Computed Tomography Visualization Research Articles

Evolution of Soil Pore Structure and Shear Strength Deterioration of Compacted Soil under Controlled Wetting and Drying Cycles

This study investigates the evolution of soil pore structure and shear strength deterioration in compacted clayey soil under controlled wetting and drying (wd) cycles, which are expected to become more frequent due to climate change. Thirty soil samples were compacted at optimal moisture content and 90% maximum dry density. These samples were then subjected to 0, 1, 5, 10, and 15 controlled wd cycles from saturation to the wilting point, and volumetric changes were recorded during each cycle. After the wd treatment, the soil samples were scanned using X-ray computed tomography (CT) at 50 μm resolution and then sheared under unconsolidated–undrained and consolidated–undrained conditions in a triaxial test. Significant shrinkage and swelling of soil samples were observed during wd cycles, with average volumetric strain fluctuating between +12% at saturation and −5% at the wilting point. X-ray CT visualisation and analysis revealed higher porosity, more prominent pores, and increased pore length in soil samples with increasing wd cycles. Both undrained and effective soil shear strength markedly decreased with increasing wd cycles. CT-derived macroporosity and pore length were significant predictors of the soil’s undrained and effective shear strength when exposed to wd cycles. The findings emphasise the considerable impact of climate change, specifically wd cycles, on clayey soil, highlighting the need for consideration in the design of earth-based infrastructure.

Using Patient-Specific Contrast Enhancement Optimizer Simulation Software During the Transcatheter Aortic Valve Implantation-Computed Tomography Angiography in Patients With Aortic Stenosis.

This study assessed whether patient-specific contrast enhancement optimizer simulation software (p-COP) can reduce the contrast material (CM) dose compared with the conventional body weight (BW)-tailored scan protocol during transcatheter aortic valve implantation-computed tomography angiography (TAVI-CTA) in patients with aortic stenosis. We used the CM injection protocol selected by the p-COP in group A (n = 30). p-COP uses an algorithm that concerns data on an individual patient's cardiac output. Group B (n = 30) was assigned to the conventional BW-tailored CM injection protocol group. We compared the CM dose, CM amount, injection rate, and computed tomography (CT) values in the abdominal aorta between the 2 groups and classified them as acceptable (>280 Hounsfield units (HU)) or unacceptable (<279 HU) based on the optimal CT value and visualization scores for TAVI-CTA. We used the Mann-Whitney U test to compare patient characteristics and assess the interpatient variability of subjects in both groups. Group A received 56.2 mL CM and 2.6 mL/s of injection, whereas group B received 76.9 mL CM and 3.4 mL/s of injection ( P < 0.01). The CT value for the abdominal aorta at the celiac level was 287.0 HU in group A and 301.7HU in group B ( P = 0.46). The acceptable (>280 HU) and unacceptable (<280 HU) CT value rates were 22 and 8 patients in group A and 24 and 6 patients in group B, respectively ( P = 0.76). We observed no significant differences in the visualization scores between groups A and B (visualization score = 3, P = 0.71). The utilization of p-COP may decrease the CM dosage and injection rate by approximately 30% in individuals with aortic stenosis compared with the body-weight-tailored scan protocol during TAVI-CTA.

Model construction and software design of computed tomography radiation system based on visualization

The Monte Carlo N-Particle (MCNP) is often used to calculate the radiation dose during computed tomography (CT) scans. However, the physical calculation process of the model is complicated, the input file structure of the program is complex, and the three-dimensional (3D) display of the geometric model is not supported, so that the researchers cannot establish an accurate CT radiation system model, which affects the accuracy of the dose calculation results. Aiming at these two problems, this study designed a software that visualized CT modeling and automatically generated input files. In terms of model calculation, the theoretical basis was based on the integration of CT modeling improvement schemes of major researchers. For 3D model visualization, LabVIEW was used as the new development platform, constructive solid geometry (CSG) was used as the algorithm principle, and the introduction of editing of MCNP input files was used to visualize CT geometry modeling. Compared with a CT model established by a recent study, the root mean square error between the results simulated by this visual CT modeling software and the actual measurement was smaller. In conclusion, the proposed CT visualization modeling software can not only help researchers to obtain an accurate CT radiation system model, but also provide a new research idea for the geometric modeling visualization method of MCNP.

Targeted Computed Tomography Visualization and Healing of Inflammatory Bowel Disease by Orally Delivered Bacterial-Flagella-Inspired Polydiiododiacetylene Nanofibers.

Accurate diagnosis and timely therapeutic intervention of inflammatory bowel disease (IBD) is essential in preventing the progression of the disease, although it still represents an insurmountable challenge. Here we report the design of bacterial-flagella-inspired polydiiododiacetylene (PIDA) nanofibers and its performance in targeted computed tomography (CT) imaging and on-demand therapeutic intervention of IBD. With a morphology mimicking bacterial flagella, PIDA nanofibers attach on the mucus layer of the gastrointestinal (GI) tract after oral administration, evenly distributing on the GI surface to portray the GI lining under CT scan within 2 h. PIDA can retain for a longer time in the damaged mucosa at the inflamed lesions than in normal GI tissues to enable the targeted CT visualization of IBD. PIDA also scavenges reactive oxygen species and ameliorates gut dysbiosis attributed to its iodine-substituted polydiacetylene structure, so that the enriched PIDA nanofibers at the targeted IBD lesions can alleviate the inflammation while maintaining the gut microbiota homeostasis, thus promoting the rebalance of GI microenvironment and the mucosal healing.

Interventional Magnetic Resonance Imaging Suite (IMRIS): How to build and how to use

Over the last ten years, the number of minimally invasive interventional procedures has been increasing steadily. Magnetic resonance imaging (MRI) is still far less frequently used for image-guided percutaneous procedures or as an intervention method than computed tomography (CT) and ultrasound (US). However, MRI has many advantages, such as lack of ionizing radiation, real-time MR-fluoroscopy placement high resolution, no bone and gas artifacts, the ability to display lesions that are difficult to observe on CT and US visualization of blood vessels without a contrast agent, free selection of imaging planes and in the case of procedures such as thermos or cryoablation it is possible to make an intraprocedural assessment of the process without the application of a contrasting agent (Marini et al. in Diagn Interv Imaging 102: 531-538, 2021; Li et al. in BMC Cancer 21: 366, 2021; Barkhausen et al. in Rofo 189: 611, 2017). Furthermore, in addition to its use in Interventional Radiology, MRI is also becoming a reality in cardiology thanks to the possibility of overcoming all the limits related to the fusion technology used up to now in cardiac ablations (Chubb et al. Arrhythm Electrophysiol Rev 6: 85, 2017). Some suites have been built in Northern Europe and in the United States, but based only on personal experience and industry indication. In our hospital, we have built a new Interventional Magnetic Resonance Imaging Suite (IMRIS), the first in Southern Europe and we have defined what the necessary requirements and equipment were for the safety of the patient and the operator.

Improving Safety in Chondrolaryngoplasty.

Improving Safety in Chondrolaryngoplasty.

Acoustic emission and computed tomography investigation on fatigue failure of fissure‐contained hollow‐cylinder granite: Cavity diameter effect

AbstractThis work aims to investigate the influence of cavity diameter on fracture behaviors for fissure‐contained hollow‐cylinder granite subjected to multistage cyclic loads, using acoustic emission detection, and post‐test computed tomography (CT) scanning. The influence of the cavity diameter on rock fracture was revealed in terms of volumetric deformation, stiffness degradation, AE output activities, hole spalling, and crack coalescence pattern. The testing results show the both the volumetric strain and AE b value decrease with increasing cavity diameter. An increase of volumetric strain and a decrease of AE b value are found during rock failure and their relationship was established. In addition, damage is quantificationally characterized by the released energy, and a damage evolution model is defined to characterize rock damage process. Moreover, post‐test CT visualization highlights the communication between the hole and fissures at the rock bridge segment, and it is suggested that failure severity decreases with the increase of hole diameter.

Maisonneuve Fractures of the Ankle: A Critical Analysis Review.

Maisonneuve fractures (MFs), originally described as subcapital (high) fibular fractures with additional injury to the anterior and interosseous tibiofibular ligaments, display a variable injury pattern, ranging from stable to highly unstable fractures. The high incidence of associated fractures of the posterior malleolus, the medial malleolus, and the anterolateral distal tibia (the "anterior malleolus") as well as the variable position of the fibula in the fibular notch (FN) warrant preoperative examination via computed tomography (CT). The main goal of treatment is anatomic reduction of the distal fibula into the FN, which requires prior reduction of displaced posterior malleolar fractures, if present, to restore the integrity of the FN. Open reduction of the distal fibula into the FN and fixation with 2 transsyndesmotic screws or fixation with a screw(s) and suture-button implant, under direct vision, on the lateral aspect of the ankle joint and anterior tibiofibular alignment are preferred over closed reduction to avoid sagittal or rotational malpositioning, which is associated with an inferior outcome. Intra- or postoperative 3D CT visualization is essential for assessment of the accuracy of the reduction of the distal fibula into the FN.

In vitro CT visualization of the biopsy location by filling the core biopsy needle with contrast media.

BackgroundWhen performing computed tomography (CT)-guided biopsy procedures with non-disposable, automatic biopsy instruments, the actual course of the biopsy needle is not registered.PurposeTo evaluate the ability to visualize the sampling location after CT-guided biopsy in vitro using a novel method, where the space between the inner needle and the outer cannula in a core biopsy needle is filled with contrast media; and to compare the grade of visibility for two different concentrations of contrast media.Material and MethodsCore needle biopsies were performed in a tissue phantom using biopsy needles primed with two different iodine contrast media concentrations (140 mg I/mL and 400 mg I/mL). Commercially available needle-filling contraptions with sealing membranes were used to fill the needles. Each biopsy was imaged with CT, and the visibility was evaluated twice by three senior radiologists in a randomized order.ResultsThe presence of traces was confirmed after biopsy, almost without exception for both concentrations. The visibility was sufficient to determine the biopsy location in all observations with the 400 mg I/mL filling, and in 7/10 observations with the 140 mg I/mL filling. The grade of visibility of the trace and the proportion of the biopsy needle course outlined were higher with the 400 mg I/mL filling.ConclusionWith CT-guided biopsy in vitro, the sampling location can be visualized using a novel method of priming the biopsy needle with iodine contrast media, specifically highly concentrated contrast media.

Characterization of an Iodinated Rectal Spacer for Prostate Photon and Proton Radiation Therapy

PurposeConventional rectal spacers (nonI-SPs) are low-contrast on computed tomography (CT), often necessitating magnetic resonance imaging for accurate delineation. A new formulation of spacers (I-SPs) incorporates iodine to improve radiopacity and CT visualization. We characterized placement, stability, and plan quality of I-SPs compared to nonI-SPs. Methods and MaterialsPatients with intact prostate cancer (n = 50) treated with I-SPs and photons were compared to randomly selected patients (n = 50) with nonI-SPs (photon or proton therapy). The I-SP was contoured on the planning CT and cone beam CTs at 3 timepoints: first, middle, and final treatment (n = 200 scans). I-SPs Hounsfield units (HU), volume, surface area (SA), centroid position relative to prostate centroid, and distance between prostate/rectum centroids were compared on the planning CTs between each cohort. I-SP changes were evaluated on cone beam CTs over courses of treatment. Dosimetric evaluations of plan quality and robustness were performed. I-SP was tested in a phantom to characterize its relative linear stopping power for protons. ResultsI-SPs yielded a distinct visible contrast on planning CTs compared to nonI-SPs (HU 138 vs 12, P < .001), allowing delineation on CT alone. The delineated volume and SA of I-SPs were smaller than nonI-SPs (volume 8.9 vs 10.6 mL, P < .001; SA 28 vs 35 cm2, P < .001), yet relative spacer position and prostate-rectal separation were similar (P = .79). No significant change in HU, volume, SA, or relative position of the I-SPs hydrogel occurred over courses of treatment (all P > .1). Dosimetric analysis concluded there were no significant changes in plan quality or robustness for I-SPs compared to nonI-SPs. The I-SP relative linear stopping power was 1.018, necessitating HU override for proton planning. ConclusionsI-SPs provide a manifest CT contrast, allowing for delineation on planning CT alone with no magnetic resonance imaging necessary. I-SPs radiopacity, size, and relative position remained stable over courses of treatment from 28 to 44 fractions. No changes in plan quality or robustness were seen comparing I-SPs and nonI-SPs.

X-ray tomographic data of planktonic foraminifera species Globigerina bulloides from the Eastern Tropical Atlantic across Termination II.

Increased planktonic foraminifera shell weights were recorded during the course of Termination II at a tropical site off the shore of the Mauritanian coast. In order to investigate these increased shell mass values, a series of physicochemical analyses were performed, including X-ray computed tomography (CT). The data are given here. Furthermore, the relevant CT setup, scanning, reconstruction, and visualization methods are explained and the acquired datasets are given, together with 3D volumes and models of the scanned specimens.

Advanced CT visualization improves the accuracy of orthopaedic trauma surgeons and residents in classifying proximal humeral fractures: a feasibility study.

Osteosynthesis of proximal humeral fractures remains challenging with high reported failure rates. Understanding the fracture type is mandatory in surgical treatment to achieve an optimal anatomical reduction. Therefore, a better classification ability resulting in improved understanding of the fracture pattern is important for preoperative planning. The purpose was to investigate the feasibility and added value of advanced visualization of segmented 3D computed tomography (CT) images in fracture classification. Seventeen patients treated with either plate-screw-osteosynthesis or shoulder hemi-prosthesis between 2015 and 2019 were included. All preoperative CT scans were segmented to indicate every fracture fragment in a different color. Classification ability was tested in 21 orthopaedic residents and 12 shoulder surgeons. Both groups were asked to classify fractures using three different modalities (standard CT scan, 3D reconstruction model, and 3D segmented model) into three different classification systems (Neer, AO/OTA and LEGO). All participants were able to classify the fractures more accurately into all three classification systems after evaluating the segmented three-dimensional (3D) models compared to both 2D slice-wise evaluation and 3D reconstruction model. This finding was significant (p < 0.005) with an average success rate of 94%. The participants experienced significantly more difficulties classifying fractures according to the LEGO system than the other two classifications. Segmentation of CT scans added value to the proximal humeral fracture classification, since orthopaedic surgeons were able to classify fractures significantly better into the AO/OTA, Neer, and LEGO classification systems compared to both standard 2D slice-wise evaluation and 3D reconstruction model.

Mechanical behaviours of granite containing two flaws under uniaxial increasing‐amplitude fatigue loading conditions: An insight into fracture evolution analyses

AbstractThis work aims to investigate the fracture evolution of granite containing two pre‐existing flaws under uniaxial increasing‐amplitude fatigue conditions using macroscopic stress strain descriptions and posttest three‐dimensional (3D) computed tomography (CT) technique. The impacts of flaw arrangement (i.e., approach angle of 20°, 50° and 70°) on the stress strain responses, hysteresis loop shape, damage evolution and crack coalescence pattern at rock bridge segment were investigated. Results show that rock structure has an obvious impact on macroscopic stress strain responses, volumetric strain, dynamic elastic modulus and damping ratio. The sparse‐dense pattern of hysteresis loop is different at each loading stage caused by the differential accumulative damage. The damping ratio increases and dynamic elastic modulus decreases with the increasing fatigue loading stage. Posttest 3D CT visualization reveals a most striking finding that crack coalescence is easy for rock having low approach angle, and complex crack network forms for rock having high approach angle.

Addition of Iodinated Contrast to Rectal Hydrogel Spacer to Facilitate MRI-Independent Target Delineation and Treatment Planning for Prostate Cancer

Rectal hydrogel spacers are increasingly used to reduce dose and thereby limit toxicity to the rectum during prostate radiotherapy. Commercially available products require magnetic resonance imaging (MRI) for hydrogel visualization and treatment planning, with only anecdotal reports of treatment planning with computed tomography (CT) alone. MRI-incompatible hardware, patient intolerance, and added cost provide incentives for MRI-independent alternatives for treatment planning. This case series evaluates the addition of iodinated contrast to spacer gel and assesses its impact on CT visualization. Three prostate cancer patients underwent contrasted rectal spacer placement in preparation for external beam radiotherapy. Standard low-osmolar iodinated contrast was added to a commercially available rectal hydrogel. 0.5cc of contrast was added to 4.5cc of accelerator and subsequently combined with 5cc of diluent. The resultant 10cc of hydrogel was injected into each patient as per standard procedure, utilizing transrectal ultrasound guidance. Two patients were simulated with MRI; a third with a non-MRI compatible pacemaker was planned with CT alone. CT was performed on the day of hydrogel placement within 2 hours of procedure and again 7-12 days later to account for fiducial migration and dissipation of injected air. The second CT was used for treatment planning. Hydrogel visibility was compared between CT and MRI through standardized symmetry scoring, volume calculation, and measurements taken at prostate base, mid-gland, and apex. Spacer contrast was visible only on the day of hydrogel placement by CT, allowing target delineation for treatment planning. On comparison to MRI delineation of spacer one week later, minimal changes in relevant spacer measurements were observed. In one patient, a significant amount of injected air dissipated between the time of hydrogel placement and repeat CT. CT visualization of rectal hydrogel with iodinated contrast on day of placement is feasible and allows MRI-independent treatment planning with spacer gel, but requires repeat CT on a subsequent day to allow for resolution of prostatic edema, fiducial migration, and air within the hydrogel spacer.Abstract 3673; Table 1PatientSimulation Type (Day)Spacer Volume (cc)CC Dimension (mm)AP Dimension (mm)TV Dimension (mm)Base Thickness (mm)Mid-gland Thickness (mm)Apex Thickness (mm)Symmetry Score1CT* (0)16.661.416.430.815.714.715.91CT (8)15.951.417.629.519.017.716.91MR (8)15.555.817.32616.516.816.212CT* (0)12.636.613.839.215.813.811.82CT (12)14.138.812.641.512.811.502MR (12)14.748.615.343.213.212.511.213CT* (0)18.1†58.7†11†40.5†11.8†12.3†15.7†3†CT (7)11.352.41030.411.910.59.52*Spacer contrast visible, †Includes injected air Open table in a new tab

Computed Tomography Cinematic Rendering in the Evaluation of Colonic Pathology: Technique and Clinical Applications.

Three-dimensional (3D) visualizations of computed tomography (CT) data have found use in the display of complex anatomy and pathology. A new method of 3D CT image creation known as cinematic rendering (CR) makes use of a global lighting model to produce photorealistic images. Cinematic rendering images contain high levels of detail with shadowing and depth that are not available from traditional 3D CT techniques. As yet, the role of CR in evaluating colonic pathology has not been investigated. However, given the breadth of pathologic processes that affect the colon, including inflammatory bowel disease, diverticulitis, neoplastic conditions, herniation, and gastrointestinal bleeding, we undertook a survey of recent cases at our institution to demonstrate colon pathology as visualized with CR. The following review discusses the role of 3D CT visualizations for colonic pathology with an emphasis on CR example images.

Study on Visualization and Failure Mode of Model Test of Rock-Socketed Pile in Soft Rock

Computed tomography (CT) technology is a kind of nondestructive image reconstruction technology. CT visualization technology is introduced into the physical model test of a single pile, which can visualize a rock-socketed pile in soft rock under different pile top loads. In this article, the visualization process of a model test of a rock-socketed pile in soft rock is carried out by medical CT. The implementation procedure, the composition of the device, and the technical requirements of the test equipment, as well as the CT scanning operation of nondestructive visualization technique of the single pile model test, are introduced in detail. The influence of a marked layer setting, side wall effect, size of the model cylinder, and model pile on the visualization effect of a single pile model test is discussed. The feasibility and reliability of the model test visualization technology of a rock-socketed pile in soft rock are demonstrated by examples, and the failure mode of rock-socketed pile in soft rock is intuitively revealed to be the spherical cavity expansion mode of the pile end.

Intraoperative Computed Tomography Navigational Assistance for Transforaminal Endoscopic Decompression of Heterotopic Foraminal Bone Formation After Oblique Lumbar Interbody Fusion

Transforaminal endoscopic spine surgery is an emerging technique in spine surgery, but it offers 2 distinct challenges to spine surgeons looking to adopt it: 1) targeting spine pathology and 2) understanding the endoscopic anatomy visualized through the endoscope. Intraoperative computed tomography (CT)-guided navigation is also an emerging technique in spine surgery that is becoming widely adopted for its benefits in assisting surgeons in localizing pathology and guided spine instrumentation placement. In this technical note, we describe a technique that uses intraoperative CT-guided navigation concomitantly with a transforaminal endoscopic approach to decompress a L4-L5 foraminal heterotopic bone formation after an oblique lumbar interbody fusion. The addition of intraoperative CT-guided navigation proved beneficial in targeting the pathology during the procedure and ensuring that the pathology was resolved by offering postoperative CT visualization of the decompressed neural foramen.

Myocardial perfusion imaging in women for the evaluation of stable ischemic heart disease—state-of-the-evidence and clinical recommendations

This document from the American Society of Nuclear Cardiology represents an updated consensus statement on the evidence base of stress myocardial perfusion imaging (MPI), emphasizing new developments in single-photon emission tomography (SPECT) and positron emission tomography (PET) in the clinical evaluation of women presenting with symptoms of stable ischemic heart disease (SIHD). The clinical evaluation of symptomatic women is challenging due to their varying clinical presentation, clinical risk factor burden, high degree of comorbidity, and increased risk of major ischemic heart disease events. Evidence is substantial that both SPECT and PET MPI effectively risk stratify women with SIHD. The addition of coronary flow reserve (CFR) with PET improves risk detection, including for women with nonobstructive coronary artery disease and coronary microvascular dysfunction. With the advent of PET with computed tomography (CT), multiparametric imaging approaches may enable integration of MPI and CFR with CT visualization of anatomical atherosclerotic plaque to uniquely identify at-risk women. Radiation dose-reduction strategies, including the use of ultra-low-dose protocols involving stress-only imaging, solid-state detector SPECT, and PET, should be uniformly applied whenever possible to all women undergoing MPI. Appropriate candidate selection for stress MPI and for post-MPI indications for guideline-directed medical therapy and/or invasive coronary angiography are discussed in this statement. The critical need for randomized and comparative trial data in female patients is also emphasized.

Computer based CT scoring versus visual CT scores: identifying optimal predictors of functional decline and mortality in IPF

Purpose: Visual computed tomography (CT) scoring and change in forced vital capacity (FVC) are constrained by measurement variation, and may be eclipsed in the near future by computer analysis of CTs. We compared the ability of visual and computer scoring of CTs to predict functional decline (FVC change) in idiopathic pulmonary fibrosis (IPF) and evaluated visual, computer-aided lung informatics for pathology evaluation and rating (CALIPER) and FVC change scores in predicting mortality in IPF.

X‐ray CT‐Derived Soil Characteristics Explain Varying Air, Water, and Solute Transport Properties across a Loamy Field

Core Ideas We used CT‐derived parameters to explain solute, water, and air transport at field scale. CTmatrix was found to be the best parameter to explain solute transport. Limiting macroporosity gave the highest correlations with water and air transport. Combining macroporosity and CTmatrix improved the relationships of water and air flow. The characterization of soil pore space geometry is important for explaining fluxes of air, water, and solutes through soil and understanding soil hydrogeochemical functions. X‐ray computed tomography (CT) can be applied for this characterization, and in this study CT‐derived parameters were used to explain water, air, and solute transport through soil. Forty‐five soil columns (20 by 20 cm) were collected from an agricultural field in Estrup, Denmark, and subsequently scanned using a medical CT scanner. Nonreactive tracer leaching experiments were performed in the laboratory along with measurements of air permeability (Ka) and saturated hydraulic conductivity (Ksat). The CT number of the matrix (CTmatrix), which represents the moist bulk density of the soil matrix, was obtained from the CT scans as the average CT number of the voxels in the grayscale image excluding macropores and stones. The CTmatrix showed the best relationships with the solute transport characteristics, especially the time by which 5% of the applied mass of tritium was leached, known as the 5% arrival time (t0.05). The CT‐derived macroporosity (pores &gt;1.2 mm) was correlated with Ka and log10(Ksat). The correlation improved when the limiting macroporosity (the minimum macroporosity for every 0.6‐mm layer along the soil column) was used, suggesting that soil layers with the narrowest macropore section restricted the flow through the whole soil column. Water, air, and solute transport were related with the CT‐derived parameters by using a best subsets regression analysis. The regression coefficients improved using CTmatrix, limiting macroporosity, and genus density, while the best model for t0.05 used CTmatrix only. The scanning resolution and the time for soil structure development after mechanical activities could be factors that increased the uncertainty of the relationships. Nevertheless, the results confirmed the potential of X‐ray CT visualization techniques for estimating fluxes through soil at the field scale.