Clinical features and outcome in pediatric arteriovenous malformation: institutional multimodality treatment.

PURPOSE: Intracranial arteriovenous-malformation (AVM) is a relatively rare condition in pediatrics, yet is a major cause of spontaneous intracranial hemorrhage with a risk of fatal hemorrhage reported to be between 4 and 29%. Little is known about vessel morphology and optimum treatment modalities including multimodality combination therapy and prognosis in children. METHODS: A retrospective review of all children presenting to our institution from 2006 to 2020 that had an AVM was undertaken. RESULTS: A total of 50 children were identified with median age of 11 (range 1-16) years. The mean follow-up was 7.6 years. Forty-one children presented as an emergency and of those, 40 had hemorrhage identified on initial brain imaging. The average nidus size was 25 mm, drainage was superficial in 51% of cases, and located in eloquent cortex in 56%. The supplemental Spetzler-Martin grading indicated 78% (39/50) were grade 4 and above (moderate to high risk). Primary treatment modalities included embolization in 50% (25) or SRS in 30% (15) and surgery in 20% (10).The AVM was obliterated on follow-up DSA in 66% children. Three children had post-treatment hemorrhage, two related to embolization and one the day following SRS, giving a re-bleed rate of 6%. The GOSE was available for 32 children at long term follow and 94% had a good outcome (GOSE 5-8). Two children died due to acute hemorrhage (4%). CONCLUSION: The majority of children with AVM present with hemorrhage. The rebleed rate during definitive treatment is low at 6% over the study period. The selective use of the 3 modalities of treatment has significantly reduced mortality and severe disability.

Photoinitiator Selection and Concentration in Photopolymer Formulations towards Large-Format Additive Manufacturing.

Photopolymers are an attractive option for large-format additive manufacturing (LFAM), because they can be formulated from structural thermosets and cure rapidly in ambient conditions under low-energy ultraviolet light-emitting diode (UV LED) lamps. Photopolymer cure is strongly influenced by the depth penetration of UV light, which can be limited in the 2-4 mm layer thicknesses typical of LFAM. Photoinitiator (PI) systems that exhibit photobleaching have proven useful in thick-section cure applications, because they generate a photoinitiation wavefront, but this effect is time-dependent. This study investigates the light transmission and through-thickness cure behavior in (meth)acrylate photopolymer formulations with the photobleaching initiator bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide (BAPO). Utilizing an optical model developed by Kenning et al., lower concentrations (0.1 wt% to 0.5 wt%) of BAPO were predicted to yield rapid onset of photoinitiation. In situ cure measurements under continuous UV LED irradiation of 380 mW/cm2 showed that a 0.1 wt% concentration of BAPO achieved peak polymerization rate within 2.5 s at a 3-mm depth. With only 1 s of irradiation at 1.7 W/cm2 intensity, the 0.1 wt% BAPO formulation also achieved the highest level of cure of the formulas tested. For an irradiation dose of 5.5 J/cm2 at a duration of 3.7 s, cured polymer specimens achieved a flexural strength of 108 MPa and a flexural modulus of 3.1 GPa. This study demonstrates the utility of optical modeling as a potential screening tool for new photopolymer formulations, primarily in identifying an upper limit to PI concentration for the desired cure depth. The results also show that photobleaching provides only a limited benefit for LFAM applications with short (1.0 s to 3.7 s) UV irradiation times and indicate that excess PI concentration can inhibit light transmission even under extended irradiation times up to 60 s.

New QSPRs for Liquid Heat Capacity.

Quantitative Structure-Property Relationships (QSPRs) have found applications in many areas of chemistry and engineering as effective prediction methods. QSPRs use molecular descriptors to simplify complex molecular properties to a single value and have been used extensively for constant value properties. Liquid heat capacity ( cpl ) is another property where QSPRs can be helpful prediction tools. Researchers have shown strong correlation between the cpl and various molecular descriptors, but these predictions are limited to a single temperature, usually 298.15 K. Additionally, other QSPRs have had problems with oxygen-containing functional groups. In this work, QSPRs for cpl at various temperatures were developed using data selected from the DIPPR database using a novel search method. This method improves on existing QSPRs for cpl by using unique descriptors but does not overcome the issue of oxygen-containing species.

Automatic large quantity landmark pairs detection in 4DCT lung images.

PURPOSE: To automatically and precisely detect a large quantity of landmark pairs between two lung computed tomography (CT) images to support evaluation of deformable image registration (DIR). We expect that the generated landmark pairs will significantly augment the current lung CT benchmark datasets in both quantity and positional accuracy. METHODS: A large number of landmark pairs were detected within the lung between the end-exhalation (EE) and end-inhalation (EI) phases of the lung four-dimensional computed tomography (4DCT) datasets. Thousands of landmarks were detected by applying the Harris-Stephens corner detection algorithm on the probability maps of the lung vasculature tree. A parametric image registration method (pTVreg) was used to establish initial landmark correspondence by registering the images at EE and EI phases. A multi-stream pseudo-siamese (MSPS) network was then developed to further improve the landmark pair positional accuracy by directly predicting three-dimensional (3D) shifts to optimally align the landmarks in EE to their counterparts in EI. Positional accuracies of the detected landmark pairs were evaluated using both digital phantoms and publicly available landmark pairs. RESULTS: Dense sets of landmark pairs were detected for 10 4DCT lung datasets, with an average of 1886 landmark pairs per case. The mean and standard deviation of target registration error (TRE) were 0.47 ± 0.45 mm with 98% of landmark pairs having a TRE smaller than 2 mm for 10 digital phantom cases. Tests using 300 manually labeled landmark pairs in 10 lung 4DCT benchmark datasets (DIRLAB) produced TRE results of 0.73 ± 0.53 mm with 97% of landmark pairs having a TRE smaller than 2 mm. CONCLUSION: A new method was developed to automatically and precisely detect a large quantity of landmark pairs between lung CT image pairs. The detected landmark pairs could be used as benchmark datasets for more accurate and informative quantitative evaluation of DIR algorithms.

Paediatric intracranial aneurysms: a British institutional review.

INTRODUCTION: Paediatric intracranial aneurysms are rare, with a differing natural history and thought to account for only up to 7% of all intracranial aneurysms. There is much uncertainty that surrounds the prevalence of unruptured intracranial aneurysms and it is estimated to be anywhere between 2 and 90 per 1000. This is the largest British single-centre analysis of paediatric intracranial aneurysms. We present the patient course from their initial presentations to the outcome of treatment and evaluate a serial assessment of adequacy of aneurysmal obliteration radiologically. RESULTS: Twenty-two paediatric cases were identified that required treatment. The median age of presentation was 11.3 years (mean 9.9, range 0 to 15.9), 68% (15/22) were male and 77% (17/22) were ruptured on presentation. The majority of aneurysms were located at the anterior circulation (77% (17/22)). The overall median aneurysm size (n = 21) was 7.4 mm (mean 5 mm, range 2.5-19 mm). Twenty patients survived the acute phase and 80% (16/20) underwent coil embolisation and the other patients' surgical clipping. The overall outcomes were available for the 20 patients; on discharge, 90% (18/20) had a favourable clinical outcome (GOS score of 3-5). Treatment-specific clinical favourable outcomes were 88% (14/16) for coil embolisation against 100% (4/4) after surgical clipping. Of the two patients that died in the acute phase, one had sickle cell anaemia. Aneurysm aetiology was unknown in all other cases. None of the patients had a family history of aneurysms. CONCLUSION: Paediatric intracranial aneurysms while rare should be considered a differential diagnosis of children presenting with unexplained loss of consciousness with or without focal neurological deficit and/or headache. There is a two to one preponderance for males with a larger proportion of aneurysms within the posterior circulation (25%). Coil embolisation is the preferred method of securing a paediatric intracranial aneurysm.

Design and numerical simulations of W-diamond transmission target for distributed x-ray sources.

Distributed x-ray sources enable novel designs of x-ray imaging systems. However, the x-ray power of such sources is limited by the focal spot power density of the fixed anode. To further improve x-ray output, we have designed and evaluated a diamond-W transmission target for multi-pixel x-ray sources. The target features a thin layer of tungsten deposited on a diamond substrate. The thickness of tungsten layer was optimized for maximum fluence through Monte Carlo simulations. Finite element thermal simulations were performed to evaluate focal spot temperature in the target under different power loadings and dwell duration. The results showed that the optimal thickness of the tungsten layer in the W-diamond transmission target is linearly proportional to the electron energy. A 5-6 µm tungsten thickness is suitable for the kVps ranges from 60 kVp to 140 kVp. A W-diamond transmission target produces up to 20% more x-ray fluence than a traditional W reflection target in the beam center depending on the kVp settings. The x-ray spectrum of the transmission target shows less characteristic x-rays than that of reflection target. The thermal performance of W-diamond targets for peak power is significantly better than that of reflection targets. The maximum focal spot power densities of W-diamond transmission and W reflection targets are both strongly dependent on the dwell duration. For longer pulse durations, the W-diamond target allows as much as a four-fold increase in power and an eight-fold increase in power density in comparison to a traditional W reflection target for the same temperature spikes. The stability of the W-diamond bond needs to be tested experimentally. Nevertheless, the W-diamond transmission target is an appealing target that can significantly simplify the design and improve the performance of distributed x-ray sources.

Traumatic dural venous sinus thrombosis; a challenge in management of head injury patients.

Venous sinus thrombosis secondary to traumatic brain injury and head trauma is increasingly detected following contrast enhanced cranial imaging in acute trauma. The presence of sinus thrombosis poses further challenges in the management of traumatic brain injury patients with cerebral contusions, intraparenchymal haemorrhages or subdural/extradural haemorrhages. The decision to anti-coagulate such trauma induced venous sinus thrombosis is controversial and requires further attention and research to delineate risks versus benefits of treatment. In this article we report 4 cases of venous sinus thrombosis following head trauma and review the literature on management of such patients.

Safety results from the treatment of 109 cerebral aneurysms using the Woven EndoBridge technique: preliminary results in the United Kingdom.

OBJECTIVE The Woven Endobridge (WEB) device has been in clinical use for the treatment of brain aneurysms for the past 4 years. Observational studies to assess clinical outcome and related complications have been published. Clear evidence is required to better understand the safety profile of the WEB device. The authors here present a multicenter series that provides a detailed safety analysis focused on patient selection, procedural events, and technical issues of treated patients throughout the United Kingdom (UK). METHODS A nationwide password-protected database was set up to collect anonymous information across the UK (14 centers). Complications and clinical outcome were analyzed for the initial 109 patients (112 procedures). An independent root cause analysis classified the complications into groups (procedural, disease, device, ancillary device, and other). The modified Rankin Scale (mRS) was used as a marker of clinical outcome. RESULTS Each of the 109 patients had 1 aneurysm suitable for WEB treatment (109 aneurysms). Three patients had 2 procedures, making a total of 112 procedures performed. Eight procedures were abandoned because of access issues; 2 patients went on to have a successful procedure. All 109 patients had a preprocedure and discharge mRS scores recorded. One hundred patients had a recorded mRS score from a > 3-month follow-up. Deployment of the WEB device was successful in 103 (94.5%) of 109 patients and 104 (92.9%) of 112 procedures. One patient had 2 successful WEB procedures on separate occasions. Patients without a successfully implanted WEB device were included in the analysis. Selection analysis showed that the average patient age was 56.5 years among 34 men and 75 women. The percentage of incidental aneurysms was 58.7%, acute 16.5%, symptomatic 18.3%, and recurrent 6.4%. Further results analysis showed that 40 (36.7%) of 109 patients had recorded adverse events, including those unrelated to the WEB device. Events that could be related to the WEB device numbered 17 (15.6%) among the 109 patients. Two patients with device-related complications were symptomatic. Overall, 11 patients (10.1%) had persistent clinical sequelae. Thromboembolism was the most prevalent event, affecting 15.6% of the patients (17 of 109), and 6.4% of the patients (7 of 109) with a thromboembolism were symptomatic. Overall mortality before discharge was 0% and at the > 3-month follow-up was 5% (5 of 100 patients). Morbidity was defined as an mRS score increase to > 2. Overall morbidity at discharge was 1.8% (2 of 109) and at the > 3-month follow-up was 6% (6 of 100). No device-related morbidity or mortality was associated with this group. CONCLUSIONS The UK data show that the WEB device is safe for clinical use. Thromboembolic complication adds a risk that should be minimized with appropriate anticoagulation and correct sizing of the device. There is scope for further evaluation and standardization of an anticoagulation regimen for the WEB device.

Spontaneous Microguidewire Extrusion From the Foot Following Cerebral Aneurysm Treatment: First Case Report.

BACKGROUND AND IMPORTANCE: Microguidewire entrapment and failure related to endovascular therapy is a rare complication with limited case reports available, most of which are from cardiac endovascular intervention. Migration of the microguidewire has been reported in coronary intervention with some resulting in severe complications, but there are no reported cases of spontaneous extrusion of wire fragment following a neurointerventional procedure. We report the first case of a microguidewire entrapment with subsequent fracture, followed by spontaneous extrusion of the wire fragment. CLINICAL PRESENTATION: A 40-yr-old woman was admitted for an elective flow-diversion stent treatment of an unruptured paraophthalamic aneurysm. Microguidewire entrapment occurred during an attempted balloon-aided dilatation of the partially opened stent. Careful attempts failed to retrieve the wire; hence, the decision was made to leave it behind. She presented to her family doctor 6 mo later with spontaneous extrusion of a 60-cm fragment of the retained wire, from her heel ipsilateral to the femoral puncture site. This had not resulted in any further vascular or non-vascular complications. CONCLUSION: Fracture with extrusion is a potential consequence of a retained microguidewires. While this is an extremely rare complication, it is important to alert clinicians and patient about the possibility of wire migration and extrusion. Early follow-up with clinical assessment, and targeted imaging should lead to identification of this occurrence.

Changes in free amino acid content during naupliar development of the Calanoid copepod Acartia tonsa.

Changes in free amino acids (FAA) were investigated in the potentially important live feed and neritic copepod species Acartia tonsa during naupliar development. Total content of FAA in A. tonsa nauplii was around 17% of dry weight at first development stage, and declined to 6% for later stages. Relative to body-volume and biomass, the FAA content indicated possible volume-dependent changes. However, changes in FAA with osmolytic activity could not account for this decline in FAA content, but suggests that the decline reflected degradation of residual FAAs from the embryonic stage. Glutamic acid revealed the largest change in relative abundance during naupliar development and declined from 29.0% at first nauplius stage to 7.1% at later stages. The high FAA pool in early naupliar stages may be necessary for naupliar development due to an absence of feeding at first development stages. The high FAA content in early nauplii indicates that A. tonsa is a valuable source for nutritional energy for first-feeding fish larvae and should be further exploited for aquaculture purposes. Enhancements to FAA abundances in nauplii through manipulation of maternal diets could be of future interest, as copepod nauplii can contain a substantial pool of FAAs at first development stage.

Preliminary experience with the liquid embolic material agent PHIL (Precipitating Hydrophobic Injectable Liquid) in treating cranial and spinal dural arteriovenous fistulas: technical note.

BACKGROUND: Liquid embolic agents are the preferred embolic material in endovascular treatment of pial and brain arteriovenous malformations and dural arteriovenous fistulas (DAVFs). There is little choice available in interventional neuroradiology practice other than two of the most commonly used liquid embolic agents-n-butyl cyanoacrylate and the Onyx liquid embolic system (ev3 Neurovascular, Irvine, California, USA). PHIL (Precipitating Hydrophobic Injectable Liquid) (Microvention, Inc California, USA) is a new liquid embolic agent, CE marked and available for clinical use in Europe. OBJECTIVE: To present our preliminary experience using PHIL in treating cranial and spinal DAVFs. METHODS: Between September 2014 and January 2015, eight patients, with five cranial DAVFs and three spinal DAVFs were treated with PHIL as the sole embolic agent used with intent to cure. Clinical presentation, location of DAVF, Borden type, fluoroscopic time, radiation dose, procedural time, injecting microcatheter used, volume of PHIL injected, complications, immediate angiographic data, premorbid and discharge modified Rankin Scale score, and any neurologic deficits were included in the analysis. RESULTS: Seven patients were successfully treated with complete angiographic exclusion of the fistula in a single sitting. Treatment failed in one patient where only suboptimal microcatheter positioning could be achieved and PHIL failed to penetrate the fistula's nidus. Venous penetration was achieved in all other patients except one with a small fistula, but with adequate fistula penetration by the embolic material. No other technical complication or neurologic deterioration occurred in any of the patients. CONCLUSIONS: PHIL liquid embolic agent appears to be an excellent alternative embolic material with certain advantages compared with other available liquid embolic agents. Further studies are required to fully evaluate its safety and efficacy.

An unusual complication following translabyrinthine resection of an acoustic neuroma.

We report the case of a 58-year old man who presented with a 4 cm right acoustic neuroma. He underwent a translabyrinthine resection. Two years later he presented with multiple strokes and progressive generalised deterioration. A cerebral angiogram demonstrated an extensive right side cerebellar dural arteriovenous fistula with retrograde flow causing corticovenous reflux. The fistula was treated successfully endovascularly. There is only one published report of a dural arteriovenous fistula occurring following acoustic neuromas surgery. The pathogenesis and management of this unusual complication is discussed.