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Phenoxide-Bridged Zinc(II)-Bis(dipicolylamine) Probes for Molecular Imaging of Cell Death

Thu, 02/18/2016 - 12:09pm

Cell death is involved in many pathological conditions, and there is a need for clinical and preclinical imaging agents that can target and report cell death. One of the best known biomarkers of cell death is exposure of the anionic phospholipid phosphatidylserine (PS) on the surface of dead and dying cells. Synthetic zinc(II)-bis(dipicolylamine) (Zn2BDPA) coordination complexes are known to selectively recognize PS-rich membranes and act as cell death molecular imaging agents. However, there is a need to improve in vivo imaging performance by selectively increasing target affinity and decreasing off-target accumulation. This present study compared the cell death targeting ability of two new deep-red fluorescent probes containing phenoxide-bridged Zn2BDPA complexes. One probe was a bivalent version of the other and associated more strongly with PS-rich liposome membranes. However, the bivalent probe exhibited self-quenching on the membrane surface, so the monovalent version produced brighter micrographs of dead and dying cells in cell culture and also better fluorescence imaging contrast in two living animal models of cell death (rat implanted tumor with necrotic core and mouse thymus atrophy). An 111In-labeled radiotracer version of the monovalent probe also exhibited selective cell death targeting ability in the mouse thymus atrophy model, with relatively high amounts detected in dead and dying tissue and low off-target accumulation in nonclearance organs. The in vivo biodistribution profile is the most favorable yet reported for a Zn2BDPA complex; thus, the monovalent phenoxide-bridged Zn2BDPA scaffold is a promising candidate for further development as a cell death imaging agent in living subjects.

Imaging Inflammation in Cerebrovascular Disease

Thu, 02/18/2016 - 12:09pm

Imaging inflammation in large intracranial artery pathology may play an important role in the diagnosis of and risk stratification for a variety of cerebrovascular diseases. Looking beyond the lumen has already generated widespread excitement in the stroke community, and the potential to unveil molecular processes in the vessel wall is a natural evolution to develop a more comprehensive understanding of the pathogenesis of diseases, such as ICAD and brain aneurysms.

Conventional Medical Education and the History of Simulation in Radiology

Thu, 02/18/2016 - 12:09pm

Simulation is a promising method for improving clinician performance, enhancing team training, increasing patient safety, and preventing errors. Training scenarios to enrich medical student and resident education, and apply toward competency assessment, recertification, and credentialing are important applications of simulation in radiology. This review will describe simulation training for procedural skills, interpretive and noninterpretive skills, team-based training and crisis management, professionalism and communication skills, as well as hybrid and in situ applications of simulation training. A brief overview of current simulation equipment and software and the barriers and strategies for implementation are described. Finally, methods of measuring competency and assessment are described, so that the interested reader can successfully implement simulation training into their practice.

A Finite Element Method to Predict Adverse Events in Intracranial Stenting Using Microstents: In Vitro Verification and Patient Specific Case Study

Thu, 02/18/2016 - 12:09pm

Clinical studies have demonstrated the efficacy of stent supported coiling for intra-cranial aneurysm treatment. Despite encouraging outcomes, some matters are yet to be addressed. In particular closed stent designs are influenced by the delivery technique and may suffer from under-expansion, with the typical effect of "hugging" the inner curvature of the vessel which seems related to adverse events. In this study we propose a novel finite element (FE) environment to study potential failure able to reproduce the microcatheter "pull-back" delivery technique. We first verified our procedure with published in vitro data and then replicated the intervention on one patient treated with a 4.5 x 22 mm Enterprise microstent (Codman Neurovascular; Raynham MA, USA). Results showed good agreement with the in vitro test, catching both size and location of the malapposed area. A simulation of a 28 mm stent in the same geometry highlighted the impact of the delivery technique, which leads to larger area of malapposition. The patient specific simulation matched the global stent configuration and zones prone to malapposition shown on the clinical images with difference in tortuosity between actual and virtual treatment around 2.3%. We conclude that the presented FE strategy provides an accurate description of the stent mechanics and, after further in vivo validation and optimization, will be a tool to aid clinicians to anticipate the acute procedural outcome avoiding poor initial results.

Digital Breast Tomosynthesis: State of the Art

Thu, 02/18/2016 - 12:09pm

This topical review on digital breast tomosynthesis (DBT) is provided with the intent of describing the state of the art in terms of technology, results from recent clinical studies, advanced applications, and ongoing efforts to develop multimodality imaging systems that include DBT. Particular emphasis is placed on clinical studies. The observations of increase in cancer detection rates, particularly for invasive cancers, and the reduction in false-positive rates with DBT in prospective trials indicate its benefit for breast cancer screening. Retrospective multireader multicase studies show either noninferiority or superiority of DBT compared with mammography. Methods to curtail radiation dose are of importance.

Scatter and crosstalk corrections for (99m)Tc/(123)I dual-radionuclide imaging using a CZT SPECT system with pinhole collimators

Thu, 02/18/2016 - 12:08pm

PURPOSE: The energy spectrum for a cadmium zinc telluride (CZT) detector has a low energy tail due to incomplete charge collection and intercrystal scattering. Due to these solid-state detector effects, scatter would be overestimated if the conventional triple-energy window (TEW) method is used for scatter and crosstalk corrections in CZT-based imaging systems. The objective of this work is to develop a scatter and crosstalk correction method for (99m)Tc/(123)I dual-radionuclide imaging for a CZT-based dedicated cardiac SPECT system with pinhole collimators (GE Discovery NM 530c/570c).

METHODS: A tailing model was developed to account for the low energy tail effects of the CZT detector. The parameters of the model were obtained using (99m)Tc and (123)I point source measurements. A scatter model was defined to characterize the relationship between down-scatter and self-scatter projections. The parameters for this model were obtained from Monte Carlo simulation using SIMIND. The tailing and scatter models were further incorporated into a projection count model, and the primary and self-scatter projections of each radionuclide were determined with a maximum likelihood expectation maximization (MLEM) iterative estimation approach. The extracted scatter and crosstalk projections were then incorporated into MLEM image reconstruction as an additive term in forward projection to obtain scatter- and crosstalk-corrected images. The proposed method was validated using Monte Carlo simulation, line source experiment, anthropomorphic torso phantom studies, and patient studies. The performance of the proposed method was also compared to that obtained with the conventional TEW method.

RESULTS: Monte Carlo simulations and line source experiment demonstrated that the TEW method overestimated scatter while their proposed method provided more accurate scatter estimation by considering the low energy tail effect. In the phantom study, improved defect contrasts were observed with both correction methods compared to no correction, especially for the images of (99m)Tc in dual-radionuclide imaging where there is heavy contamination from (123)I. In this case, the nontransmural defect contrast was improved from 0.39 to 0.47 with the TEW method and to 0.51 with their proposed method and the transmural defect contrast was improved from 0.62 to 0.74 with the TEW method and to 0.73 with their proposed method. In the patient study, the proposed method provided higher myocardium-to-blood pool contrast than that of the TEW method. Similar to the phantom experiment, the improvement was the most substantial for the images of (99m)Tc in dual-radionuclide imaging. In this case, the myocardium-to-blood pool ratio was improved from 7.0 to 38.3 with the TEW method and to 63.6 with their proposed method. Compared to the TEW method, the proposed method also provided higher count levels in the reconstructed images in both phantom and patient studies, indicating reduced overestimation of scatter. Using the proposed method, consistent reconstruction results were obtained for both single-radionuclide data with scatter correction and dual-radionuclide data with scatter and crosstalk corrections, in both phantom and human studies.

CONCLUSIONS: The authors demonstrate that the TEW method leads to overestimation in scatter and crosstalk for the CZT-based imaging system while the proposed scatter and crosstalk correction method can provide more accurate self-scatter and down-scatter estimations for quantitative single-radionuclide and dual-radionuclide imaging.

Calibration and optimization of 3D digital breast tomosynthesis guided near infrared spectral tomography

Thu, 02/18/2016 - 12:08pm

Calibration of a three-dimensional multimodal digital breast tomosynthesis (DBT) x-ray and non-fiber based near infrared spectral tomography (NIRST) system is challenging but essential for clinical studies. Phantom imaging results yielded linear contrast recovery of total hemoglobin (HbT) concentration for cylindrical inclusions of 15 mm, 10 mm and 7 mm with a 3.5% decrease in the HbT estimate for each 1 cm increase in inclusion depth. A clinical exam of a patient's breast containing both benign and malignant lesions was successfully imaged, with greater HbT was found in the malignancy relative to the benign abnormality and fibroglandular regions (11 muM vs. 9.5 muM). Tools developed improved imaging system characterization and optimization of signal quality, which will ultimately improve patient selection and subsequent clinical trial results.

Association Between Confidence Level of Acute Pulmonary Embolism Diagnosis on CTPA images and Clinical Outcomes

Thu, 02/18/2016 - 12:08pm

RATIONALE AND OBJECTIVES: The purpose was to evaluate clinical characteristics associated with low confidence in diagnosis of acute pulmonary embolism (PE) as expressed in computed tomography pulmonary angiography (CTPA) reports and to evaluate the effect of confidence level in PE diagnosis on patient clinical outcomes.

MATERIALS AND METHODS: This study included radiology reports from 1664 consecutive CTPA considered positive for acute PE (8/2003-5/2010). All reports were retrospectively assessed for the level of confidence in diagnosis. Baseline characteristics and outcomes (therapies related to PE and short-term mortality) were compared between high and low confidence groups. Multivariable logistic and Cox regression analyses were used to analyze the relationship between the confidence level and outcomes.

RESULTS: One-hundred sixty of 1664 (9.6%) reports had language that reflected a low confidence in PE diagnosis. The low confidence group had smaller (segmental and subsegmental) suspected emboli (prevalence, 72.5% vs. 50.7%; P < .001) and more comorbidities. The low confidence group had a lower likelihood of receiving PE-related therapies (adjusted odds ratio [OR], 0.18; 95% confidence interval, 0.10-031, P < .001), but there was no change in the all-cause and PE-related 30-day and/or 90-day mortality (OR of death for low confidence, 0.81-1.13, P values > .5).

CONCLUSIONS: Roughly 10% of positive CTPA reports had uncertainty in PE findings, and patients with reports categorized as low confidence had smaller emboli and more comorbidities. Although the low confidence group was less likely to receive PE-related therapies, patients in this group were not associated with higher probability of short-term mortality.

Safety, efficacy, and short-term follow-up of the use of Pipeline Embolization Device in small ( < 2.5mm) cerebral vessels for aneurysm treatment: single institution experience

Thu, 02/18/2016 - 12:08pm

INTRODUCTION: Flow diversion is being increasingly used to treat cerebral aneurysms. We present our experience using these stents to treat aneurysms distal to the circle of Willis with parent arteries smaller than 2.5 mm.

METHODS: Aneurysms treated with a Pipeline Embolization Device in vessels less than 2.5 mm between June 2012 and August 2014 were included. We evaluated risk factors, family history of aneurysms, aneurysm characteristics, National Institute of Health Stroke Scale (NIHSS), and modified Rankin scale (mRS) on admission and angiography and clinical outcome at discharge, 6 months, and 1 year.

RESULTS: We included seven patients with a mean age of 65 years. The parent vessel size ranged from 1.5 to 2.3 mm; mean 1.9 mm. Location of the aneurysms was as follows: two aneurysms centered along the pericallosal artery (one left, one right), one on the right angular artery, one aneurysm at the anterior communicating artery (ACom), one at the ACom-right A2 anterior cerebral artery (ACA), one at the lenticulostriate artery, and one at the A1-A2 ACA artery. Aneurysms ranged from 1 to 12 mm in diameter. All aneurysms were treated with a single Pipeline Embolization Device (PED). No peri- or post-procedural complications or mortality occurred. The patients were discharged with no change in NIHSS or mRS score. Angiographic follow-up was available in six patients. Angiography showed complete aneurysm occlusion in all. NIHSS and mRS remained unchanged at follow-up.

CONCLUSION: Our preliminary results show that flow diversion technology is an effective and safe therapy for aneurysms located on small cerebral arteries. Larger studies with long-term follow-up are needed to validate our promising results.

Quantitative microstructural deficits in chronic phase of stroke with small volume infarcts: A Diffusion Tensor 3-D Tractographic Analysis

Thu, 02/18/2016 - 12:08pm

BACKGROUND: Non-infarct zone white matter wallerian degeneration is well-documented in large volume territorial infarctions. However to what extent these abnormalities exist in small volume infarction is not known, particularly since routine T2/FLAIR MR images show minimal changes in such cases. We therefore utilized DTI based quantitative 3D tractography for quantitative assessment of white matter integrity in chronic phase of small volume anterior circulation infarcts.

METHODS: Eleven chronic stroke subjects with small anterior circulation large vessel infarcts ( < /=10 cc volume of primary infarct) were compared with 8 age matched controls. These infarcts had negligible to mild gliosis and encephalomalacia in the primary infarct territory without obvious wallerian degeneration on conventional MRI. Quantitative Diffusion Tensor 3-D tractography was performed for CST, genu and splenium of corpus callosum. Tract based Trace and fractional anisotropy (FA) was compared with age matched controls.

RESULTS: On univariate analysis, Chronic stroke subjects had significant elevation in Trace measurement in genu of corpus callosum (GCC), ipsilesional and contralesional CST, (p < 0.05), compared to controls. After adjusting for smoking, hypertension (HTN) and non-specific white matter hyperintensities, (WMHs), there was significant elevation in trace within the ipsilesional CST (p=0.05). Contralesional CST FA correlated significantly with walking speed, r=0.67, p=0.03.

CONCLUSIONS: Stroke subjects with small volume infarcts demonstrate significant quantitative microstructural white matter abnormalities in chronic phase, which are otherwise subthreshold for detection on routine imaging. Ability to quantify these changes provides an important marker for assessing non-infarct zone neuroaxonal integrity in the chronic phase even in the setting of small infarction.

Prototypes of self-powered radiation detectors employing intrinsic high-energy current

Thu, 02/18/2016 - 12:08pm

PURPOSE: The authors experimentally investigate the effect of direct energy conversion of x-rays via selfpowered Auger- and photocurrent, potentially suitable to practical radiation detection and dosimetry in medical applications. Experimental results are compared to computational predictions. The detector the authors consider is a thin-film multilayer device, composed of alternating disparate electrically conductive and insulating layers. This paper focuses on the experiments while a companion paper introduces the fundamental concepts of high-energy current (HEC) detectors.

METHODS: The energy of ionizing radiation is directly converted to detector signal via electric current induced by high-energy secondary electrons generated in the detector material by the incident primary radiation. The HEC electrons also ionize the dielectric and the resultant charge carriers are selfcollected due to the contact potential of the disparate electrodes. Thus, an electric current is induced in the conductors in two different ways without the need for externally applied bias voltage or amplification. Thus, generated signal in turn is digitized by a data acquisition system. To determine the fundamental properties of the HEC detector and to demonstrate its feasibility for medical applications, the authors used a planar geometry composed of multilayer microstructures. Various detectors with up to seven conducting layers with different combinations of materials (250 mum Al, 35 mum Cu, 100 mum Pb) and air gaps (100 mum) were exposed to nearly plane-parallel 60-120 kVp x-ray beams. For the experimental design and verification, the authors performed coupled electron-photon radiation transport computations. The detector signal was measured using a commercial data acquisition system with 24 bits dynamic range, 0.4 fC sensitivity, and 0.9 ms sampling time.

RESULTS: Measured signals for the prototype detector varied depending on the number of layers, material type, and incident photon energy, and it was in the range of 30-150 nA/cm(2) for unit air kerma (1 Gy), which is viable for practical applications. The experiments had an excellent agreement with the computations. Within the examined range of 60-120 kVp, the energy dependence of the HEC (normalized to the x-ray tube output) was relatively small.

CONCLUSIONS: Based on the experimental results for 100 ms sampling time, it would be possible to measure the time dependence of x-ray beams for x-ray tube current of 0.1 mA or higher. Significant advantages of the HEC device are that generation of its signal does not require external power supply, it can be made in any size and shape, including flexible curvilinear forms, and it is inexpensive. It remains to be determined, which of the potential applications in medical dosimetry (both in vivo and external), or radiation protection would benefit from such selfpowered detectors.

Limited-angle effect compensation for respiratory binned cardiac SPECT

Thu, 02/18/2016 - 12:08pm

PURPOSE: In cardiac single photon emission computed tomography (SPECT), respiratory-binned study is used to combat the motion blur associated with respiratory motion. However, owing to the variability in respiratory patterns during data acquisition, the acquired data counts can vary significantly both among respiratory bins and among projection angles within individual bins. If not properly accounted for, such variation could lead to artifacts similar to limited-angle effect in image reconstruction. In this work, the authors aim to investigate several reconstruction strategies for compensating the limited-angle effect in respiratory binned data for the purpose of reducing the image artifacts.

METHODS: The authors first consider a model based correction approach, in which the variation in acquisition time is directly incorporated into the imaging model, such that the data statistics are accurately described among both the projection angles and respiratory bins. Afterward, the authors consider an approximation approach, in which the acquired data are rescaled to accommodate the variation in acquisition time among different projection angles while the imaging model is kept unchanged. In addition, the authors also consider the use of a smoothing prior in reconstruction for suppressing the artifacts associated with limited-angle effect. In our evaluation study, the authors first used Monte Carlo simulated imaging with 4D NCAT phantom wherein the ground truth is known for quantitative comparison. The authors evaluated the accuracy of the reconstructed myocardium using a number of metrics, including regional and overall accuracy of the myocardium, uniformity and spatial resolution of the left ventricle (LV) wall, and detectability of perfusion defect using a channelized Hotelling observer. As a preliminary demonstration, the authors also tested the different approaches on five sets of clinical acquisitions.

RESULTS: The quantitative evaluation results show that the three compensation methods could all, but to different extents, reduce the reconstruction artifacts over no compensation. In particular, the model based approach reduced the mean-squared-error of the reconstructed myocardium by as much as 40%. Compared to the approach of data rescaling, the model based approach further improved both the overall and regional accuracy of the myocardium; it also further improved the lesion detectability and the uniformity of the LV wall. When ML reconstruction was used, the model based approach was notably more effective for improving the LV wall; when MAP reconstruction was used, the smoothing prior could reduce the noise level and artifacts with little or no increase in bias, but at the cost of a slight resolution loss of the LV wall. The improvements in image quality by the different compensation methods were also observed in the clinical acquisitions.

CONCLUSIONS: Compensating for the uneven distribution of acquisition time among both projection angles and respiratory bins can effectively reduce the limited-angle artifacts in respiratory-binned cardiac SPECT reconstruction. Direct incorporation of the time variation into the imaging model together with a smoothing prior in reconstruction can lead to the most improvement in the accuracy of the reconstructed myocardium.

Opportunities for Patient-centered Outcomes Research in Radiology

Thu, 02/18/2016 - 12:08pm

Recently created in 2010, the Patient-Centered Outcomes Research Institute (PCORI) supports patient-centered comparative effectiveness research with a focus on prioritizing high-impact studies and improving trial design methodology. The Association of University Radiologists Radiology Research Alliance Task Force on patient-centered outcomes research in Radiology aims to review recently funded imaging-centric projects that adhere to the methodologies established by PCORI. We provide an overview of the successful application of PCORI standards to radiology topics, highlight how these methodologies differ from other forms of radiology research, and identify opportunities for new projects as well as potential barriers for involvement. Our hope is that review of specific case examples in radiology will clarify the use and value of PCORI methods mandated and supported nationally by the Affordable Care Act.

Three-dimensional reconstruction of Haversian systems in human cortical bone using synchrotron radiation-based micro-CT: morphology and quantification of branching and transverse connections across age

Thu, 02/18/2016 - 12:08pm

This study uses synchrotron radiation-based micro-computed tomography (CT) scans to reconstruct three-dimensional networks of Haversian systems in human cortical bone in order to observe and analyse interconnectivity of Haversian systems and the development of total Haversian networks across different ages. A better knowledge of how Haversian systems interact with each other is essential to improve understanding of remodeling mechanisms and bone maintenance; however, previous methodological approaches (e.g. serial sections) did not reveal enough detail to follow the specific morphology of Haversian branching, for example. Accordingly, the aim of the present study was to identify the morphological diversity of branching patterns and transverse connections, and to understand how they change with age. Two types of branching morphologies were identified: lateral branching, resulting in small osteon branches bifurcating off of larger Haversian canals; and dichotomous branching, the formation of two new osteonal branches from one. The reconstructions in this study also suggest that Haversian systems frequently target previously existing systems as a path for their course, resulting in a cross-sectional morphology frequently referred to as 'type II osteons'. Transverse connections were diverse in their course from linear to oblique to curvy. Quantitative assessment of age-related trends indicates that while in younger human individuals transverse connections were most common, in older individuals more evidence of connections resulting from Haversian systems growing inside previously existing systems was found. Despite these changes in morphological characteristics, a relatively constant degree of overall interconnectivity is maintained throughout life. Altogether, the present study reveals important details about Haversian systems and their relation to each other that can be used towards a better understanding of cortical bone remodeling as well as a more accurate interpretation of morphological variants of osteons in cross-sectional microscopy. Permitting visibility of reversal lines, synchrotron radiation-based micro-CT is a valuable tool for the reconstruction of Haversian systems, and future analyses have the potential to further improve understanding of various important aspects of bone growth, maintenance and health.

Reducing Radiation Exposure Without Compromising Image Quality for Lumbar Spine CT

Thu, 02/18/2016 - 12:08pm

Case study in clinical practice management on reducing radiation exposure without compromising image quality for lumbar spine CT.

Detection of Klebsiella. Pneumoniae Infection with an Antisense Oligomer Against its Ribosomal RNA

Thu, 02/18/2016 - 12:08pm

PURPOSE: Previously, we demonstrated specific accumulation into bacteria of a 12-mer phosphorodiamidate morpholino (MORF) oligomer complementary to a ribosomal RNA (rRNA) segment found in all bacteria using the universal probe called Eub338 (Eub). Here, two MORF oligomers Eco and Kpn with sequences specific to the rRNA of Escherichia coli (Eco) and Klebsiella pneumoniae (Kpn) were investigated along with Eub and control (nonEub).

PROCEDURES: To determine bacterial rRNA binding, oligomers were tagged with Alexa Fluor 633 (AF633) for fluorescence in situ hybridization (FISH) and fluorescence microscopy, and radiolabeled with technetium-99m (Tc-99m) for biodistribution and SPECT imaging in infected mice.

RESULTS: By both FISH and fluorescence microscopy, Eub showed a positive signal in both E. coli and K. pneumoniae as expected, and Kpn showed significantly higher accumulation in K. pneumoniae with near background in E. coli (p < 0.01). Conversely, Eco was positive in both E. coli and K. pneumoniae, hence nonspecific. As determined by biodistribution, the accumulation of [99mTc]Kpn was higher in the thigh infected with live K. pneumoniae than with live E. coli (p = 0.05), and significantly higher than with heat-killed K. pneumoniae (p = 0.02) in the target thigh. By SPECT imaging, the accumulation of [99mTc]Kpn was obviously higher in its specific target of K. pneumoniae compared to an E. coli infected thigh.

CONCLUSIONS: Kpn complementary to the rRNA of K. pneumoniae, labeled with Tc-99m or AF633, demonstrated specific binding to fixed and live K. pneumoniae in culture and in infected mice such that Tc-99m-labeled Kpn as the MORF oligomer may be useful for K. pneumoniae infection detection through imaging.

Risk of distal embolization with stent retriever thrombectomy and ADAPT

Thu, 02/18/2016 - 12:07pm

BACKGROUND: There is a discrepancy in clinical outcomes and the achieved recanalization rates with stent retrievers in the endovascular treatment of ischemic stroke. It is our hypothesis that procedural release of embolic particulate may be one contributor to poor outcomes and is a modifiable risk. The goal of this study is to assess various treatment strategies that reduce the risk of distal emboli.

METHODS: Mechanical thrombectomy was simulated in a vascular phantom with collateral circulation. Hard fragment-prone clots (HFC) and soft elastic clots (SECs) were used to generate middle cerebral artery (MCA) occlusions that were retrieved by the Solitaire FR devices through (1) an 8 Fr balloon guide catheter (BGC), (2) a 5 Fr distal access catheter at the proximal aspect of the clot in the MCA (Solumbra), or (3) a 6 Fr guide catheter with the tip at the cervical internal carotid artery (guide catheter, GC). Results from mechanical thrombectomy were compared with those from direct aspiration using the Penumbra 5MAX catheter. The primary endpoint was the size distribution of emboli to the distribution of the middle and anterior cerebral arteries.

RESULTS: Solumbra was the most efficient method for reducing HFC fragments (p < 0.05) while BGC was the best method for preventing SEC fragmentation (p < 0.05). The risk of forming HFC distal emboli ( > 1000 microm) was significantly increased using GC. A non-statistically significant benefit of direct aspiration was observed in several subgroups of emboli with size 50-1000 microm. However, compared with the stent-retriever mechanical thrombectomy techniques, direct aspiration significantly increased the risk of SEC fragmentation (microm) by at least twofold.

CONCLUSIONS: The risk of distal embolization is affected by the catheterization technique and clot mechanics.

Quantitative assessment of device-clot interaction for stent retriever thrombectomy

Thu, 02/18/2016 - 12:07pm

PURPOSE: Rapid revascularization in emergent large vessel occlusion with endovascular embolectomy has proven clinical benefit. We sought to measure device-clot interaction as a potential mechanism for efficient embolectomy.

METHODS: Two different radiopaque clot models were injected to create a middle cerebral artery occlusion in a patient-specific vascular phantom. A radiopaque stent retriever was deployed within the clot by unsheathing the device or a combination of unsheathing followed by pushing the device (n=8/group). High-resolution cone beam CT was performed immediately after device deployment and repeated after 5 min. An image processing pipeline was created to quantitatively evaluate the volume of clot that integrates with the stent, termed the clot integration factor (CIF).

RESULTS: The CIF was significantly different for the two deployment variations when the device engaged the hard clot (p=0.041), but not the soft clot (p=0.764). In the hard clot, CIF increased significantly between post-deployment and final imaging datasets when using the pushing technique (p=0.019), but not when using the unsheathing technique (p=0.067). When we investigated the effect of time on CIF in the different clot models disregarding the technique, the CIF was significantly increased in the final dataset relative to the post-deployment dataset in both clot models (p=0.004-0.007).

CONCLUSIONS: This study demonstrates in an in vitro system the benefit of pushing the Trevo stent during device delivery in hard clot to enhance integration. Regardless of delivery technique, clot-device integration increased in both clot models by waiting 5 min.

Targeted scVEGF/(177)Lu radiopharmaceutical inhibits growth of metastases and can be effectively combined with chemotherapy

Thu, 02/18/2016 - 12:07pm

BACKGROUND: scVEGF/(177)Lu is a novel radiopharmaceutical targeted by recombinant single-chain (sc) derivative of vascular endothelial growth factor (VEGF) that binds to and is internalized by vascular endothelial growth factor receptors (VEGFR). scVEGF/(177)Lu potential as adjuvant and neoadjuvant anti-angiogenic therapy was assessed in metastatic and orthotopic mouse models of triple-negative breast cancer.

METHODS: Metastatic lesions in Balb/c mice were established by intracardiac injection of luciferase-expressing 4T1luc mouse breast carcinoma cells. Mice with metastatic lesions received single intravenous (i.v.) injection of well-tolerated dose of scVEGF/(177)Lu (7.4 MBq/mouse) at day 8 after 4T1luc cell injection. Primary orthotopic breast tumors in immunodeficient mice were established by injecting luciferase-expressing MDA231luc human breast carcinoma cells into mammary fat pad. Tumor-bearing mice were treated with single injections of scVEGF/(177)Lu (7.4 MBq/mouse, i.v), or liposomal doxorubicin (Doxil, 1 mg doxorubicin per kg, i.v.), or with a combination of Doxil and scVEGF/(177)Lu given at the same doses, but two hours apart. "Cold" scVEGF-targeting conjugate was included in controls and in Doxil alone group. The effects of treatments were defined by bioluminescent imaging (BLI), computed tomography (CT), computed microtomography (microCT), measurements of primary tumor growth, and immunohistochemical analysis.

RESULTS: In metastatic model, adjuvant treatment with scVEGF/(177)Lu decreased overall metastatic burden and improved survival. In orthotopic primary tumor model, a combination of Doxil and scVEGF/(177)Lu was more efficient in tumor growth inhibition than each treatment alone. scVEGF/(177)Lu treatment decreased immunostaining for VEGFR-1, VEGFR-2, and pro-tumorigenic M2-type macrophage marker CD206.

CONCLUSIONS: Selective targeting of VEGFR with well-tolerated doses of scVEGF/(177)Lu is effective in metastatic and primary breast cancer models and can be combined with chemotherapy. As high level of VEGFR expression is a common feature in a variety of cancers, targeted delivery of (177)Lu for specific receptor-mediated uptake warrants further exploration.

PHPartners.org: Single Point Access to Credible Public Health Information

Tue, 02/16/2016 - 8:45am

Webinar presentation that provided an overview of public health information resources available from the public health web portal, PHPartners.org, including the Healthy People 2020 Structured Evidence Queries (pre-formulated searches of PubMed). PHPartners.org provides a single point of access to credible public health information including public health topic pages, health data tools and statistics, research reports, grant opportunities, news articles, conference proceedings, and continuing education opportunities.

At the conclusion of this webinar, participants were able to: 1) navigate the PHPartners.org website to access credible and authoritative public health information and data; 2) locate research articles indexed in PubMed to support achieving Healthy People 2020 objectives; and 3) demonstrate the ability to search and retrieve information relevant to the public health workforce from mobile devices such as smartphones and tablets.