Medical Imaging Compatibility of Magnesium- and Iron-Based Bioresorbable Flow Diverters.

Background And Purpose: Bioresorbable flow diverters are under development to mitigate complications associated with conventional flow-diverter technology. One proposed advantage is the ability to reduce metal-induced artifacts in follow-up medical imaging. In the current work, the medical imaging compatibility of magnesium- and iron-based bioresorbable flow diverters is assessed relative to an FDA-approved control in phantom models.

A training program to reduce reader search errors for liver metastasis detection in CT.

Detection of low contrast liver metastases varies between radiologists. Training may improve performance for lower-performing readers and reduce inter-radiologist variability. We recruited 31 radiologists (15 trainees, 8 non-abdominal staff, and 8 abdominal staff) to participate in four separate reading sessions: pre-test, search training, classification training, and post-test.

Measurement of enhanced vasa vasorum density in a porcine carotid model using photon counting detector CT.

Purpose: The onset of atherosclerosis is preceded by changes in blood perfusion within the arterial wall due to localized proliferation of the vasa vasorum. The purpose of this study was to quantify these changes in spatial density of the vasa vasorum using a research whole-body photon-counting detector CT (PCD-CT) scanner and a porcine model.

Approach: Vasa vasorum angiogenesis was stimulated in the left carotid artery wall of anesthetized pigs ( ) while the right carotid served as a control.

Benchtop proof of concept and comparison of iron- and magnesium-based bioresorbable flow diverters.

Objective: Bioresorbable flow diverters (BRFDs) could significantly improve the performance of next-generation flow diverter technology. In the current work, magnesium and iron alloy BRFDs were prototyped and compared in terms of porosity/pore density, radial strength, flow diversion functionality, and resorption kinetics to offer insights into selecting the best available bioresorbable metal candidate for the BRFD application.

Methods: BRFDs were constructed with braided wires made from alloys of magnesium (MgBRFD) or iron (FeBRFD).

Magnetic resonance radiomic feature performance in pulmonary nodule classification and impact of segmentation variability on radiomics.

Objective: Investigate the performance of multiparametric MRI radiomic features, alone or combined with current standard-of-care methods, for pulmonary nodule classification. Assess the impact of segmentation variability on feature reproducibility and reliability.

Methods: Radiomic features were extracted from 74 pulmonary nodules of 68 patients who underwent nodule resection or biopsy after MRI exam.

Prediction of Kidney Stone Fragility Using Radiomics-Based Regression Models.

The surgical technique for urinary stone removal is partly influenced by its fragility, as prognosticated by the clinician. This feasibility study aims to develop a linear regression model from CT-based radiomic markers to predict kidney stone comminution time with two ultrasonic lithotrites. Patients identified by urologists at our institution as eligible candidates for percutaneous nephrolithotomy were prospectively enrolled.

Evaluation of neural innervation in the human conventional outflow pathway distal to Schlemm's canal.

The distal outflow pathway of the human eye consists of the outer wall of Schlemm's canal, collector channels, and the deep-scleral, mid-scleral and episcleral vessels. It is the last region of transit for aqueous humor before returning to the venous system. While the trabecular meshwork, scleral spur, and inner wall of Schlemm's canal have been extensively analyzed to define their contributions to aqueous outflow, the role of the distal outflow pathway is not completely understood.

Semantic Instance Segmentation of Kidney Cysts in MR Images: A Fully Automated 3D Approach Developed Through Active Learning.

Total kidney volume (TKV) is the main imaging biomarker used to monitor disease progression and to classify patients affected by autosomal dominant polycystic kidney disease (ADPKD) for clinical trials. However, patients with similar TKVs may have drastically different cystic presentations and phenotypes. In an effort to quantify these cystic differences, we developed the first 3D semantic instance cyst segmentation algorithm for kidneys in MR images.

Preconditioning with Foam-mediated External Suction on Flap Microvasculature and Perfusion in a Rodent Model.

Unlabelled: Foam-mediated external suction (FMES) has previously shown to improve tissue microcirculation. We hypothesized that preconditioning fasciocutaneous perforator flaps with FMES would augment perfusion and demonstrate greater capillary recruitment.

Methods: Gluteal perforator flaps were designed on sixteen 400 g rats.

A Blooming correction technique for improved vasa vasorum detection using an ultra-high-resolution photon-counting detector CT.

Proliferation of vasa vasorum, the microvasculature within artery walls, is an early marker of atherosclerosis. Detection of subtle changes in the spatial density of vasa vasorum using contrast-enhanced CT is challenging due to the limited spatial resolution and blooming effects. We report a forward model-based blooming correction technique to improve vasa vasorum detection in a porcine model imaged using an ultra-high resolution photon-counting detector CT.

Evaluation of a photon counting Medipix3RX cadmium zinc telluride spectral x-ray detector.

We assess the performance of a cadmium zinc telluride (CZT)-based Medipix3RX energy-resolving and photon-counting x-ray detector as a candidate for spectral microcomputed tomography (micro-CT) imaging. It features an array of , pixels, each with four simultaneous threshold counters that utilize real-time charge summing. Each pixel's response is assessed by imaging with a range of incident x-ray intensities and detector integration times.

Probing the Depth of the Myocardium: Vasculature, Transit Time, and Perfusion Within the Left Ventricular Wall.

The branching architecture of arterial trees traversing the thickness of the left ventricular wall is studied to determine the way in which adequate blood supply is provided to myocardial tissue at different depths within the wall thickness from arterial trees originating at the epicardial surface. The study is based on micro-CT images of tissue biopsies, coupled with a dedicated vascular tree analysis program. The results show that this combination of methodologies allows a more detailed and much more accurate exploration of the vasculature within the sampled tissue than is possible by histological means.

Impact of Effective Detector Pixel and CT Voxel Size on Accurate Estimation of Blood Volume in Opacified Microvasculature.

Rationale And Objectives: The purpose of this study was to determine the impact of effective detector-pixel-size and image voxel size on the accurate estimation of microvessel density (ratio of microvascular lumen volume/tissue volume) in an excised porcine myocardium specimen using microcomputed tomography (CT), and the ability of whole-body energy-integrating-detector (EID) CT and photon-counting-detector (PCD) CT to measure microvessel density in the same ex vivo specimen.

Materials And Methods: Porcine myocardial tissue in which the microvessels contained radio-opaque material was scanned using a micro-CT scanner and data were generated with a range of detector pixel sizes and image voxel sizes from 20 to 260 microns, to determine the impact of these parameters on the accuracy of microvessel density estimates. The same specimen was scanned in a whole-body EID CT and PCD CT system and images reconstructed with 600 and 250 micron slice thicknesses, respectively.

Arterial Wall Perfusion Measured with Photon Counting Spectral X-ray CT.

Early atherosclerosis changes perfusion of the arterial wall due to localized proliferation of the vasa vasorum. When contrast agent passes through the artery, some enters the vasa vasorum and increases radiopacity of the arterial wall. Technical challenges to detecting changes in vasa vasorum density include the thin arterial wall, partial volume averaging at the arterial lumen/wall interface and calcification within the wall.

Evaluation of a photon counting Medipix3RX CZT spectral x-ray detector.

We assessed the performance of a cadmium zinc telluride (CZT)-based Medipix3RX x-ray detector as a candidate for micro-computed tomography (micro-CT) imaging. This technology was developed at CERN for the Large Hadron Collider. It features an array of 128 by 128, 110 micrometer square pixels, each with eight simultaneous threshold counters, five of which utilize real-time charge summing, significantly reducing the charge sharing between contiguous pixels.

A Three-Dimensional Micro-Computed Tomographic Study of the Intraosseous Lunate Vasculature: Implications for Surgical Intervention and the Development of Avascular Necrosis.

Background: The purpose of this study was to use micro-computed tomography to demonstrate the intraosseous vascularity of the lunate within a three-dimensional orientation to identify areas of greatest perfusion and define vascular "safe zones" for surgical intervention.

Methods: Fourteen upper extremities were injected with a lead-based contrast agent. The lunates were harvested and scanned using a micro-computed tomography scanner.

Myocardial Perfusion: Characteristics of Distal Intramyocardial Arteriolar Trees.

A combination of experimental, theoretical, and imaging methodologies is used to examine the hierarchical structure and function of intramyocardial arteriolar trees in porcine hearts to provide a window onto a region of myocardial microvasculature which has been difficult to fully explore so far. A total of 66 microvascular trees from 6 isolated myocardial specimens were analyzed, with a cumulative number of 2438 arteriolar branches greater than or equal to 40 μm lumen diameter. The distribution of flow rates within each tree was derived from an assumed power law relationship for that tree between the diameter of vessel segments and flow rates that are consistent with that power law and subject to conservation of mass along hierarchical structure of the tree.

Anatomic changes in Schlemm's canal and collector channels in normal and primary open-angle glaucoma eyes using low and high perfusion pressures.

Purpose: To examine the anatomy of Schlemm's canal (SC) and collector channels (CCs) in normal human and primary open-angle glaucoma (POAG) eyes under low and high perfusion pressure.

Methods: In normal (n = 3) and POAG (n = 3) eye pairs, one eye was perfused at 10 mm Hg while the fellow eye was perfused at 20 mm Hg for 2 hours. Eyes were perfusion fixed at like pressures, dissected into quadrants, embedded in Epon Araldite, and scanned by three-dimensional micro-computed tomography (3D micro-CT).

Anatomy of hepatic arteriolo-portal venular shunts evaluated by 3D micro-CT imaging.

The liver differs from other organs in that two vascular systems deliver its blood - the hepatic artery and the portal vein. However, how the two systems interact is not fully understood. We therefore studied the microvascular geometry of rat liver hepatic artery and portal vein injected with the contrast polymer Microfil(®).

Changes in CT angiographic opacification of porcine coronary artery wall with patchy altered flow in vasa vasorum.

To evaluate the potential of whole-body CT to detect localized areas of decreased or increased vascularity in coronary arterial walls. We used both microsphere embolization of coronary artery vasa vasorum to generate small areas of hypoperfusion and surrounding hyperperfusion of the arterial wall and diet-induced hypercholesterolemia. As a stimulus for localized angiogenesis, such as occurs in early plaque formation in the coronary arterial wall, microspheres were injected selectively into the LAD coronary artery lumens of anesthetized pigs.

Intrinsic microvasculature of the sciatic nerve in the rat.

Microvasculature associated with the sciatic nerve was examined using high-resolution micro-CT scanning in one group of rats and surgical exploration in another. The results indicate that blood supply to the sciatic nerve is an "open-ended" system in which the vessels run longitudinally within the epineurium and connect with external vasculature primarily at junction points. Although the range of vasculature found extended down to 4-5 μ, only a few isolated vessels of this size were found, with no capillary "mesh" as such, possibly because of the close proximity of the intrinsic vessel to nerve fibers within the epineurium.

Complementary vascular and matrix regulatory pathways underlie the beneficial mechanism of action of sorafenib in liver fibrosis.

Unlabelled: Paracrine signaling between hepatic stellate cells (HSCs) and liver endothelial cells (LECs) modulates fibrogenesis, angiogenesis, and portal hypertension. However, mechanisms regulating these processes are not fully defined. Sorafenib is a receptor tyrosine kinase inhibitor that blocks growth factor signaling in tumor cells but also displays important and not yet fully characterized effects on liver nonparenchymal cells including HSCs and LECs.

Imaging the aqueous humor outflow pathway in human eyes by three-dimensional micro-computed tomography (3D micro-CT).

The site of outflow resistance leading to elevated intraocular pressure in primary open-angle glaucoma is believed to be located in the region of Schlemm's canal inner wall endothelium, its basement membrane and the adjacent juxtacanalicular tissue. Evidence also suggests collector channels and intrascleral vessels may have a role in intraocular pressure in both normal and glaucoma eyes. Traditional imaging modalities limit the ability to view both proximal and distal portions of the trabecular outflow pathway as a single unit.

Reproducibility of global and local reconstruction of three-dimensional micro-computed tomography of iliac crest biopsies.

Variation in computed tomography (CT) image gray-scale and spatial geometry due to specimen orientation, magnification, voxel size, differences in X-ray photon energy and limited field-of-view during the scan, were evaluated in repeated micro-CT scans of iliac crest biopsies and test phantoms. Using the micro-CT scanner on beamline X2B at the Brookhaven National Laboratory's National Synchrotron Light Source, 3-D micro-CT images were generated. They consisted of up to 1024 x 2400(2), 4-microm cubic voxels, each with 16-bit gray-scale.