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.

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.

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.

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.

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.

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.

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.

Comparison of outcomes between endovascular treatment and bypass surgery in Takayasu arteritis.

OBJECTIVES: There is currently a lack of evidence regarding the optimal revascularization method for Takayasu arteritis (TA). This study compares outcomes between endovascular treatment and surgical therapy in TA patients requiring revascularization. METHOD: From September 1994 to January 2011, 235 patients were diagnosed with TA according to the diagnostic criteria of the 1990 American College of Rheumatology, and of these, arterial revascularizations were performed in 65 (27.7%). Symptomatic or angiographic recurrence and peri-operative use of immunosuppressive drugs were investigated by retrospectively reviewing medical records. RESULTS: A total of 111 arterial lesions in the 65 (27.7%) patients were revascularized during the follow-up period (median 3.2 years, range 0.01-12.7 years). At the 2-year follow-up, the symptomatic recurrence rate was significantly higher in the endovascular treatment group (32.3% vs. 11.5%, p = 0.016), as was the incidence of angiographic recurrence (32.1% vs. 11.1%, p = 0.026). The symptomatic recurrence rate was not influenced by the need for peri-operative immunosuppressive drugs (20% vs. 34.1%, p = 0.34). CONCLUSIONS: In TA patients, surgical revascularization seems to be superior to endovascular treatment with regard to patency. Further investigation to identify novel and optimal arterial revascularization methods for TA patients should be undertaken.

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.

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.

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.

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.

Three-dimensional finite element analysis of stress in the periodontal ligament of the maxillary first molar with simulated bone loss.

The purpose of the study was to use the finite element method to simulate the effect of alveolar bone loss on orthodontically induced stress in the periodontal ligament of the maxillary first molar. A 3-dimensional finite element model of a tooth with different levels of bone height was constructed to estimate the reduction in force and the increase in moment to force (M/F) ratio necessary to obtain evenly distributed stress in the periodontal ligament of a tooth with horizontal bone loss. The 3-dimensional finite model comprised a maxillary first molar, the periodontal ligament, and alveolar bone and consisted of 3097 nodes and 2521 elements. An anterior force of 300 g was applied at the center of the buccal crown surfaces of teeth with normal bone height and with bone loss that ranged from 2.0 to 6.0 mm. The results showed that force magnitude required lowering from 80% (2-mm bone loss) and gradually to 37% (6-mm bone loss) of the initial load applied to the tooth without bone loss. The countertipping moment (gram-millimeters) to force (gram) ratio should increase from 9 (no bone loss) to nearly 13 (6-mm bone loss) to maintain the same range of stress in the periodontal ligament as was obtained without bone loss. A linear relationship was observed between the amount of bone loss, the desired reduction in force magnitude, and the increase in M/F ratio. The results of this study indicate that a combination of force reduction and increased M/F ratio is required to achieve uniform stress in the periodontal ligament of a tooth with bone loss.