Vessel Overlap Research Articles

The utility of angiography-derived fractional flow reserve in predicting graft occlusions prior to bypass surgery

Abstract Background Occurrence of graft occlusion following coronary artery bypass graft (CABG) surgery has been linked to the presence of native coronary artery competitive flow (1). Despite its routine use in guiding revascularization, coronary angiography lacks sensitivity for assessing coronary stenosis significance. Data regarding the use of pressure-derived fractional flow reserve (FFR) to assess the hemodynamic significance of coronary stenoses prior to CABG are inconclusive (2) and the penetration of FFR in clinical routine is limited for various reasons (3). Different systems have been developed to predict FFR based on coronary angiographic images, eliminating pressure wires or hyperemic agents (4). Preliminary data demonstrated a high concordance between off-site angiography-derived FFR and pressure wire–based FFR (5-7). However, the use of this technique prior to CABG is not well studied. Purpose This study aims to correlate pre-CABG angiography-derived FFR with graft occlusion. Secondary endpoint is the correlation between the presence of at least one occluded bypass graft and overall mortality. Methods Retrospective study of patients undergoing CABG in whom a follow-up angiogram has been performed. Angiography-based FFR was calculated with a dedicated software (vFFR, CAAS 8.2 Workstation, Pie Medical Imaging), obtaining each major native coronary vessel before CABG. Post-CABG angiograms were conducted at least 6 weeks post-surgery to exclude graft-failures due to technical factors and thrombosis. Results From 2005 and 2014, 204 patients underwent pre-CABG angiography, with post-CABG angiograms at a median of 3.85 years [IQR 1.33-8.80] post-surgery. In total, 125 patients had to be excluded due to inadequate angiogram quality for vFFR assessment (outdated imaging system, improper vessel angles, vessel overlap, insufficient contrast). Consequently, 79 patients were suitable for pre-CABG vFFR analysis, including 132 grafted vessels (93 arterial and 39 saphenous grafts). The median patient age was 68 years [IQR 58-72] and mean time for clinical follow-up was 9.9±3.6 years. Vessels analyzed using vFFR were left anterior descending (LAD) (n=60, 45.5%), left circumflex (LCX) (n=39, 29.5%), ramus intermedius (RIM) (n=8, 6.1%) and right coronary artery (RCA) (n=25, 18.9%). Mean pre-CABG vFFR was 0.59±0.15. To predict graft occlusion, a vFFR cut-off value of 0.745 with an area under the curve (AUC) of 0.847 (95%CI 0.752–0.942) had a specificity of 0.722 and a sensitivity of 0.902 (Figure A). There was no difference in overall-mortality when comparing patients with at least one occluded bypass graft to those without (57.1% vs. 57.9%, p=0.949, Figure B). Conclusions vFFR can be used as a noninvasive tool to predict graft patency in patients undergoing CABG with acceptable sensitivity and specificity. Bypass graft occlusion did not correlate with overall-survival in this cohort.

Enhancing cerebral vasculature analysis with pathlength-corrected 2D angiographic parametric imaging: A feasibility study.

2D angiographic parametric imaging (API) quantitatively extracts imaging biomarkers related to contrast flow and is conventionally applied to 2D digitally subtracted angiograms (DSA's). In the interventional suite, API is typically performed using 1-2 projection views and is limited by vessel overlap, foreshortening, and depth-integration of contrast motion. This work explores the use of a pathlength-correction metric to overcome the limitations of 2D-API: the primary objective was to study the effect of converting 3D contrast flow to projected contrast flow using a simulated angiographic framework created with computational fluid dynamics (CFD) simulations, thereby removing acquisition variability. The pathlength-correction framework was applied to in-silico angiograms, generating a reference (i.e., ground-truth) volumetric contrast distribution in four patient-specific intracranial aneurysm geometries. Biplane projections of contrast flow were created from the reference volumetric contrast distributions, assuming a cone-beam geometry. A Parker-weighted reconstruction was performed to obtain a binary representation of the vessel structure in 3D. Standard ray tracing techniques were then used to track the intersection of a ray from the focal spot with each voxel of the reconstructed vessel wall to a pixel in the detector plane. The lengths of each ray through the 3D vessel lumen were then projected along each ray-path to create a pathlength-correction map, where the pixel intensity in the detector plane corresponds to the vessel width along each source-detector ray. By dividing the projection sequences with this correction map, 2D pathlength-corrected in-silico angiograms were obtained. We then performed voxel-wise (3D) API on the ground-truth contrast distribution and compared it to pixel-wise (2D) API, both with and without pathlength correction for each biplane view. The percentage difference (PD) between the resultant API biomarkers in each dataset were calculated within the aneurysm region of interest (ROI). Intensity-based API parameters, such as the area under the curve (AUC) and peak height (PH), exhibited notable changes in magnitude and spatial distribution following pathlength correction: these now accurately represent conservation of mass of injected contrast media within each arterial geometry and accurately reflect regions of stagnation and recirculation in each aneurysm ROI. Improved agreement was observed between these biomarkers in the pathlength-corrected biplane maps: the maximum PD within the aneurysm ROI is 3.3% with pathlength correction and 47.7% without pathlength correction. As expected, improved agreement with ROI-averaged ground-truth 3D counterparts was observed for all aneurysm geometries, particularly large aneurysms: the maximum PD for both AUC and PH was 5.8%. Temporal parameters (mean transit time, MTT, time-to-peak, TTP, time-to-arrival, TTA) remained unaffected after pathlength correction. This study indicates that the values of intensity-based API parameters obtained with conventional 2D-API, without pathlength correction, are highly dependent on the projection orientation, and uncorrected API should be avoided for hemodynamic analysis. The proposed metric can standardize 2D API-derived biomarkers independent of projection orientation, potentially improving the diagnostic value of all acquired 2D-DSA's. Integration of a pathlength correction map into the imaging process can allow for improved interpretation of biomarkers in 2D space, which may lead to improved diagnostic accuracy during procedures involving the cerebral vasculature.

A multi-stage neural network approach for coronary 3D reconstruction from uncalibrated X-ray angiography images

We present a multi-stage neural network approach for 3D reconstruction of coronary artery trees from uncalibrated 2D X-ray angiography images. This method uses several binarized images from different angles to reconstruct a 3D coronary tree without any knowledge of image acquisition parameters. The method consists of a single backbone network and separate stages for vessel centerline and radius reconstruction. The output is an analytical matrix representation of the coronary tree suitable for downstream applications such as hemodynamic modeling of local vessel narrowing (i.e., stenosis). The network was trained using a dataset of synthetic coronary trees from a vessel generator informed by both clinical image data and literature values on coronary anatomy. Our multi-stage network achieved sub-pixel accuracy in reconstructing vessel radius (RMSE = 0.16 ± 0.07 mm) and stenosis radius (MAE = 0.27 ± 0.18 mm), the most important feature used to inform diagnostic decisions. The network also led to 52% and 38% reduction in vessel centerline reconstruction errors compared to a single-stage network and projective geometry-based methods, respectively. Our method demonstrated robustness to overcome challenges such as vessel foreshortening or overlap in the input images. This work is an important step towards automated analysis of anatomic and functional disease severity in the coronary arteries.

Digital subtraction angiography image segmentation based on multiscale Hessian matrix applied to medical diagnosis and clinical nursing of coronary stenting patients

ObjectiveTo introduce an improved method of digital subtraction angiography image segmentation based on a multi-scale Hessian matrix, to accurately segment vascular images before and after coronary stent implantation, which will have strong applications in medical diagnostics and clinical nursing of patients who underwent coronary stents implantation. MethodsFirstly, a vessel edge enhancement algorithm is proposed, which enhances the gradient of the vessel edge, which not only makes the obtained vessel edge smoother, but also enhances the visual effect of the intersection of vessels; secondly, introduces noise filtering based on morphology, which can detect and remove linear noise similar to blood vessels; finally, in view of the problem that each image in the DSA blood vessel sequence can only show part of the blood vessels, which is not conducive to observing the overall state of the blood vessels, a blood vessel sequence image fusion is designed to display the blood vessels in each image on the same image. The state of blood vessels can be understood as a whole in one image. ResultsCompared with the segmentation method in the literature, the blood vessel overlap rate increased by 0.0089, and the mis-segmentation rate decreased by 0.0334. In the quantitative analysis, the improved blood vessel segmentation algorithm in this paper improves the overlapping rate and reduces the mis-segmentation rate. ConclusionFor the comparison of visual effects, the blood vessels segmented by the algorithm in this paper have higher clarity, which is helpful for doctors and nurses to comprehensively synthesize blood vessel clinical information. There is a more objective image basis in the preoperative diagnosis and postoperative rehabilitation nursing of coronary angiographic stent implantation.

Validating angiographically derived FFR in the NSTEMI patient: An important step forward.

Key Points Despite concerns of altered physiology impacting fractional flow reserve (FFR) values in acute coronary syndrome, angiographic FFR compared with wire‐based FFR in patients with NSTEMI demonstrated excellent correlations. Limits to the accuracy of FFRangio include the need for optimal angiographic angles to avoid vessel overlap and assumptions for myocardial resistance, mass, and blood flow. Clinical outcome studies will be required before FFRangio becomes a standard of care.

Angiography-derived radial wall strain predicts coronary lesion progression in non-culprit intermediate stenosis.

Intermediate coronary lesions (ICLs) are highly prevalent but ported mixed prognosis. Radial strain has been associated with plaque vulnerability, yet its role in predicting lesion progression is largely unknown. The purpose of this study was to determine the predictive value of angiography-derived radial wall strain (RWS) for progression of untreated non-culprit ICLs. Post-hoc analysis was conducted in a study cohort including 603 consecutive patients with 808 ICLs identified at index procedure with angiographic follow-up of up to two years. RWS analysis was performed on selected angiographic frames with minimal foreshortening and vessel overlap. Lesion progression was defined as ≥ 20% increase in percent diameter stenosis. Lesion progression occurred in 49 ICLs (6.1%) with a median follow-up period of 16.8 months. Maximal RWS (RWSmax), frequently located at the proximal and throat plaque regions, distinguished progressive ICLs from silent ones. The largest area under the curve value of 0.75 (95% CI: 0.67-0.82, P < 0.001) was reached at the optimal RWSmax cutoff value of > 12.6%. According to this threshold, 178 ICLs were classified as having a high strain pattern. Exposure to a high strain amplitude with RWSmax > 12.6% was independently associated with an increased risk of lesion progression (adjusted HR = 6.82, 95% CI: 3.67-12.66, P < 0.001). Assessment of RWS from coronary angiography is feasible and provides independent prognostic value in patients with untreated ICLs.

3D reconstruction of coronary arteries using deep networks from synthetic X-ray angiogram data

Cardiovascular disease (CVD) is one of the most common health problems that are responsible for one-third of all deaths around the globe. Although X-Ray angiography has deficiencies such as two-dimensional (2D) representation of three dimensional (3D) structures, vessel overlapping, noisy background, the existence of other tissues/organs in images, etc., it is used as the gold standard technique for the diagnosis and in some cases treatment of CVDs. To overcome the deficiencies, great efforts have been drawn on retrieval of actual 3D representation of coronary arterial tree from 2D X-ray angiograms. However, the proposed algorithms are based on analytical methods and enforce some constraints. With the evolution of deep neural networks, 3D reconstruction from images can be achieved effectively. In this study, we propose a new data structure for the representation of objects in a tubular shape for 3D reconstruction of arteries using deep learning. Moreover, we propose a method to generate synthetic coronaries from data of real subjects. Then, we validate tubular shape representation using 3 typical deep learning architectures with synthetic X-ray data we produced. The input to deep learning architectures is multi-view segmented X-Ray images and the output is the structured tubular representation. We compare results qualitatively in terms of visual appearance and quantitatively in terms of Chamfer Distance and Mean Squared Error. The results demonstrate that tubular representation has promising performance in 3D reconstruction of coronaries. We observe that convolutional neural network (CNN) based architectures yield better 3D reconstruction performance with 9.9e-3 on Chamfer Distance. On the other hand, LSTM-based network fails to learn the coronary tree structure and we conclude that LSTMs are not appropriate for auto-regression problems as depicted in this study.

Integrating immersion withGPSdata improves behavioural classification for wandering albatrosses and shows scavenging behind fishing vessels mirrors natural foraging

AbstractAdvances in biologging techniques and the availability of high‐resolution fisheries data have improved our ability to understand the interactions between seabirds and fisheries and to evaluate mortality risk due to bycatch. However, it remains unclear whether movement patterns and behaviour differ between birds foraging naturally or scavenging behind vessels and whether this could be diagnostic of fisheries interactions. We deployed novel loggers that record the GPS position of birds at sea and scan the surroundings to detect radar transmissions from vessels and immersion (activity) loggers on wandering albatrossesDiomedea exulansfrom South Georgia. We matched these data to remotely sensed fishing vessel positions and used a combination of hidden Markov and random forest models to investigate whether it was possible to detect a characteristic signature from the seabird tracking and activity data that would indicate fine‐scale vessel overlap and interactions. Including immersion data in our hidden Markov models allowed two distinct foraging behaviours to be identified, both indicative of Area Restricted Search (ARS) but with or without landing behaviour (likely prey capture attempts) that would not be detectable with location data alone. Birds approached vessels during all behavioural states, and there was no clear pattern associated with this type of scavenging behaviour. The random forest models had very low sensitivity, partly because foraging events at vessels occurred very rarely, and did not contain any diagnostic movement or activity pattern that was distinct from natural behaviours away from vessels. Thus, we were unable to predict accurately whether foraging bouts occurred in the vicinity of a fishing vessel, or naturally, based on behaviour alone. Our method provides a coherent and generalizable framework to segment trips using auxiliary biologging (immersion) data and to refine the classification of foraging strategies of seabirds. These results nevertheless underline the value of using radar detectors that detect vessel proximity or remotely sensed vessel locations for a better understanding of seabird–fishery interactions.

Retinal Vessel Printings on Fundus Autofluorescence Imaging Represent Retinal Displacement: Proof of Prior Hypothesis

A 68-year-old male presented with a macula-off rhegmatogenous retinal detachment (RRD) in the right eye that was treated with pars plana vitrectomy (PPV). Post-operative FAF following the right eye PPV revealed retinal displacement/low integrity retinal attachment (LIRA) with retinal vessel printings (RVPs) that are quite subtle. Uniquely, pre-RRD ultra-widefield FAF images were available to us. Overlay of ultra-widefield images of pre and post-RRD repair revealed severe displacement with perfect alignment of the RVPs with the pre-RRD blood vessels. Notably, the optic nerve in the pre and post-operative images is perfectly aligned, as are the nasal retinal vessels where the retina remained attached. Furthermore, we observe that the inferior arcade is initially well overlapped as it emanates from the optic nerve, but then becomes increasingly displaced with increasing distance from the optic nerve. This suggests that retinal displacement could be considered a rotational stretch around absolute and relative points of fixation such as the optic nerve and parts of the retina that are attached, respectively. Overlap of color images demonstrated perfect overlap of choroidal vessels, pigmentary changes and nasal retinal vessels with substantial displacement of temporal retinal vessels, which offers further proof of substantial retinal displacement relative to the aligned stationary choroidal vessels.

Point-of-Care Ultrasound for Central Venous Assessment in the Emergency Department: A Prospective Study Comparing the Femoral and Internal Jugular Veins.

The objective of this study was to estimate the width, height, and depth of the femoral vein (FV) and internal jugular vein (IJV), both sites of potential central line placement in children, using point-of-care ultrasound. This was a prospective observational study. Point-of-care ultrasound was used to measure the width, height, and depth of the right FV and IJV in 100 children. The primary outcome was a comparison of the widths of the FV and the IJV in the same child. Our primary hypothesis was that the IJV would be wider than the FV. Secondary outcome measures included comparison of the heights and depths the FV and IJV and description of vessel overlap frequency between the 2 sites. A total of 106 children were enrolled, with 6 subjects excluded, and equally divided into 5 age groups (0-30 days, 1-24 months, 2-5 years, 6-11 years, and 12-17 years). The FV/IJV width ratios (95% confidence interval) by age were 0.58 (0.49-0.68), 0.53 (0.43-0.66), 0.57 (0.49-0.67), 0.68 (0.55-0.85), and 0.73 (0.62-0.85), all P < 0.002. The FV/IJV height ratios were <1 in all age groups, with P < 0.003 in the 4 youngest age groups. The FV/IJV depth ratios were >1 in 6 to 11 years (P = 0.018) and 12 to 17 years (P < 0.001). The IJV was significantly wider and taller than the FV in the same child in all age groups. The FV was significantly deeper than the IJV in children 6 years and older. This supports the use of the IJV as a potential site when placing ultrasound-guided central lines in children.

Point-Cloud Method for Automated 3D Coronary Tree Reconstruction From Multiple Non-Simultaneous Angiographic Projections.

X-ray angiography is the most commonly used imaging modality for the detection of coronary stenoses due to its high spatial and temporal resolution of lumen contour and its utility to guide coronary interventions in real time. However, the high inter- and intra-observer variability in interpreting the geometry of 3D vascular structure based on multiple 2D image projections is a limitation in the accurate determination of lesion severity. This could be addressed by the 3D reconstruction of the coronary arterial (CA) tree. The automated reconstruction of 3D CA tree from 2D projections is challenging due to the existence of several imaging artifacts, such as vessel overlap, foreshortening, and most importantly respiratory and cardiac motion. Along with these artifacts, the acquisition geometry introduces the possibility of generating false vessel segments in the reconstruction. Our approach aims to reduce the motion artifacts in angiographic projections by developing a new method for rigid and non-rigid motion correction. A novel point-cloud based approach is subsequently introduced for reconstruction of 3D vessel centerlines by iteratively minimizing the reconstruction error. The performance of the proposed 3D reconstruction is evaluated using angiographic projections from 45 patients, producing average reprojection errors of 0.092 ±0.055 mm and 0.910 ±0.352 mm for 3D centerlines reconstruction, when co-registered with the parent vessels on projection planes that were/were not used to derive the 3D reconstruction, respectively. A comparison of the reconstructed 3D lumen surface with optical coherence tomography (OCT) measurements has been performed, showing no statistically significant difference in the luminal cross-sections reconstructed with our method, compared to OCT.

Impact of Three Dimensional In-Room Imaging (3DCA) in the Facilitation of Percutaneous Coronary Interventions

Introduction: Coronary angiography is a two-dimensional (2D) imaging modality and thus is limited in its ability to represent complex three-dimensional (3D) vascular anatomy. Lesion length, bifurcation angles/lesions, and tortuosity are often inadequately assessed using 2D angiography due to vessel overlap and foreshortening. 3D Rotational Angiography (3DRA) with subsequent reconstruction generates models of the coronary vasculature from which lesion length measurements and Optimal View Maps (OVM) defining the amount of vessel foreshortening for each gantry angle can be derived. This study sought to determine if 3DRA-assisted percutaneous coronary interventions resulted in improved procedural results by minimizing foreshortening and optimizing stent selection. Methods: 26 patients with obstructive coronary artery disease were included. Rotational angiographic acquisitions were performed and a 3D model was generated from two images greater than 30° apart. An optimal view map identifying the least amount of vessel foreshortening and overlap was derived from the 3D model. 3DRA derived and operator predicted optimal working view and stent lengths were compared. Results: 3DRA assistance significantly reduced target vessel foreshortening when compared to operator’s choice of working view for PCI (2.99% ± 2.96 vs. 9.48% ± 7.56, p=0.0001). The operators concluded that 3DRA recommended better optimal view selection for PCI in 14 of 26 (54%) total cases. In 9 (35%) of 26 cases 3DRA assistance facilitated stent positioning. 3DRA based imaging prompted stent length changes in 4/26 patients (15%). Conclusion: The use of 3DRA positively impacts the performance of percutaneous coronary interventions by optimizing working views through reductions in vessel foreshortening and overlap and assisting in stent positioning by improvements in stent and lesion measurements.

Optimization of Percutaneous Coronary Intervention Using Optical Coherence Tomography.

Compared to the luminogram obtained by angiography, intravascular modalities produce cross-sectional images of coronary arteries with a far greater spatial resolution. It is capable of accurately determining the vessel size and plaque morphology. It also eliminates some disadvantages such as contrast streaming, foreshortening, vessel overlap, and angle dependency inherent to angiography. Currently, the development of its system and the visualization of coronary arteries has shown significant advancement. Of those, optical coherence tomography (OCT) makes it possible to obtain high-resolution images of intraluminal and transmural coronary structures leading to navigation of the treatment strategy before and after stent implantations. The aim of this review is to summarize the published data on the clinical utility of OCT, focusing on the use of OCT in interventional cardiology practice to optimize percutaneous coronary intervention.

Assessing the effect of recreational scallop harvest on the distribution and behaviour of foraging marine turtles

AbstractThe impact of fisheries on marine megafauna is widely known but most studies have focused on commercial fisheries, overlooking the effect of local recreational fisheries. This is particularly important for marine turtles in near-shore habitats that overlap with recreational fisheries. We assessed the effect of recreational scallop fisheries on the distribution and behaviour of foraging marine turtles in the coastal waters of the upper Eastern Gulf of Mexico. Before and during the scallop season we quantified the density and overlap of marine turtles and vessels sighted, and satellite tracked four turtles to assess their distribution and behaviour. The relative distribution of marine turtles sighted during the scallop season overlapped with 48% of the area most frequently used by harvesters, and marine turtle activity hotspots shifted between seasons. In addition, during the scallop season the home range size of individual turtles appeared to decrease, and turtles displayed frequent changes in travel speed and directionality. We hypothesize that such changes are probably related to the distribution and movement of vessels and the abundant presence of people in the water. Our study highlights the importance of considering recreational fisheries and their local effect on marine megafauna for informing future adaptive management practices. However, further studies are needed to quantify the direct and indirect impacts of recreational fisheries and to assess the degree of risk of associated activities to marine turtle populations.

Morphometric Analysis of the Retroperitoneal Vessels With Respect to Lateral Access Surgery in Adult Scoliosis.

Cross-sectional study reviewing 62 magnetic resonance imaging or computed tomography scans from consecutive adult patients with scoliotic spinal deformity in the thoracolumbar spine. To investigate the variation in anatomic position of retroperitoneal vessels in relationship to curve direction, location, magnitude, and axial rotation of curves in adult scoliosis. The minimally invasive lateral approach to the thoracolumbar spine avoids manipulation of abdominal and retroperitoneal structures and decreases risk of injury to paraspinal musculature. In adult patients with scoliosis, the varying anatomic relationship between retroperitoneal vessels and intervertebral disk spaces can increase the risk of vascular injury. Axial images were used to measure the anterior-posterior diameter of the inferior vertebral endplate with respect to the disk space perpendicular to the widest length of the disk. The overlap of the retroperitoneal vessels with the endplate were measured at the cephalad end vertebra, apex, and caudad end vertebra of each curve. Overlap and accessible disk space for individual disk spaces were also measured. There was a significant difference in percentage overlap of the apex and cephalad vertebral endplate and inferior vena cava in right versus left-sided curves (P=0.002). Overlap between the inferior vertebral endplate and inferior vena cava at the cephalad, apex, and caudad end of the curve was significantly different between thoracolumbar and lumbar curves (P<0.05). Axial rotation significantly affected vessel overlap at multiple curve locations. There was a statistically significant difference in accessible disk space when approaching the curve from the concavity versus convexity. Overlap between retroperitoneal vessels and inferior vertebral endplates at the disk level in scoliotic spines varies significantly with direction of the curvature, level of the deformity, and degree of axial rotation. There is decreased accessible disk space and increased vessel overlap on the concavity of the curve. Surgeons, as usual, will take an individualized case by case approach to avoid approach-related vascular complications, but the general relationships reported in this study can guide side of approach.

Use of navigation channels by Lake Sturgeon: Does channelization increase vulnerability of fish to ship strikes?

Channelization for navigation and flood control has altered the hydrology and bathymetry of many large rivers with unknown consequences for fish species that undergo riverine migrations. In this study, we investigated whether altered flow distributions and bathymetry associated with channelization attracted migrating Lake Sturgeon (Acipenser fulvescens) into commercial navigation channels, potentially increasing their exposure to ship strikes. To address this question, we quantified and compared Lake Sturgeon selection for navigation channels vs. alternative pathways in two multi-channel rivers differentially affected by channelization, but free of barriers to sturgeon movement. Acoustic telemetry was used to quantify Lake Sturgeon movements. Under the assumption that Lake Sturgeon navigate by following primary flow paths, acoustic-tagged Lake Sturgeon in the more-channelized lower Detroit River were expected to choose navigation channels over alternative pathways and to exhibit greater selection for navigation channels than conspecifics in the less-channelized lower St. Clair River. Consistent with these predictions, acoustic-tagged Lake Sturgeon in the more-channelized lower Detroit River selected the higher-flow and deeper navigation channels over alternative migration pathways, whereas in the less-channelized lower St. Clair River, individuals primarily used pathways alternative to navigation channels. Lake Sturgeon selection for navigation channels as migratory pathways also was significantly higher in the more-channelized lower Detroit River than in the less-channelized lower St. Clair River. We speculated that use of navigation channels over alternative pathways would increase the spatial overlap of commercial vessels and migrating Lake Sturgeon, potentially enhancing their vulnerability to ship strikes. Results of our study thus demonstrated an association between channelization and the path use of migrating Lake Sturgeon that could prove important for predicting sturgeon-vessel interactions in navigable rivers as well as for understanding how fish interact with their habitat in landscapes altered by human activity.

4D DSA reconstruction using tomosynthesis projections.

We investigate the use of tomosynthesis in 4D DSA to improve the accuracy of reconstructed vessel time-attenuation curves (TACs). It is hypothesized that a narrow-angle tomosynthesis dataset for each time point can be exploited to reduce artifacts caused by vessel overlap in individual projections. 4D DSA reconstructs time-resolved 3D angiographic volumes from a typical 3D DSA scan consisting of mask and iodine-enhanced C-arm rotations. Tomosynthesis projections are obtained either from a conventional C-arm rotation, or from an inverse geometry scanning-beam digital x-ray (SBDX) system. In the proposed method, rays of the tomosynthesis dataset which pass through multiple vessels can be ignored, allowing the non-overlapped rays to impart temporal information to the 4D DSA. The technique was tested in simulated scans of 2 mm diameter vessels separated by 2 to 5 cm, with TACs following either early or late enhancement. In standard 4D DSA, overlap artifacts were clearly present. Use of tomosynthesis projections in 4D DSA reduced TAC artifacts caused by vessel overlap, when a sufficient fraction of non-overlapped rays was available in each time frame. In cases where full overlap between vessels occurred, information could be recovered via a proposed image space interpolation technique. SBDX provides a tomosynthesis scan for each frame period in a rotational acquisition, whereas a standard C-arm geometry requires the grouping of multiple frames.

TU‐H‐CAMPUS‐IeP3‐02: Neurovascular 4D Parametric Imaging Using Co‐Registration of Biplane DSA Sequences with 3D Vascular Geometry Obtained From Cone Beam CT

Purpose:To create 4D parametric images using biplane Digital Subtraction Angiography (DSA) sequences co‐registered with the 3D vascular geometry obtained from Cone Beam‐CT (CBCT).Methods:We investigated a method to derive multiple 4D Parametric Imaging (PI) maps using only one CBCT acquisition. During this procedure a 3D‐DSA geometry is stored and used subsequently for all 4D images. Each time a biplane DSA is acquired, we calculate 2D parametric maps of Bolus Arrival Time (BAT), Mean Transit Time (MTT) and Time to Peak (TTP). Arterial segments which are nearly parallel with one of the biplane imaging planes in the 2D parametric maps are co‐registered with the 3D geometry. The values in the remaining vascular network are found using spline interpolation since the points chosen for co‐registration on the vasculature are discrete and remaining regions need to be interpolated. To evaluate the method we used a patient CT volume data set for 3D printing a neurovascular phantom containing a complete Circle of Willis. We connected the phantom to a flow loop with a peristaltic pump, simulating physiological flow conditions. Contrast media was injected with an automatic injector at 10 ml/sec. Images were acquired with a Toshiba Infinix C‐arm and 4D parametric image maps of the vasculature were calculated.Results:4D BAT, MTT, and TTP parametric image maps of the Circle of Willis were derived. We generated color‐coded 3D geometries which avoided artifacts due to vessel overlap or foreshortening in the projection direction.Conclusion:The software was tested successfully and multiple 4D parametric images were obtained from biplane DSA sequences without the need to acquire additional 3D‐DSA runs. This can benefit the patient by reducing the contrast media and the radiation dose normally associated with these procedures.Partial support from NIH Grant R01‐EB002873 and Toshiba Medical Systems Corp.

Magnetic positioning system in coronary angiography and percutaneous intervention

This study sought to evaluate the safety and feasibility of a magnetic medical positioning system (MPS) to determine the three-dimensional (3D) position and orientation of intracoronary wires and catheters and to guide angiography and percutaneous coronary intervention (PCI). Coronary angiography relies on fluoroscopy for catheter navigation and often fails to accurately portray vessel tortuosity, overlap, and length because of complex anatomy and foreshortening of curved coronary segments. Forty adult participants underwent coronary angiography and/or PCI with MPS guidance. Two interventional cardiologists independently scored (1-5) the accuracy of MPS catheter tracking projected on live fluoroscopy, recorded cine loops, and 3D vessel reconstructions. Measurements from MPS reconstructions were compared to conventional two-dimensional (2D) quantitative coronary angiography (QCA) measurements. Device procedural success was defined as the ability of the MPS-enabled catheter to reach the target vessel, perform the intended operations, and be retrieved without major adverse cardiac events. Diagnostic coronary angiography was performed in 19 (47.5%) and PCI in 21 patients (52.5%). MPS procedural success was achieved in 36 (90%) of the cases. MPS accuracy was highest with the MPS superimposed on live fluoroscopy (4.9 ± 0.2/5) and the 3D vessel reconstruction (4.7 ± 0.5/5). MPS length measurements were more accurate than conventional QCA. This study demonstrates the feasibility and safety of magnetic catheter tracking with 3D positional data during diagnostic angiography and PCI. Catheter position was accurately projected on real-time fluoroscopy, recorded cine loops, and 3D reconstructions. An MPS may serve as a platform for device navigation and positioning during PCI.

Usefulness of three-dimensional angiographic analysis of perigastric vessels before laparoscopic gastrectomy

Recognition of perigastric vessel anatomy is important to safely perform gastric surgery, especially in the case of laparoscopic gastrectomy. This study was designed to reevaluate the efficacy of preoperative three-dimensional (3D) angiography reconstructed from enhanced multidetector-row computed tomography (MDCT) data and to classify right gastric artery (RGA) branching patterns. Perigastric vessel anatomy was preoperatively analyzed using MDCT-based 3D angiography reconstructed by computer software in patients undergoing laparotomic (n = 75) and laparoscopic (n = 25) gastrectomy. Results were compared with intraoperative findings in all cases, and were also compared with maximum intensity projection (MIP) imaging, which is similar to conventional angiography, in 10 patients. Preoperative diagnoses by 3D angiography were identical to intraoperative findings. The rates of branching patterns of the celiac artery and left gastric vein were comparable with previous reports. The detection rate of the right gastric artery (RGA) was 77.0%. Branching patterns of the hepatic artery were classified into four types: right hepatic artery (RHA) + left hepatic artery (LHA) type, replaced RHA + LHA type, RHA + replaced LHA type, and replaced RHA + replaced LHA type. RGA ramification patterns were classified into three types according to hepatic arterial running patterns: distal (68.8%), proximal (14.3%), and caudal (16.9%). Because of vessel overlapping, RGA ramified points were misdiagnosed under MIP images in two of ten cases (20%). Preoperative 3D angiography is useful for a new system of classifying RGA ramification patterns into three types. With this system, surgeons can perform laparoscopic gastrectomy with lymph node dissection more safely.