Computed Tomography Measurements Research Articles

Psoas Muscle Index – Could It Be an Indicator of Postoperative Complications in Colorectal Cancer? Case Presentation and Review of the Literature

Abstract Introduction: Colorectal cancer is the third most commonly diagnosed cancer worldwide, and its incidence is rising in developing countries. Studies have shown an association between sarcopenia and various poor short-term outcomes in cancer patients who underwent surgery. In this case study, we sought to highlight the importance of a modern prognostic factor, the psoas muscle index (PMI), in colorectal cancer. Case Presentation: We present the case of a 59-year-old male patient with sigmoid cancer. We calculated the PMI as the sum of the areas of the left and right psoas muscle at the level of the L3 vertebra, divided by the square of the patient’s height, using computed tomography measurements. We also measured the density of the proas muscles. Prior to surgery, the left psoas muscle had an area of 14.52 cm2, and the right 14.54 cm2, with a PMI of 9.4967 cm2/m2. The mean density of the psoas muscles was 43.60 UH. The surgery consisted in a rectosigmoid resection with termino-terminal colorectal anastomosis. The histopathological examination confirmed moderately differentiated adenocarcinoma, stage IIIB (pT3N1M0). The patient left the hospital eight days after surgery in good general condition. Long-term follow-up was performed by phone and CT scans at 1, 6, and 12 months. Conclusions: CT-measured PMI may be a potential prognostic imaging marker in patients with colorectal cancer that can be easily and routinely assessed preoperatively.

Modeling the volumetric expansion of the lithium-sulfur battery considering charge and discharge profiles

As an alternative battery technology to the established lithium-ion battery, the lithium–sulfur battery shows great potential due to its greater energy density, safety and possible lower material costs. In the next few years 500-600Wh kg-1 could be implemented. However, there are still challenges in the commercialization and condition monitoring of the battery. Conventional methods of the lithium-ion technology, such as state of charge prediction via open circuit voltage (the discharge curve/charge curve has two plateaus), as well as coulomb counting are ineffective for the lithium-sulfur battery. However, due to the continuous volumetric change during battery operation, this could be a possible approach to monitor and predict the condition of the battery. Therefore, this paper presents a model that determines the volumetric change as a function of a constant discharge/charge profile. The influence of the selected values is investigated by a parameter variation. The parameter set for the model is further characterized by a computer tomography measurement. The simulation model is verified by literature and measurement data. This modeling approach could influence the development of a future battery management system for lithium–sulfur battery.

The Impact of Computed Tomography Measurements of Sarcopenia on Postoperative and Oncologic Outcomes in Patients Undergoing Cytoreductive Surgery and Hyperthermic Intraperitoneal Chemotherapy

Cytoreductive surgery with hyperthermic intraperitoneal chemotherapy (CRS-HIPEC) is a treatment option for peritoneal metastases (PM) but is associated with significant postoperative morbidity. The aim of this study was to determine the prognostic value of computed tomographic (CT)-measured sarcopenia on postoperative outcomes and survival in patients undergoing CRS-HIPEC for PM from various origins. A retrospective cohort study was conducted between 2012 and 2020. Three-hundred and twelve patients (mean age 57.6 ± 10.3, 34.3% male) were included, of which 88 (28.2%) were sarcopenic. PM from a colorectal origin was the most common in both groups. The proportion of major postoperative complications (Clavien-Dindo ≥ III) was not higher in the sarcopenic group (15.9% in sarcopenic patients vs. 23.2% in nonsarcopenic patients, p = 0.17). The mean Comprehensive Complication Index scores, HIPEC-related toxicities, length of hospital stay, and duration of parenteral nutrition were comparable regardless of sarcopenia status. In the multivariate logistic regression analysis of severe complications, only peritoneal carcinomatosis index reached statistical significance (OR, 1.05; 95% CI, 1.01 to 1.08, p = 0.007). Sarcopenia did not impact origin-specific overall survival on Cox regression analysis. Sarcopenia was not associated with worse rates of postoperative severe complications or worse survival rates. Future prospective studies are required before considering sarcopenia as part of preoperative risk assessment.

Introduction of a bone-centered three-dimensional coordinate system enables computed tomographic canine femoral angle measurements independent of positioning.

Measurement of torsional deformities and varus alignment in the canine femur is clinically and surgically important but difficult. Computed tomography (CT) generates true three-dimensional (3D) information and is used to overcome the limitations of radiography. The 3D CT images can be rotated freely, but the final view for angle measurements remains a subjective variable decision, especially in severe and complex angular and torsional deformities. The aim of this study was the development of a technique to measure femoral angles in a truly three-dimensional way, independent of femoral positioning. To be able to set reference points in any image and at arbitrary positions of the CT series, the 3D coordinates of the reference points were used for mathematical calculation of the angle measurements using the 3D medical imaging Software VoXim®. Anatomical reference points were described in multiplanar reconstructions and volume rendering CT. A 3D bone-centered coordinate system was introduced and aligned with the anatomical planes of the femur. For torsion angle measurements, the transverse projection plane was mathematically defined by orthogonality to the longitudinal diaphyseal axis. For varus angle measurements, the dorsal plane was defined by a femoral retrocondylar axis. Independence positioning was tested by comparison of angle measurement results in repeated scans of 13 femur bones in different parallel and two double oblique (15/45°) positions in the gantry. Femoralvarus (or valgus), neck version (torsion), and inclination angles were measured, each in two variations. Resulting mean differences ranged between -0.9° and 1.3° for all six determined types of angles and in a difference of <1° for 17 out of 18 comparisons by subtraction of the mean angles between different positions, with one outlier of 1.3°. Intra- and inter-observer agreements determined by repeated measurements resulted in coefficients of variation for repeated measurements between 0.2 and 13.5%. The introduction of a bone-centered 3D coordinate system and mathematical definition of projection planes enabled 3D CT measurements of canine femoral varus and neck version and inclination angles. Agreement between angular measurements results of bones scanned in different positions on the CT table demonstrated that the technique is independent of femoral positioning.

Ultrasound Versus Computed Tomography for Diaphragmatic Thickness and Skeletal Muscle Index during Mechanical Ventilation.

Background: Diaphragmatic alterations occurring during mechanical ventilation (MV) can be monitored using ultrasound (US). The performance of computed tomography (CT) to evaluate diaphragmatic thickness is limited. Further, the association between muscle mass and outcome is increasingly recognized. However, no data are available on its correlation with diaphragmatic thickness. We aimed to determine correlation and agreement of diaphragmatic thickness between CT and US; and its association with muscle mass and MV parameters. Methods: Prospective observational study. US measurements of the diaphragmatic thickness were collected in patients undergoing MV within 12 h before or after performing a CT scan of the thorax and/or upper abdomen. Data on skeletal muscle index (SMI), baseline, and ventilatory data were recorded and correlated with US and CT measures of diaphragmatic thickness. Agreement was explored between US and CT data. Results: Twenty-nine patients were enrolled and the diaphragm measured by CT resulted overall thicker than US-based measurement of the right hemidiaphragm. The US thickness showed the strongest correlation with the left posterior pillar at CT (r = 0.49, p = 0.008). The duration of the controlled MV was negatively correlated with US thickness (r = -0.45, p = 0.017), the thickness of the right anterior pillar (r = -0.41, p = 0.029), and splenic dome by CT (r = -0.43, p = 0.023). SMI was positively correlated with US diaphragmatic thickness (r = 0.50, p = 0.007) and inversely correlated with the duration of MV before enrollment (r = -0.426, p = 0.027). Conclusions: CT scan of the left posterior pillar can estimate diaphragmatic thickness and is moderately correlated with US measurements. Both techniques show that diaphragm thickness decreases with MV duration. The diaphragmatic thickness by US showed a good correlation with SMI.

Quantitative Assessment and Comparative Analysis of Longitudinal Lung CT Scans of Chest-Irradiated Nonhuman Primates.

Computed tomography (CT) imaging has been used to diagnose radiation-induced lung injury for decades. However, histogram-based quantitative tools have rarely been applied to assess lung abnormality due to radiation-induced lung injury (RILI). Here, we used first-order summary statistics to derive and assess threshold measures extracted from whole lung histograms of CT radiodensity in rhesus macaques. For the present study, CT scans of animals exposed to 10 Gy of whole thorax irradiation were utilized from a previous study spanning 2-9 months postirradiation. These animals were grouped into survivors and non-survivors based on their clinical and experimental endpoints. We quantified the change in lung attenuation after irradiation relative to baseline using three density parameters; average lung density (ALD), percent change in hyper-dense lung volume (PCHV), hyperdense volume as a percent of total volume (PCHV/TV) at 2-month intervals and compared each parameter between the two irradiated groups (non-survivors and survivors). We also correlated our results with histological findings. All the three indices (ALD, PCHV, PCHV/TV) obtained from density histograms showed a significant increase in lung injury in non-survivors relative to survivors, with PCHV relatively more sensitive to detect early RILI changes. We observed a significant positive correlation between histologic pneumonitis scores and each of the three CT measurements, indicating that CT density is useful as a surrogate for histologic disease severity in RILI. CT-based three density parameters, ALD, PCHV, PCHV/TV, may serve as surrogates for likely histopathology patterns in future studies of RILI disease progression.

Abstract 12938: Intrathoracic Visceral Adiposity is Inversely Associated With Insulin Like Growth Factor Binding Protein 1: The Longenity Study

Introduction: Higher insulin-like growth factor binding protein 1 (IGFBP-1) level in serum has been variably associated with better insulin sensitivity and lower rates of obesity, diabetes mellitus, and atherosclerosis; suggesting that it may have a protective role in cardiometabolic aging. We hypothesized that epicardial, intrathoracic, or total thoracic adiposity (EAT, IAT, or TTA, respectively) measured on thoracic CT, were inversely associated with IGFBP-1, providing an assessment of cardiometabolic status by computed tomography (CT). Methods: Participants (n=104) were prospectively enrolled from the LonGenity study at Albert Einstein Institute of Aging. Participants were of Ashkenazi descent and ≥65 years, 53% were offspring of parents with exceptional longevity (OPEL) and 47% were offspring with usual survival (OPUS). Exclusion criteria were prior coronary artery bypass or stent, heart rate &gt; 100 beats/minute or not in sinus rhythm. Participants underwent a non-contrast gated CT. Adiposity was quantified using QFAT software (Cedars Sinai, CA). IGFBP-1 measures closest to the CT were used, ranging from 58 months before to 16 months after, with the majority within 1 year of the scan. Associations between IGFBP-1 and the adiposity were evaluated with linear regression with square-root of adiposity measures as the outcome. Each subject was weighted by the inverse of the years between CT and closest IGFBP-1 measurement. Results: IGFBP-1 levels were inversely associated with EAT (p =0.007), IAT (p = 0.003) and TTA (p = 0.003) after adjustment for age, sex, body mass index, OPEL/OPUS, diabetic medication, statin use, and high- and low-density lipoprotein levels. BMI explained 27.2% of the variation of TTA (p &lt; 0.001) and IGFBP-1 explained an additional 6% of the variation. There was no association of OPEL/OPUS status with adiposity measures. Conclusion: In conclusion, higher IGFBP-1 was associated with lower cross-sectional TTA, suggesting that IGFBP-1 may be indicative of a favorable cardiometabolic environment in aging. Future studies should evaluate the utility of IGFBP-1, epicardial and thoracic visceral adiposity as indicators of cardiometabolic disease.

Computed Tomographic Thickness of Retrobulbar Optic Nerve Is Decreased in Glaucoma Patients and Is Negatively Correlated With Disease Severity.

Purpose The purpose of the study was toquantitatively measure the width of the retrobulbar optic nerve-sheath complex by computed tomography (CT) in glaucoma and evaluate its relationship with optic nerve changes and visual field loss parameters. Methods Sixty-six eyes of 33 patients with bilateral asymmetric glaucomatous optic nerve damage and 20 eyes of 20 age- and sex-matched control subjects without glaucoma were included. Axial retrobulbar optic nerve-sheath complex was measured by CT in the eyes with advanced glaucomatous damage (group 1); in the fellow eyes of the same patients with moderate glaucomatous damage (group 2); and in control subjects (group 3). Measurements were obtained at three different points: just behind the globe, near the optic canal, and in the middle. Results Mean age and sex distribution between groups were comparable (p>0.05). The mean diameters of the retrobulbar optic nerve at three measurement points in group 1 (4.00±0.42mm, 3.49±0.44mm, 3.18±0.45mm) were significantly (for each, p<0.05) lower when compared with the corresponding points of group 2 eyes (4.24±0.41mm, 3.77±0.47nn, 3.47mm±0.44mm) and normal controls (4.58±0.44mm, 4.15±0.45mm, 3.92±0.48mm). Optic disc changes and visual field parameters were negatively correlated with retrobulbar optic nerve diameter (for each, p < 0.05). Conclusion Radiological alterations of the retrobulbar optic nerve in glaucomatous eyes revealed a decreased optic nerve diameter which correlated with disease severity. Optic nerve dimensions below the lower limit for normal individuals may be considered pathologically reduced and, therefore, CT measurements of the retrobulbar nerve may be additive to the traditional triad of raised intraocular pressure, field defects, and optic disc changes in some cases with opaque optic media preventing the fundus examination or with optic nerve anomalies.

Establishment of a formula for the estimation of kidney depth in adults and its effect on glomerular filtration rate assessment.

Gates' analysis method for kidney depth (KD) calculation is the only way to determine the glomerular filtration rate (GFR) of the kidney in clinical practice, which posits that the influence of KD on the GFR is more important than other factors. Computed tomography (CT) measurement of the donor KD can improve the accuracy of GFR measurement by Gates' method but will also increase the radiation exposure of kidney transplantation donors. Thus, it is particularly important to establish an accurate empirical formula for KD measurement that is more consistent with the real KD. In total, 326 potential renal transplantation donors were enrolled in this study. Among these, 167 donors were assigned to the training set to estimate the regression formula of KD measured by CT. The remaining 159 donors were included in the validation set to verify the regression formula. The KD measured by CT and its corresponding GFR was taken as the reference standard. The performances of formulas were then compared. There was no significant statistical difference between the CT-measured KD and the current fitting, Li Q, and Xue JJ formulas (P>0.05). However, significant differences were observed between the KDs calculated using the Taylor, Ma G, and Uchiyama formulas and the CT-measured reference standard KD (P<0.05). Furthermore, there was no notable difference in the GFRL and GFRR corresponding to the CT-measured KD with that of the fitting, Ma G, and Xue JJ formulas (P>0.05). There were also marked differences in the GFRR corresponding to the Li Q's formula (P<0.05), and in the GFR between other estimation methods and the CT measurement (P<0.05). The fitting formula established in this study can play a more important role if an accurate measurement method of the body thickness at the level of the hilum on the body surface can be found.

Comparison of computed tomography and 3D magnetic resonance imaging in evaluating glenohumeral instability bone loss.

To determine whether the addition of 3-dimensional (3D) magnetic resonance imaging (MRI) to standard MRI sequences is comparable to 3D computed tomographic (CT) scan evaluation of glenoid and humeral bone loss in glenohumeral instability. Eighteen patients who presented with glenohumeral instability were prospectively enrolled and received both MRI and CT within 1 week of each other. The MRI included an additional sequence (volumetric interpolated breath-hold examination [VIBE]) that underwent postprocessing for reformations. The addition of a VIBE protocol, on average, is an additional 4-4.5 minutes in the scanner. CT data also underwent 3D postprocessing, and therefore each patient had 4 imaging modalities (2D CT, 2D MRI, 3D CT reformats, and 3D MRI reformats). Each sequence underwent the following measurements from 2 separate reviewers: glenoid defect, glenoid defect percentage, humeral defect, humeral defect percentage, and evaluation of glenoid track and version. Paired t tests were used to assess differences between imaging modalities and χ2 for glenoid track. Intra- and interobserver reliability were evaluated. Bland-Altman tests were also performed to assess the agreement between CT and MRI. In addition, we determined the cost of each imaging modality at our institution. 3D MRI measurements for glenoid and humeral bone loss measurements were comparable to 3D CT (Table1). There were no significant differences for glenoid defect size and percentage, or humeral defect size and percentage (P>.05) (Table2). Bland-Altman analysis demonstrated strong agreement, with small measurement errors for 3D CT and 3D MRI percentage glenoid bone loss. There was also no difference in evaluation for determining on vs. off track between any of the imaging modalities. Inter- and intrarater reliability was good to excellent for all CT and MRI measurements (r ≥ 0.7). 3D MRI measurements for bone loss in glenohumeral instability through use of VIBE sequence were equivalent to 3D CT. At our institution, undergoing MRI with 3D reconstruction was 1.67 times cheaper than MRI and CT with 3D reconstructions. 3D MRI may be a useful adjuvant to standard MRI sequences to allow concurrent soft tissue and accurate assessment of glenoid and humeral bone loss in glenohumeral instability.

Assessment of Lumbar Vertebrae Morphology by Computed Tomography in Older Adults with Osteoporosis.

Hounsfield Units (HU) values derived from Computerized Tomography (CT) have been used in the diagnosis of osteoporosis in the lumbar spine. This study aimed to identify anatomical dimensions of lumbar vertebrae on CT images, which were different between older normal, osteopenic, and osteoporotic subjects. This prospective pilot study enrolled 79 older adults. Based on CT measurements of lumbar vertebrae in HU, participants were classified into three groups: normal (HU > 109), osteopenia (HU: 94-108), and osteoporosis (HU < 93). Altogether, 42 anatomical variables of lumbar vertebrae, L2, L3, L4, and L5, were measured in each participant by CT, including 24 parameters measurable by MRI or plain X-ray and 18 parameters measurable by MRI only. Among the morphological measurements also measurable by MRI and plain X-ray, the length upper curve, 50% and 75% of L5, length upper with the cortex of L4, length center of the cortex of L3, as well as width upper curve 75% of L2, were significantly different between the three groups (p= 0.008, 0.007, 0.035, 0.036, and 0.003 respectively). Among the morphological measurements also measurable by MRI, only the width upper cortex 75% of L5 and the width lower cortex 25% of L3, were significantly different between the three groups (p= 0.031 and 0.020, respectively). Seven CT morphological measurements may be used as "reference standard" CT measurements for preliminarily diagnosing osteoporosis and osteopenia in older adults.

Comparison of orbital volume measured using computed tomography and fluid displacement: A comparative study using dry skull

Objectives: The purpose of the study was as follows: (1) To compare orbital volume calculated using computed tomography (CT) scans with real-time measurements. (2) To evaluate if the orbital volume of the adjacent orbit can be taken as a tool of comparison for orbital volume correction in orbital fractures. Materials and Methods: A prospective study was conducted on 30 orbital cavities with intact orbital walls. The foramina and fissures were sealed using molding wax. Alginate impressions of the orbital cavity were taken to determine the orbital volume using the Archimedes principle. GE light speed 64 slices CT scanner was used to scan the orbits with 0.8 mm sections. Orbital volume was calculated using the CT software GE ADW 4.5 workstation. Results: The comparison of CT measurement and Archimedes principle measurement shows a mean and standard error of 0.2333 mm and 0.09794, respectively, on the right orbits and a mean and standard error of 0.10011 mm and 0.0981, respectively, on the left orbits. The comparison of the right and left orbits shows a mean and standard error of 0.4067 mm and 0.2771 mm, respectively, using the Archimedes principle and a mean and standard error of 0.3300 mm and 0.2775, respectively, using CT scans. Conclusion: It was found that the difference in orbital volume between CT and real-time measurement is very negligible. The study shows that CT is a reliable tool for the orbital volume measurement and the adjacent orbit can be taken as a comparative tool for the orbital volume corrections.

Calibration of 3D scan trajectories for an industrial computed tomography setup with 6-DOF object manipulator system using a single sphere

In industrial x-ray computed tomography (CT), the application of more complex scan paths in comparison to the typical circular trajectory ( rotation of the measurement object) can extend the potential of CT. One way to enable such 3D scan trajectories is to use a 6-degrees-of-freedom (DOF) object manipulator system. In our case, a hexapod is mounted on top of the rotary table of a commercial CT scanner. This allows for adaptive tilting of the measurement object during the scan. For high accuracy, the geometry calibration of such setups is typically done using the x-ray projections of a calibrated multi-sphere object. Contrary to this, here, we demonstrate a procedure that is based on only a single sphere and can therefore experimentally be implemented with low effort. Using the intrinsic geometry parameters of the CT device as prior information, the hexapod coordinate system with respect to the CT machine coordinate system is determined by means of a one-step optimization approach. The resulting parameters are used to calculate projection matrices that enable the volume reconstruction for 3D scan trajectories. The method is validated using simulated x-ray images and experimental investigations including dimensional measurements. For the used setup, geometric measurement results for 3D scan trajectories that are calibrated with the presented method show in sum increased errors compared to the circular scans. A limited pose accuracy of the manipulator system is discussed as a potential cause. The results nevertheless indicate that the presented method is generally feasible for dimensional CT measurements provided that the pose accuracy is sufficient. The calibration procedure can therefore be a low-cost and easier to implement alternative compared to trajectory calibration methods based on multi-sphere objects, but with a tendency towards lower measurement accuracy. The methodology can in principle be transferred to different setups with 6-DOF manipulator systems, e.g. C-arm CT devices with a robot arm.

Experimental and numerical study on SMA modified with an encapsulated polymeric healing agent

The present study aims at experimentally and numerically investigating the effect an encapsulated healing agent on the mechanical characteristics of a stone mastic asphalt (SMA). As a healing agent a thiol-containing urethane AR-polymer is used in this study. In order to gain a numerical insight into mechanical behavior of the capsules in SMA, a micromechanical finite element modeling is employed. The developed model allows capturing the stresses induced in the capsules at different load cases applied to the SMA on macro-scale. Particular attention is paid presently to the numerical evaluation of the local stress state that arises around capsules during compaction, operation, and also during crack initiation. SMA mixtures with various volumetric contents of healing capsules were manufactured and the capsules survival during mixture production was evaluated based on X-Ray Computed Tomography measurements. The effect of capsules on the self-healing properties of asphalt mixtures has furthermore been examined with repeated compressive strength tests. The obtained experimental results indicate that the absolute majority of capsules survive mixture production, and that their addition increases the SMA strength recovery during the healing period. The experimental and numerical results concerning capsules breakage are found to be in reasonable agreement. The developed micromechanical model may thus potentially provide a useful tool for optimization of capsules mechanical properties in order to improve their survival during mixture production as well as their timely activation.

Rostral nasopharyngeal CT measurements in Chihuahuas and Pomeranians are smaller than those measured in Dachshunds.

Chihuahuas and Pomeranians are often afflicted with obstructive upper respiratory tract disease. Previous computed tomographic (CT) studies have described the dimensions and abnormalities of different parts of the upper respiratory tract in brachycephalic dogs. However, Chihuahuas and Pomeranians were not included. The objective of this study was to determine the transverse-sectional (TSA) dimensions of the nasopharynx, cricoid, and trachea of Chihuahuas and Pomeranians, and investigate whether or not Chihuahuas and Pomeranians had smaller airway dimensions than another non-brachycephalic breed (Dachshund). A retrospective, descriptive, single-center cross-sectional cohort study was performed. CT studies of 88 dogs were included (42 Chihuahuas, 29 Dachshunds, and 17 Pomeranians). The TSA of the rostral, mid, and caudal aspect of the nasopharynx, the cricoid and trachea at the level of C4 were determined. For all these locations, TSA/weight, nasopharynx/cricoid, nasopharynx/trachea, and cricoid/trachea ratios were determined. The rostral nasopharynx was the smallest part of the upper airways in Chihuahuas and Pomeranians. Chihuahuas had significantly smaller rostral nasopharynx TSA/weight ratios compared to Dachshunds (P<0.0001). The rostral nasopharynx TSA/cricoid ratio and the rostral nasoharynx/trachea ratio for Chihuahuas were significantly smaller than both that of Pomeranians (P<0.0001 and P=0.00027) and Dachshunds (P<0.0001 and P=0.00084). Pomeranians had significantly smaller cricoid TSA/weight ratios compared to Chihuahuas (P=0.0014) and Dachshunds (P=0.00028). This study demonstrated that the nasopharynx is narrow in Chihuahuas and Pomeranians, with the smallest dimensions located at the rostral part of the nasopharynx.

Modeling Low Muscle Mass Screening in Hemodialysis Patients

Introduction: Computed tomography (CT) can accurately measure muscle mass, which is necessary for diagnosing sarcopenia, even in dialysis patients. However, CT-based screening for such patients is challenging, especially considering the availability of equipment within dialysis facilities. We therefore aimed to develop a bedside prediction model for low muscle mass, defined by the psoas muscle mass index (PMI) from CT measurement. Methods: Hemodialysis patients (n = 619) who had undergone abdominal CT screening were divided into the development (n = 441) and validation (n = 178) groups. PMI was manually measured using abdominal CT images to diagnose low muscle mass by two independent investigators. The development group’s data were used to create a logistic regression model using 42 items extracted from clinical information as predictive variables; variables were selected using the stepwise method. External validity was examined using the validation group’s data, and the area under the curve (AUC), sensitivity, and specificity were calculated. Results: Of all subjects, 226 (37%) were diagnosed with low muscle mass using PMI. A predictive model for low muscle mass was calculated using ten variables: each grip strength, sex, height, dry weight, primary cause of end-stage renal disease, diastolic blood pressure at start of session, pre-dialysis potassium and albumin level, and dialysis water removal in a session. The development group’s adjusted AUC, sensitivity, and specificity were 0.81, 60%, and 87%, respectively. The validation group’s adjusted AUC, sensitivity, and specificity were 0.73, 64%, and 82%, respectively. Discussion/Conclusion: Our results facilitate skeletal muscle screening in hemodialysis patients, assisting in sarcopenia prophylaxis and intervention decisions.

MRI-Based Score for Assessment of Bone Mineral Density in Operative Spine Patients.

Retrospective comparison. The aim was to determine whether a previously developed magnetic resonance imaging (MRI)-derived bone mineral density (BMD) scoring system can differentiate between healthy and osteoporotic vertebrae and to validate this scoring system against quantitative computed tomography measurements. BMD is an important preoperative consideration in spine surgery. Techniques to measure BMD are subject to falsely elevated values in the setting of spondylosis (dual-energy X-ray absorptiometry) or require significant exposure to radiation [quantitative computed tomography (QCT)]. Previous studies have shown that MRI may be utilized to measure bone quality using changes in the bone marrow signal observed on T1-weighted MRIs. Retrospective study of patients who underwent operative lumbar procedures at a single tertiary institution between 2016 and 2021 (n=61). Vertebral bone quality (VBQ) scores were measured by dividing the median signal intensities of L1-L4 by the signal intensity of cerebrospinal fluid on noncontrast T1W MRI. Demographic data, comorbidities, VBQ scores, and QCT-derived T scores and BMD of the lumbar spine were compared between healthy ( T score ≥-1; n=21), osteopenic (-2.5 < T score < -1; n=21), and osteoporotic ( T score ≤-2.5; n=19) cohorts using analysis of variance with post hoc Tukey test. Linear regression and receiver operating characteristic curve analyses were performed to assess the predictive value of VBQ scores. Pearson correlation test was used to evaluate the association between VBQ scores and QCT-derived measurements. VBQ differentiated between healthy and osteoporotic groups ( P =0.009). Receiver operating characteristic curve analysis revealed that a greater VBQ score was associated with presence of osteoporosis (area under the curve=0.754, P =0.006). Cutoff VBQ for osteoporosis was 2.6 (Youden index 0.484; sensitivity: 58%; specificity: 90%). VBQ scores weakly correlated with QCT-derived BMD ( P =0.03, r =-0.27) and T scores ( P =0.04, r =-0.26). This study attempted to further validate a previously developed MRI-based BMD scoring system against QCT-derived measurements. VBQ score was found to be a significant predictor of osteoporosis and could differentiate between healthy and osteoporotic vertebrae.

Thoracic computed tomography measures have predictive value in the diagnosis of chronic obstructive pulmonary disease

Chronic Obstructive Pulmonary Disease (COPD) is diagnosed with pulmonary function tests (PFTs). However, since not all patients can be diagnosed with PFTs, some are diagnosed with radiological or clinical findings. The purpose of this study was to define the properties of obstructive airway disease through thoracic computed tomography (CT) and to identify the diagnostic efficacy of CT findings. A total of 160 patients who underwent PFT and thoracic CT assessment July 2018 - January 2019, were retrospectively analyzed. Based on PFT findings, patients were categorized into three groups as having normal, restrictive or obstructive airways. Age, height, weight, and body mass indexes of the groups were recorded. Pulmonary height, width, right-left hemi-diaphragm height, sterno-diaphragmatic angle and retrosternal transparent area length in axial sections were also recorded. Diagnostic efficacies of these parameters in the detection of obstructive airway disease were measured. Of the 160 patients (109 males, 51 females; mean age = 59.5), 91 (56.9) had normal PFT, 58 (36.2%) had obstructive and 11 (6.9%) had restrictive airway disease. Pulmonary height, width, sterno-diaphragmatic angle, and retrosternal transparent area length were significantly higher in patients with obstructive airway disease while the right-left hemi-diaphragm height was significantly lower (p&lt;0.001). About 60-75% sensitivity and specificity were obtained when identifying the obstructive airway disease with these parameters. These values obtained from the axial and sagittal sections could contribute to the diagnosis of obstructive airway disease.

The correlation between different ultrasound planes and computed tomography measures of abdominal aortic aneurysms.

Ultrasound measurements of the aorta are typically taken in the axial plane, with the transducer perpendicular to the aorta, and diameter measurements are obtained by placing the callipers from the anterior to the posterior wall and the transverse right to the left side of the aorta. While the 'conventional' anteroposterior walls in both sagittal and transverse plains may be suitable for aneurysms with less complicated geometry, there is controversy regarding the suitability of this approach for complicated, particularly tortuous aneurysms, as they may offer a more challenging situation. Previous work undertaken within our research group found that when training inexperienced users of ultrasound, they demonstrated more optimal calliper placement to the abdominal aorta when approached from a decubitus window to obtain a coronal image compared to the traditional ultrasound approach. To observe the level of agreement in real-world reporting between computed tomography (CT) and ultrasound measurements in three standard planes; transverse AP, sagittal AP and coronal (left to right) infra-renal abdominal aortic aneurysm (AAA) diameter. This is a retrospective review of the Otago Vascular Diagnostics database for AAA, where ultrasound and CT diameter data, available within 90 days of each other, were compared. In addition to patient demographics, the infrarenal aorta ultrasound diameter measurements in transverse AP and sagittal AP, along with a coronal decubitus image of the aorta was collected. No transverse measurement was performed from the left to the right of the aorta. Three hundred twenty-five participants (238 males, mean age 76.4 ± 7.5) were included. Mean ultrasound outer to the outer wall, transverse AP and sagittal AP diameters were 48.7 ± 10.5 mm and 48.9 ± 9.9 mm, respectively. The coronal diameter measurement of the aorta from left to right was 53.9 ± 12.8 mm in the left decubitus window. The mean ultrasound max was 54.3 ± 12.6 mm. The mean CT diameter measurement was 55.6 ± 12.7 mm. Correlation between the CT max and ultrasound max was r 2 = 0.90, and CT with the coronal measurement r 2 = 0.90, CT and AP transverse was r2=0.80, and CT with AP sagittal measurement was r 2 = 0.77. The decubitus ultrasound window of the abdominal aorta, with measurement of the coronal plane, is highly correlated and in agreement with CT scanning. This window may offer an alternative approach to measuring the infrarenal abdominal aortic aneurysm and should be considered when performing surveillance of all infra-renal AAA.

Simulation of micro cracks introduced by environmental stress in amorphous plastics

Environmental stress crack resistance (ESCR) is a major problem especially for amorphous polymers. The interaction between aggressive substances and both mechanical external and residual stresses can lead to a fracture of the plastic part. In a previous study, a method was developed to measure the ESCR. The specimens are bent over a circular jig to introduce external stresses and a softener is applied as aggressive substance. After a certain time, the samples fracture giving a measure for the ESCR. In this study, this method is under further investigation using the example of acrylonitrile butadiene styrene. Before the sample fractures, there are several micro cracks visible on the surface. The growth of these micro cracks was measured by dye penetrant testing and the shape of the cracks was determined with computer tomographic measurements. From these measurements, artificial samples were constructed for a simulation. Through the simulation, the stresses in the samples were determined to get an insight into the failure mechanism of the samples. It has been shown that the number of the micro cracks in a sample is constant at all times even though there is a great variation in the number of cracks in the different samples. The cracks grow almost linearly with time. This means that all cracks initiate in one specimen at the same time and in the following phase these cracks grow while no more new cracks initiate. This can be explained by the simulation showing that the stress accumulates at the tips of the cracks and the tensile stress at the surface of the specimens decreases. These results were compared with the results from a stress relaxation test which also showed a decrease in the tensile stress at the surface with time, hence verifying the simulative results.