients with mild cognitive impairment (MCI) due to AD, and 36 cognitively normal (NC) subjects from four centers were included. A hybrid sequence was performed by using 3-T MRI with a 3D multi-echo GRE sequence to obtain both a T1-weighted image for VBM and phase images for QSM. The index was calculated from specific voxels in QSM and VBM images by using a linear support vector machine. The method of voxel extraction was optimized to maximize diagnostic accuracy, and the optimized index was compared with the conventional VBM-based index using receiver operating characteristic analysis. RESULTS: The index was optimal when voxels were extracted as increased susceptibility (AD > NC) in the parietal lobe and decreased gray matter volume (AD < NC) in the limbic system. The optimized proposed index showed excellent performance for discrimination between AD and NC (AUC = 0.94, p = 1.1 × 10-10) and good performance for MCI and NC (AUC = 0.87, p = 1.8 × 10-6), but poor performance for AD and MCI (AUC = 0.68, p = 0.018). Compared with the conventional index, AUCs were improved for all cases, especially for MCI and NC (p < 0.05). CONCLUSIONS: In this preliminary study, the proposed index based on QSM and VBM improved the diagnostic performance between MCI and NC groups compared with the VBM-based index. KEY POINTS: • We developed a novel diagnostic index for Alzheimer's disease based on quantitative susceptibility mapping (QSM) and voxel-based morphometry (VBM). • QSM and VBM images can be acquired simultaneously in a single sequence with little increasing scan time. • In this preliminary study, the proposed diagnostic index improved the discriminative performance between mild cognitive impairment and normal control groups compared with the conventional VBM-based index.

A Synthetic Model for the Possible FeIV2(µ-O)2 Core of Methane Monooxygenase Intermediate Q Derived from a Structurally Characterized FeIIIFeIV(µ-O)2 Complex.

A bis(µ-oxo)diiron(IV,IV) complex as a model for intermediate Q in the methane monooxygenase reaction cycle has been prepared. The precursor complex with a [FeIIIFeIV(µ-O)2] core was fully characterized by X-ray crystallography and other spectroscopic analyses and was converted to the [FeIV2(µ-O)2] complex via electrochemical oxidation at 1000 mV (vs Ag/Ag+) in acetone at 193 K. The UV-vis spectral features, Mössbauer parameters (ΔEQ = 2.079 mm/s and δ = -0.027 mm/s), and EXAFS analysis (Fe-O/N = 1.73/1.96 Å and Fe···Fe = 2.76 Å) support the structure of the low-spin (S = 1, for each Fe) [FeIV2(µ-O)2] core. The rate constants of the hydrogen abstraction reaction from 9,10-dihydroanthracene at 243 K suggest the high reactivity of these synthetic bis(µ-oxo)diiron complexes supported by simple N4 tripodal ligand.

Magnetic resonance imaging characteristics of polypoid endometriosis and review of the literature.

AIM: Polypoid endometriosis is a rare variant of endometriosis and may mimic malignancy. The purpose of this study is to evaluate magnetic resonance (MR) imaging characteristics of polypoid endometriosis for the differential diagnosis with malignancy. METHODS: MR imaging findings of four histologically proven polypoid endometriosis were retrospectively evaluated with the review of the literature. RESULTS: All polypoid endometriosis exhibited high signal intensity on T2-weighted images reflecting abundant dilated endometrial glands. Peritoneal lesions were surrounded by low signal intensity rim represented the "black rim sign" reflecting endometriotic fibrous adhesion. Two cases arising from endometriotic cysts showed transmural extension (peritoneal extension and myometrial infiltration). Endometriotic hemorrhagic foci were demonstrated in four lesions as high signal intensity on T1-weighted images and/or susceptibility-induced signal voids on susceptibility-weighted MR sequence. Diffusion-weighted images showed high signal intensity with relatively high apparent diffusion coefficient (ADC) due to T2 shine-through effect but no diffusion restriction, and dynamic contrast-enhanced (DCE) MR imaging showed gradually increasing contrast-enhancement pattern like benign pathologies. CONCLUSIONS: Polypoid endometriosis may mimic malignancy; however, black rim sign may be a characteristic MR imaging finding for the peritoneal lesions, and no diffusion restriction and gradually increasing contrast-enhancement pattern may reflect its benign nature.

Combined Small-Angle Neutron Scattering/Small-Angle X-ray Scattering Analysis for the Characterization of Silver Nanoparticles Prepared via Photoreduction in Water-in-Oil Microemulsions.

In this study, we used small-angle neutron scattering (SANS) and small-angle X-ray scattering (SAXS) to investigate the formation process of silver (Ag) nanoparticles (NPs) in water-in-oil (w/o) reverse microemulsions comprising sodium bis(2-ethylhexyl) sulfosuccinate (AOT), water, and organic solvents (such as benzene, octane, and decane) by the photoreduction of silver perchlorate (AgClO4). Combining SANS and SAXS, the structural changes in the w/o microemulsions before and after the formation of Ag NPs via photoreduction were quantitatively evaluated. From the SANS experiments performed using the contrast-variation method, the size of water cores containing Ag NPs and the thickness of the AOT shells were calculated using the core-shell hard-sphere model. The size of the Ag NPs and their aggregates was calculated via SAXS analysis based on the polydisperse sphere model with a Schulz-Zimm distribution. We found that aggregates of three or four primary Ag NPs are formed by, first, the aggregation of water droplets through the entanglement of the tails of the AOT shell, followed by the self-assembly of Ag NPs into their aggregates because of particle-particle attractive interactions.

MR spectroscopy and imaging-derived measurements in the supplementary motor area for biomarkers of amyotrophic lateral sclerosis.

The diagnosis of amyotrophic lateral sclerosis (ALS) requires both upper and lower motor neuron signs. However, quite a few patients with ALS lack the upper motor neuron sign during the disease. This study sought to investigate whether metabolites, including glutamate (Glu), N-acetyl aspartate (NAA), and gamma aminobutyric acid (GABA), in the supplementary motor area (SMA) measured by magnetic resonance spectroscopy (MRS), could be a surrogate biomarker for ALS. Twenty-five patients with ALS and 12 controls underwent 3.0-T MR scanning, which measured Glu, NAA, and GABA. Finally, receiver operating characteristic (ROC) curves were created and the area under curve (AUC) was calculated to assess the diagnostic power. Logistic regression analysis revealed the usefulness of both Glu and NAA for the differentiation of ALS from controls (Glu, P = 0.009; NAA, P = 0.033). The ratio of Glu to NAA or GABA was significantly increased in patients with ALS (Glu/NAA, P = 0.027; Glu/GABA, P = 0.003). Both the AUCs were more than 0.7, with high specificity but low sensitivity. The present findings might indicate that both the Glu/NAA and the Glu/GABA ratios in the SMA could be potential biomarkers for the diagnosis of ALS.

Characterization of Sporadic Creutzfeldt-Jakob Disease and History of Neurosurgery to Identify Potential Iatrogenic Cases.

We previously reported a phenotype of Creutzfeldt-Jakob disease (CJD), CJD-MMiK, that could help identify iatrogenic CJD. To find cases mimicking CJD-MMiK, we investigated clinical features and pathology of 1,155 patients with diagnosed sporadic CJD or unclassified CJD with and without history of neurosurgery. Patients with history of neurosurgery more frequently had an absence of periodic sharp-wave complexes on electroencephalogram than patients without a history of neurosurgery. Among 27 patients with history of neurosurgery, 5 had no periodic sharp-wave complexes on electroencephalogram. We confirmed 1 case of CJD-MMiK and suspected another. Both had methionine homozygosity at codon 129 of the prion protein gene and hyperintensity lesions in the thalamus on magnetic resonance images of the brain, which might be a clinical marker of CJD-MMiK. A subgroup with a history of neurosurgery and clinical features mimicking dura mater graft-associated CJD might have been infected during neurosurgery and had symptoms develop after many years.

MM2-type sporadic Creutzfeldt-Jakob disease: new diagnostic criteria for MM2-cortical type.

OBJECTIVE: To clinically diagnose MM2-cortical (MM2C) and MM2-thalamic (MM2T)-type sporadic Creutzfeldt-Jakob disease (sCJD) at early stage with high sensitivity and specificity. METHODS: We reviewed the results of Creutzfeldt-Jakob disease Surveillance Study in Japan between April 1999 and September 2019, which included 254 patients with pathologically confirmed prion diseases, including 9 with MM2C-type sCJD (MM2C-sCJD) and 10 with MM2T-type sCJD (MM2T-sCJD), and 607 with non-prion diseases. RESULTS: According to the conventional criteria of sCJD, 4 of 9 patients with MM2C- and 7 of 10 patients with MM2T-sCJD could not be diagnosed with probable sCJD until their death. Compared with other types of sCJD, patients with MM2C-sCJD showed slower progression of the disease and cortical distribution of hyperintensity lesions on diffusion-weighted images of brain MRI. Patients with MM2T-sCJD also showed relatively slow progression and negative results for most of currently established investigations for diagnosis of sCJD. To clinically diagnose MM2C-sCJD, we propose the new criteria; diagnostic sensitivity and specificity to distinguish 'probable' MM2C-sCJD from other subtypes of sCJD, genetic or acquired prion diseases and non-prion disease controls were 77.8% and 98.5%, respectively. As for MM2T-sCJD, clinical and laboratory features are not characterised enough to develop its diagnostic criteria. CONCLUSIONS: MM2C-sCJD can be diagnosed at earlier stage using the new criteria with high sensitivity and specificity, although it is still difficult to diagnose MM2T-sCJD clinically.

Role of Central Hypo-enhancement in the Hepatic Arterial Phase of Dynamic Computed Tomography in Patients with Mass-Forming Intrahepatic Cholangiocarcinoma.

BACKGROUND/PURPOSE: The enhancement pattern in the hepatic arterial phase (HAP) of dynamic computed tomography (CT) is reportedly a prognostic marker in patients with intrahepatic cholangiocarcinoma (IHCC). This study was performed to clarify the significance of central hypo-enhancement in the HAP in patients with mass-forming IHCC. METHODS: Forty patients who had undergone initial surgical resection for mass-forming IHCC were enrolled. The dynamic CT was scanned 40 s after contrast agent injection as the HAP. A radiologist classified the patients into three groups based on the vascular pattern: the hyper-enhancement group (Hyper group), rim-enhancement group (Rim group), and hypo-enhancement group (Hypo group). The surgical specimens were immunohistochemically stained for hypoxia-inducible factor 1 (HIF-1). The correlation with clinicopathological findings and HIF-1 expression was investigated. RESULTS: The Hyper, Rim, and Hypo groups comprised 8, 7, and 25 patients, respectively. There were no significant correlations between the groups and clinicopathological factors. Overall survival (OS) was significantly worse in the Hypo than in the Hyper group (p = 0.03). OS was also significantly worse in the Rim + Hypo group (i.e., hypo-enhancement in the central tumor) than in the Hyper group (p = 0.04). Furthermore, inclusion in the Rim + Hypo group was a prognostic factor for OS (hazard ratio 6.68). High HIF-1 expression in the central part of the tumor was correlated with central hypo-enhancement (Hyper group: 25% and Rim + Hypo group: 72%). CONCLUSIONS: Central hypo-enhancement was a prognostic factor in patients with IHCC. The high malignant potential of tumors with central hypo-enhancement might be associated with HIF-1 upregulation.

Development of Quality Indicators of Stroke Centers and Feasibility of Their Measurement Using a Nationwide Insurance Claims Database in Japan　­ J-ASPECT Study ­

BACKGROUND: We aimed to develop quality indicators (QIs) related to primary and comprehensive stroke care and examine the feasibility of their measurement using the existing Diagnosis Procedure Combination (DPC) database. METHODS AND RESULTS: We conducted a systematic review of domestic and international studies using the modified Delphi method. Feasibility of measuring the QI adherence rates was examined using a DPC-based nationwide stroke database (396,350 patients admitted during 2013-2015 to 558 hospitals participating in the J-ASPECT study). Associations between adherence rates of these QIs and hospital characteristics were analyzed using hierarchical logistic regression analysis. We developed 17 and 12 measures as QIs for primary and comprehensive stroke care, respectively. We found that measurement of the adherence rates of the developed QIs using the existing DPC database was feasible for the 6 QIs (primary stroke care: early and discharge antithrombotic drugs, mean 54.6% and 58.7%; discharge anticoagulation for atrial fibrillation, 64.4%; discharge antihypertensive agents, 51.7%; comprehensive stroke care: fasudil hydrochloride or ozagrel sodium for vasospasm prevention, 86.9%; death complications of diagnostic neuroangiography, 0.4%). We found wide inter-hospital variation in QI adherence rates based on hospital characteristics. CONCLUSIONS: We developed QIs for primary and comprehensive stroke care. The DPC database may allow efficient data collection at low cost and decreased burden to evaluate the developed QIs.

"One line": A method for differential diagnosis of parkinsonian syndromes.

BACKGROUND: Neurological findings are important for the differential diagnosis of Parkinson's disease (PD), multiple system atrophy with predominant parkinsonian features (MSA-P), and progressive supranuclear palsy (PSP). There is currently no fast and reliable method to distinguish these patients. OBJECTIVES: To address this, we propose a novel approach to measure midbrain and pons size using a longitudinal "one line" method from the mid-sagittal view. METHODS: Structural images were acquired from 101 subjects who underwent 3.0 T MRI (20 controls, 44 PD, 20 MSA, 12 PSP, and 5 corticobasal syndrome). We measured the middle cerebellar peduncle (MCP), superior cerebellar peduncle (SCP), midbrain, and pons. Brainstem size was measured by area or length of the longitudinal axis, which we named the "one line" method. We conducted intraclass correlation coefficients to assess the extent of agreement and consistency among raters, and receiver operating characteristic curves were used to determine diagnostic accuracy. RESULTS: Intraclass correlation coefficients (ICC) of MCP width were excellent in sagittal and axial sections while those of SCP width were moderate. There were also excellent ICCs between raters for "one line" method of the midbrain and pons, while areas showed good ICCs. "One line" method and area of the midbrain were better than SCP width for the differential diagnosis of PSP from MSA-P and PD. In contrast, there was no clearly superior measurement for differentially diagnosing MSA-P. CONCLUSIONS: The "one line" method was comparable with area for inter-rater agreement and diagnostic accuracy even though this was a simple and fast way.

The diagnostic ability of SPECT/CT fusion imaging for gastrointestinal bleeding: a retrospective study.

BACKGROUND: Blood loss from the gastrointestinal tract can be an acute and life-threatening event. For the treatment of gastrointestinal bleeding, it is important to accurately detect gastrointestinal bleeding and to localize the sites of bleeding. The purpose of this study was to retrospectively assess the capabilities of SPECT/CT in the diagnosis of gastrointestinal bleeding by a comparison with planar imaging alone as well as planar and SPECT. METHODS: We conducted a retrospective analysis of 20 patients (21 examinations) who underwent gastrointestinal bleeding scintigraphy in the past 7 years and in whom the bleeding site was identified by endoscopy or capsule endoscopy, or in whom no evidence of gastrointestinal bleeding was identified during the clinical course. Five patients (5 examinations) were diagnosed by planar imaging (planar group). Eight patients (9 examinations) were diagnosed by planar imaging and SPECT (planar + SPECT group). Seven patients (7 examinations) were diagnosed by planar imaging and SPECT/CT (planar + SPECT/CT group). We calculated the diagnostic ability of each method in detecting the presence of bleeding, as well as the ability of each method to identify the sites of bleeding. The sensitivity, specificity, and accuracy of the methods were compared. RESULTS: The diagnostic ability of the three imaging methods in detecting the presence of gastrointestinal bleeding was as follows. Planar imaging showed 100% sensitivity (3/3), 100% specificity (2/2), and 100% accuracy (5/5). Planar + SPECT imaging showed 85.7% sensitivity (6/7), 100% specificity (2/2), and 88.9% accuracy (8/9). Planar + SPECT/CT imaging showed 100% sensitivity (6/6), 100% specificity (1/1), and 100% accuracy (7/7). The diagnostic ability of the three modalities in detecting the site of bleeding was as follows: planar, 33.3% (1/3); planar + SPECT, 71.4% (5/7); and planar + SPECT/CT, 100% (6/6). CONCLUSIONS: All 3 imaging methods showed good accuracy in detecting the presence of gastrointestinal bleeding. The addition of SPECT or SPECT/CT made the anatomical position of the uptake clear and contributed to the localization of the site of gastrointestinal bleeding. Planar + SPECT/CT imaging therefore showed the highest diagnostic ability for detecting the site of gastrointestinal bleeding.

Local Thickness of Epicardial Adipose Tissue Surrounding the Left Anterior Descending Artery Is a Simple Predictor of Coronary Artery Disease　- New Prediction Model in Combination With Framingham Risk Score.

BACKGROUND: Compared with global cardiac adiposity, the local accumulation of fat surrounding coronary arteries might have a more direct impact on coronary artery disease (CAD). Here, we compared the local epicardial adipose tissue (EAT) thickness and global cardiac adiposity volumes for predicting CAD.Methods and Results:A total of 197 consecutive subjects underwent 320-slice multi-detector computed tomography coronary angiography and were segregated into CAD (≥1 coronary artery branch stenosis ≥50%) and non-CAD groups. EAT thickness was measured at the right coronary artery (EATRCA), the left anterior descending artery (EATLAD), and the left circumflex artery (EATLCX). Although EATRCAand EATLCXwere similar between the 2 groups, EATLADwas larger in the CAD group than in the non-CAD group (5.45±2.16 mm vs. 6.86±2.19 mm, P<0.001). EATLAD, after correcting for confounding factors, was strongly associated with CAD (r=0.276, P<0.001) and Gensini score (r=0.239, P<0.001). On multiple regression analysis, Framingham risk score combined with EATLADwas a strong predictor of CAD (adjusted R2=0.121; P<0.001). CONCLUSIONS: The local fat thickness surrounding the LAD is a simple and useful surrogate marker for estimating the presence, severity, and extent of CAD, independent of classical cardiovascular risk factors.

Effect of the Epicardial Adipose Tissue Volume on the Prevalence of Paroxysmal and Persistent Atrial Fibrillation.

BACKGROUND: Although increasing evidence suggests that epicardial adipose tissue volume (EATV) is associated with atrial fibrillation (AF), it is controversial whether there is a dose-response relationship of increasing EATV along the continuum of AF. We evaluated the effect of the EATV on the prevalence of paroxysmal AF (PAF) and persistent AF (PeAF) and the relationships with cardiac structure and functional remodeling.Methods and Results:Subjects who underwent multidetector computed tomography (MDCT) coronary angiography because of symptoms suggestive of coronary artery disease were divided into sinus rhythm (SR) (n=112), PAF (n=133), and PeAF (n=71) groups. The EATV index (EATV/body surface area, mL/m2) was strongly associated with the prevalence of PAF and PeAF on the model adjusted for known AF risk factors. The effect of the EATV index on the prevalence of PeAF, but not on that of PAF, was modified by the left atrial (LA) dimension, suggesting that extension of the LA dimension is related to EATV expansion in PeAF. The cutoff value of the EATV index for the prevalence was higher in PeAF than in PAF (64 vs. 55 mL/m2, P<0.01). CONCLUSIONS: The EATV index is associated with the prevalence of PAF and PeAF, and its cutoff values are predictive for PAF and PeAF development independently of other AF risk factors.

Usefulness of perfusion- and diffusion-weighted imaging to differentiate between pilocytic astrocytomas and high-grade gliomas: a multicenter study in Japan.

PURPOSE: Imaging findings of pilocytic astrocytoma (PA) vary widely, sometimes resembling those of high-grade glioma (HGG). This study aimed to identify the imaging parameters that can be used to differentiate PA from HGG. METHODS: Altogether, 60 patients with PAs and 138 patients with HGGs were included in the study. Tumor properties and the presence of hydrocephalus, peritumoral edema, and dissemination were evaluated. We also measured the maximum relative cerebral blood flow (rCBFmax) and volume (rCBVmax) and determined the minimum apparent diffusion coefficient (ADCmin) in the tumor's solid components. The relative T1 (rT1), T2 (rT2), and contrast-enhanced T1 (rCE-T1) intensity values were evaluated. Parameters were compared between PAs and HGGs using the Mann-Whitney U test. Receiver operating characteristic (ROC) curve analysis was also used to evaluate these imaging parameters. A value of P < .05 was considered to indicate significance. RESULTS: Intratumoral hemorrhage and calcification were observed in 10.0% and 21.7% of PAs, respectively. The rCBFmax and rCBVmax values were significantly lower in PAs (0.50 ± 0.35, 1.82 ± 1.21) than those in HGGs (2.98 ± 1.80, 9.54 ± 6.88) (P < .0001, P = .0002, respectively). The ADCmin values were significantly higher in PAs (1.36 ± 0.56 × 10-3 mm2/s) than those in HGGs (0.86 ± 0.37 × 10-3 mm2/s) (P < .0001). ROC analysis showed that the best diagnostic performance was achieved with rCBFmax. CONCLUSION: The rCBFmax, rCBVmax, and ADCmin can differentiate PAs from HGGs.

Development of Correction for Signal-to-Noise Ratio Using a T2* With Improved Phase Method.

OBJECTIVE: This study aims to improve the signal-to-noise ratio (SNR) of the phase image focusing T2 and to develop an improved phase (iPhase) image acquired high SNR. METHODS: The iPhase images of phantom and brain were acquired with multi-echo spoiled gradient-echo. The phantom component was a gadopentetate dimeglumine (Gd-DTPA) solution made of different concentrations (0.1, 0.5, and 1 wt%) and Gd-DTPA (0.1, 0.5, and 1 wt%) with agar (1.0 wt%). We applied the iPhase image to susceptibility weighed image (SWI) and evaluated SNR of SWI. RESULTS: In phantom study, SNRs of conventional SWI at each sample were 19.8, 15.7, 7.4, 20.0, 17.4, and 27.3, respectively. Signal-to-noise ratios of SWI derived from iPhase method were 29.5, 33.7, 21.7, 28.5, 24.3, and 14.7, respectively. Then, the SNR showed an improvement of 196% at maximum (for the Gd-DTPA 1 wt% sample). In healthy volunteer study, SWI derived from iPhase method had the good contrast between white matter and gray matter. CONCLUSIONS: The iPhase image was able to improve the phase SNR. Moreover, iPhase method makes it possible to obtain a high SNR image when applying to SWI.