Curie-Weiss behavior of liquid structure and ideal glass state.

We present the results of a structural study of metallic alloy liquids from high temperature through the glass transition. We use high energy X-ray scattering and electro-static levitation in combination with molecular dynamics simulation and show that the height of the first peak of the structure function, S(Q) - 1, follows the Curie-Weiss law. The structural coherence length is proportional to the height of the first peak, and we suggest that its increase with cooling may be related to the rapid increase in viscosity. The Curie temperature is negative, implying an analogy with spin-glass. The Curie-Weiss behavior provides a pathway to an ideal glass state, a state with long-range correlation without lattice periodicity, which is characterized by highly diverse local structures, reminiscent of spin-glass.

Complications in Stent-Assisted Endovascular Therapy of Ruptured Intracranial Aneurysms and Relevance to Antiplatelet Administration: A Systematic Review.

BACKGROUND AND PURPOSE: Despite the increasing use of stent-assisted coiling for ruptured intracranial aneurysms, there is little consensus regarding the appropriate antiplatelet administration for this. The objectives of this systematic review were to provide an overview of complications and their association with the method of antiplatelet administration in stent-assisted coiling for ruptured intracranial aneurysms. MATERIALS AND METHODS: A comprehensive search of the literature in the data bases was conducted to identify studies reporting complications of stent-assisted coiling for ruptured intracranial aneurysms. The pooled event rate of preprocedural thromboembolisms, hemorrhages, and mortality was estimated from the selected studies. Subgroup analyses were performed by the method of antiplatelet administration (pre-, postprocedural, and modified). Meta-analysis was conducted to compare periprocedural complications and mortality between ruptured intracranial aneurysms and unruptured intracranial aneurysms. RESULTS: Of the 8476 studies identified, 33 with 1090 patients were included. The event rates of thromboembolism and intra- and postprocedural hemorrhage were 11.2% (95% CI, 9.2%-13.6%), 5.4% (95% CI, 4.1%-7.2%), and 3.6% (95% CI, 2.6%-5.1%), respectively. Subgroup analyses of thromboembolism showed a statistically significant difference between groups (P < .05). In the preprocedural and modified antiplatelet groups, the risk for thromboembolism in stent-assisted coiling for ruptured intracranial aneurysm was not significantly different from that for unruptured intracranial aneurysm, though this risk of the postprocedural antiplatelet group was significantly higher in ruptured intracranial aneurysms than in unruptured intracranial aneurysms. CONCLUSIONS: On the basis of current evidence, complications of stent-assisted coiling for ruptured intracranial aneurysm may be affected by the method of antiplatelet administration.

Gadolinium enhancement of atherosclerotic plaque in the middle cerebral artery: relation to symptoms and degree of stenosis.

BACKGROUND AND PURPOSE: High-resolution MR imaging can depict intracranial arterial atherosclerotic plaques. Our aim was to evaluate the relationship between the degree of enhancement of MCA plaques on contrast-enhanced high-resolution MR imaging and ischemic stroke and stenosis severity. MATERIALS AND METHODS: This study enrolled 36 patients diagnosed with moderate-to-severe atherosclerotic MCA stenosis. A contrast-enhanced T1-weighted volume isotropic turbo spin-echo acquisition sequence was acquired for assessing plaque enhancement. Plaque-to-CSF contrast ratio was calculated after the signal intensity of plaques at the stenotic segment was measured. Univariate comparison and multivariate logistic regression analyses were performed for symptomatic and asymptomatic groups to assess the relationship between symptomatic stenosis and independent variables, including plaque-to-CSF contrast ratio, degree of stenosis, and clinical risk factors. Plaque-to-CSF contrast ratio was compared between the moderate and severe stenosis groups. RESULTS: Twenty-one patients had symptomatic MCA stenosis, and 15 had asymptomatic stenosis. The plaque-to-CSF contrast ratio was significantly higher in the symptomatic group than in the asymptomatic group (63.6 ± 10.6% versus 54.1 ± 13.5%, respectively; P < .05). The degree of stenosis also differed significantly between the 2 groups (P < .05). Multivariate analysis revealed that the degree of stenosis was the only independent predictor of ischemic stroke symptoms. The plaque-to-CSF contrast ratio of severe stenosis was significantly higher than that of moderate stenosis (66.8 ± 8.7% versus 55.9 ± 12.8%, respectively; P < .05). CONCLUSIONS: Plaque enhancement was significantly higher in patients with symptomatic plaques and may have been affected by the degree of stenosis. A difference in plaque enhancement according to the degree of stenosis has implications for understanding the development of intracranial atherosclerotic plaques.

Successful endosaccular coiling after a balloon occlusion test of the caudal channel of a double origin of the posterior inferior cerebellar artery originating from the aneurysm neck.

Therapeutic strategies for unruptured aneurysms in elective procedures must be carefully planned with respect to safety. We describe the case of a patient who presented with an unruptured aneurysm associated with a double origin of the posterior inferior cerebellar artery (DOPICA), a rare variant of aberrant origin. A three-dimensional rotational angiogram clearly showed that the aneurysm incorporated the origin of the DOPICA caudal channel, which was more dominant than the cranial one. The aneurysm was completely obliterated using detachable coils after a balloon occlusion test (BOT) of the caudal channel was conducted to confirm the tolerance of the patient following sudden interruption of the more prominent flow coming from the caudal channel of the DOPICA. This report affirms the need to suspect anomalies associated with a DOPICA that predispose to intracranial aneurysms and highlights the potential role of a BOT in pretreatment hemodynamic evaluations of unusual aneurysms accompanying a particular developmental anomaly.

The detection and discrimination of malignant and benign focal hepatic lesions: T2 weighted vs diffusion-weighted MRI.

OBJECTIVE: The purpose of this study was to evaluate the use of diffusion-weighted imaging (DWI) for the detection and characterisation of focal hepatic lesions compared with the use of T(2) weighted imaging. METHOD: 45 patients with 97 hepatic lesions (51 malignant lesions and 46 benign lesions) were included in this retrospective study. Malignant hepatic lesions included 12 hepatocellular carcinomas, 26 metastases and 13 intrahepatic cholangiocarcinomas. Benign hepatic lesions included 19 haemangiomas and 27 cysts. The MRI protocol for the upper abdomen included T(2) weighted images, in- and opposed-phase T(1) weighted images and dynamic T(1) weighted images. Breath-hold fat-suppressed single-shot echo planar DWI was performed with the following parameters: 1338/66; b factors, 0, 50 and 800 s mm(-2). Two independent observers reviewed the T(2) weighted images and the DWI to detect and to characterise the hepatic lesions. RESULTS: For detection of malignant hepatic lesions, the use of DWI showed a significantly higher detection rate than the use of T(2) weighted images (p<0.05). However, there was no significant difference between the use of DWI and T(2) weighted images for benign hepatic lesions. For the differentiation between malignant and benign hepatic lesions, there was no significant difference in sensitivity, specificity and accuracy between the use of T(2) weighted images and the use of DWI. CONCLUSION: The use of DWI was better for the detection of malignant hepatic lesions than the use of T(2) weighted images. However, for detection of benign hepatic lesions and characterisation of hepatic lesions, the use of DWI was equivalent to the use of T(2) weighted images.

Dissection of the distal vertebral artery treated by modified parent artery trapping and a contralateral stent barricade. A case report.

Endovascular trapping is the preferred treatment method for a vertebral dissecting aneurysm. We describe a case of ruptured dissecting aneurysms located just proximal to the vertebrobasilar junction treated by trapping the dissecting segment and barricading the basilar artery with a stent to protect against coil protrusion. Modified parent artery trapping with a stent barricade allows preservation of the adjoining confluent zone or side branch during endovascular trapping of the vertebral dissection.

Combination of high-resolution susceptibility-weighted imaging and the apparent diffusion coefficient: added value to brain tumour imaging and clinical feasibility of non-contrast MRI at 3 T.

The purpose of this study was to determine the benefit of high-resolution susceptibility-weighted imaging and the apparent diffusion coefficient for brain tumour imaging, and to assess the clinical feasibility of using a non-contrast MR protocol at 3 T. 73 patients with intra-axial tumours were enrolled into the study. Two experienced neuroradiologists reviewed three MRI sessions: (i) a non-contrast protocol including high-resolution susceptibility-weighted images and apparent diffusion coefficient; (ii) a contrast protocol including MR perfusion images; and (iii) combined contrast and non-contrast protocols. The two observers categorised tumours as glial or non-glial tumours, and then subcategorised the gliomas into low-grade or high-grade tumours. For semi-quantitative analysis, a scoring system based on the degree of intra-tumoral susceptibility signals and the visual apparent diffusion coefficient was used. The two observers diagnosed accurate tumour pathology in 52 (71%) of 73 tumours in the first review, 55 (75%) of 73 tumours in the second review and 61 (84%) of 73 tumours in the third review. The addition of the non-contrast protocol to the contrast protocol significantly differentiated glioblastoma multiforme and metastatic tumours, which was not possible with the contrast protocol alone. The sensitivity, specificity, positive predictive value and negative predictive value for glioma grading with the non-contrast protocol were 83.2%, 100%, 100% and 79.3%, respectively. The addition of both high-resolution susceptibility-weighted imaging and the apparent diffusion coefficient improved the diagnostic performance of the contrast MR protocol for brain tumour imaging and could be feasible in selected patients who cannot tolerate a contrast agent.

Persistent falcine sinus: is it really rare?

BACKGROUND AND PURPOSE: The falcine sinus has been considered as a rare variation of the venous pathway between the dural layers of the falx cerebri. The purpose of this study was to evaluate the incidence of falcine sinus and its anatomic characteristics by using CTA. MATERIALS AND METHODS: A total of 586 consecutive patients were enrolled in this study. A falcine sinus on CTA was defined as a midline venous structure connecting the vein of Galen or the internal sagittal sinus with the superior sagittal sinus. When present, anatomic features of the falcine sinus were evaluated. RESULTS: Falcine sinuses were present in 12 patients (2.1%). Only 1 case was associated with a congenital anomaly, a dysplastic tentorium. Eight patients had absent or rudimentary straight sinuses, and 4 patients had normal straight sinuses. CONCLUSIONS: In contrast to previous reports, falcine sinuses were not rare in the adult population, and most falcine sinuses were not associated with a congenital anomaly or sinus occlusion. Knowledge and recognition of these falcine sinuses are useful and important during the interpretation of brain CTA.

The intravertebral cleft in benign vertebral compression fracture: the diagnostic performance of non-enhanced MRI and fat-suppressed contrast-enhanced MRI.

We compared the diagnostic performance of non-enhanced MRI and fat-suppressed contrast-enhanced MRI (CEMRI) in diagnosing intravertebral clefts in benign vertebral compression fractures (VCFs). We retrospectively reviewed 99 consecutive patients who had undergone percutaneous vertebroplasty for VCFs. A cleft was defined as a signal void or hyperintense area on non-enhanced MRI (T(1) and T(2) weighted imaging) or as a hypointense area within a diffusely enhanced vertebra on CEMRI. A cleft was confirmed as a solid opacification on post-procedural radiographs. The interobserver reliability and MRI diagnostic performance were evaluated. The interobserver reliability of non-enhanced MRI was substantial (k _ 0.698) and the interobserver reliability of CEMRI was almost perfect (k _ 0.836). Post-procedural radiographs showed solid cleft opacification in 32 out of the 99 cases. The sensitivity and specificity of non-enhanced MRI were 0.72 and 0.82 (observer 1) and 0.63 and 0.87 (observer 2), respectively. The sensitivity and specificity of CEMRI were 0.94 and 0.63 (observer 1) and 0.85 and 0.60 (observer 2), respectively. The sensitivity of CEMRI was significantly higher than that of non-enhanced MRI, and the specificity of non-enhanced MRI was higher than that of CEMRI. CEMRI was highly reliable and sensitive, and non-enhanced MRI was specific for intravertebral clefts. Therefore, spine MRIs, including CEMRI, could provide useful information about intravertebral clefts before percutaneous vertebroplasty.

Added value and diagnostic performance of intratumoral susceptibility signals in the differential diagnosis of solitary enhancing brain lesions: preliminary study.

BACKGROUND AND PURPOSE: It has been reported that high-resolution susceptibility-weighted imaging (HR-SWI) is a promising tool for assessing brain tumor characterization noninvasively. The purpose of this study was to determine the added value and diagnostic performance of HR-SWI for differentiating solitary enhancing brain lesions (SELs) by assessing intratumoral susceptibility signals (ITSSs). MATERIALS AND METHODS: Sixty-four consecutive patients with SELs, without previous surgery, were retrospectively reviewed. We performed 2 consensus reviews, by using conventional MR images alone and with adjunctive HR-SWI. We applied an ITSS grading system based on the degree of the ITSS. Then, we compared the presence and grade of the ITSSs among specific pathologic types of SELs. RESULTS: Two observers diagnosed tumor pathology accurately in 43 (67%) of 64 SELs after reviewing the conventional images alone and 50 (78%) of 64 SELs after reviewing the adjunctive HR-SWI (P = .016, McNemar test). ITSSs were seen in 25 (100%) of 25 glioblastoma multiformes (GBMs), in 2 (40%) of 5 anaplastic astrocytomas, and in 11 (73%) of 15 metastatic tumors. Although the ITSSs were unable to distinguish between GBMs and solitary metastatic tumors, differentiation between GBMs and solitary metastatic tumors was achieved (P = .01) by using a high ITSS degree (grade 3). Moreover, the ITSSs could discriminate high-grade gliomas from lymphomas and nontumorous lesions with a specificity of 100% (P < .0001). CONCLUSIONS: The use of ITSSs on HR-SWIs significantly improves the accuracy for the differential diagnosis of SELs compared with the use of conventional MR imaging alone.

Semiquantitative assessment of intratumoral susceptibility signals using non-contrast-enhanced high-field high-resolution susceptibility-weighted imaging in patients with gliomas: comparison with MR perfusion imaging.

BACKGROUND AND PURPOSE: It has been reported that high-resolution susceptibility-weighted imaging (HR-SWI) may demonstrate brain tumor vascularity. We determined whether the degree of intratumoral susceptibility signal intensity (ITSS) on HR-SWI correlates with maximum relative cerebral blood volume (rCBVmax) and to compare its diagnostic accuracy for glioma grading with that of dynamic susceptibility contrast (DSC) perfusion MR imaging. MATERIALS AND METHODS: Forty-one patients with diffuse astrocytomas underwent both non-contrast-enhanced HR-SWI and DSC at 3T. We correlated the degree and morphology of ITSS with rCBVmax within the same tumor segment. The degree of ITSS and rCBVmax were compared among 3 groups with different histopathologic grades. Spearman correlation coefficients were determined between the degree of ITSS, rCBVmax, and glioma grade. Receiver operating characteristic (ROC) curve analyses were performed to determine the diagnostic accuracy for glioma grading. RESULTS: The degree of ITSS showed a significant correlation with the value of rCBVmax in the same tumor segments (r = 0.72, P < .0001). However, the areas of densely prominent ITSSs did not accurately correspond with those of rCBVmax. Spearman correlation coefficients between ITSS degree and glioma grade were 0.88 (95% confidence interval, 0.79-0.94). In the ROC curve analysis of histopathologic correlation by using the degree of ITSS, the optimal sensitivity, specificity, positive predictive value, and negative predictive value for determining a high-grade tumor were 85.2%, 92.9%, 95.8%, and 76.5%, respectively. CONCLUSIONS: The degree of ITSS shows a significant correlation with the value of rCBVmax in the same tumor segments, and its diagnostic performance for glioma grading is comparable with that of DSC.

Imaging findings of idiopathic localized dilatation of the ileum.

We report imaging findings in a case of idiopathic localized dilatation of the ileum (ILDI). CT revealed a large cystic mass containing air in the pelvic cavity. Sonography showed a cystic lesion with internal echo in the pelvic cavity. In addition, slow peristaltic movement was seen in the lesion. Small bowel series showed a bilobular dilatation of the ileum with two narrow transitions connecting the proximal and distal bowel loops.

Percutaneous direct puncture glue embolization of high-flow craniofacial arteriovenous lesions: a new circular ring compression device with a beveled edge.

SUMMARY: The purpose of this study was to evaluate the efficacy of a newly designed circular ring compression device that allows safe and effective glue injection during preoperative embolization of high-flow superficial craniofacial arteriovenous malformations (AVMs). The device was used in 4 cases of craniofacial AVM with multiple feeding arteries and draining veins. It provided a safe glue injection route as well as effective compression of radiating multiple venous drainage routes.

Dissecting aneurysm of the basilar arterial trunk presenting with pontine infarction. Coil obliteration of the dissecting aneurysm including the diseased basilar arterial segment.

SUMMARY: Dissecting basilar aneurysms have rarely been reported but are associated with high morbidity and mortality. Therefore, controversy exists as to the proper management of such lesions because their natural course is not well understood. We describe a 50-year-old man with a dissecting aneurysm involving the lower basilar trunk who presented with pontine infarction corresponding to the aneurysmal sac location. We obliterated the dissecting basilar aneurysm by coil embolization of the aneurysmal sac as well as the diseased segment of the basilar trunk after confirmation of collateral filling of the basilar artery through the posterior communicating artery. The patient recovered without any procedural complication. Eight month follow-up revealed complete disappearance of the aneurysm without symptom recurrence together with preservation of collateral flow in the distal basilar artery. Obliteration of the parent artery as well as the aneurysmal sac with coils could be considered in a lower basilar aneurysm of a dissecting nature.

Acquisition of MR perfusion images and contrast-enhanced MR angiography in acute ischaemic stroke patients: which procedure should be done first?

Multimodal MRI for acute ischaemic stroke usually includes perfusion imaging (PI) and contrast-enhanced neck MR angiography (CE-MRA), as well as diffusion-weighted imaging and T2* weighted imaging. Because both PI and CE-MRA require the infusion of contrast medium, the likelihood exists that one study may conflict with the other due to the accumulation of previously injected contrast medium. The purpose of this study is to determine the appropriate order of PI and CE-MRA in this multimodal MRI protocol for evaluation of acute ischaemic stroke. We studied 35 patients with acute ischaemic stroke in the unilateral middle cerebral artery territory. 17 patients underwent CE-MRA following PI (group A) and 18 patients underwent PI following CE-MRA (group B). For qualitative analysis of the CE-MRA and colour-coded maps of the PI, two independent observers graded the image quality. Interobserver agreement was assessed using kappa statistics, and we assessed the statistical differences of imaging quality between groups A and B using the Mann-Whitney U-test). For the quantitative analysis of PI, two parameters--the maximum change in the transverse relaxation rate (DeltaR2(max)) and the relative signal drop (DeltaS/S(0))--were calculated from the time-signal intensity curve of an unaffected middle cerebral artery territory, and we compared the differences in the parameters of group A and B (t-test). Interobserver agreements for CE-MRA and PI were good. In the qualitative analysis of CE-MRA and PI, no significant difference was observed between groups A and B. In the quantitative analysis of PI, there were no relevant differences in DeltaR2(max) and DeltaS/S(0) between the two groups. In simultaneous CE-MRA and PI, there was no deterioration of diagnostic imaging quality with regard to the order of the two post-contrast sequences. They can be performed according to the preference of each institution.

Cerebral fat embolism: diffusion-weighted magnetic resonance imaging findings.

PURPOSE: To demonstrate the diffusion-weighted (DWI) magnetic resonance imaging (MRI) findings, and the follow-up MRI findings, of cerebral fat embolism in the acute stage. MATERIAL AND METHODS: The initial DWI and clinical findings of six patients with cerebral fat embolism were retrospectively evaluated. The finding of DWI with a b-value of 1000 s/mm2 (b=1000) was compared with that of DWI with a b-value of 0 s/mm2 (b=0). In three patients who underwent follow-up MRI, the interval change of the lesion on T2-weighted images was investigated. RESULTS: The characteristic DWI finding of cerebral fat embolism in the acute stage was multiple, hyperintense, dot-like lesions disseminated in the brain. These lesions were distributed dominantly in the bilateral border-zone areas. Some lesions had an ancillary location including the cortex, deep white matter, basal ganglia, and cerebellum. The lesions were more intense and numerous in DWI (b=1000) than in DWI (b=0). The findings on the follow-up T2-weighted images were multiple confluent hyperintense lesions in the white matter with progression since the initial MRI. CONCLUSION: DWI could be a sensitive tool for detecting cerebral fat embolism in the acute phase. It is recommended that DWI be included in the initial evaluation of cerebral fat embolism with MRI.

High-resolution CT findings of varicella-zoster pneumonia.

OBJECTIVE: The purpose of this study is to describe the high-resolution CT findings of varicella-zoster pneumonia in three immunocompetent patients. CONCLUSION: High-resolution CT findings of varicella-zoster pneumonia include nodules, nodules with surrounding ground-glass attenuation, patchy ground-glass attenuation, and coalescence of nodules; the disappearance of these features on imaging studies corresponded to healing of skin lesions in patients after antiviral chemotherapy.