CT Techniques Research Articles

Quantification of spinal bone marrow fat fraction using three-material decomposition technique on dual-energy CT: A phantom study.

Two-material decomposition is insufficient to quantify the fat fraction of spinal bone marrow, which is comprised of a mixture of bone minerals, water, and yellow marrow (fat). To develop an accurate three-material decomposition-based bone marrow fat fraction ( ) quantification technique for dual-energy CT. Bone marrow edema phantoms containing trabecular bone minerals, water, and fat were constructed using fat fractions and bone mineral density values matching those expected in healthy and edematous bone, and scanned on a commercial dual-energy CT. Fat quantified by were compared to MRI-based fat fraction ( ) and conventional two-material-decomposition-based fat fraction ( ) to evaluate its accuracy and dependency on various bone mineral densities. demonstrated an excellent correlation with (r=0.97, R2 =0.96) in the phantom, significantly more accurate than FF2MD when confounding bone minerals are present (50mg/cm3 : r=1.02, R2 =0.95vs. r=0.65, R2 =0.79 (p<0.01); 100mg/cm3 : r=0.81, R2 =0.47vs. r=0.21, R2 =0.21 (p<0.05)). accurately quantified bone marrow fat fraction, when compared with , in the specially constructed bone marrow phantom.

Back-forward bending CT in simulated surgical position to evaluate the remaining real angle and flexibility of thoracolumbar kyphosis secondary to old osteoporotic vertebral compression fracture

To introduce a scout view scanning technique of back-forward bending CT (BFB-CT) in simulated surgical position for evaluating the remaining real angle and flexibility of thoracolumbar kyphosis secondary to old osteoporotic vertebral compression fracture. A total of 28 patients with thoracolumbar kyphosis secondary to old osteoporotic vertebral compression fracture who met the selection criteria between June 2018 and December 2021 were included in the study. There were 6 males and 22 females with an average age of 69.5 years (range, 56-92 years). The injured vertebra were located at T 10-L 2, including 11 cases of single thoracic fracture, 11 cases of single lumbar fracture, and 6 cases of multiple thoracolumbar fractures. The disease duration ranged from 3 weeks to 36 months, with a median of 5 months. All patients received examinations of BFB-CT and standing lateral full-spine X-ray (SLFSX). The thoracic kyphosis (TK), thoracolumbar kyphosis (TLK), local kyphosis of injured vertebra (LKIV), lumbar lordosis (LL), and the sagittal vertical axis (SVA) were measured. Referring to the calculation method of scoliosis flexibility, the kyphosis flexibility of thoracic, thoracolumbar, and injured vertebra were calculated respectively. The sagittal parameters measured by the two methods were compared, and the correlation of the parameters measured by the two methods was analyzed by Pearson correlation. Except LL ( P>0.05), TK, TLK, LKIV, and SVA measured by BFB-CT were significantly lower than those measured by SLFSX ( P<0.05). The flexibilities of thoracic, thoracolumbar, and injured vertebra were 34.1%±18.8%, 36.2%±13.8%, and 39.3%±18.6%, respectively. Correlation analysis showed that the sagittal parameters measured by the two methods were positively correlated ( P<0.001), and the correlation coefficients of TK, TLK, LKIV, and SVA were 0.900, 0.730, 0.700, and 0.680, respectively. Thoracolumbar kyphosis secondary to old osteoporotic vertebral compression fracture shows an excellent flexibility and BFB-CT in simulated surgical position can obtain the remaining real angle which need to be corrected surgically.

Spinal Hematoma Visualized with Dual-energy CT-derived Electron Density Overlay Maps.

HomeRadiologyRecently Published PreviousNext Reviews and CommentaryFree AccessImages in RadiologySpinal Hematoma Visualized with Dual-energy CT-derived Electron Density Overlay MapsChristian Nelles, Simon Lennartz Christian Nelles, Simon Lennartz Author AffiliationsInstitute for Diagnostic and Interventional Radiology, Faculty of Medicine and University Hospital Cologne, University of Cologne, Kerpener Strasse 62, 50937 Cologne, Germany.Address correspondence to S.L. (email: [email protected]).Christian NellesSimon Lennartz Published Online:Apr 11 2023https://doi.org/10.1148/radiol.222680MoreSectionsPDF ToolsImage ViewerAdd to favoritesCiteTrack CitationsPermissionsReprints ShareShare onFacebookTwitterLinked In A 67-year-old man was admitted to the hospital with spontaneous, sudden-onset, severe thoracic back pain, radiating to the neck and lower back, accompanied by an episode of transient paraplegia of unknown severity, which lasted for 30–45 minutes. Three years prior, he had undergone mechanical aortic valve replacement with resection of an ascending aortic aneurysm associated with a bicuspid aortic valve. Consecutively, he had been treated with phenprocoumon for anticoagulation, with an international normalized ratio value of 4.5 at the time of admission (therapeutic range: 2.0–3.0). As the symptoms raised suspicion for aortic dissection, CT angiography of the chest and abdomen was performed with dual-layer dual-energy CT (dlDECT). dlDECT is a detector-based dual-energy CT technique in which a stacked scintillator registers lower energetic photons in the upper layer, whereas higher energetic photons are detected within the subjacent layer (1). The examination did not show signs of aortic dissection or other acute vascular pathologic conditions. Apart from persistent back pain, the patient’s symptoms receded. He was kept under surveillance for 3 days, after which worsening of the pain and the development of new high-grade paraplegia occurred, prompting an emergency MRI examination of the spine. The MRI scan showed extensive spinal hematoma, ranging from T1 to L1, with the maximum diameter and spinal cord compression at the level of T4-6 but without abnormal signal intensity of the spinal cord (Figure, A). The hematoma could not unequivocally be assigned to either the epi- or subdural space. Additionally, subarachnoid hemorrhage was noted along the cauda equina. The patient underwent successful emergency surgical evacuation of the hematoma, which during surgery showed extension to both the epi- and subdural as well as the subarachnoid space. Because digital subtraction angiography scans showed no vascular cause of the hematoma, spontaneous hemorrhage due to over-anticoagulation was determined as the most likely cause. After surgery, the pain and neurologic symptoms resolved rapidly, and the patient was discharged for subsequent rehabilitation. At retrospective review, different spectral data were reconstructed to determine if any of them might have facilitated earlier diagnosis of spinal hematoma with CT. Besides conventional images, virtual noncontrast and iodine images were also unremarkable. However, electron density overlay maps (Figure, B) clearly depicted the hematoma. The increased content of hemoglobin within the hematoma results in a higher material density at this location with a lesser effect on the average atomic number. There is only one study that showed that electron density maps may improve detection of prevertebral hematoma (2), which is in line with the finding in the case presented here. However, the application for detecting intraspinal hematoma has not been described yet. This might be a promising topic for systematic scientific evaluation, as electron density maps could improve CT-based detection of spinal hematoma in the emergency setting, potentially decreasing morbidity by enabling earlier treatment.(A) MRI scans of the spine in a 67-year-old man. Sagittal T2-weighted (top left) and T1-weighted (top right) images and axial contrast-enhanced, fat-saturated, T1-weighted image (bottom) show extensive spinal hematoma (arrows). The maximum diameter is located at the level of thoracic vertebrae T4-6 with effacement of the perimedullary cerebrospinal fluid and spinal cord compression. (B) Dual-layer dual-energy CT reconstructions show the corresponding CT angiography scans of the chest. Electron density overlay images (left) clearly depict the hematoma (green; arrows) that is protruding in the spinal canal. Conventional images (right) in the sagittal and axial plane. The hematoma is almost entirely imperceivable (arrows).Download as PowerPointOpen in Image Viewer Disclosures of conflicts of interest: C.N. No relevant relationships. S.L. Senior deputy editor for Radiology In Training; member of the Radiology editorial board.

3D-Printed Iodine-Ink CT Phantom for Radiomics Feature Extraction - Advantages and Challenges.

To test and validate novel CT techniques, such as texture analysis in radiomics, repeat measurements are required. Current anthropomorphic phantoms lack fine texture and true anatomic representation. 3D-printing of iodinated ink on paper is a promising phantom manufacturing technique. Previously acquired or artificially created CT data can be used to generate realistic phantoms. To present the design process of an anthropomorphic 3D-printed iodine ink phantom, highlighting the different advantages and pitfalls in its use. To analyze the phantom's x-ray attenuation properties, and the influences of the printing process on the imaging characteristics, by comparing it to the original input dataset. Two patient CT scans and artificially generated test patterns were combined in a single dataset for phantom printing and cropped to a size of 26×19×30 cm3 . This DICOM dataset was printed on paper using iodinated ink. The phantom was CT-scanned and compared to the original image dataset used for printing the phantom. The water-equivalent diameter of the phantom was compared to that of a patient cohort (N = 104). Iodine concentrations in the phantom were measured using dual-energy CT. 86 radiomics features were extracted from 10 repeat phantom scans and the input dataset. Features were compared using a histogram analysis and a PCA individually and overall, respectively. The frequency content was compared using the normalized spectrum modulus. Low density structures are depicted incorrectly, while soft tissue structures show excellent visual accordance with the input dataset. Maximum deviations of around 30 HU between the original dataset and phantom HU values were observed. The phantom has x-ray attenuation properties comparable to a lightweight adult patient (∼54 kg, BMI 19 kg/m2 ). Iodine concentrations in the phantom varied between 0 and 50 mg/ml. PCA of radiomics features shows different tissue types separate in similar areas of PCA representation in the phantom scans as in the input dataset. Individual feature analysis revealed systematic shift of first order radiomics features compared to the original dataset, while some higher order radiomics features did not. The normalized frequency modulus |f(ω)| of the phantom data agrees well with the original data. However, all frequencies systematically occur more frequently in the phantom compared to the maximum of the spectrum modulus than in the original data set, especially for mid-frequencies (e.g. for ω = 0.3942 mm-1 , |f(ω)|original = 0.09 * |fmax |original and |f(ω)|phantom = 0.12 * |fmax |phantom ). 3D-iodine-ink-printing technology can be used to print anthropomorphic phantoms with a water-equivalent diameter of a lightweight adult patient. Challenges include small residual air enclosures and the fidelity of HU values. For soft tissue, there is a good agreement between the HU values of the phantom and input data set. Radiomics texture features of the phantom scans are similar to the input data set, but systematic shifts of radiomics features in first order features, due to differences in HU values, need to be considered. The paper substrate influences the spatial frequency distribution of the phantom scans. This phantom type is of very limited use for dual-energy CT analyses. This article is protected by copyright. All rights reserved.

Erratum: Noninvasive assessment of hepatic steatosis using a pathologic reference standard: comparison of CT, MRI, and US-based techniques

Ultrasonography (renamed from the Journal of Korean Society of Ultrasound in Medicine in January 2014), the official English-language journal of the Korean Society of Ultrasound in Medicine (KSUM), is an international peer-reviewed academic journal dedicated to practice, research, technology, and education dealing with medical ultrasound, Aims and Scope:Ultrasonography (renamed from the Journal of Korean Society of Ultrasound in Medicine in January 2014), the official English-language journal of the Korean Society of Ultrasound in Medicine (KSUM), is an international peer-reviewed academic journal dedicated to practice, research, technology, and education dealing with medical ultrasound.It is published four times per year: January 1, April 1, July 1, and October 1. Original articles, topical reviews, pictorial essays, and notable case reports are published in Ultrasonography covering state-of-the-art content. Ultrasonography also serves as a medium for cooperation among physicians and specialists from around the world who are focusing on various ultrasound technology and disease problems.

Advanced imaging of head and neck infections.

When head and neck infection is suspected, appropriate imaging contributes to treatment decisions and prognosis. While contrast-enhanced CT is the standard imaging modality for evaluating head and neck infections, MRI can better characterize the skull base, intracranial involvement, and osteomyelitis, implying that these are complementary techniques for a comprehensive assessment. Both CT and MRI are useful in the evaluation of abscesses and thrombophlebitis, while MRI is especially useful in the evaluation of intracranial inflammatory spread/abscess formation, differentiation of abscess from other conditions, evaluation of the presence and activity of inflammation and osteomyelitis, evaluation of mastoid extension in middle ear cholesteatoma, and evaluation of facial neuritis and labyrinthitis. Apparent diffusion coefficient derived from diffusion-weighted imaging is useful for differential diagnosis and treatment response of head and neck infections in various anatomical sites. Dynamic contrast-enhanced MRI perfusion may be useful in assessing the activity of skull base osteomyelitis. MR bone imaging may be of additional value in evaluating bony structures of the skull base and jaw. Dual-energy CT is helpful in reducing metal artifacts, evaluating deep neck abscess, and detecting salivary stones. Subtraction CT techniques are used to detect progressive bone-destructive changes and to reduce dental amalgam artifacts. This article provides a region-based approach to the imaging evaluation of head and neck infections, using both conventional and advanced imaging techniques.

TC torácica en espiración. Cuándo la hago y cómo la interpreto

Expiratory CT scan is a complementary technique of inspiratory CT that provide valuable physiological information and may be more sensitive to detect air trapping than pulmonary function tests. It is useful in many obstructive airway diseases, including obliterative bronchiolitis, asthma, Swyer-James syndrome, tracheomalacia, hypersensitivity pneumonitis and sarcoidosis. In obliterative bronchiolitis, expiratory CT scan may be the only imaging technique that shows abnormalities in the early phase of disease. In order to obtain a good quality study, we should explain the procedure to the patient, use precise instructions and do some practice before image acquisition. Here we describe strategies to optimize the technique and propose an algorithm that help in interpretation of imaging findings in patients with obstructive airway disease.

Deterioration Performance of Recycled Aggregate Pervious Concrete under Freezing–Thawing Cycle and Chloride Environment

To study the performance of recycled aggregate pervious concrete (RAPC) in severe cold regions, the influence of the water–binder ratio, design porosity, micro silica fume (SF) and enhancer agent (EA) on the permeability and mechanical properties of the RAPC were evaluated using the orthogonal design method. Based on the optimal mixture proportion, freeze–thaw (F-T) experiments were carried out to investigate the effect of different media (water, 3.5 wt% NaCl solution) on the mechanical properties, permeability and anti-frost durability of the RAPC. Moreover, the porosity and pore structure characteristics of RAPC were evaluated after frost damage using an X-ray CT technique. The results indicate that the influence of the salt solution on the deterioration of the RAPC specimen is greater than water. The deterioration degree of the mass loss ratio, relative dynamic elastic modulus (RDEM), average compressive strength and porosity of the RAPC increase with increasing F–T cycles. Based on the two-parameter Weibull probabilistic distribution function, damage evolution models of RAPC are established, which can be used to quantitatively characterize the damage degree of the RAPC specimens under different F–T media. The results obtained can provide an experimental reference and data support for the promotion and application of RAPC pavement in severe cold regions.

Clinical application of VATS combined with 3D-CTBA in anatomical basal segmentectomy.

This study aimed to summarize the clinical application experience of video-assisted thoracic surgery (VATS) combined with three-dimensional computed tomography-bronchography and angiography (3D-CTBA) in anatomical basal segmentectomy. Clinical data of 42 patients who underwent bilateral lower sub-basal segmentectomy by VATS combined with 3D-CTBA in our hospital from January 2020 to June 2022 were retrospectively analyzed; the patients included 20 males and 22 females, with a median age of 48 (30-65) years. Combined with the preoperative enhanced CT and 3D-CTBA techniques to identify the altered bronchi, arteries, and veins during the operation, the anatomical resection of each basal segment of both lower lungs was completed through the fissure approach or inferior pulmonary vein approach. All operations were successfully completed without conversion to thoracotomy or lobectomy. The median operation time was 125 (90-176) min, the median intraoperative blood loss was 15 (10-50) mL, the median postoperative thoracic drainage time was 3 (2-17) days, and the median postoperative hospital stay was 5 (3-20) days. The median number of resected lymph nodes was 6 (5-8). There was no in-hospital death. Postoperative pulmonary infection occurred in 1 case, lower extremity deep vein thrombosis (DVT) in 3 cases, pulmonary embolism in 1 case, and persistent air leakage in the chest in 5 cases, all of which were improved by conservative treatment. Two cases of pleural effusion after discharge were improved after ultrasound guided drainage. Postoperative pathology showed 31 cases of minimally invasive adenocarcinoma, 6 cases of adenocarcinoma in situ (AIS), 3 cases of severe atypical adenomatous hyperplasia (AAH), and 2 cases of other benign nodules. All cases were lymph node-negative. VATS combined with 3D-CTBA is safe and feasible in anatomical basal segmentectomy; consequently, this approach should be promoted and applied in clinical work.

Monte Carlo simulations of deformation behaviour of unbound granular materials based on a real aggregate library

ABSTRACT The Monte Carlo simulation (MCS) has been developed to estimate the strength distributions of heterogeneous materials influenced by different factors. The method presents a statistical correlation between the macroscopic properties and the non-uniform characteristics at meso scale. This study proposes an extensive MCS to investigate the influence of the aggregate morphology on deformation behaviour of unbound granular materials (UGMs) based on a real aggregate library and the discrete element method. Two indexes, elongation index (EI) and flatness index (FI), were used to evaluate the morphological characteristics of 3D aggregates rebuilt by the X-ray CT technique. Furthermore, repeated load triaxial tests of UGMs were simulated by 50 MCS samples. The effects of shapes and sizes of aggregates on deformation behaviours were statistically analysed. The results show that the deformation behaviour is dependent on the size and the EI distribution, but insensitive to the loading frequencies and FI distribution.

Oxidation-Affected Erosion of Porous Ni-Al Intermetallic Alloy in Combustion Applications: Pore-Scale Simulation

Advanced high-temperature oxidation resistance is a crucial characteristic of metallic materials in porous burners. Extreme combustion conditions could lead to oxidation-affected erosion of porous media at a long-time period of burner operation. In this paper, we numerically simulated oxide scale growth at a porous radiant burner fabricated by Ni-Al intermetallic alloy using the combustion synthesis method, focusing on the structure degradation caused by periodic oxide scale spallation. A three-dimensional geometrical model of a porous intermetallic scaffold was obtained by scanning the porous burner using the X-ray CT technique. The surface erosion was modeled by the surface reconstruction based on calculated values of spalled oxide layer thickness. The simulation revealed that the submerged flame results in non-uniform distribution of the temperature at the solid surface. Such non-isothermal conditions lead to a two-times thicker oxide scale at the external surface of the burner. Thin struts of the intermetallic scaffold are prone to oxidation-affected erosion first, which forms discontinues and further fragmentation. The porous scaffold could lose about 50% of initial weight before fragmentation under conditions with intense oxide spallation. In such large structural degradation, the average flow velocity could reduce by a factor of 3, leading to changing of flame stabilization region.

Ultra-Low Dose CT Chest in Acute COVID-19 Pneumonia: A Pilot Study from India.

The rapid increase in the number of CT acquisitions during the COVID-19 pandemic raised concerns about increased radiation exposure to patients and the resultant radiation-induced health risks. It prompted researchers to explore newer CT techniques like ultra-low dose CT (ULDCT), which could improve patient safety. Our aim was to study the utility of ultra-low dose CT (ULDCT) chest in the evaluation of acute COVID-19 pneumonia with standard-dose CT (SDCT) chest as a reference standard. This was a prospective study approved by the institutional review board. 60 RT-PCR positive COVID-19 patients with valid indication for CT chest underwent SDCT and ULDCT. ULDCT and SDCT were compared in terms of objective (noise and signal-to-noise ratio) and subjective (noise, sharpness, artifacts and diagnostic confidence) image quality, various imaging patterns of COVID-19, CT severity score and effective radiation dose. The sensitivity, specificity, positive and negative predictive value, and diagnostic accuracy of ULDCT for detecting lung lesions were calculated by taking SDCT as a reference standard. The mean age of subjects was 47.2 ± 10.7 years, with 66.67% being men. 90% of ULDCT scans showed no/minimal noise and sharp images, while 93.33% had image quality of high diagnostic confidence. The major imaging findings detected by SDCT were GGOs (90%), consolidation (76.67%), septal thickening (60%), linear opacities (33.33%), crazy-paving pattern (33.33%), nodules (30%), pleural thickening (30%), lymphadenopathy (30%) and pleural effusion (23.33%). Sensitivity, specificity and diagnostic accuracy of ULDCT for detecting most of the imaging patterns were 100% (p < 0.001); except for GGOs (sensitivity: 92.59%, specificity: 100%, diagnostic accuracy: 93.33%), consolidation (sensitivity: 100%, specificity: 71.43%, diagnostic accuracy: 93.33%) and linear opacity (sensitivity: 90.00%, specificity: 100%, diagnostic accuracy: 96.67%). CT severity score (range: 15-25) showed 100% concordance on SDCT and ULDCT, while effective radiation dose was 4.93 ± 1.11 mSv and 0.26 ± 0.024 mSv, respectively. A dose reduction of 94.38 ± 1.7% was achieved with ULDCT. Compared to SDCT, ULDCT chest yielded images of reasonable and comparable diagnostic quality with the advantage of significantly reduced radiation dose; thus, it can be a good alternative to SDCT in the evaluation of COVID-19 pneumonia.

Uloga konvencionalnog CT pregleda, CT perfuzije i analize teksture tumorskog tkiva u predikciji rizika gastrointestinalnih stromalnih tumora želuca

As the most common mesenchymal tumors of the digestive tract, gastrointestinal stromal tumors (GIST) can have significant metastatic potential with a high rate of dissemination to the liver and peritoneal cavity. Based on the modified NIH (National Institutes of Health) classification, these tumors are classified into four stages: very low, low, intermediate and high-risk tumors. For low-risk tumors (LRG), minimally invasive surgery with R0 resection is the most common therapeutic option, while for high-risk tumors (HRG), imatinib adjuvant therapy is included post-surgically. Preoperative risk stratification is important for determining the therapeutic treatment and the patient's prognosis. With modern advances in diagnostic modalities, imaging analysis is no longer limited to visual assessment. As a modality of functional multidetector CT diagnostics, CT perfusion enables the quantification of tumor vascularization, while texture analysis provides a quantitative assessment of the degree of tumor heterogeneity, which overall can help in differentiating the metastatic potential of these tumors. The importance of morphological characteristics of tumors obtained by conventional CT examination in risk prediction has already been proven by numerous studies, and it is considered that, together with the advanced CT techniques mentioned above, it can provide a predictive model for the preoperative assessment of GIST risk stratification.

Experimental study on cracking behavior of concrete containing hole defects

Cavity often exists in the mass concrete when insufficient vibration occurs. These defects play an important role in the failure mechanism of concrete. Cracking behavior of surface flaws in concrete is widely investigated, while research on failure mechanism of internal flaws is limited because it is difficult to cut internal flaws in specimens and cannot capture the cracking processes of internal flaws through direct observations. In this study, a novel method for preparing concrete samples with embedded flaws is first proposed by volatilization of camphor. AE and CT techniques are adopted to investigate the internal damage failure behavior of hollowed concrete. Experimental results demonstrate that internal hole defects result in a reduction of strength and deformation properties of concrete materials. The peak strength, crack initiation stress, and deformation properties of hollowed concrete specimen decrease with the cavity diameters. Since hole defects induce high stress concentration which exacerbates crack initiation, AE events of specimen with an internal cavity occurred much earlier than the case of intact specimen. The ultimate failure modes of concretes are dominated by tension failure. For intact specimens, tension cracks mainly happen near to the boundaries of specimens. While for hollowed specimens, tension cracks initiated at the cavity perimeter, which then propagated to the boundaries of specimens.

The characterization of porosity and its relationship with externally solidified crystal in a high-pressure die-cast AlSi10MnMg alloy via a laboratory CT technique

The characterization of porosity and its relationship with externally solidified crystal (ESC) in a high-pressure die-cast AlSi10MnMg alloy is investigated using a laboratory CT technique. Results show that in the bar sample, pores with a high sphericity exhibit a radial distribution under a higher fast shot speed. The appropriate decrease of fast shot speed reduces the porosity but increases the proportion of irregular shrinkage. Without applying intensification pressure, the porosity is rapidly increased and further decreasing fast shot speed, large-size pores are formed in ESC interdendritic gap. In sheet sample, the decrease of fast shot speed increases the porosity and promotes the formation of large-size shrinkage and it is related to the enrichment of ESC.

Study on the Application of Elastic Wave CT Technique to Detect the Effect of Post-Grouting of Pile Foundation

The post-grouting technology can effectively improve the bearing capacity and reliability of foundation piles, and it is of great academic and economic significance to evaluate the effect of post-grouting. However, in general, the evaluation of the effect of post-grouting slurry on foundation piles is still relatively single, and most researchers only test the improvement of the bearing characteristics of post-grouting piles, but there are few research results on the distribution state of slurry consolidation and the range of the reinforced soil. In this paper, elastic wave CT was used to detect the bridge piles of Taizhou Bay Du Xiaipu Bridge, and elastic wave CT technology was applied to the detection of the post-grouting effect of foundation piles experimentally. The spatial distribution characteristics of the underground grouting reinforcement area were revealed from the perspective of visualization, and the influencing factors of the elastic wave inversion results were analyzed. The conclusions obtained from elastic wave CT detection were similar to those of electromagnetic wave CT, and the laws are basically consistent with the current engineering experience, reflecting the applicability of using elastic wave CT to detect the effect of post-grouting of pile foundation.

Sarcopenia in chronic liver disease, can we predict complications?

Introduction. Sarcopenia is a common complication of chronic liver disease. Today many studies are devoted to sarcopenia impact on the course of liver diseases. At the same time, many studies are being performed on the correlation of sarcopenia in patients with cirrhosis of the liver and the incidence of early complications after liver transplantation. In this regard, we conducted our own retrospective study of the correlation relationship of sarcopenia in patients with chronic liver diseases. Aim. To determine the correlation between the severity of sarcopenia and the incidence of complications of liver cirrhosis in patients on the waiting list for liver transplantation. Material and methods. In our own retrospective observational study, 87 patients suffering from chronic liver diseases and treated at the Minsk Scientific and Practical Center of Surgery, Transplantation and Hematology were included. The assessment of sarcopenia was carried out using the CT technique for assessing indexed parameters of the patient's muscle mass. Mathematical processing was performed using the FDA-approved Osirix TM software. The study was conducted within the framework of the project "ClinicalTrials: NCT04281797" Results. Body mass index was significantly correlated with the presence of sarcopenia (r pb =-0.48, 95% CI [-0.65;-0.27]). At the same time, the groups of patients with and without sarcopenia differed significantly (p&lt;0.0001), (Hedges g=-0.93, 95% CI [-1.37;-0.48]). In groups of patients with various etiological factors of chronic liver diseases, sarcopenia occurred most often among patients with autoimmune hepatitis, while the uneven distribution of the incidence of sarcopenia in different nosological groups was significant (p=0.028;  2 =14.1). Conclusion. Body mass index plays an important prognostic role in muscle mass loss among patients with clinically advanced liver disease. However, skeletal muscle index and Body Mass Index differ significantly between patients with and without sarcopenia. In addition, our study showed a significant difference in the occurrence of sarcopenia in patients on the waiting list of different etiological groups. Thus, further extensive randomized studies in this direction are needed today.

Evaluation of relative electron densities calculated by CT numbers in different techniques of dual-energy CT

Evaluation of relative electron densities calculated by CT numbers in different techniques of dual-energy CT

Modified Polar Grid-based Accelerated Image Reconstruction Technique for X-ray CT

Image reconstruction by projections is basically a mathematical problem. The speed and accuracy of the reconstruction mainly depend upon, (1) discretization scheme (2) solution technique. Solution by Algebraic Method (AM) is the most promising technique for manufacturing the low-cost (few detectors arrangement) X-ray CT set-up. Slow converging rate and huge memory requirement are the two major drawbacks of the AM algorithms. Projection coefficient calculations and their storages are major time and storage-consuming processes of the algebraic methods. Among all algebraic methods, the Multiplicative Algebraic Reconstruction Technique (MART) is more effective because it maximizes the entropy of the image space. The conventional MART algorithm uses square grids (SG) in the discretization process of the image reconstruction. In the present work, we employed a modified polar grid to cope with the shortcomings of the MART method. In this new discretization scheme, only the projection coefficients of the first view, need to be calculated. Projection coefficients for other views can be easily calculated by using the symmetries of the modified polar grid. This method significantly reduces the reconstruction time and storage requirement of the MART algorithm. In addition, we also presented the direct method of polar to square grid transformation for the visualization of the reconstructed images. We tested the proposed method to fan-beam geometry for 2D image reconstruction. Structural similarity index(SSIM) and L2 error are used for quality assessment of the reconstructed images.

CBCT –THE GOLDEN GLORY OF PROSTHODONTICS: A REVIEW

Cone beam computed tomography (CBCT, also referred to as C-arm computed tomography [CT], cone beam volume CT, or at panel CT) is a medical imaging technique of X-ray CT where the X-rays are divergent,forming a cone. It provides a complete 3D view of the maxilla, mandible, teeth, and supporting structures with relatively high resolution allowing a more accurate diagnosis, treatment planning and monitoring, and analysis of outcomes than conventional 2D images, along with low radiation exposure to the patient. This article is intended to elaborate and enunciate on the various applications and benets of CBCT, in the realm of maxillofacial prosthodontics, over and beyond its obvious benets in the rehabilitation of patients with implants. A web-based search for relevant articles in this specic area of interest was also conducted.The selected articles were critically reviewed and the data acquired were systematically compiled.