Analysis Of Computed Tomography Data Research Articles

A multichannel analysis of imbalanced computed tomography data for lung cancer classification

Lung cancer holds the highest fatality rate among cancers, emphasizing the importance of early detection. Computer algorithms have gained prominence across various domains, including lung cancer diagnosis. These algorithms assist specialists, especially in medical imaging, yet current efforts lack comprehensive CT data analysis; especially in handling imbalanced datasets and fully exploiting spatial information. The lack of spatial analysis hinders the ability to identify subtle variations in texture and structure that are crucial for detecting lung cancer early and accurately. Therefore, this study uses a multichannel analysis of computed tomography (CT) images and deep learning-based ensemble learning (MC-ECNN) to find lung cancer even when the data is not balanced. Firstly, the data imbalance issue is tackled through the synthetic minority oversampling technique (SOMTE); afterwards, a multi-channel analysis of the data is performed to explore a distinct set of abstract features. Lastly, a deep ensemble learning method is used to classify the extracted distinct abstract feature set into the appropriate classes. The proposed method uses the discrete Fast Fourier transform (DFFT) and discrete cosine transform (DCT), along with the actual CT scans, for the multi-channel analysis of the data in different domains. The proposed model yielded 99.60% test accuracy on unseen data, which is at least 3% better than the other state-of-the-art studies considered for the comparison. In addition to the classification accuracy, the efficacy of the proposed model has also been justified through precision, recall, F1-score, support value, and misclassification rate.

VT ablation based on CT imaging substrate visualization: results from a large cohort of ischemic and non-ischemic cardiomyopathy patients

IntroductionThe eradication of ventricular tachycardia (VT) isthmus sites constitutes the minimal procedural endpoint for VT ablation procedures. Contemporary high-resolution computed tomography (CT) imaging, in combination with computer-assisted analysis and segmentation of CT data, facilitates targeted elimination of VT isthmi. In this context, inHEART offers digitally rendered three-dimensional (3D) cardiac models which allow preoperative planning for VT ablations in ischemic and non-ischemic cardiomyopathies. To date, almost no data have been collected to compare the outcomes of VT ablations utilizing inHEART with those of traditional ablation approaches.MethodsThe presented data are derived from a retrospective analysis of n = 108 patients, with one cohort undergoing VT ablation aided by late-enhancement CT and subsequent analysis and segmentation by inHEART, while the other cohort received ablation through conventional methods like substrate mapping and activation mapping. The ablations were executed utilizing a 3D mapping system (Carto3), with the mapping generated via the CARTO® PENTARAY™ NAV catheter and subsequently merged with the inHEART model, if available.ResultsResults showed more successful outcome of ablations for the inHEART group with lower VT recurrence (27% vs. 42%, p < 0.06). Subsequent analyses revealed that patients with ischemic cardiomyopathies appeared to derive a significant benefit from inHEART-assisted VT ablation procedures, with a higher rate of successful ablation (p = 0.05).ConclusionOur findings indicate that inHEART-guided ablation is associated with reduced VT recurrence compared to conventional procedures. This suggests that employing advanced imaging and computational modeling in VT ablation may be valuable for VT recurrences.Graphical abstract

4D evolutions of cracks, voids, and corrosion products in reinforced concrete materials

This research paper presents a comprehensive investigation into the corrosion process in reinforced concrete structures using advanced analytical techniques, namely non-destructive X-ray computed tomography (CT) imaging, scanning electron microscopy (SEM) images, energy dispersive x-ray spectrometry (EDS), and Raman spectroscopy. The CT image analysis allowed for the identification and quantification of pore structures, crack propagation, and corrosion progression at different stages of corrosion. CT scanning and data analysis offer valuable 4D (3D spatial + time) insights into corrosion in reinforced concrete, revealing changes in pore sizes, with smaller pores increasing and larger pores decreasing as corrosion progresses. Our investigation reveals dynamic changes in reinforced concrete pores during the accelerated corrosion test leading to new pore formation and cracking. The research identifies two distinct types of cracks: one filled with corrosion products and the other, zipper-like cracks, resulting from the connection of deformed pores without corrosion products. The SEM images and EDS analysis confirmed the absence of corrosion products within these unique zipper cracks, suggesting a different mechanism of crack formation compared to the first type of cracks. The results revealed two distinct categories of corrosion products: iron oxides and iron hydroxides, with their distribution correlated to the duration of accelerated corrosion testing. The integration and verification of results from X-ray CT imaging and Raman spectroscopy established a comprehensive understanding of corrosion-induced damage in the reinforced concrete specimen, shedding light on complex interactions among different corrosion products during the corrosion process. These findings offer crucial insights for better understanding of the corrosion process in reinforced concrete paving the way for future development of effective treatments and strategies to mitigate corrosion impact.

Deep learning based porosity prediction for additively manufactured laser powder-bed fusion parts

Machine learning techniques are extensively used to understand and predict complex non-linear phenomena across various applications. Moreover, these techniques minimize the time and costs associated with experimental and numerical analysis. In this work, a deep learning technique, specifically artificial neural networks (ANN), was employed to predict the density/porosity of laser powder-bed fusion (LPBF) additively manufactured (AM) parts by training the ANN model with X-ray computed tomography (CT) images. In addition to the experimental data, synthetic CT data was generated and used to improve the performance of the ANN model. The ANN model was then optimized for the number of hidden layers and neurons. Different errors like mean absolute error (MAE), root mean square error (RMSE), and square of co-relation coefficient (R2) were used as performance metrics to determine the accuracy and effectiveness of the network. The proposed ANN model was validated and showed excellent predictions (R2 = 0.9981, MAE = 1.6944 x 10−5). The framework proposed in this work can be used to speed-up the quality assurance of AM parts by reducing the time required for the analysis of CT data.

Diagnosis of cervical lymph node metastasis with thyroid carcinoma by deep learning application to CT images.

The incidence of thyroid diseases has increased in recent years, and cervical lymph node metastasis (LNM) is considered an important risk factor for locoregional recurrence. This study aims to develop a deep learning-based computer-aided diagnosis (CAD) method to diagnose cervical LNM with thyroid carcinoma on computed tomography (CT) images. A new deep learning framework guided by the analysis of CT data for automated detection and classification of LNs on CT images is proposed. The presented CAD system consists of two stages. First, an improved region-based detection network is designed to learn pyramidal features for detecting small nodes at different feature scales. The region proposals are constrained by the prior knowledge of the size and shape distributions of real nodes. Then, a residual network with an attention module is proposed to perform the classification of LNs. The attention module helps to classify LNs in the fine-grained domain, improving the whole classification network performance. A total of 574 axial CT images (including 676 lymph nodes: 103 benign and 573 malignant lymph nodes) were retrieved from 196 patients who underwent CT for surgical planning. For detection, the data set was randomly subdivided into a training set (70%) and a testing set (30%), where each CT image was expanded to 20 images by rotation, mirror image, changing brightness, and Gaussian noise. The extended data set included 11,480 CT images. The proposed detection method outperformed three other detection architectures (average precision of 80.3%). For classification, ROI of lymph node metastasis labeled by radiologists were used to train the classification network. The 676 lymph nodes were randomly divided into 70% of the training set (73 benign and 401 malignant lymph nodes) and 30% of the test set (30 benign and 172 malignant lymph nodes). The classification method showed superior performance over other state-of-the-art methods with an accuracy of 96%, true positive and negative rates of 98.8 and 80%, respectively. It outperformed radiologists with an area under the curve of 0.894. The extensive experiments verify the high efficiency of the proposed method. It is considered instrumental in a clinical setting to diagnose cervical LNM with thyroid carcinoma using preoperative CT images. The future research can consider adding radiologists' experience and domain knowledge into the deep-learning based CAD method to make it more clinically significant. The extensive experiments verify the high efficiency of the proposed method. It is considered instrumental in a clinical setting to diagnose cervical LNM with thyroid carcinoma using preoperative CT images.

Spinal Metastases without Pedicle Signs on Radiograph and their Associated Clinical and Radiological Features.

The pedicle sign is a radiographic indicator of spinal metastases. However, it is not only the pedicle sign that is important in radiographic diagnosis of bone metastases. In the present study, the radiological features of symptomatic spinal metastases in patients without the pedicle sign were retrospectively examined. Among 186 patients with symptomatic spinal metastases who visited our department between January 1, 2011, and December 31, 2017, 64 without the pedicle sign and with available computed tomography (CT) and magnetic resonance imaging (MRI) data in the first visit were enrolled and their data were analyzed. One author evaluated radiographs for findings suggestive of spinal metastases, CT to assess bone destruction, and MRI to evaluate the extent of lesions. Clinical variables were also examined and compared between patients with and without bone changes on radiography. Bone changes strongly suggesting bone metastasis, other than the pedicle sign, were observed in 31 out of 64 patients: bone cortical disappearance in 20, increased radiolucency of the central area in the vertebral body in 8, an irregular osteoblastic change in 5, and asymmetrical vertebral collapse in 10. An analysis of CT data revealed that intertrabecular, mildly osteolytic, and mildly osteoblastic types were more frequent in patients without any changes suggestive of bone metastases on radiographs. Radiographic findings other than the pedicle sign are useful for diagnosing bone metastases. The key to a radiographic diagnosis of spinal metastases is to pay attention to changes in the bone cortex of all vertebral components on radiographs in addition to the pedicle.

Prognosis of Continuous Positive Airway Pressure Treatment to Velopharyngeal Insufficiency: Preliminary Study.

Cleft palate is a congenital malformation that causes hypernasality and decreases the intelligibility of pronunciation and leads to velopharyngeal insufficiency. It causes difficulty in language development. Many studies and treatments have been conducted to reduce this problem, but there are limitations. In this study, the effect obtained through continuous positive airway pressure (CPAP) treatment was analyzed by statistical methods. From May 2012 to December 2018, using patient demographics, computed tomography (CT) scan, and nasalance test was performed on 25 patient groups treated with CPAP devices for 8 weeks to confirm the effect after 6 months. After CPAP treatment in a total of 25 patients, 13 patients had a therapeutic effect. The average age of the patient group with treatment effect (effective group [EG]) was 51.2months, and the patient group with no treatment effect (ineffective group [iG]) was 73.6 months. ( P < 0.05). In CT data analysis, the highest palatal arch point was 6.31 mm in EG and 7.36 mm in IG, which was lower in EG ( P < 0.01), and the distance from incisive foramen to posterior pharyngeal wall was 41.39 mm in EG and 49.07 mm in IG ( P < 0.05). Through the statistical analysis, the group of patients who were effective in treatment had a low age at the beginning of treatment, the height of highest palatal arch point was low on CT data, and the length of distance from incisive foramen to posterior pharyngeal wall was short. It will be helpful to set the CPAP treatment patient group with respect to the results and age and CT data when treating VPI patients.

Stem Geometry Recommendation for Total Hip Replacement Planning Using Computed Tomography Data Analysis

Total Hip Replacement (THR) requires careful planning preparation, especially in the geometry suitability between the patient's bone and the implant. If it is applied incorrectly, it will be dangerous for the patient, such as the risk of complications, dislocation, and re-surgery. This paper aims to compare the size of the patient's THR geometry as a basis for consideration in implant designs to minimize the risk of harm after implantation. This study was limited to male patients only. The computed tomography scanning data (CT-Scan data) in the lower abdomen, segmented to hip joint area belonging to the American race and an Indonesian male, were compared. The comparison indicates that the American race data has a greater dimension than Indonesian. The American hip bone geometry result is following the standard modern implant by Johnson and Johnson size. By all analysis, the fittest geometry for the Indonesian male patient needs to adjust and has a smaller size than the commercial implant. This study finally recommends the specific length of the femoral stem for the optimal THR implant with the parameter values of Femoral Head Offset, Neck Length, Neck Shaft Angle, Mediolateral Width 1, Mediolateral Width 2, Mediolateral Width 3 respectively for the right THR, namely 37.9; 31.6; 134.3; 43.1; 13.62; 12.36; while the left THR is 38.9; 31.7; 134.5; 43.1; 13.70; 12.4 in mm. Overall, the precise implant planning based on real patient conditions and anthropometry is necessary to match implants and bone anatomy.

Topological analysis of X-ray CT data for the recognition and trending of subtle changes in microstructure under material aging

X-ray computed tomography (CT) is an established non-destructive tool for 3D imaging of multiphasic composites. Numerous applications of X-ray CT in medical diagnosis and materials characterization have been reported, many involving field-specific innovations in the imaging technology itself. Yet, quantitative summarization to link image features to properties of interest has been rare. We address this issue by employing state-of-the-art technics in scalar field topology for the summarization of X-ray CT images of an example biphasic system. By varying processing-parameters we create different microstructures, evolve them through accelerated thermal aging, CT-image them pre- and post-aged, and demonstrate the ability of our image summarization method to systematically track process- and age-related changes, which can often be very subtle. A novel aspect of the algorithm involves recognition over multiple resolution levels, which provides deeper insight into the pattern relationship between grain-like features and their neighbors. The method is general, adaptable to diverse image reconstruction methods and materials systems, and particularly useful in applications where practical constraints on the sample-size limits the reliable use of more complex models, e.g., convolutional neural networks.

A New-Designed Lung-Bending Device for Bronchoscopic Lung Volume Reduction of Severe Emphysema: A Feasibility Study in Pigs

Background: Bronchoscopic therapies are less invasive alternatives of surgical lung volume reduction for severe emphysema. Bending of lung tissue by implanting metallic coils into bronchi is one of the procedures. A new-designed device with a similar rationale, Reverser, has been developed with some improvements. Objectives: The aim of the study was to evaluate the safety and feasibility of the Reversers. Methods: Twelve healthy pigs were randomly divided into 3 groups (groups A, B, and C). The Reversers were implanted bronchoscopically into the selected airways using a proprietary delivery system. Physical examination, chest fluoroscopy, computed tomography (CT) scans, and bronchoscopic observations were performed before implantation and during the follow-up period. Necropsy was performed respectively at 1 month (group A), 3 months (group B), and 6 months (group C) after implantation. Results: A total of 47 Reversers were implanted successfully. The procedure was feasible and well tolerated by all pigs. No severe complications, such as pneumothorax, abscesses, and airway hemorrhage, were found. No unintended injuries or death occurred. Mild granulation and inflammation were observed in the airway wall. Opacities around Reversers were shown on CT scans in some pigs. In the pigs with opacities, histological evaluation revealed widened alveolar septa due to inflammatory cell infiltration in the vicinity of the Reversers. On the analysis of CT data, there was a trend for volume reduction of the treated lung at 1 and 3 months after treatment compared with baseline. Conclusions: This study showed that Reversers were safe and feasible for bronchoscopic lung volume reduction in pigs.

Automatic diagnosis of pectus carinatum for children based on the improved Haller index

Pectus carinatum (PC) is one of the most common chest wall anomalies, which is characterized by the protrusion of the anterior chest wall including the sternum and adjacent costal cartilages. Mildly patients suffer from mental problems such as self-abasement, while severely suffering patients are disturbed by significant cardiopulmonary symptoms. The traditional Haller index, which is widely used clinically to evaluate the severity of PC, is deficient in diagnosis efficiency and classification. This paper presents an improved Haller index algorithm for PC: first, the contour of the patient chest in the axial computed tomography (CT) slice where the most convex thorax presents is extracted; and then a cubic B-spline curve is employed to fit the extracted contour followed by an eclipse fitting procedure; finally, the improved Haller index and the classification index are automatically calculated based on the analytic curves. The results of CT data analysis using 22 preoperative and postoperative patient CT datasets show that the proposed diagnostic index for PC can diagnose and classify PC patients correctly, which confirms the feasibility of the evaluation index. Furthermore, digital measurement techniques can be employed to improve the diagnostic efficiency of PC, achieving one small step towards the computer-aided intelligent diagnosis and treatment for pediatric chest wall malformations.

A Method of Accurate Bone Tunnel Placement for Anterior Cruciate Ligament Reconstruction Based on 3-Dimensional Printing Technology: A Cadaveric Study

To explore a method of bone tunnel placement for anterior cruciate ligament (ACL) reconstruction based on 3-dimensional (3D) printing technology and to assess its accuracy. Twenty human cadaveric knees were scanned by thin-layer computed tomography (CT). To obtain data on bones used to establish a knee joint model by computer software, customized bone anchors were installed before CT. The reference point was determined at the femoral and tibial footprint areas of the ACL. The site and direction of the bone tunnels of the femur and tibia were designed and calibrated on the knee joint model according to the reference point. The resin template was designed and printed by 3D printing. Placement of the bone tunnels was accomplished by use of templates, and the cadaveric knees were scanned again to compare the concordance of the internal opening of the bone tunnels and reference points. The twenty 3D printing templates were designed and printed successfully. CT data analysis between the planned and actual drilled tunnel positions showed mean deviations of 0.57mm (range, 0-1.5mm; standard deviation, 0.42mm) at the femur and 0.58mm (range, 0-1.5mm; standard deviation, 0.47mm) at the tibia. The accuracy of bone tunnel placement for ACL reconstruction in cadaveric adult knees based on 3D printing technology is high. This method can improve the accuracy of bone tunnel placement for ACL reconstruction in clinical sports medicine.

Evaluation of a semi-automated computer algorithm for measuring total fat and visceral fat content in lambs undergoing in vivo whole body computed tomography

Computed tomography (CT) is a suitable tool for measuring body fat, since it is non-destructive and can be used to differentiate metabolically active visceral fat from total body fat. Whole body analysis of body fat is likely to be more accurate than single CT slice estimates of body fat. The aim of this study was to assess the agreement between semi-automated computer analysis of whole body volumetric CT data and conventional proximate (chemical) analysis of body fat in lambs. Data were collected prospectively from 12 lambs that underwent duplicate whole body CT, followed by slaughter and carcass analysis by dissection and chemical analysis. Agreement between methods for quantification of total and visceral fat was assessed by Bland–Altman plot analysis. The repeatability of CT was assessed for these measures using the mean difference of duplicated measures. When compared to chemical analysis, CT systematically underestimated total and visceral fat contents by more than 10% of the mean fat weight. Therefore, carcass analysis and semi-automated CT computer measurements were not interchangeable for quantifying body fat content without the use of a correction factor. CT acquisition was repeatable, with a mean difference of repeated measures being close to zero. Therefore, uncorrected whole body CT might have an application for assessment of relative changes in fat content, especially in growing lambs.

Subtraction CT angiopulmonographic assessment of the vascular bed and lung perfusion in patients with chronic thromboembolic pulmonary hypertension: A pilot study

To evaluate the vascular bed and lung perfusion in patients with chronic thromboembolic pulmonary hypertension (CTEPH) by computed tomography (CT) and to compare the severity of pulmonary arterial (PA) thrombotic lesions concurrent with parenchymal perfusion disorders with angiopulmonographic findings and clinical and hemodynamic characteristics. In the period from November 2015 to May 2016, 22 patients (7 men, 15 women) aged 27 to 67 years with a verified diagnosis of CTEPH were examined using an Aquilion ONE VISION Edition 640 (Toshiba Medical Systems, Japan) CT scanner with a 320-row detector. Perfusion defect in this study was evaluated with the new software allowing one to combine contrast and contrast-free images by a subtraction method. CT data analysis included visual assessment of the vascular bed and lung parenchyma and quantitative assessment with perfusion map construction and semi-automatic determination of the obstruction index (OI) and perfusion defect index (PDI). OI was compared with PDI and mean LA pressure according to the data of right heart catheterization and 6-minute walk test. A statistically significant correlation was found between OI and PDI in patients with CTEPH (Pearson r=0.56; p=0.0065). There were no relationships between mean LA pressure and vascular perfusion indices (OI and PDI) or between vascular perfusion parameters and 6-minute walk test results. CT angiopulmonography in conjunction with pulmonary perfusion assessment (within one study) allows evaluation of the severity of vascular lesions and perfusion disorders and determination of the efficiency of treatment in patients with CTEPH.

Analysis of high‐resolution X‐ray computed tomography images of Bentheim sandstone under elevated confining pressures

ABSTRACTA sample of Bentheim sandstone was characterized using high‐resolution three‐dimensional X‐ray microscopy at two different confining pressures of 1 MPa and 20 MPa. The two recordings can be directly compared with each other because the same sample volume was imaged in either case. After image processing, a porosity reduction from 21.92% to 21.76% can be deduced from the segmented data. With voxel‐based numerical simulation techniques, we determined apparent hydraulic transport properties and effective elastic properties. These results were compared with laboratory measurements using reference samples. Laboratory and computed volumes, as well as hydraulic transport properties, agree fairly well. To achieve a reasonable agreement for the effective elastic properties, we define pressure‐dependent grain contact zones in addition to mineral phases in the digital rock images. From that, we derive a specific digital rock physics template resulting in a very good agreement between laboratory data and simulations. The digital rock physics template aims to contribute to a more standardized approach of X‐ray computed tomography data analysis as a tool to determine and predict elastic rock properties.

Experimental investigation of surface determination process on multi-material components for dimensional computed tomography

The possibility of measuring multi-material components, while assessing inner and outer features simultaneously makes X-ray computed tomography (CT) the latest evolution in the field of coordinate measurement systems (CMSs).However, the difficulty in selecting suitable scanning parameters and suitable surface determination settings, limits a better acceptance of CT as a CMS. Moreover, standard CT users are subject to the algorithms and boundary conditions implied by the use of commercial analysis software.In this context, this paper is concerned with the experimental evaluation of the influence of surface determination process on multi-material measurements, using functions available in the commercial CT data analysis software Volume Graphics VGStudio Max 2.2.6.Calibrated step gauges made of different materials, i.e. PEEK, PPS, and Al were used as reference standards. The step gauges were assembled in such a way as to have different multi-material X-ray absorption ratios. Comparative measurements of mono-material assemblies were performed as well. Different segmentation processes were considered (e.g. ISO-50%, local threshold, region growing, etc.), patch-based bidirectional length analyses were carried out to perform in-material measurements on the assemblies.This work discusses the different approaches based on real CT scans, and aims to provide advice on the segmentation process for multi-material measurements.

Stress Myocardial Perfusion CT in Patients Suspected of Having Coronary Artery Disease: Visual and Quantitative Analysis-Validation by Using Fractional Flow Reserve.

To assess the diagnostic accuracy of stress myocardial perfusion computed tomography (CT) by using visual and quantitative analytic methods in patients with coronary artery disease, with fractional flow reserve (FFR) as a reference standard. The institutional review board approved the study, and written informed consent was obtained from all patients. The diagnostic accuracy of myocardial perfusion CT was assessed for 75 patients who underwent myocardial perfusion CT and conventional coronary angiography with reference to hemodynamically significant stenosis, defined as the presence of an FFR of 0.8 or less or an angiographically severe (≥90%) stenosis. Results of quantitative analysis of myocardial perfusion CT data were compared with those of visual analysis by using areas under the receiver operating characteristic curve (AUCs). Among the 75 patients and 210 epicardial arteries, 61 patients (81%) with 86 arteries (41%) had hemodynamically significant stenosis. The per-patient sensitivity and specificity of the visual assessment of myocardial perfusion CT data for all patients were 89% and 86%, respectively. At per-vessel analysis, the sensitivities and specificities, respectively, of myocardial perfusion CT were 80% and 95% for all vessels, 85% and 100% for 63 vessels with severe coronary calcification (defined as an Agatston score > 400), and 76% and 91% for 56 vessels in patients with multivessel disease. In severely calcified vessels, visual assessment of myocardial perfusion CT data in combination with CT angiography provided incremental value over CT angiography alone for the detection of myocardial ischemia (integrated discrimination improvement index, 0.38; P < .001). Quantitative assessment of transmural perfusion ratio had a lower AUC than visual analysis of myocardial perfusion CT (0.759 vs 0.877, P = .002). Stress myocardial perfusion CT provides incremental value over CT angiography in patients with a high calcium score for the detection of myocardial ischemia as defined by FFR.

Automated Voxel-Based Analysis of Volumetric Dynamic Contrast-Enhanced CT Data Improves Measurement of Serial Changes in Tumor Vascular Biomarkers

Development of perfusion imaging as a biomarker requires more robust methodologies for quantification of tumor physiology that allow assessment of volumetric tumor heterogeneity over time. This study proposes a parametric method for automatically analyzing perfused tissue from volumetric dynamic contrast-enhanced (DCE) computed tomography (CT) scans and assesses whether this 4-dimensional (4D) DCE approach is more robust and accurate than conventional, region-of-interest (ROI)-based CT methods in quantifying tumor perfusion with preliminary evaluation in metastatic brain cancer. Functional parameter reproducibility and analysis of sensitivity to imaging resolution and arterial input function were evaluated in image sets acquired from a 320-slice CT with a controlled flow phantom and patients with brain metastases, whose treatments were planned for stereotactic radiation surgery and who consented to a research ethics board-approved prospective imaging biomarker study. A voxel-based temporal dynamic analysis (TDA) methodology was used at baseline, at day 7, and at day 20 after treatment. The ability to detect changes in kinetic parameter maps in clinical data sets was investigated for both 4D TDA and conventional 2D ROI-based analysis methods. A total of 7 brain metastases in 3 patients were evaluated over the 3 time points. The 4D TDA method showed improved spatial efficacy and accuracy of perfusion parameters compared to ROI-based DCE analysis (P<.005), with a reproducibility error of less than 2% when tested with DCE phantom data. Clinically, changes in transfer constant from the blood plasma into the extracellular extravascular space (Ktrans) were seen when using TDA, with substantially smaller errors than the 2D method on both day 7 post radiation surgery (±13%; P<.05) and by day 20 (±12%; P<.04). Standard methods showed a decrease in Ktrans but with large uncertainty (111.6 ± 150.5) %. Parametric voxel-based analysis of 4D DCE CT data resulted in greater accuracy and reliability in measuring changes in perfusion CT-based kinetic metrics, which have the potential to be used as biomarkers in patients with metastatic brain cancer.

Correlating Gas Transport Parameters and X-Ray Computed Tomography Measurements in Porous Media

Gas transport parameters and X-ray computed tomography (CT) measurements in porous medium under controlled and identical conditions provide a useful methodology for studying the relationships among them, ultimately leading to a better understanding of subsurface gaseous transport and other soil physical processes. The objective of this study was to characterize the relationships between gas transport parameters and soil-pore geometry revealed by X-ray CT. Sands of different shapes with a mean particle diameter (d 50) ranging from 0.19 to 1.51 mm were used as porous media under both air-dried and partially saturated conditions. Gas transport parameters including gas dispersivity (α), diffusivity (D P/D 0), and permeability (k a) were measured using a unified measurement system (UMS). The 3DMA-Rock computational package was used for analysis of three-dimensional CT data. A strong linear relationship was found between α and tortuosity calculated from gas transport parameters ( ), indicating that gas dispersivity has a linear and inverse relationship with gas diffusivity. A linear relationship was also found between k a and d 50/T UMS 2, indicating a strong dependency of k a on mean particle size and direct correlation with gas diffusivity. Tortuosity (T MFX) and equivalent pore diameter (d eq.MFX) analyzed from microfocus X-ray CT increased linearly with increasing d50 for both Granusil and Accusand and further showing no effect of particle shape. The T UMS values showed reasonably good agreement with T MFX values. The k a showed a strong relationship when plotted against d eq.MFX/T MFX 2, indicating its strong dependency on pore size distribution and tortuosity of pore space.

Quantitative analysis of pulmonary pathophysiology using postmortem computed tomography with regard to the cause of death

Radiological lung transparency depends on the air contents involved in respiratory function. The present study quantitatively investigated postmortem lung air distribution in forensic autopsy cases (n=135) using computed tomography (CT) to analyze cardiopulmonary pathophysiology in the death process, involving emphysema, congestion and edema. Combined analyses of the CT morphology and attenuation value (Hounsfield unit, HU) of the bilateral lungs, with reference to histopathology, could categorize CT findings (10-90 percentile mode/mean HU values) with regard to the causes of death as follows: (I) hyperaeration (mode/mean HU below -760/-560: emphysema) for obstructive pulmonary disease, starvation and hypothermia (cold exposure); (II) mostly normal aeration with partial ground glass opacification (mode/mean HU, -850 to -360/-700 to -380: partial congestion and edema), consisting of subtype II-a with peri-bronchial/-vascular opacity for mechanical asphyxia, drowning and fire fatality, and subtype II-b with decreased vascularity for gunshot head injury, cerebrovascular disease and hemopericardium; (III) hypoaeration to airless with predominant hypostatic ground glass opacification (mode/mean HU, -870 to 0/-720 to -200: mottled hypostatic congestion and edema) for blunt head/neck injury, intoxication, hyperthermia (heat stroke) and congestive heart failure; (IV) hypoaeration to airless with predominant hypostatic consolidation (mode/mean HU, -790 to 0/-520 to -70: intense hypostatic congestion with edema) for acute ischemic heart disease; and (V) airless to consolidated (mode/mean HU over -420/-370: segmental or multiple patchy consolidations with edema) for pneumonia. Mode HU represents the major alveolar status, while the mean HU reflects the whole lung air contents. CT data analysis is useful for quantitative evaluation of pulmonary pathology as a supplementary procedure.