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This study characterized the impact of vein wall biomechanics on inflow diameter and luminal flow during venous angioplasty and stent placement, using postthrombotic and healthy biomechanical properties from an ovine venous stenosis and thrombosis model. Finite element analysis demonstrated more pronounced inflow channel narrowing in the postthrombotic vein compared with the healthy control vein during angioplasty and stent placement (relative inflow diameter reduction of 42% versus 13%, P.0001). Computational fluid dynamics modeling showed increased relative areas of low wall shear rate in the postthrombotic vein compared with the normal vein (0.46 vs 0.24 for shear rate50 s

Purpose To characterize the Poisson effect in response to angioplasty and stent placement in veins and identify potential implications for guiding future venous-specific device design. Materials and Methods In vivo angioplasty and stent placement were performed in 3 adult swine by using an established venous stenosis model. Iron particle endothelium labeling was performed for real-time fluoroscopic tracking of the vessel wall during intervention. A finite-element computational model of a vessel was created with ADINA software (version 9.5) with arterial and venous biomechanical properties obtained from the literature to compare the response to radial expansion. Results In vivo angioplasty and stent placement in a venous stenosis animal model with iron particle endothelium labeling demonstrated longitudinal foreshortening that correlated with distance from the center of the balloon (R2 = 0.87) as well as adjacent segment narrowing that correlated with the increase in diameter of the treated stenotic segment (R2 = 0.89). Finite-element computational analysis demonstrated increased Poisson effect in veins relative to arteries (linear regression coefficient slope comparison, arterial slope 0.033, R2 = 0.9789; venous slope 0.204, R2 = 0.9975; P Conclusions Clinically observed adjacent segment narrowing during venous angioplasty and stent placement is a result of the Poisson effect, with redistribution of radially applied force to the longitudinal direction. The Poisson effect is increased in veins relative to arteries as a result of unique venous biomechanical properties, which may be relevant to consider in the design of future venous interventional devices.

Advanced cases of phlegmasia cerulea dolens (PCD) with absent pedal pulses, sensory/motor deficits, and/or venous gangrene likely require more rapid restoration of flow compared to cases without these factors to prevent progression and associated morbidity/mortality. We present a case of PCD with absent pedal pulses and sensory deficit managed successfully with emergent percutaneous mechanical thrombectomy using Inari ClotTriever (Inari Medical, Irvine, CA) with immediate clinical resolution, including restoration of pedal pulses ~ 45 min after thrombectomy. Percutaneous mechanical thrombectomy with the ClotTriever device has the ability to immediately restore venous flow reversing the pathophysiology of PCD in a short time period similar to surgical embolectomy and may be an alternative treatment strategy in patients with phlegmasia cerulea dolens of high severity.

There is no classification system for describing inferior vena cava (IVC) injuries. The objective of this study was to develop a standardized grading system for venographic appearance of the IVC following percutaneous IVC filter retrieval.A classification system for the appearance of the IVC on cavograms following percutaneous IVC filter removal was developed consisting of two grading elements; luminal characteristics and extravasation. Luminal narrowing from 0% up to 50% from any cause is grade 1; narrowing between 50 and 99% is grade 2; occlusion is grade 3; and avulsion is grade 4. Absence of extravasation is grade A, contained extravasation is grade B, and free extravasation is grade C. This system was then applied retrospectively to pre- and post-IVC filter retrieval cavograms performed at a single institution from October 2004 through February 2019.546 retrieval attempts were identified with 509 (93.2%) filters successfully retrieved. 449 cases (88.2%) had both pre-retrieval and post-retrieval imaging appropriate for application of the proposed classification system. Inter-rater reliability was 0.972 for luminal characteristics, 0.967 for extravasation, and 0.969 overall. Consensus grading demonstrated a distribution of 97.3% grade 1, 1.3% grade 2, 1.3% grade 3, and 0.0% grade 4 for post-retrieval luminal characteristics. For extravasation classification, 96.4% of the cases were classified as grade A, 2.7% grade B, and 0.9% grade C.A classification system was developed for describing IVC appearance after IVC filter retrieval, and retrospectively validated using a single center dataset.

Open surgical repair of dissections and post-dissection degenerative aneurysms involving the ascending thoracic aorta and aortic arch, whether in the acute or post-repair state, is associated with high rates of morbidity and mortality. Recent advancements in minimally invasive endovascular techniques have expanded the role of thoracic endovascular aortic repair (TEVAR) for dissections and dissection-related arch pathologies. Image-guided endovascular techniques, such as in situ fenestrated grafts, chimney and/or periscope grafts, along with newly developed commercially available branched aortic devices, have allowed for an increasing number of high-risk operative candidates to undergo definitive repair of aortic arch pathology who otherwise would have been destined for non-operative management. This paper reviews the data, pre-procedural planning, and technical considerations for complex TEVAR techniques for ascending and aortic arch dissections and dissection-related aneurysms.

Purpose The purpose of this study was to characterize the hemodynamics of peripheral artery stent grafts to guide intelligent stent redesign. Materials and methods Two surgically explanted porcine arteries were mounted in an ex vivo system with subsequent deployment of an Xpert self-expanding nitinol stent or Viabahn stent graft. The arteries were casted with radiopaque resin, and the cast then scanned using micro-computed tomography at 8 μm isotropic voxel resolution. The arterial lumen was segmented and a computational mesh grid surface generated. Computational fluid dynamics (CFD) analysis was subsequently performed using COMSOL Multiphysics 5.1. Results CFD analysis demonstrated low endothelial shear stress (ESS) involving 9.4 and 63.6% surface area of the central stent graft and bare metal stent, respectively. Recirculation zones were identified adjacent to the bare metal stent struts, while none were identified in the central stent graft. However, the stent graft demonstrated malapposition of the proximal stent graft edge with low velocity flow between the PTFE lining and arterial wall, which was associated with longitudinally and radially oriented recirculation zones and low ESS. Conclusion Computational hemodynamic analysis demonstrates that peripheral artery stent grafts have a superior central hemodynamic profile compared to bare metal stents. Stents grafts, however, suffer from malapposition at the proximal stent edge which is likely a major contributor to edge stenosis.

The clinical presentation of a patient with acute pulmonary embolism (PE) can be classified into 3 categories: low-risk, submassive (presence of right heart strain), and massive (hemodynamic compromise). Massive PE is associated with high morbidity or mortality and typically treated with systemic intravenous thrombolysis. Over the last 2 decades, however, catheter-directed techniques have become an increasingly popular treatment modality for patients with a contraindication to systemic thrombolysis or without clinical improvement after systemic thrombolysis. Furthermore, endovascular treatment for patients with submassive PE has been of great interest due to the significantly increased mortality associated with right heart strain, and prospective clinical trials have demonstrated catheter-directed thrombolysis to decrease right heart strain earlier than systemic anticoagulation alone. This article describes available devices and endovascular techniques used to treat patients with massive and submassive acute PE.

OBJECTIVE. The evidence regarding pulmonary embolism treatment has greatly advanced over the past 10 years, particularly in patients with right ventricular dysfunction or hemodynamic instability. Treatment options include systemic anticoagulation, systemic thrombolysis, catheter-assisted thrombus removal (mechanical with or without catheter-directed thrombolysis), and surgical embolectomy. CONCLUSION. This article will review the data available for treatment options and summarize the evidence-based guidelines on treatment of intermediate- or high-risk pulmonary embolism.

To evaluate yttrium-90 (Y90) radioembolization outcomes across Child-Pugh scores in patients with advanced hepatocellular carcinoma (HCC).From April 2005 to December 2018, 106 consecutive patients with BCLC Stage C HCC who underwent Y90 radioembolization were retrospectively analyzed. Exclusion criteria included additional malignancy (n = 7), death unrelated to liver disease (n = 2), metastases (n = 2), or lack of follow-up data (n = 4). Ninety-one patients were analyzed. Overall survival (OS) was calculated using the Kaplan-Meier method and compared between groups with the log-rank test. Cox regression modeling was used to evaluate the prognostic factors for survival.Mean age was 63 years and 85.7% were male. HCV infection was the most common etiology of liver disease (58.2%). Sixty-four (70.3%) patients were Child-Pugh A, 19 (20.9%) patients were B7, and eight (8.8%) patients were B8-9. Median OS after radioembolization was 20.2 [95% confidence interval (CI) 13.0-27.4], 6.0 (95% CI 4.4-7.6), and 5.5 (95% CI 2.5-8.5) months for Child-Pugh A, B7, and B8/9 groups, respectively (P 0.001 for B7 vs. A; P = 0.537 for B7 vs. B8/9). The multivariable Cox regression analysis showed that Eastern Cooperative Oncology Group (ECOG) score (P 0.001), Child-Pugh class (P = 0.005), tumor morphology pattern (P = 0.012), and Y90 delivery location (P = 0.020) were significant independent predictors of overall survival.Outcomes from Y90 for BCLC C HCC for Child-Pugh B7 patients were equivalent to B8/9 patients and significantly worse compared to Child-Pugh A patients. Although further research is warranted, these results suggest continued cautious patient selection for radioembolization in advanced HCC.

Purpose To describe initial single-center experience with a thrombectomy device in managing right atrial and caval thrombi, tumors, and vegetations. Materials and Methods A retrospective analysis of AngioVac thrombectomy performed in 16 patients (mean age 53 y ± 13; 8 men, 8 women) between August 2013 and August 2015 was performed. Indications included right atrial mass/thrombus (6/16; 37.5%) and iliocaval thrombus (10/16; 62.5%). Procedural success was defined as aspiration of > 70% volume of atrial mass/thrombus or restoration of antegrade caval flow. Results Procedural success was achieved in 4/6 (67%) right atrial masses/thrombi and 10/10 (100%) caval thrombi. All patients (8/8; 100%) with caval thrombus presenting with swelling/edema had improvement or resolution of symptoms. There were no procedural or periprocedural mortalities; complications included one major (6.3%; intraprocedural pulmonary embolus) and one minor (6.3%; access site hematoma not requiring transfusion) complication. Of 16 patients, 14 (87.5%) survived to discharge at a mean of 10 days ± 8 (range, 1–23 d), and 12 patients (75%) were alive at last known follow-up at a mean of 385 days ± 267 (range, 63–730 d). At a mean of 194 days ± 177 (range, 41–372 d), 4/16 (25%) patients were dead; no death was related to AngioVac thrombectomy. At a mean of 66 days ± 21 (range, 49–90 d) after intervention, 3/14 (21.4%) cases with procedural success had local recurrence of mass/thrombus. Conclusions AngioVac thrombectomy can be performed with high procedural success with clinical benefit in patients with right atrial and caval masses/thrombi.

Five consecutive cases in which the AngioVac aspiration cannula was used for the management of pulmonary embolism (PE) were retrospectively reviewed. Four cases (80%) presented with massive PE, and two (40%) were technically successful (reduction in Miller index ≥ 5). Four patients (80%) died at a mean of 7.3 days after the procedure, including one death related to right ventricular free wall perforation. Although the AngioVac aspiration cannula has shown clinical promise in a variety of clinical applications, early experience in the pulmonary arteries has shown limited success, and further study and careful patient selection are required.

BACKGROUND Inflammation and platelet activation have been shown to be involved in acute thromobogenicity following venous occlusive conditions. The aim of this study was to identify the association of baseline platelet count and neutrophil/lymphocyte ratio (NLR) with venous stent failure. Methods and Results: Patients who underwent technically successful iliocaval venous stent placement with available baseline complete blood count and follow-up stent patency data were selected (n=50). Stent failure was defined as >50% stenosis or occlusion at follow-up angiography, contrast-enhanced CT, MRI or duplex US. Median patient age was 49.5 years (range, 13-76 years), and 62% were female. Median follow-up time was 10.2 months (range, 0.1-76.4 months). Stent failure occurred in 13 patients (26%) after a median of 1.2 months (range, 1 day-76.4 months). On multivariable-adjusted Cox modeling, baseline platelets (HR, 2.28; P=0.004) and WBC count (HR, 2.03; P=0.013) were significantly associated with stent failure on follow-up; neutrophils (HR, 16.10; P=0.050); and NLR (HR, 12.19; P=0.050) had borderline significance. Compared with patients without stent failure, those with early, but not late, stent failure had higher baseline platelets (P=0.031) and neutrophils (P=0.025), and NLR (P=0.026). CONCLUSIONS Baseline platelet count and NLR are associated with early but not late failure of iliocaval venous stents. This suggests different pathophysiologic mechanisms and a role for both platelet activation and inflammatory mechanisms in early rather than late stent thrombosis. Future research is needed to better explain this novel finding.

Thoracic endovascular aortic repair (TEVAR) is a rapidly growing and improving technique for the management of thoracic aortic aneurysms, dissections, and traumatic aortic injury. These disease processes were previously treated exclusively by surgery, but TEVAR has substantially improved patient outcomes including reduced mortality, reduced paraplegia rate, and shorter hospital and/or intensive care unit stay compared to open surgery. TEVAR was initially isolated to the descending thoracic aorta, but the advent of advanced techniques has extended the scope to well beyond the left subclavian artery and into Zone 0. Recent techniques include chimney grafts, periscope grafts, in situ fenestrations, and physician modified grafts. In addition, commercial branched aortic devices are currently on trial and will likely vastly extend the off-the-shelf capabilities of TEVAR for aortic arch disease. This paper reviews the data, concepts, and technical aspects of current advanced TEVAR techniques, as well as ongoing clinical trials for thoracic branched aortic devices.

PURPOSE To investigate the efficacy of palmar warming to induce radial artery vasodilation. MATERIALS AND METHODS After informed consent was obtained, healthy volunteers (n = 45) were randomized 2:1 in palmar warming and control groups, respectively, for this prospective, randomized, single-blind clinical trial (NCT03620383). The palmar warming group was given a warm, commercially available, air-activated heat pack (Kobayashi Consumer Products LLC, Dalton, Georgia) to hold in the left hand for palmar warming. The control group was given a deactivated version of the same heat pack. Left radial artery cross-sectional area (CSA) measurements were obtained at baseline and in 5-minute intervals up to 20 minutes in both groups. Differences in the trends of changes in the radial artery CSA between palmar warming and control groups were examined with the age- and sex-adjusted repeated measure analysis of variance. Propensity score-matched treatment effect analysis was conducted to quantify the effect of heat on radial artery CSA. RESULTS The palmar warming group and the control group were significantly different in terms of subject sex (males/females: 7/23 and 10/5, respectively; P = .005) and baseline CSA (2.5±0.2 mm2 vs 3.2±0.3 mm2, respectively; P = .014). Radial artery CSA showed an increasing trend over time in the palmar warming group compared to a stable trend over time in the control group (P < .0001). Propensity score-matched comparison showed a 43.9% increase (95% confidence interval: 34.1%-53.8%) in CSA in the palmar warming group compared to the control group (P < .0001). CONCLUSIONS The palmar warming technique is effective at dilating the radial artery and may be a beneficial technique to facilitate transradial access.

An 83-year-old man with bilateral common iliac artery aneurysms (right, 3.0 cm; left, 2.7 cm), bilateral internal iliac artery aneurysms (right, 3.4 cm; left, 2.6 cm), and an abdominal aortic aneurysm (3.8 cm) was treated with an aortobi-iliac stent graft and bilateral iliac branch devices. The internal iliac components were extended into opposing posterior (left) and anterior (right) divisions of the internal iliac artery using stent grafts. Computed tomography angiography demonstrated that all aneurysms decreased or were stable in size with patent stent grafts at 1 month. The patient was asymptomatic without complications of pelvic ischemia at the last clinical follow-up at 6 months.

The Indigo Mechanical Thrombectomy System (Penumbra, Inc, Alameda, California) was used to treat 6 patients with submassive pulmonary embolism (PE) and a contraindication to thrombolysis. Systolic pulmonary artery pressure (58.2 mm Hg vs 43.0 mm Hg, P .05), right ventricular/left ventricular ratio (1.7 vs 1.1, P.05), Miller index (15.0 vs 9.8, P0.01), and CT obstructive index (60.4% vs 47.0%, P.01) were significantly reduced after mechanical thrombectomy. There were no procedural or periprocedural complications. Continuous aspiration mechanical thrombectomy is a feasible and promising technique for management of submassive PE to decrease thrombus burden and reduce right heart strain.

This case reports describes a 39-year-old female with a history of surgically repaired hypoplastic left heart syndrome who presented with a left peripherally inserted central catheter (PICC) with associated large volume subclavian and brachiocephalic vein thrombus. Due to the presence of a right-to-left shunt via a fenestrated Fontan, there was clinical concern for a paradoxical embolism during removal of the PICC. The AngioVac aspiration system was successfully utilized to aspirate thromboemboli from the level of the proximal Glenn shunt during manipulation and removal of the PICC. This is the first reported case to demonstrate the safe and effective use of the AngioVac aspiration system for protection of paradoxical emboli through a cardiac right-to-left shunt during a procedure at high risk for thromboembolism.

To investigate pulmonary microwave ablation metrics including ablation work, ablation resistance score, and involution.Retrospective review was performed of 98 pulmonary tumor ablations using the NeuWave Certus Microwave Ablation System (NeuWave Medical, Madison, Wisconsin) in 71 patients (32 men and 39 women; mean age, 64.7 y ± 11.5). Ablation work was defined as sum of (power) * (time) * (number of antennas) for all phases during an ablation procedure. Ablation zone was measured on CT at 3 time points: after procedure, 1-3 months (mean 47 d), and 3-12 months (mean 292 d). Ablation zones were scored based on location for pulmonary lobe (upper = 1, middle/lingula = 2, lower = 3) and region (peripheral = 1, parenchymal = 2, central = 3), and the 2 were summed for ablation resistance score.Ablation zone on CT at 1-3 months was significantly smaller in regions with higher ablation resistance score (P.05). There was a significant correlation between ablation work and ablation zone measured on CT performed after procedure (P.001), at 1-3 months (P.001), and at 3-12 months (P.05). Ablation zone significantly decreased from after procedure to 1-3 months (P.001) and from 1-3 months to 3-12 months (P.001), with change from after procedure to 1-3 months significantly greater (P.01).Pulmonary microwave ablation zone is significantly smaller in regions with higher ablation resistance score. Ablation work correlates to ablation zone with a nonlinear involution pattern in the first year and may be useful for planning before the procedure.

Extensive research supports an association between radiation exposure and cataractogenesis. New data suggests that radiation-induced cataracts may form stochastically, without a threshold and at low radiation doses. We first review data linking cataractogenesis with interventional work. We then analyze the lens dose typical of various procedures, factors modulating dose, and predicted annual dosages. We conclude by critically evaluating the literature describing techniques for lens protection, finding that leaded eyeglasses may offer inadequate protection and exploring the available data on alternative strategies for cataract prevention.

The loop snare technique is a method for inferior vena cava (IVC) filter retrieval that creates a wire loop between the filter legs; this technique may fail in cases with an embedded hook. This report describes the hangman technique, a modified loop snare technique for filter retrieval that creates a wire loop between the filter neck and IVC wall for release of embedded filter hooks. The hangman technique was attempted in 11 cases complicated by tilt (mean tilt, 13.3 degrees ± 3.9) and an embedded hook (mean dwell time, 194.5 d) with a retrieval success rate of 81.8% (9 of 11 cases) and no associated complications.

The striatum is the input component of the basal ganglia from the cerebral cortex. It includes the caudate, putamen, and nucleus accumbens. Thus, the striatum is an important component in limbic frontal-subcortical circuitry and is believed to be relevant both for reward-guided behaviors and for the expression of psychosis. The dorsal striatum is composed of the caudate and putamen, both of which are further subdivided into pre- and post-commissural components. The ventral striatum (VS) is primarily composed of the nucleus accumbens. The striatum can be functionally divided into three broad regions: 1) a limbic; 2) a cognitive and 3) a sensor-motor region. The approximate corresponding anatomic subregions for these 3 functional regions are: 1) the VS; 2) the pre/post-commissural caudate and the pre-commissural putamen and 3) the post-commissural putamen. We believe assessing these subregions, separately, in disorders with limbic and cognitive impairment such as schizophrenia may yield more informative group differences in comparison with normal controls than prior parcellation strategies of the striatum such as assessing the caudate and putamen. The manual parcellation of the striatum into these subregions is currently defined using certain landmark points and geometric rules. Since identification of these areas is important to clinical research, a reliable and fast parcellation technique is required. Currently, only full manual parcellation using editing software is available; however, this technique is extremely time intensive. Previous work has shown successful application of heuristic rules into a semi-automatic platform1. We present here a semi-automatic algorithm which implements the rules currently used for manual parcellation of the striatum, but requires minimal user input and significantly reduces the time required for parcellation.

Purpose: To investigate the success and safety of routine versus advanced inferior vena cava (IVC) filter retrieval techniques. Materials And Methods: A retrospective review was performed of patients who underwent IVC filter placement and/or a retrieval attempt over a 10-year period. Retrieval technique(s), preretrieval computed tomography, preretrieval venography, and clinical/imaging follow-up for 30 days after retrieval were analyzed. Mean filter dwell time was 134 days (range, 0–2,475 d). Results: Filter retrieval was attempted 231 times in 217 patients (39% female, 61% male; mean age, 50.7 y), with success rates of 73.2% (169 of 231) and 94.7% (54 of 57) for routine and advanced filter retrieval techniques, respectively. The overall filter retrieval complication rate was 1.7% (four of 231); complications in four patients (with multiple complications in some cases) included IVC dissection, IVC intussusception, IVC thrombus/stenosis, filter fracture with embedded strut, IVC injury with hemorrhage, and vascular injury from complicated venous access. The rate of complications associated with filter retrievals that required advanced technique was significantly higher than seen with routine technique (5.3% vs 0.4%; P o .05). Longer dwell time, more transverse tilt, and presence of an embedded hook were associated with significantly increased rates of failed retrieval via routine technique (P o .05). Conclusions: IVC filters can be retrieved with a high overall success rate (98.2%) and a low complication rate (1.7%) by using advanced techniques when the routine approach has failed; however, the use of advanced techniques is associated with a significantly higher complication rate.

Anatomic anterior cruciate ligament (ACL) reconstruction has proven to be a reliable method to restore knee stability. However, the risk of physeal arrest with transphyseal tunnel placement in skeletally immature patients has raised concern regarding this technique. Conservative nonoperative management also has its limitations resulting in meniscal and chondral damage that may lead to degenerative joint disease and poor return to sport. Researchers have used animal models to study the threshold of physeal damage producing growth deformity. The purpose of this study was to examine the distal femoral and proximal tibial physes and determine the damage produced by drilling transphyseal tunnels. In addition, we attempted to find a reproducible angle at which to drill the tibial tunnel for safe interference screw placement. To do this, we used a custom software module.A custom software package designed by our team was used: Module for Adolescent ACL Reconstructive Surgery (MAARS). This module created a 3-dimensional model of the distal femur and proximal tibia. The data required for MAARS were sagittal and coronal T1 magnetic resonance imagings of at least 1.5 T. Thirty-one knee magnetic resonance imaging studies from patients aged 10 to 15 years old were used. The physes were segmented out to obtain volumetric measurements. Transphyseal tunnels were simulated based on the anatomic trajectory of the native ACL. The module calculated volume of physis was removed with the use of an 8-mm tunnel and the optimum angle for trajectory.Average volume of the tibial and femoral physis was 12,683.1 microL and 14,708.3 microL, respectively. The volume increased linearly with age. Average volume removed from the tibial and femoral physis was 318.4 microL and 306.29 microL, respectively. This represented 2.4% of the distal femoral physis and 2.5% of the proximal tibial physis. The volume percent removed decreased linearly with age.Manipulation of the variables demonstrates graft radius is the most critical parameter affecting the volume of physeal injury. Variation of graft diameter from 6 mm to 11 mm will increase volume percent removed from 2.3% to 7.8%, which averages 1.1% for every 1 mm increase. Increasing tunnel drill angle from 45 degrees to 70 degrees will decrease volume percent removed from 4.1% to 3.1% which averages 0.2% removed for each 5 degrees increase in drill angle. The average angle to maintain a distance of 20 mm from the proximal tibial physis was 65 degrees with a range of 40 degrees to 85 degrees.Less than 3% injury occurs when drilling an 8-mm tunnel across the physis. A vertical tunnel has minimal effect, but the tunnel diameter is critical. Interference screws can be placed safely to avoid the physis but requires careful planning. The MAARS module may be helpful in preoperative planning.Diagnostic, level IV.

The hippocampus is often a difficult structure to visualize with magnetic resonance imaging (MRI) and functional MRI (fMRI) due to its convoluted nature and susceptibility to signal dropout. Improving our ability to pinpoint changes in neural activity using fMRI in this structure remains an important challenge. Current fMRI/MRI methods typically do not permit visualization of the hippocampus and surrounding cortex at a resolution less than 1 mm. We present here improvements to our previous methods for obtaining structural MR images of the hippocampus, which provided an in-plane resolution of 0.4 mm(2) mm and two-dimensional "flat" maps of the hippocampus with an interpolated isotropic resolution of 0.4 mm(3) (Engel, S.A., Glover, G.H., and Wandell, B.A., (1997). Retinotopic organization in human visual cortex and the spatial precision of functional MRI. Cereb. Cortex 7, 181-192.; Zeineh, M.M., Engel, S.A., and Bookheimer, S.Y., (2000). Application of cortical unfolding techniques to functional MRI of the human hippocampal region. NeuroImage 11, 668-683.). We present changes to existing structural imaging sequences that now augment the resolution of previous scans, permitting visualization of the anterior portion of CA1, parts of the dentate gyrus, and CA23. These imaging improvements are of relevance generally to the field of imaging because they permit higher overall resolution imaging of the hippocampus than previously possible (at 3 T). We also introduce a novel application of a computational interpolation method that improves our ability to capture the convoluted three-dimensional shape of the hippocampus. Furthermore, we have developed a quantitative method for obtaining group activation patterns based on producing averaged flat maps using vector field warping techniques, allowing localization of activations to specific hippocampal subregions across groups of subjects. Together, these methods provide a means to improve imaging of neural activity in the human hippocampus and surrounding cortex during cognitive tasks.

An Insight Toolkit (ITK) implementation of our knowledgebased segmentation algorithm applied to brain MRI scans is presented in this paper. Our algorithm is a refinement of the work of Teo, Saprio, and Wandall. The basic idea is to incorporate prior knowledge into the segmentation through Bayesrule. Image noise is removed via an affine invariant anisotropic smoothing of the posteriors as in Haker et. al. We present the results of this code on two different projects. First, we show the effect of applying this code to skull-removed brain MRI scans. Second, we show the effect of applying this code to the extraction of the DLPFC from a user-defined subregion of brain MRI data.We present our results on brain MRI scans, comparing the results of the knowledge-based segmentation to manual segmentations on datasets of schizophrenic patients.

Purpose: To investigate the relationship between inferior vena cava (IVC) filter strut penetration with clinical symptoms preand post-retrieval. Materials and Methods: Retrospective analysis was performed of patients who underwent IVC filter retrieval over a 10 year period. Filter penetration associated symptoms included any patient complaint which could potentially be explained by filter penetration (i.e. abdominal and/or back pain) which was not consistent with an alternative clinical diagnosis. Chart review for alleviation of symptoms up to 30 days post-retrieval was then performed. IVC filter penetration was graded on pre-retrieval computed tomography (CT) according to increasing depth of strut penetration (grade 0-2) and evidence of contact with adjacent structures (grade 3). Results: 49 filter retrievals with pre-retrieval CT were included in our analysis, with a mean dwell time of 232 days. There was no significant difference in filter dwell time between low grade (grade 0 or 1) and high grade (grade 2 or 3) penetration or filter type. Of 21 patients with low grade penetration (grade 0, n 1⁄4 12; grade 1, n 1⁄4 9) and 19 patients with grade 2 penetration, there were no filter penetration associated symptoms. There were 9 patients with grade 3 penetration, with 4 cases of penetration associated symptoms (abdominal pain, n 1⁄4 3; back pain, n 1⁄4 1) which all had complete resolution of symptoms following filter retrieval. These 4 cases with symptomatic resolution had evidence of fat stranding on CT, while the remaining 45 cases did not (sensitivity 100% [95% CI: 39100%]; specificity 100% [95% CI: 90-100%]). Two cases of high grade penetration (without fat stranding) had symptoms which were highly consistent with an alternative clinical diagnosis, and neither had alleviation of symptoms with retrieval (back pain with chronic compression fractures; nausea with heavy non-steroidal anti-inflammatory drug use alleviated with decrease in dosage). Conclusion: Patients with high grade filter strut penetration and associated symptoms not consistent with an alternative diagnosis have a high likelihood of symptom alleviation after filter retrieval, particularly in patients with evidence of fat stranding on pre-retrieval CT. JVIR ’ Distinguished Abstracts S11