Geometric Features Associated with Middle Cerebral Artery Bifurcation Aneurysm Formation: A Matched Case-Control Study.

OBJECTIVES: The pathogenesis of intracranial aneurysms is multifactorial and includes genetic, environmental, and anatomic influences. We aimed to identify image-based morphological parameters that were associated with middle cerebral artery (MCA) bifurcation aneurysms. MATERIALS AND METHODS: We evaluated three-dimensional morphological parameters obtained from CT angiography (CTA) or digital subtraction angiography (DSA) from 317 patients with unilateral MCA bifurcation aneurysms diagnosed at the Brigham and Women's Hospital and Massachusetts General Hospital between 1990 and 2016. We chose the contralateral unaffected MCA bifurcation as the control group, in order to control for genetic and environmental risk factors. Diameters and angles of surrounding parent and daughter vessels of 634 MCAs were examined. RESULTS: Univariable and multivariable statistical analyses were performed to determine statistical significance. Sensitivity analyses with smaller (≤ 3 mm) aneurysms only and with angles excluded, were also performed. In a multivariable conditional logistic regression model we showed that smaller diameter size ratio (OR 0.0004, 95% CI 0.0001-0.15), larger daughter-daughter angles (OR 1.08, 95% CI 1.06-1.11) and larger parent-daughter angle ratios (OR 4.24, 95% CI 1.77-10.16) were significantly associated with MCA aneurysm presence after correcting for other variables. In order to account for possible changes to the vasculature by the aneurysm, a subgroup analysis of small aneurysms (≤ 3 mm) was performed and showed that the results were similar. CONCLUSIONS: Easily measurable morphological parameters of the surrounding vasculature of the MCA may provide objective metrics to assess MCA aneurysm formation risk in high-risk patients.

Relative Magnetic Force Measures and Their Potential Role in MRI Safety Practice.

BACKGROUND: Magnetic field markings are occasionally used at MRI sites to provide visual feedback of magnetic field strength at locations within the MRI scan room for safety purposes. In addition to magnetic field line markings, relative magnetic force, or ratio of magnetic to gravitational forces on an object, may be considered a useful complementary metric to quantify the risk associated with bringing objects containing ferromagnetic material into the magnetic field. PURPOSE: To develop and validate methods for deriving useful relative magnetic-force measures including a simple force index for application to MRI safety. STUDY TYPE: Phantom. PHANTOM: A special-purpose rig was built to experimentally measure relative magnetic forces on small ferromagnetic objects. FIELD STRENGTH: Ranging from 1.5T to 7T. ASSESSMENT: Quantitative comparisons were made between theoretical and measured relative magnetic forces on six objects containing ferromagnetic material: a piece of iron, a paper clip, a Kelly clamp, nail clippers, a cell phone, and a small permanent magnet. STATISTICAL TESTS: An analysis based on the Bland-Altman method was employed. RESULTS: After correction of the 1.5T data to account for assumed positioning errors of the test rig, limits of agreement between measured and estimated relative forces in the four MRI systems were ±0.16, where a relative force of 1.0 indicates that the magnetic force is equal to gravitation force. There was no significant bias in the data (P < = 0.05). DATA CONCLUSION: Accurate measures of relative magnetic forces on ferromagnetic objects can be derived for MRI safety purposes. LEVEL OF EVIDENCE: 1 Technical Efficacy Stage: 1 J. Magn. Reson. Imaging 2020;51:1260-1271.

PD-1 blockade with nivolumab in relapsed/refractory primary central nervous system and testicular lymphoma.

Primary central nervous system (CNS) lymphoma (PCNSL) and primary testicular lymphoma (PTL) are rare extranodal large B-cell lymphomas with similar genetic signatures. There are no standard-of-care treatment options for patients with relapsed and refractory PCNSL and PTL, and the overall prognosis is poor. PCNSLs and PTLs exhibit frequent 9p24.1 copy-number alterations and infrequent translocations of 9p24.1 and associated increased expression of the programmed cell death protein 1 (PD-1) ligands, PD-L1 and PD-L2. The activity of PD-1 blockade in other lymphomas with 9p24.1 alterations prompted us to test the efficacy of the anti-PD1 antibody, nivolumab, in 4 patients with relapsed/refractory PCNSL and 1 patient with CNS relapse of PTL. All 5 patients had clinical and radiographic responses to PD-1 blockade, and 3 patients remain progression-free at 13+ to 17+ months. Our data suggest that nivolumab is active in relapsed/refractory PCNSL and PTL and support further investigation of PD-1 blockade in these diseases.

Blunt traumatic vascular injuries of the head and neck in the ED.

Cerebrovascular injury is increasingly identified in patients presenting after blunt trauma due to the implementation of screening criteria and advances in noninvasive angiographic imaging by CT. The variable latent time before onset of secondary stroke presents a window of opportunity for prevention, reinforcing the importance of detection of asymptomatic patients via screening. Furthermore, the high morbidity and mortality associated with secondary stroke makes it imperative that radiologists recognize these challenging injuries. This article reviews the epidemiology of and the various proposed screening criteria for blunt cerebrovascular injury. The imaging findings of extra- and intracranial vascular injuries, including arterial and venous trauma, are reviewed along with the grading system. Conservative management with anticoagulation has gained favor over the years with intervention restricted to high-grade injuries such as transection and hemodynamically significant arteriovenous fistula. Many of these injuries also evolve over time, with or without anticoagulation, necessitating imaging follow-up.

Neurosurgical complications: what the radiologist needs to know.

Visits to the emergency department by patients who have recently undergone neurosurgery are a common occurrence, and these patients frequently receive emergent cross-sectional head imaging in order to evaluate for complications. Different neurosurgical approaches may have typical postoperative imaging findings that can be confused with pathology. Furthermore, particular abnormal postoperative imaging findings may signal an evolving complication. It is essential for the radiologist to understand common neurosurgical procedures and their potential complications in order to provide proper diagnostic evaluation of the postoperative neurosurgical patient. The purpose of this review is to assist radiologists in the evaluation of the postoperative neurosurgical patient and educate them on associated complications. Familiarity with common neurosurgical techniques and postoperative complications will help radiologists make the correct diagnosis, communicate effectively with the neurosurgeon, and expedite patient care.

Clinical applications of dynamic CT angiography for intracranial lesions.

BACKGROUND: Dynamic CT angiography (dCTA) augments traditional CTA with temporal resolution and has been demonstrated to influence operative planning in skull base surgery. METHODS: Three hundred twenty-five dynamic CTA cases from a single institution were reviewed for indication of study, findings, and comparison to other modalities of imaging. RESULTS: The most frequent application of dCTA was pre-operative surgical planning (59.4%); resection of skull base tumors represented the majority of these pre-operative studies (93.3%). It was also used to evaluate new neurological symptoms (20.9%). Of these, the most common symptoms prompting a dCTA study included headache (22.1%) and visual field deficit (11.8%). The most commonly visualized vascular lesions were partial (22.9%) and complete vascular occlusions (9.0%). Dynamic CTA has also been useful in post-operative imaging for vascular malformations (9.5%) and tumors (2.5%). Finally, dCTA was employed to evaluate ambiguous abnormal findings observed on other imaging modalities (7.7%). Cerebral dCTA ruled out inconclusive abnormal vascular findings visualized on other imaging modalities (64.0%) more frequently than it confirmed them (32.0%), and was inconclusive in a singular case (4.0%). CONCLUSIONS: Cerebral dCTA is an evolving new technology with a diverse spectrum of potential applications. In addition to its role in guiding pre-operative planning for skull base surgical cases, dynamic CTA offers excellent spatial and temporal resolution for assessment of vascular lesions.

Ferumoxytol-Enhanced Magnetic Resonance Imaging in Late-Stage CKD.

Ferumoxytol is a superparamagnetic iron oxide particle encapsulated by a semisynthetic carbohydrate with properties that can be used by the nephrologist for diagnosis and therapy. Ferumoxytol is approved by the US Food and Drug Administration for treating iron deficiency anemia in the setting of chronic kidney disease, but not for clinical diagnostic imaging. It has gained appeal as a magnetic resonance imaging contrast agent in patients with estimated glomerular filtration rates < 30mL/min/1.73m(2) in whom gadolinium-based contrast magnetic resonance imaging agents are relatively contraindicated because of the association with gadolinium deposition and nephrogenic systemic fibrosis. Ferumoxytol metabolism is not dependent on kidney function, but rather is removed from the circulation by the reticuloendothelial system of the liver, spleen, and bone marrow. Additionally, the prolonged intravascular half-life (>14 hours) of ferumoxytol allows for longer image acquisition and repeat imaging, if necessary. In patients with contraindications for gadolinium contrast agents, ferumoxytol is an alternative agent for vascular assessment, including patency and course.

The utility of high-resolution intraoperative MRI in endoscopic transsphenoidal surgery for pituitary macroadenomas: early experience in the Advanced Multimodality Image Guided Operating suite.

OBJECTIVE: Endoscopic skull base surgery has become increasingly popular among the skull base surgery community, with improved illumination and angled visualization potentially improving tumor resection rates. Intraoperative MRI (iMRI) is used to detect residual disease during the course of the resection. This study is an investigation of the utility of 3-T iMRI in combination with transnasal endoscopy with regard to gross-total resection (GTR) of pituitary macroadenomas. METHODS: The authors retrospectively reviewed all endoscopic transsphenoidal operations performed in the Advanced Multimodality Image Guided Operating (AMIGO) suite from November 2011 to December 2014. Inclusion criteria were patients harboring presumed pituitary macroadenomas with optic nerve or chiasmal compression and visual loss, operated on by a single surgeon. RESULTS: Of the 27 patients who underwent transsphenoidal resection in the AMIGO suite, 20 patients met the inclusion criteria. The endoscope alone, without the use of iMRI, would have correctly predicted extent of resection in 13 (65%) of 20 cases. Gross-total resection was achieved in 12 patients (60%) prior to MRI. Intraoperative MRI helped convert 1 STR and 4 NTRs to GTRs, increasing the number of GTRs from 12 (60%) to 16 (80%). CONCLUSIONS: Despite advances in visualization provided by the endoscope, the incidence of residual disease can potentially place the patient at risk for additional surgery. The authors found that iMRI can be useful in detecting unexpected residual tumor. The cost-effectiveness of this tool is yet to be determined.

Defining language networks from resting-state fMRI for surgical planning--a feasibility study.

Presurgical language mapping for patients with lesions close to language areas is critical to neurosurgical decision-making for preservation of language function. As a clinical noninvasive imaging technique, functional MRI (fMRI) is used to identify language areas by measuring blood-oxygen-level dependent (BOLD) signal change while patients perform carefully timed language vs. control tasks. This task-based fMRI critically depends on task performance, excluding many patients who have difficulty performing language tasks due to neurologic deficits. On the basis of recent discovery of resting-state fMRI (rs-fMRI), we propose a "task-free" paradigm acquiring fMRI data when patients simply are at rest. This paradigm is less demanding for patients to perform and easier for technologists to administer. We investigated the feasibility of this approach in right-handed healthy control subjects. First, group independent component analysis (ICA) was applied on the training group (14 subjects) to identify group level language components based on expert rating results. Then, four empirically and structurally defined language network templates were assessed for their ability to identify language components from individuals' ICA output of the testing group (18 subjects) based on spatial similarity analysis. Results suggest that it is feasible to extract language activations from rs-fMRI at the individual subject level, and two empirically defined templates (that focuses on frontal language areas and that incorporates both frontal and temporal language areas) demonstrated the best performance. We propose a semi-automated language component identification procedure and discuss the practical concerns and suggestions for this approach to be used in clinical fMRI language mapping.

Histogram analysis of apparent diffusion coefficient within enhancing and nonenhancing tumor volumes in recurrent glioblastoma patients treated with bevacizumab.

While patients with recurrent glioblastoma receiving anti-angiogenic therapy demonstrate significant response rates, the benefit on patient survival is less clear. We assessed whether histogram analysis of diffusion weighted MRI can stratify for progression-free and overall survival. Baseline and 3-6 week post-treatment MRI exams of 91 patients with recurrent glioblastoma treated with bevacizumab were retrospectively evaluated. Histograms of apparent diffusion coefficient (ADC) within the volume of contrast enhancing and nonenhancing T2/FLAIR lesions were analyzed using curve-fit analysis. Overall survival (OS) and progression-free survival (PFS) were assessed using ADC parameters in a Cox proportional hazards model adjusted for clinical variables. Baseline ADC(L)/ADC(M) within nonenhancing T2/FLAIR volume (> or ≤0.64) can stratify OS (HR = 2.24, p = 0.002) and PFS (HR = 1.90, p = 0.005). %ADC(H) within enhancing T1+C volume (> or ≤25 %) can also stratify OS (HR = 0.59, p = 0.034) and PFS (HR = 0.56, p = 0.01). Stratification of patient survival can be improved by merging these two ADC parameters into a single combined ADC factor (HR = 0.17, p < 0.0001). The median OS ratio of patient groups stratified by this combined factor was 2.03, larger than median OS ratio when stratifying by either %ADC(H) within T1+C volume alone (1.3) or ADC(L)/ADC(M) within T2/FLAIR alone (1.86). ADC histogram analysis within both enhancing and nonenhancing components of tumor can be used to stratify for PFS and OS in patients with recurrent glioblastoma.

Intervention for critical aortic stenosis in Hutchinson-Gilford progeria syndrome.

Hutchinson-Gilford Progeria Syndrome (HGPS) is an ultra-rare genetic premature aging disease that is historically fatal in teenage years, secondary to severe accelerated atherosclerosis. The only approved treatment is the farnesyltransferase inhibitor lonafarnib, which improves vascular structure and function, extending average untreated lifespan of 14.5 years by 4.3 years (30%). With this longer lifespan, calcific aortic stenosis (AS) was identified as an emerging critical risk factor for cardiac death in older patients. Intervention to relieve critical AS has the potential for immediate improvement in healthspan and lifespan. However, HGPS patient-device size mismatch, pervasive peripheral arterial disease, skin and bone abnormalities, and lifelong failure to thrive present unique challenges to intervention. An international group of experts in HGPS, pediatric and adult cardiology, cardiac surgery, and pediatric critical care convened to identify strategies for successful treatment. Candidate procedures were evaluated by in-depth examination of 4 cases that typify HGPS clinical pathology. Modified transcatheter aortic valve replacement (TAVR) and left ventricular Apico-Aortic Conduit (AAC) placement were deemed high risk but viable options. Two cases received TAVR and 2 received AAC post-summit. Three were successful and 1 patient died perioperatively due to cardiovascular disease severity, highlighting the importance of intervention timing and comparative risk stratification. These breakthrough interventions for treating critical aortic stenosis in HGPS patients could rewrite the current clinical perspective on disease course by greatly improving late-stage quality of life and increasing lifespan. Expanding worldwide medical and surgical competency for this ultra-rare disease through expert information-sharing could have high impact on treatment success.

Recurrent high-grade glioma treated with bevacizumab: prognostic value of MGMT methylation, EGFR status and pretreatment MRI in determining response and survival.

Although bevacizumab represented an important advance in treatment of recurrent high-grade gliomas (HGG), responses occur in fewer than half of patients. There are no validated biomarkers for anti-angiogenic therapy that are available for routine clinical use. We assessed the prognostic values of imaging and molecular markers in this patient population. MRI scans from 191 patients with recurrent HGG obtained prior to initiating bevacizumab were reviewed for areas of enhancement, necrosis, T2/FLAIR abnormality, and ADC values. Serial MRI scans following the initiation of bevacizumab were evaluated for response and progression. Non-radiographic markers including EGFR and MGMT status were also assessed with respect to response and patient survival. 65 of 191 patients (34 %) showed complete or partial response at the time of their best response MRI and demonstrated longer progression free survival (PFS) and overall survival (OS) compared to the group without response (PFS: 6.9 vs 3.5 months, OS: 10.9 vs 6.1 months). Minimum ADC values within enhancing and non-enhancing regions were lower in responders compared to those of non-responders (1,099 vs 984 × 10(-6) mm(2)/s, p = 0.006). Smaller enhancing area was associated with longer OS (HR = 1.99, p = 0.017). The ratio of T2/FLAIR to enhancing area was prognostic of OS for only the Grade III HGG subgroup (HR = 0.14, p = 0.004). Area of enhancing tumor at baseline can stratify survival in patients with recurrent HGG treated with bevacizumab. The extent of edema relative to enhancing area may have a prognostic role specific to Grade III HGG.

Factors associated with external ventricular drain placement accuracy: data from an electronic health record repository.

BACKGROUND: We evaluated external ventricular drain placement for factors associated with placement accuracy. Data were acquired using an electronic health record data requisition tool. METHOD: Medical records of all patients who underwent ventriculostomy from 2003 to 2010 were identified and evaluated. Patient demographics, diagnosis, type of guidance and number of catheter passes were searched for and recorded. Post-procedural hemorrhage and/or infection were identified. A grading scale was used to classify accuracy of catheter placements. A multiple logistic regression model was developed to assess features associated with accurate catheter placement. RESULTS: One hundred nine patients who underwent 111 ventriculostomies from 2003 to 2010 were identified. Patient diagnoses were classified into vascular (63 %), tumor (21 %), trauma (14 %), and cyst (2 %). Procedures were performed freehand in 90 (81 %), with the Ghajar guide in 17 (15 %), and with image guidance in 4 (4 %) patients. Eighty-eight (79 %) catheters were placed in the correct location. Trauma patients were more likely to have catheters misplaced (p = 0.007) whereas patients in other diagnostic categories were not significantly associated with misplaced catheters. Post-procedural hemorrhage was noted in 2 (1.8 %) patients on post-procedural imaging studies. Five (4.5 %) definite and 6 (5.4 %) suspected infections were identified. CONCLUSIONS: External ventricular drain placement can be performed accurately in most patients. Patients with trauma are more likely to have catheters misplaced. Further development is required to identify and evaluate procedure outcomes using an electronic health record repository.

Comparison of wideband steady-state free precession and T2-weighted fast spin echo in spine disorder assessment at 1.5 and 3 T.

Wideband steady-state free precession (WB-SSFP) is a modification of balanced steady-state free precession utilizing alternating repetition times to reduce susceptibility-induced balanced steady-state free precession limitations, allowing its use for high-resolution myelographic-contrast spinal imaging. Intertissue contrast and spatial resolution of complete-spine-coverage 3D WB-SSFP were compared with those of 2D T2-weighted fast spin echo, currently the standard for spine T2-imaging. Six normal subjects were imaged at 1.5 and 3 T. The signal-to-noise ratio efficiency (SNR per unit-time and unit-volume) of several tissues was measured, along with four intertissue contrast-to-noise ratios; nerve-ganglia:fat, intradural-nerves:cerebrospinal fluid, nerve-ganglia:muscle, and muscle:fat. Patients with degenerative and traumatic spine disorders were imaged at both MRI fields to demonstrate WB-SSFP clinical advantages and disadvantages. At 3 T, WB-SSFP provided spinal contrast-to-noise ratios 3.7-5.2 times that of fast spin echo. At 1.5 T, WB-SSFP contrast-to-noise ratio was 3-3.5 times that of fast spin echo, excluding a 1.7 ratio for intradural-nerves:cerebrospinal fluid. WB-SSFP signal-to-noise ratio efficiency was also higher. Three-dimensional WB-SSFP disadvantages relative to 2D fast spin echo are reduced edema hyperintensity, reduced muscle signal, and higher motion sensitivity. WB-SSFP's high resolution and contrast-to-noise ratio improved visualization of intradural nerve bundles, foraminal nerve roots, and extradural nerve bundles, improving detection of nerve compression in radiculopathy and spinal-stenosis. WB-SSFP's high resolution permitted reformatting into orthogonal planes, providing distinct advantages in gauging fine spine pathology.

Clinical experience with an in-NICU magnetic resonance imaging system.

OBJECTIVE: To evaluate the utility of the 1 Tesla (1 T) Embrace (Aspect Imaging) neonatal magnetic resonance imaging (MRI) scanner in a level III NICU. STUDY DESIGN: Embrace brain MRI findings for 207 infants were reviewed, including 32 scans directly compared within 5 days with imaging on a 3 T Siemens Trio. Clinical MRI scan abnormalities were also compared to cranial ultrasound findings. RESULT: Of the 207 Embrace brain MRIs, 146 (70.5%) were obtained for clinical indications and 61 (29.5%) were research cases. Abnormal findings were found in 80 scans, most commonly hemorrhage and white matter injury. Notable findings included a stroke, medullary brainstem tumor, and polymicrogyria. In the 1 T versus 3 T comparison cohort, results were discordant in only one infant with punctate foci of susceptibility noted only on the 3 T scan. CONCLUSION: The Embrace MRI scans detected clinically relevant brain abnormalities and in a subset were clinically comparable to 3 T scans.

Influence of metopic suture fusion associated with sagittal synostosis.

Some patients with sagittal synostosis present with a fused metopic suture. We hypothesize that premature metopic suture fusion consistently and identifiably alters form associated with sagittal synostosis. We previously validated three-dimensional vector analysis as a tool for the study of cranial morphology and used it herein to distinguish between dysmorphologies of isolated sagittal synostosis (ISS) and combined sagittal-metopic synostosis (CSM). Preoperative computed tomographic scans for patients with ISS and CSM were compared with matched normative counterparts. Premature metopic suture fusion was defined by established radiographic criteria. Color-coded point clouds were created for each scan, with color gradient based on patient deviation from normal across the dysmorphic skull. Standard deviation data were evaluated in 7 cranial regions and compared between ISS and CSM. Mean ISS and CSM point clouds were evaluated. Using three-dimensional vector analysis, standard anthropometric data/indices were determined and compared between the 2 groups. Differences in ISS and CSM regional deviations and index measurements were not statistically significant. Mean ISS and CSM representations depicted similar overall morphology. Using accepted criteria for identification of metopic synostosis in CSM, only subtle differences appear between the 2 populations on average. Expected morphologic changes associated with metopic synostosis are present in only a small number of patients with CSM, arguing against our hypothesis, and calling into question the criteria used to identify premature metopic suture fusion. Normal metopic suture fusion occurs for a continuum of time. Our findings suggest that the normal continuum may begin earlier than the literature suggests. In the setting of sagittal synostosis, the influence of metopic suture fusion and treatment is best determined by individual morphologic analysis.

Geometric variations associated with posterior communicating artery aneurysms.

BACKGROUND: Hemodynamic stress, conditioned by the morphology of the surrounding vasculature, plays an important role in aneurysm formation. Our goal was to identify image-based location-specific parameters that are associated with posterior communicating artery (PCoA) aneurysms. METHODS: Three-dimensional morphological parameters obtained from CT angiography or digital subtraction angiography from 187 patients with unilateral PCoA aneurysms, diagnosed at the Brigham and Women's Hospital and Massachusetts General Hospital between 1990 and 2016, were evaluated. In order to control for genetic and clinical risk factors, we chose the contralateral unaffected PCoA as a control group. We examined diameters and angles of the surrounding parent and daughter vessels. Univariable and multivariable statistical analyses were performed to determine statistical significance. Sensitivity analyses with small aneurysms (≤5 mm) only and an unmatched analysis of 432 PCoA aneurysms and 197 control patients without PCoA aneurysms were also performed. RESULTS: In a multivariable conditional logistic regression model we showed that smaller diameter size ratio (OR 1.45×10-5, 95% CI 1.12×10-7 to 1.88×10-3) and larger daughter-daughter angle (OR 1.04, 95% CI 1.02 to 1.07) were significantly associated with PCoA aneurysm presence after correcting for other variables. In subgroup analyses of small aneurysms (≤5 mm) and in an unmatched analysis the significance and direction of these results were preserved. CONCLUSIONS: Larger daughter-daughter angles and smaller diameter size ratio are significantly associated with the presence of PCoA aneurysms. These simple parameters can be utilized to guide the risk assessment for the formation of PCoA aneurysms in high risk patients.

Tobacco use and age are associated with different morphologic features of anterior communicating artery aneurysms.

We present a cohort of patients with anterior communicating artery (ACoA) aneurysms to investigate morphological characteristics and clinical factors associated with rupture of the aneurysms. 505 patients with ACoA aneurysms were identified at the Brigham and Women's Hospital and Massachusetts General Hospital between 1990 and 2016, with available CT angiography (CTA). Three-dimensional (3D) reconstructions were performed to evaluate aneurysmal morphologic features, including location, projection, irregularity, the presence of daughter dome, height, height/width ratio, and relationships between surrounding vessels. Patient risk factors assessed included patient age, sex, tobacco use, alcohol use, and family history of aneurysms and aneurysmal subarachnoid hemorrhage. Logistic regression was used to build a predictive ACoA score for rupture. Morphologic features associated with ruptured ACoA aneurysms were the presence of a daughter dome (OR 21.4, 95% CI 10.6-43.1), smaller neck diameter (OR 0.55, 95% CI 0.42-0.71), larger aspect ratio (OR 3.57, 95% CI 2.05-6.24), larger flow angle (OR 1.03, 95% CI 1.02-1.05), and smaller ipsilateral A2-ACoA angle (OR 0.98, 95% CI 0.97-1.00). Tobacco use was predominantly associated with morphological factors intrinsic to the aneurysm that were associated with rupture while younger age was also associated with morphologic features extrinsic to the aneurysm that were associated with rupture. The ACoA score had good predictive capacity for rupture with AUC = 0.92 using the 0.632 bootstrap cross-validation for correction of overfitting bias. Ruptured ACoA aneurysms were associated with morphological features that are simple to assess using a simple scoring system. Tobacco use and younger age were predominantly associated with intrinsic and extrinsic morphological features characteristic of rupture, respectively.

Morphological variables associated with ruptured basilar tip aneurysms.

Morphological factors of intracranial aneurysms and the surrounding vasculature could affect aneurysm rupture risk in a location specific manner. Our goal was to identify image-based morphological parameters that correlated with ruptured basilar tip aneurysms. Three-dimensional morphological parameters obtained from CT-angiography (CTA) or digital subtraction angiography (DSA) from 200 patients with basilar tip aneurysms diagnosed at the Brigham and Women's Hospital and Massachusetts General Hospital between 1990 and 2016 were evaluated. We examined aneurysm wall irregularity, the presence of daughter domes, hypoplastic, aplastic or fetal PCoAs, vertebral dominance, maximum height, perpendicular height, width, neck diameter, aspect and size ratio, height/width ratio, and diameters and angles of surrounding parent and daughter vessels. Univariable and multivariable statistical analyses were performed to determine statistical significance. In multivariable analysis, presence of a daughter dome, aspect ratio, and larger flow angle were significantly associated with rupture status. We also introduced two new variables, diameter size ratio and parent-daughter angle ratio, which were both significantly inversely associated with ruptured basilar tip aneurysms. Notably, multivariable analyses also showed that larger diameter size ratio was associated with higher Hunt-Hess score while smaller flow angle was associated with higher Fisher grade. These easily measurable parameters, including a new parameter that is unlikely to be affected by the formation of the aneurysm, could aid in screening strategies in high-risk patients with basilar tip aneurysms. One should note, however, that the changes in parameters related to aneurysm morphology may be secondary to aneurysm rupture rather than causal.