Heterologous vaccination utilizing viral vector and protein platforms confers complete protection against SFTSV

Severe fever with thrombocytopenia syndrome virus was first discovered in 2009 as the causative agent of severe fever with thrombocytopenia syndrome. Despite its potential threat to public health, no prophylactic vaccine is yet available. This study developed a heterologous prime-boost strategy comprising priming with recombinant replication-deficient human adenovirus type 5 (rAd5) expressing the surface glycoprotein, Gn, and boosting with Gn protein. This vaccination regimen induced balanced Th1/Th2 immune responses and resulted in potent humoral and T cell-mediated responses in mice. It elicited high neutralizing antibody titers in both mice and non-human primates. Transcriptome analysis revealed that rAd5 and Gn proteins induced adaptive and innate immune pathways, respectively. This study provides immunological and mechanistic insight into this heterologous regimen and paves the way for future strategies against emerging infectious diseases.

J2N-k hamster model simulates severe infection caused by severe acute respiratory syndrome coronavirus 2 in patients with cardiovascular diseases

Considering the global impact of the coronavirus disease 2019 (COVID-19) pandemic, generating suitable experimental models is imperative. For pre-clinical studies, researchers require animal models displaying pathological features similar to those observed in patients; therefore, establishing animal models for COVID-19 is crucial. The golden Syrian hamster model mimics conditions observed in humans with mild severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. However, a golden Syrian hamster model of severe infection has not been reported. J2N-k hamsters are utilized as a cardiomyopathy model; therefore, we used cardiomyopathic J2N-k hamsters showing conditions similar to those of severe COVID-19 complicated with cardiovascular diseases, as patients with cardiovascular diseases exhibit a higher risk of morbidity and mortality due to COVID-19 than patients without cardiovascular diseases. Unlike that in golden Syrian hamsters, SARS-CoV-2 infection was lethal in J2N-k hamsters, with a median lethal dose of 10^4.75 plaque-forming units for the S clade of SARS-CoV-2 (A, GenBank: MW466791.1). High viral titers and viral genomes were detected in the lungs of J2N-k and golden Syrian hamster models harvested 3 days after infection. Pathological features of SARS-CoV-2-associated lung injury were observed in both models. The J2N-k hamster model can aid in developing vaccines or therapeutics against COVID-19.

Comparison of SARS-CoV-2 variant lethality in human angiotensin-converting enzyme 2 transgenic mice

This study compared the lethality of severe acute respiratory syndrome coronavirus 2 variants belonging to the S, V, L, G, GH, and GR clades using K18-human angiotensin-converting enzyme 2 heterozygous mice. To estimate the 50% lethal dose (LD₅₀) of each variant, increasing viral loads (10⁰–10⁴ plaque-forming units [PFU]) were administered intranasally. Mouse weight and survival were monitored for 14 days. The LD₅₀ of the GH and GR clades was significantly lower than that of other clades at 50 PFU. These findings suggest that the GH and GR clades, which are prevalent worldwide, are more virulent than the other clades.

WasC, a WASP family protein, is involved in cell adhesion and migration through regulation of F-actin polymerization in Dictyostelium

The actin cytoskeleton is involved in the regulation of cell morphology and migration. Wiskott-Aldrich Syndrome proteins (WASPs) play an important role in controlling actin polymerization by activating the Arp2/3 complex. The present study investigated the roles of WasC, one of the 3 WASPs in Dictyostelium, in cellular processes. Cells lacking WasC displayed strong cell adhesion and approximately 1.5-fold increase in F-actin levels as compared to the wild-type cells. Loss of wasC caused defects in phagocytosis and decreased the migration speed in chemoattractant-mediated cell migration but did not affect directionality. WasC was localized to the protruding region in migrating cells and, transiently and rapidly translocated to the cell cortex in response to chemoattractant stimulation, in an F-actin dependent manner. Our results suggest that WasC is involved in cell adhesion and migration by regulating F-actin polymerization at the leading edge of migrating cells, probably as a negative regulator. The increased strength of adhesion in wasC null cells is likely to decrease the migration speed but not the directionality.

Efficacy and Safety of Flow-Diverter Therapy for Recurrent Aneurysms after Stent-Assisted Coiling

BACKGROUND AND PURPOSE

Flow-diverter treatment for previously stented aneurysms has been reported to be less effective and prone to complications. In this study, we evaluated the effectiveness and safety of flow diverters for recurrent aneurysms after stent-assisted coiling.

MATERIALS AND METHODS

Patients who underwent flow-diverter placement for recurrent aneurysms after stent-assisted coiling between March 2015 and March 2019 were recruited. Clinical and radiographic characteristics and clinical and angiographic outcomes were retrospectively evaluated.

RESULTS

Among 133 patients who underwent flow-diverter insertion, 17 (male/female ratio = 5:12; mean age, 53.8 years) were treated for recurrent aneurysms after stent placement with (n = 16) or without (n = 1) coiling. Eight patients initially presented with subarachnoid hemorrhage; 7, with headache; and 2, with visual field defects. Angiographic morphology included large/giant saccular in 12 patients, dissecting in 2, fusiform in 1, traumatic pseudoaneurysm in 1, and ruptured blood blister-like aneurysm in 1. The duration between the first treatment and flow-diverter placement ranged from 2 weeks to 15 months (median, 6 months). Flow-diverter placement was successful in all cases without any complications. All patients had favorable outcomes (mRS, 0-2), without any newly appearing symptoms. Aneurysms were followed up with conventional angiography at least once in 6-18 months. Sixteen aneurysms showed complete occlusion, and 1 aneurysm was enlarged.

CONCLUSIONS

Results from this case series investigating flow-diverter placement for recurrent aneurysms after stent-assisted coiling suggested that the procedure is safe and effective. Further study in a larger population may be warranted.

Cell migration directionality and speed are independently regulated by RasG and Gβ in Dictyostelium cells in electrotaxis

Motile cells manifest increased migration speed and directionality in gradients of stimuli, including chemoattractants, electrical potential and substratum stiffness. Here, we demonstrate that Dictyostelium cells move directionally in response to an electric field (EF) with specific acceleration/deceleration kinetics of directionality and migration speed. Detailed analyses of the migration kinetics suggest that migration speed and directionality are separately regulated by Gβ and RasG, respectively, in EF-directed cell migration. Cells lacking Gβ, which is essential for all chemotactic responses in Dictyostelium, showed EF-directed cell migration with the same increase in directionality in an EF as wild-type cells. However, these cells failed to show induction of the migration speed upon EF stimulation as much as wild-type cells. Loss of RasG, a key regulator of chemoattractant-directed cell migration, resulted in almost complete loss of directionality, but similar acceleration/deceleration kinetics of migration speed as wild-type cells. These results indicate that Gβ and RasG are required for the induction of migration speed and directionality, respectively, in response to an EF, suggesting separation of migration speed and directionality even with intact feedback loops between mechanical and signaling networks.

Summary: Cell migration directionality and speed are independently regulated by RasG and Gβ, respectively, in electric field-directed cell migration in Dictyostelium, suggesting the points of molecular divergence of the two characteristics.

Association between Postprocedural Infarction and Antiplatelet Drug Resistance after Coiling for Unruptured Intracranial Aneurysms

BACKGROUND AND PURPOSE

Procedure-related thromboembolism is a major limitation of coil embolization, but the relationship between thromboembolic infarction and antiplatelet resistance is poorly understood. The purpose of this study was to verify the association between immediate postprocedural thromboembolic infarction and antiplatelet drug resistance after endovascular coil embolization for unruptured intracranial aneurysm.

MATERIALS AND METHODS

This study included 338 aneurysms between October 2012 and March 2015. All patients underwent postprocedural MR imaging within 48 hours after endovascular coil embolization. Antiplatelet drug resistance was checked a day before the procedure by using the VerifyNow system. Abnormal antiplatelet response was defined as >550 aspirin response units and >240 P2Y12 receptor reaction units. In addition, we explored the optimal cutoff values of aspirin response units and P2Y12 receptor reaction units. The primary outcome was radiologic infarction based on postprocedural MR imaging.

RESULTS

Among 338 unruptured intracranial aneurysms, 134 (39.6%) showed diffusion-positive lesions on postprocedural MR imaging, and 32 (9.5%) and 105 (31.1%) had abnormal aspirin response unit and P2Y12 receptor reaction unit values, respectively. Radiologic infarction was associated with advanced age (65 years and older, P = .024) only with defined abnormal antiplatelet response (aspirin response units ≥ 550, P2Y12 receptor reaction units ≥ 240). P2Y12 receptor reaction unit values in the top 10th percentile (>294) were associated with radiologic infarction (P = .003). With this cutoff value, age (adjusted odds ratio, 2.29; 95% confidence interval, 1.28-4.08), P2Y12 receptor reaction units (>294; OR, 3.43; 95% CI, 1.53-7.71), and hyperlipidemia (OR, 2.05; 95% CI, 1.04-4.02) were associated with radiologic infarction in multivariate analysis.

CONCLUSIONS

Radiologic infarction after coiling for unruptured aneurysm was closely associated with age. Only very high P2Y12 receptor reaction unit values (>294) predicted postprocedural infarction. Further controlled studies are needed to determine the precise cutoff values, which could provide information regarding the optimal antiplatelet regimen for aneurysm coiling.

Differentiation of Hemangioblastoma from Metastatic Brain Tumor using Dynamic Contrast-enhanced MR Imaging

PURPOSE

The aim of this study was to differentiate hemangioblastomas from metastatic brain tumors using dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) and compare the diagnostic performances with diffusion-weighted imaging (DWI) and dynamic susceptibility contrast magnetic resonance imaging (DSC-MRI).

METHODS

We retrospectively reviewed 7 patients with hemangioblastoma and 15 patients with metastatic adenocarcinoma with magnetic resonance imaging (MRI) including DWI, DSC-MRI, and DCE-MRI. Apparent diffusion coefficient (ADC), relative cerebral blood volume (rCBV), and DCE-MRI parameters (K ^trans, k _ep, v _e, and v _p) were compared between the two groups. The diagnostic performance of each parameter was evaluated with receiver operating characteristic (ROC) curve analysis.

RESULTS

v _p, k _ep, and rCBV were significantly different between patients with hemangioblastoma and those with metastatic brain tumor (p < 0.001, p = 0.005, and p = 0.017, respectively). A v _p cutoff value of 0.012 and a rCBV cutoff value of 8.0 showed the highest accuracy for differentiating hemangioblastoma from metastasis. The area under the ROC curve for v _p and rCBV was 0.99 and 0.89, respectively. A v _p > 0.012 showed 100 % sensitivity, 93.3 % specificity, and 95.5 % accuracy and a rCBV > 8.0 showed 85.7 % sensitivity, 93.3 % specificity, and 90.9 % accuracy for differentiating hemangioblastoma from metastatic brain tumor.

CONCLUSION

DCE-MRI was useful for differentiating hemangioblastoma from metastatic brain tumor.

Safety and efficacy of medium-sized particle embolisation for skull-base meningioma

AIM

To determine the effectiveness and safety of preoperative tumour embolisation for skull-base meningiomas via external carotid artery (ECA) feeders using medium-sized (150-250 μm) polyvinyl alcohol (PVA) particles.

MATERIALS AND METHODS

This study included 114 consecutive patients with skull-base meningiomas who underwent preoperative tumour embolisation using medium-sized PVA particles from January 2004 to December 2013. Tumours were categorised according to feeding artery as follows: type 1, tumour staining at ECA angiography only; type 2, tumour staining at both the ECA and internal carotid artery (ICA) angiography; or type 3, little or no tumour staining at ECA angiography. The effectiveness was based on the percent reduction in the enhanced area: >75% was considered effective, 25-75% was considered partially effective, and <25% was considered ineffective.

RESULTS

Tumour embolisation was performed in patients with dominant feeding vessels originating from the ECA. Procedural-related complications occurred in two (1.8%) patients. Post-procedural MRI images were available for 51 patients, which revealed effective embolisation in only 13 (25.5%) patients. Identification of an ICA feeding vessel was associated with ineffective embolisation (p=0.011). Effective embolisation was associated with low estimated blood loss during surgery.

CONCLUSION

ECA embolisation using medium-sized PVA is ineffective in patients in whom a definitive ICA feeding vessel was identified, even if preprocedural angiography showed that the dominant feeder originated from the ECA. When the risks of surgical morbidity and mortality are expected to be high, ICA feeder embolisation should also be considered.

Contrast-enhanced angiographic cone-beam computed tomography without pre-diluted contrast medium

INTRODUCTION

Contrast-enhanced cone-beam computed tomography (CBCT) has been introduced and accepted as a useful technique to evaluate delicate vascular anatomy and neurovascular stents. Current protocol for CBCT requires quantitative dilution of contrast medium to obtain adequate quality images. Here, we introduce simple methods to obtain contrast-enhanced CBCT without quantitative contrast dilution.

METHODS

A simple experiment was performed to estimate the change in flow rate in the internal carotid artery during the procedure. Transcranial doppler (TCD) was used to evaluate the velocity change before and after catheterization and fluid infusion. In addition, 0.3 cm(3)/s (n = 3) and 0.2 cm(3)/s (n = 7) contrast infusions were injected and followed by saline flushes using a 300 mmHg pressure bag to evaluate neurovascular stent and host arteries.

RESULTS

Flow velocities changed -15 ± 6.8 % and +17 ± 5.5 % from baseline during catheterization and guiding catheter flushing with a 300 mmHg pressure bag, respectively. Evaluation of the stents and vascular structure was feasible using this technique in all patients. Quality assessment showed that the 0.2 cm(3)/s contrast infusion protocol was better for evaluating the stent and host artery.

CONCLUSION

Contrast-enhanced CBCT can be performed without quantitative contrast dilution. Adequate contrast dilution can be achieved with a small saline flush and normal blood flow.

Thromboembolic complications in patients with clopidogrel resistance after coil embolization for unruptured intracranial aneurysms

BACKGROUND AND PURPOSE

Antiplatelet resistance is known to be associated with symptomatic ischemic complication after endovascular coil embolization. The purpose of our study was to evaluate the relationship between antiplatelet resistance and clinically silent thromboembolic complications using DWI in patients who underwent coil embolization for unruptured intracranial aneurysm.

MATERIALS AND METHODS

Between October 2011 and May 2013, 58 patients with 62 unruptured aneurysms who were measured for antiplatelet response using VerifyNow assay and underwent elective coil embolization for an unruptured aneurysm with posttreatment DWI were enrolled. Diffusion-positive lesions were classified into 3 groups according to the number of lesions (n=0 [grade 0], n<6 [grade I], and n≥6 [grade II]). The relationship between antiplatelet resistance and diffusion-positive lesions was analyzed.

RESULTS

Sixty-two endovascular coiling procedures were performed on 58 patients. Clopidogrel resistance was revealed in 23 patients (39.7%) and diffusion-positive lesions were demonstrated in 28 patients (48.3%); these consisted of 19 (32.8%) grade I and 9 (15.5%) grade II lesions. Clopidogrel resistance was not relevant to the development of any diffusion-positive lesion (grade I and II, P=.789) but was associated with the development of multiple diffusion-positive lesions (grade II, P=.002). In the logistic regression prediction model, clopidogrel resistance showed significant correlation with the development of grade II lesions (P=.001).

CONCLUSIONS

Multiple diffusion-positive lesions (≥6 in number) occurred more frequently in patients with clopidogrel resistance after endovascular coiling for unruptured aneurysms.

Treatment of multiple intracranial aneurysms with 1-stage coiling

BACKGROUND AND PURPOSE

Although multiple intracranial aneurysms are frequent, determining treatment strategy and methods for them is often complicated. The aim of this study was to evaluate the safety and effectiveness of 1-stage coiling for multiple intracranial aneurysms.

MATERIALS AND METHODS

All patients who underwent 1-stage coiling for ≥2 aneurysms were identified from a prospectively registered neurointerventional data base during 10 years. The patient characteristics and clinical and angiographic outcomes at discharge and follow-up were retrospectively evaluated.

RESULTS

One hundred sixty-seven patients (male/female ratio, 30:137; mean age, 58 years) with multiple aneurysms (418 aneurysms; mean, 2.5 aneurysms/patient) underwent attempted 1-stage coiling for ≥2 aneurysms (359 aneurysms; mean, 2.1 aneurysms/patient). In 131 patients (78.4%), all detected aneurysms were treated with coiling only. Treatment-related morbidity and mortality at discharge were 1.8% and 0.6% per patient, respectively. Of the 132 patients without subarachnoid hemorrhage, 129 (97.7%) had favorable outcomes (mRS 0-2) at discharge; of the 35 patients with SAH, 27 (77.1%) had favorable outcomes at discharge. Of the 162 patients (97%) for whom clinical follow-up was available (mean, 35.8 months), 154 patients (95.1%) had favorable outcomes. Immediate posttreatment angiography showed complete occlusion in 186 (51.8%) aneurysms, neck remnants in 134 (37.3%), sac remnants in 33 (9.2%), and failure in 6 (1.7%). Of the 262 (73.9%) aneurysms that underwent follow-up imaging (mean, 24.8 months), 244 (93.1%) showed a stable or improved state, with 12 (4.6%) minor and 6 (2.3%) major recurrences.

CONCLUSIONS

One-stage coiling of multiple aneurysms seems to be safe and effective, with low morbidity and mortality.

Differentiation of tumor progression from pseudoprogression in patients with posttreatment glioblastoma using multiparametric histogram analysis

BACKGROUND AND PURPOSE

The multiparametric imaging can show us different aspects of tumor behavior and may help differentiation of tumor recurrence from treatment related change. Our aim was to differentiate tumor progression from pseudoprogression in patients with glioblastoma by using multiparametric histogram analysis of 2 consecutive MR imaging studies with relative cerebral blood volume and ADC values.

MATERIALS AND METHODS

Thirty-five consecutive patients with glioblastoma with new or increased size of enhancing lesions after concomitant chemoradiation therapy following surgical resection were included. Combined histograms were made by using the relative cerebral blood volume and ADC values of enhancing areas for initial and follow-up MR imaging, and subtracted histograms were also prepared. The histogram parameters between groups were compared. The diagnostic accuracy of tumor progression based on the histogram parameters of initial and follow-up MR imaging and subtracted histograms was compared and correlated with overall survival.

RESULTS

Twenty-four pseudoprogressions and 11 tumor progressions were determined. Diagnosis based on the subtracted histogram mode with a multiparametric approach was more accurate than the diagnosis based on the uniparametric approach (area under the receiver operating characteristic curve of 0.877 versus 0.801), with 81.8% sensitivity and 100% specificity. A high mode of relative cerebral blood volume on the subtracted histogram by using a multiparametric approach (relative cerebral blood volume ×ADC) was the best predictor of true tumor progression (P < .001) and worse survival (P = .003).

CONCLUSIONS

Multiparametric histogram analysis of posttreatment glioblastoma was useful to predict true tumor progression and worse survival.

Diffusion and perfusion MRI findings of the signal-intensity abnormalities of brain associated with developmental venous anomaly

BACKGROUND AND PURPOSE

Developmental venous anomalies are the most common intracranial vascular malformation. Increased signal-intensity on T2-FLAIR images in the areas drained by developmental venous anomalies are encountered occasionally on brain imaging studies. We evaluated diffusion and perfusion MR imaging findings of the abnormally high signal intensity associated with developmental venous anomalies to describe their pathophysiologic nature.

MATERIALS AND METHODS

We retrospectively reviewed imaging findings of 34 subjects with signal-intensity abnormalities associated with developmental venous anomalies. All subjects underwent brain MR imaging with contrast and diffusion and perfusion MR imaging. Regions of interest were placed covering abnormally high signal intensity around developmental venous anomalies on fluid-attenuated inversion recovery imaging, and the same ROIs were drawn on the corresponding sections of the diffusion and perfusion MR imaging. We measured the apparent diffusion coefficient, relative cerebral blood volume, relative mean transit time, and time-to-peak of the signal-intensity abnormalities around developmental venous anomalies and compared them with the contralateral normal white matter. The Mann-Whitney U test was used for statistical analysis.

RESULTS

The means of ADC, relative cerebral blood volume, relative mean transit time, and TTP of signal-intensity abnormalities around developmental venous anomalies were calculated as follows: 0.98 ± 0.13 10(-3)mm(2)/s, 195.67 ± 102.18 mL/100 g, 16.74 ± 7.38 seconds, and 11.65 ± 7.49 seconds, respectively. The values of normal WM were as follows: 0.74 ± 0.08 10(-3)mm(2)/s for ADC, 48.53 ± 22.85 mL/100 g for relative cerebral blood volume, 12.12 ± 4.27 seconds for relative mean transit time, and 8.35 ± 3.89 seconds for TTP. All values of ADC, relative cerebral blood volume, relative mean transit time, and TTP in the signal-intensity abnormalities around developmental venous anomalies were statistically higher than those of normal WM (All P < .001, respectively).

CONCLUSIONS

The diffusion and perfusion MR imaging findings of the signal-intensity abnormalities associated with developmental venous anomaly suggest that the nature of the lesion is vasogenic edema with congestion and delayed perfusion.

Reconstructive endovascular treatment of fusiform or ultrawide-neck circumferential aneurysms with multiple overlapping enterprise stents and coiling

BACKGROUND AND PURPOSE

Fusiform aneurysms and ultrawide-neck circumferential aneurysms are still some of the most challenging lesions. The aim of this study was to investigate the efficacy and feasibility of the use of multiple overlapping Enterprise stents with coiling for the treatment of fusiform or ultrawide-neck circumferential aneurysms.

MATERIALS AND METHODS

Twelve consecutive patients (9 men and 3 women; mean age, 56 years) with fusiform (n = 5) or ultrawide-neck circumferential (n = 7) aneurysms were treated with 2-3 overlapping Enterprise stents and coiling. The feasibility of this procedure and the clinical and angiographic outcomes of this technique were retrospectively evaluated.

RESULTS

All patients were successfully treated by using this technique without any complications. Posttreatment angiographic results revealed grade 4 occlusion of the aneurysm in 6, grade 3 in 4, and grade 2 in 2 patients. Clinical follow-up was performed in all patients (mean, 16 months; range, 5-24 months). Nine patients had an mRS score of 0. Two had an mRS score of 1, one of whom had an initial mRS score of 2 due to the mass effect of a giant aneurysm; the other had a recurrent aneurysm presenting with SAH 5 years after clipping. Angiographic follow-up was performed in 10 patients at 6-20 months posttreatment. Nine had stable or improved occlusion, while 1 had a minor recurrence.

CONCLUSIONS

In this small series, multiple overlapping Enterprise stents with coiling were a feasible and effective option for the treatment of fusiform and ultrawide-neck circumferential aneurysms. Further experience and follow-up are required to document the long-term efficacy of this treatment.

Embolization of intracranial aneurysms with HydroSoft coils: results of the Korean multicenter study

BACKGROUND AND PURPOSE

Various modifications of detachable coils have been attempted to reduce recurrence rates in aneurysmal coil embolization and HydroSoft coil is one of them. The authors report their experience using HydroSoft coils in the treatment of cerebral aneurysms.

MATERIALS AND METHODS

The present study is a prospective multicenter observational series of 127 aneurysms in 120 patients treated with HydroSoft coils.

RESULTS

Ten centers participated in this study, and there were 92 (72%) unruptured and 35 ruptured aneurysms. Aneurysm volumes were ≥ 100 mm³ in 21 (17%) and < 100 mm³ in 106 (83%) (mean, 56 mm³; range, 5-249 mm³). The average percentage length of HydroSoft coils detached in treated aneurysms was 67% (range, 42%-100%). Immediate postprocedural angiography demonstrated complete aneurysm occlusion in 69% (87/127 aneurysms), residual neck in 20% (25/127), and residual sac in 12% (15/127). Procedure-related adverse events occurred in 4.7% (6/127 aneurysms), including procedural bleeding (5/127) and thromboembolism (2/127), and immediate procedure-related morbidity and mortality rates were 0.8% and 0%. Conventional angiography or MRA follow-up was performed in 83% (105/127) at ≥ 6 months after treatment (mean interval, 11 months; range, 6-24 months). The overall recanalization rate was 3% (3/105 aneurysms; 2 major and 1 minor recanalizations). Progression to complete aneurysmal occlusion was noted in 20 of 27 aneurysms (74%) during the follow-up.

CONCLUSIONS

The safety profile of HydroSoft coils appears acceptable. In terms of initial occlusion rates and durability, embolization by using HydroSoft coils seems to be favorable compared with most large series of pure platinum or coated coils.

Emergent self-expanding stent placement for acute intracranial or extracranial internal carotid artery dissection with significant hemodynamic insufficiency

BACKGROUND AND PURPOSE

ICAD with hemodynamic insufficiency may present with either fulminant infarct or with progressive neurologic deterioration. The purpose of this study was to evaluate the safety and efficacy of emergent self-expanding stent placement for acute intracranial or extracranial ICAD with significant hemodynamic insufficiency.

MATERIALS AND METHODS

Eight patients (7 men and 1 woman; age range, 20-55 years; NIHSS score, 5-21) underwent emergent self-expanding stent placement for treatment of significant hemodynamic insufficiency due to acute ICAD. The safety and efficacy of emergent self-expanding stent placement were retrospectively evaluated.

RESULTS

All patients presented with progressive (n = 6) or fluctuating (n = 2) neurologic deficits and revealed markedly decreased perfusion on CT or MR perfusion studies. Conventional angiography revealed acute occlusion (n = 2) or critical stenosis (n = 6) in intracranial (n = 3) or extracranial (n = 5) carotid arteries with a lack of sufficient collaterals. Stent placement was successful in all patients without any procedure-related complications. In all patients, hemodynamic insufficiency was corrected immediately after stent placement, and neurologic symptoms were completely resolved during several days. Mean improvement of the NIHSS score between baseline and discharge was 11.6 (range, 5-21). All patients remained neurologically intact (mRS, 0) during clinical follow-up for a mean of 21 months (range, 8-50 months). Angiographic follow-up was available for 6 patients at 3-12 months. None of the 6 patients revealed residual or in-stent restenosis.

CONCLUSIONS

Self-expanding stent placement is a safe and effective option for selected patients with significant hemodynamic insufficiency due to acute intracranial or extracranial ICAD.

Characteristic features of unruptured intracranial aneurysms: predictive risk factors for aneurysm rupture

BACKGROUND AND PURPOSE

The purpose of this study was to identify the risk factors predisposing to aneurysm rupture and to provide a reliable estimation for likelihood of rupture in unruptured intracranial aneurysms.

METHODS

The authors performed a nested case-control study of 290 aneurysms (123 unruptured aneurysms and 167 ruptured aneurysms) occurring during a prospective cohort study in 1493 consecutive patients with newly diagnosed intracranial aneurysm and were treated in a single institute between January 1995 and December 2006. Controls were matched for age, treatment group, number of lesion, sex, region and study period in which the incidence of ruptured and unruptured intracranial aneurysm was equivalently balanced. The authors assessed the predictive risk factors associated with aneurysmal rupture based on the clinical and angiographic findings reported in the patients' medical records.

RESULTS

Between January 1997 and December 2002, 167 patients with ruptured intracranial aneurysms were assigned to group 1, and 123 patients with unruptured intracranial aneurysms during the same period were assigned to group 2. Aspect ratio (OR 3.76), maximum diameter of neck (N(max)) < or =3 mm (OR 2.56) and family history of cerebrovascular disease (OR 5.63) were strongly correlated with aneurysm rupture (p<0.05).

CONCLUSIONS

There are differences between the clinical and intrinsic characteristics of patients with unruptured and ruptured intracranial aneurysm. It will be helpful to make rational decisions regarding the optimal therapeutic strategy for unruptured intracranial aneurysm.

Prevalence and appearance of the posterior wall defects of the temporal bone caused by presumed arachnoid granulations and their clinical significance: CT findings

BACKGROUND AND PURPOSE

Arachnoid granulations (AGs) of the posterior wall of the temporal bone are a rare cause of spontaneous CSF leakage. The purpose of this study was to investigate the prevalence and appearance of presumed AGs, evidenced by the posterior wall defects of the temporal bone with lobulated or scalloped margins on CT scans.

MATERIALS AND METHODS

We retrospectively reviewed CT scans of the temporal bone obtained in 1255 patients (573 men and 682 women; mean age, 42 years). We evaluated the prevalence, multiplicity, size, and location of presumed AGs in the posterior wall of the temporal bone. Preservation of the posterior wall of the mastoid air cells was also investigated and correlated with clinical features.

RESULTS

Thirty patients (2.4%), including 13 men and 17 women, aged 27-88 years (mean, 55 years), showed a total of 40 presumed AGs on CT scans. Their prevalence tended to increase with age. They were most commonly located at the lateral third of the temporal bone at a level of or above the common crus. Although 15 lesions in 11 patients also caused focal loss of the posterior wall of the mastoid air cells, symptomatic CSF leakage was found in only 2 patients, in both of whom the adjacent mastoid air cells were also opacified on CT scans.

CONCLUSION

Although rare, radiologists need to be familiar with the posterior wall defects of the temporal bone caused by presumed AGs on CT scans, because they might cause CSF leakage.

Sinonasal inverted papilloma: value of convoluted cerebriform pattern on MR imaging

BACKGROUND AND PURPOSE

A convoluted cerebriform pattern (CCP) has been reported as a valuable MR imaging feature of inverted papilloma (IP). The purpose of this study was to validate the usefulness of CCP for distinguishing IP from various malignant sinonasal tumors in a relatively large number of patients.

MATERIALS AND METHODS

We retrospectively reviewed MR images of 30 patients with IP and 128 patients with various malignant sinonasal tumors proved on histologic examination and compared the prevalence of a CCP between the 2 groups. In 8 patients with IP concomitant with squamous cell carcinoma, we also tried to find the MR features to help suggest coexistent malignancy.

RESULTS

A CCP was demonstrated in all 30 (100%) of the IPs and 17 (13%) of the 128 malignant sinonasal tumors on MR imaging. There was a significant statistical difference in the prevalence of a CCP between IP and malignant sinonasal tumors with the overall sensitivity, specificity, positive predictive value, negative predictive value, and accuracy 100%, 87%, 64%, 100%, and 89%, respectively. Of 8 IPs concomitant with squamous cell carcinoma, a focal loss of a CCP was demonstrated in 4 tumors, 3 of which also showed aggressive bone destruction with extrasinonasal extension on MR images.

CONCLUSION

Although a CCP is a reliable MR imaging feature of sinonasal IPs, it can also be seen in various malignant sinonasal tumors. A focal loss of a CCP might be a clue to the diagnosis of IPs concomitant with malignancy.

Solitary fibrous tumor of the orbit: CT and MR imaging findings

BACKGROUND AND PURPOSE

Solitary fibrous tumor (SFT) is a rare spindle-cell neoplasm originating from mesenchymal fibroblast-like cells. The purpose of this study was to describe the CT and MR imaging features of SFTs in the orbit.

MATERIALS AND METHODS

We retrospectively reviewed CT and MR images in 6 patients (2 men and 4 women), aged 18 to 51 years, with SFT proved on histologic examination located in and around the orbit. All patients underwent CT (including dual-phase CT in 3), and MR imaging was obtained in 3. We evaluated the imaging findings with emphasis on the location, size, margin, internal architecture, and pattern of enhancement of the lesion.

RESULTS

All 6 lesions were found as a solitary, well-defined mass, ranging in size from 18 to 30 mm (mean, 24 mm). Three were located in the postseptal orbit, 2 in the lacrimal sac, and 1 on the lower eyelid. Compared with the cerebral cortex, all 3 lesions examined by MR imaging showed homogeneous isointense signal intensity on T1-weighted images and heterogeneous mixed isointense and hyperintense signal intensity on T2-weighted images. On visual inspection, all 6 lesions showed marked homogeneous (n = 4) or heterogeneous (n = 2) enhancement on postcontrast CT and MR images. In 3 patients examined with dual-phase CT, all lesions demonstrated rapid enhancement with early washout of contrast material.

CONCLUSION

SFT might be included in the differential diagnosis of soft tissue masses in the orbit, if one sees a markedly enhancing mass showing the similar characteristics to those of the internal carotid artery on postcontrast CT or MR images.

Sinonasal organized hematoma: CT and MR imaging findings

BACKGROUND AND PURPOSE

Sinonasal organized hematoma (OH) is an uncommon, nonneoplastic benign condition that can be locally aggressive. The purpose of this work was to characterize the CT and MR imaging findings of sinonasal OH.

MATERIALS AND METHODS

CT (n = 11) and MR (n = 10) images of 12 patients (9 men and 3 women; mean age, 41 years; range, 12-76 years) with pathologically proved sinonasal OH were retrospectively reviewed. Particular attention was put on the location, shape, size, extent, internal architecture, and enhancement pattern of the lesion and associated sinus wall change.

RESULTS

The lesions were seen as an expansile (n = 9) or nonexpansile (n = 3) mass, ranging in size from 2.2 to 6.0 cm (mean, 4.2 cm), primarily involving the maxillary sinus (n = 11) or nasal cavity (n = 1) unilaterally. The ipsilateral nasal cavity was also involved in 9 of 11 maxillary sinus lesions. Smooth sinus wall erosion other than the medial maxillary sinus wall was noted in 8 lesions. The internal architecture was best displayed on T2-weighted MR images on which all of the lesions were seen as a mixture of marked heterogeneous hypointensity and isointensity, surrounded by a hypointense peripheral rim, reflecting histologic heterogeneity of the lesion composed of hemorrhage, fibrosis, and neovascularization. Marked irregular nodular, papillary, or frondlike enhancement at the areas of neovascularization was also a typical finding seen in all of the lesions.

CONCLUSION

An expansile soft tissue mass, smooth sinus wall erosion, marked heterogeneous signal intensity with a hypointense peripheral rim on T2-weighted MR images, and marked irregular nodular, papillary, or frondlike enhancement are characteristic CT and MR imaging findings of sinonasal OH.

2. Use of a health advocacy essay to improve competence

We set out to determine if essay writing on health advocacy could improve scores on a Health Advocacy observed structured clinical exam (OSCE) station. A Health Advocacy station was used as one of ten stations at the annual resident OSCE in 2006. Subsequently, residents were instructed to write an essay regarding their actions as a health advocate, either in general or relating to a specific situation. For the 2007 OSCE, a different Health Advocacy station was used that was similar to the previous year in terms of the issues that residents needed to address and the scoring structure. The results on the OSCE stations between the two years were compared using Student’s T-test. Regression analysis was used to identify any predictors for a higher score. The number of residents taking the OSCE in 2006 and 2007 were 17 and 13, respectively. Nine residents completed the OSCE in both years. The number of PGY-1’s taking the OSCE for the first time in 2006 and 2007 were 8 and 4, respectively. Compliance with the essay writing was 100%. The mean score on the Health Advocacy station was significantly higher in 2007 compared to 2006 (53.0 ± 14.6 compared to 65.6 ± 10.0 vs. 53.0 ± 14.6; p=0.01). The mean score of PGY-1’s in 2007 tended to be higher than PGY-1’s in 2006 (67.5 ± 11.4 vs. 54.5 ± 12.3; p=0.11), suggesting the improvement was not due to having taken the OSCE previously. Regression analysis did not identify and other predictors of higher score on the OSCE station. These results suggest that essay writing by residents about actions they have taken as health advocates improves knowledge about the CanMEDS competency of Health Advocacy, as measured in an OSCE station. The non-randomized design of the study does not exclude the possibility of other factors influencing the improvement in score. Oandasan I, Barker K. Educating for Advocacy: Exploring the Source and Substance of Community-Responsive Physicians. Acad Med 2003; 78(1):S16-S19. Frank J, Langer B. Collaboration, Communication, Management, and Advocacy: Teaching surgeons new skills through the CanMEDS project. World J Surg 2003; 27:972-978. Verma S, Flynn L, Seguin R. Faculty’s and residents’ perceptions of teaching and evaluating the role of health advocate: A study at one Canadian university. Acad Med 2005; 80:103-108.

62. Does an expert presentation raise awareness of CanMEDs Roles among residents?s

We set out to determine whether an expert presentation on CanMEDS would raise awareness of CanMEDS roles among residents. We addressed this question with paired surveys distributed before and after the expert presentation. Each survey outlined seven different clinical scenarios each of which required one of the seven core CanMEDS competencies. Paired surveys were distributed prior to the presentation to the audience that was composed of a selection of residents from various disciplines. One survey was filled out prior to and the second survey completed following the expert presentation. Data were analysed using nonparamentric statistical methods. There was in general, a low pre-presentation background knowledge of CanMEDS roles, with wide variability between specialties. Our hypothesis that disciplines with less patient contact would have less understanding of CanMEDS roles was not fully supported. All specialties demonstrated improvement in their understanding of CanMEDS roles in the post-presentation survey. While there is a low background level of knowledge about CanMEDS roles, we determined that following an expert presentation (in this case by Dr. Serita Verma) the residents were significantly more able to correctly apply the core competencies of the CanMEDS model to the given clinical scenarios. We propose that an expert presentation could be applied as an innovative educational tool advancing CanMEDS education among residents.

Pituitary adenomas: early postoperative MR imaging after transsphenoidal resection

BACKGROUND AND PURPOSE

Although there have been several reports on postoperative MR imaging of the sella, immediate postoperative changes (usually within 3 days) have not been extensively analyzed. The purpose of this study was to establish the value of early postoperative MR imaging in differentiating residual tumor from postoperative surgical changes in the sella after transsphenoidal resection of pituitary adenomas.

METHODS

Eighty-three patients with surgically proven pituitary adenomas (32 nonfunctioning, 24 prolactin-secreting, 22 growth hormone-secreting, and five prolactin- and growth hormone-secreting tumors) were studied prospectively. All patients underwent dynamic MR imaging within 7 days after surgery. We analyzed the postoperative MR images by focusing on changes in the pituitary gland, signal intensity, resorption of implanted material, and visibility of residual tumor. The patients were divided into four groups according to enhancement pattern of the postoperative pituitary mass: no enhancement, nodular enhancement, peripheral rim enhancement, and a combination of nodular and peripheral rim enhancement.

RESULTS

Postoperative changes included resorption of implanted material and reexpansion of the pituitary gland. In 22 patients, residual tumors were found, and all patients showed nodular or combined enhancement. The residual tumors were confirmed by immediate reoperation in three patients, by hormonal assay and follow-up MR images in 11 patients with functioning adenomas, and by growth of the tumor on follow-up MR images in eight patients with nonfunctioning adenomas. Forty-eight patients showed no enhancement and 13 patients showed peripheral rim enhancement.

CONCLUSION

Early postoperative dynamic MR imaging after transsphenoidal resection in pituitary adenoma is very effective in differentiating residual tumor from postoperative surgical changes.

Cerebral cavernous malformations: serial magnetic resonance imaging findings in patients with and without gamma knife surgery

To classify the cerebral cavernous malformations and to investigate the natural history of cavernous malformations according to the classification, 41 patients with 61 cavernous malformations (40 cavernous malformations from 22 patients treated with gamma knife surgery) were regularly followed up using magnetic resonance (MR) imaging for a mean period of 25.5 months in treated cavernous malformations and 20.7 months in untreated cavernous malformations, respectively. Cavernous malformations were classified into four types: type I, extralesional gross hemorrhage beyond cavernous malformation; type II, mixture of subacute and chronic hemorrhage; type III, area of hemosiderin with small central core; and type IV, area of hemosiderin deposition without central core. Follow-up MR images were analyzed to evaluate changes in size, signal intensity, rebleeding, and perilesional adverse reaction of irradiation. A total of 61 cavernous malformations including 17 in type I, 23 in type II, 10 in type III, and 11 in type IV showed usual degradation of blood product in 22 cavernous malformations, no change in shape and signal intensity in 31 cavernous malformations, and eight cavernous malformations with rebleedings in the serial MR images. In these eight cavernous malformations with rebleedings, six occurred in type II and two in type III, but none in type I or IV. Rebleedings were more frequent in type II than in other types (p = 0.044). Adverse reaction of irradiation was observed in five of 22 patients treated with gamma knife surgery. Although most cerebral cavernous malformations showed evolution of hemorrhage or no change in size or shape on follow-up MR images, cerebral cavernous malformations represented as mixture of subacute and chronic hemorrhage with hemosiderin rim (type II) have a higher frequency to rebleed than other types of cerebral cavernous malformations. Cerebral cavernous malformations represented as hemosiderin deposition without central core (type IV) have a lower tendency to rebleed than other types and do not need any treatment. Most of the adverse reaction of irradiation after gamma knife surgery around cavernous malformations are transient findings and are considered to be perilesional edema.

MRI of germinomas arising from the basal ganglia and thalamus

We reviewed the MRI findings of germinomas originating from the basal ganglia, thalamus or deep white matter in 13 patients with 14 germinomas, excluding those in the suprasellar or pineal regions. Ten cases were confirmed as germinomas by stereotaxic biopsy, three by partial and one by total removal of the tumour. Analysis was focussed on the location and the signal characteristic of the tumour, haemorrhage, cysts within the tumour and any other associated findings. Thirteen of the tumours were in the basal ganglia and one in the thalamus. Haemorrhage was observed in seven patients, while twelve showed multiple cysts. Associated ipsilateral cerebral hemiatrophy was seen in three patients. The signal intensity of the parenchymal germinomas was heterogeneous on T1- and T2-weighted images due to haemorrhage, cysts and solid portions. We also report the MRI findings of germinomas in an early stage in two patients.

Facial nerve schwannomas: CT and MR findings

The present study was undertaken to analyze the radiologic findings of intratemporal and extratemporal schwannoma (ITS & ETS). We retrospectively reviewed the CT (9 cases), MR (3 cases) and medical records of 10 facial schwannoma patients. After classifying these into ITS and ETS, radiologic and clinical findings were analyzed. The most common clinical manifestations were facial nerve dysfunction (6/6 cases, 100%) and hearing impairment (5/6 cases, 83.3%) in ITS and parotid mass (4/4 cases, 100%) in ETS. Geniculate ganglion (GG) was the most commonly involved segment of ITS (5/6 cases, 83.5%). On CT, ITS arising in GG (4 cases) showed erosion of the petrous bone (4 cases), cochlea (3 cases), lateral semicircular canal (1 case) and ossicles (3 cases). ITS arising in the mastoid segment (1 case) showed the destruction of the jugular plate and external auditory canal wall. All three ITS in which MRI was performed showed iso- to hypointensity on T1WI, hyperintensity on T2WI and well-enhanced on post-enhanced T1WI. ETS showed various findings, but all four ETS were located in the posterolateral portion of the retromandibular vein and extended toward the stylomastoid foramen. In conclusion, ITS shows the schwannoma on MR. ETS shows various findings. However, if the tumor is located along the extratemporal facial nerve course, then facial schwannoma may be suspected.

Cerebral perfusion impairment in a patient with toluene abuse

We report the case of a 17-yr-old man diagnosed as a toluene abuser. He had an 8-mo history of toluene inhalation exposure and was admitted to this hospital with symptoms of auditory and visual hallucination. Magnetic resonance imaging (MRI) revealed no structural abnormalities both on T1- and T2-weighted images, whereas SPECT using 99mTc-ethyl cysteinate dimer (ECD) showed multifocally decreased perfusion in the cerebral cortex, basal ganglia and thalami. Our case indicates that SPECT detects early central nervous system injury from toluene inhalation even when neurological examination and neuroanatomic imaging such as MRI are normal.

Evaluation of cardiac sympathetic neuronal integrity in diabetic patients using iodine-123 metaiodobenzylguanidine

Autonomic dysfunction is associated with increased mortality in diabetic patients. To evaluate the cardiac autonomic dysfunction in these patients, a prospective study was undertaken using iodine-123 metaiodobenzylguanidine (MIBG) single-photon emission tomography (SPET). The study groups consisted of ten diabetic patients with cardiac autonomic neuropathy (group I) and six without autonomic neuropathy (group II). Autonomic nervous function tests, thallium scan, radionuclide ventriculographic data including ejection fraction and wall motion study, and 24-h urine catecholamine levels were evaluated. 123I-MIBG SPET was performed at 30 min and 4h following injection of 3 mCi of 123I-MIBG in groups I and II and in normal subjects (n=4). On planar images, the heart to mediastinum (H/M) ratio was measured. Defect pattern and severity of MIBG uptake were qualitatively analysed on SPET. Compared with control subjects, diabetic patients had a reduced H/M ratio regardless of the presence of clinical autonomic neuropathy. There was no difference in H/M ratio between groups I and II. On SPET images, focal or diffuse defects were demonstrated in all patients in group I, and in five of the six patients in group II. The extent of defects tended to be more pronounced in group I than in group II. In conclusion, 123I-MIBG scan was found to be a more sensitive method than clinical autonomic nervous function tests for the detection of autonomic neuropathy in diabetes.