Computed Tomography Studies Research Articles

Persistent hiccups as a rare presenting symptom of empyema: a case report

BackgroundEmpyema is uncommon owing to antibiotic use but still affects patient health if not treated. Hiccups as the initial symptom of empyema are rare; however, empyema should be considered if a patient has persistent hiccups with unexplained fever.Case presentationWe present a case of persistent hiccups, left upper quadrant abdominal pain, and fever on day 1, and total left lung white-out and empyema on day 3. The hiccups resolved gradually after antibiotic treatment and surgical decortication.ConclusionsClinicians should consider the possibility of empyema and conduct a chest computed tomography study if unexplained fever and persistent hiccups coexist.

Oblique lateral interbody fusion at L5-S1: feasibility, surgical approach window, incision line, and influencing factors.

The primary aim of this study was to describe the feasibility, surgical approach window (SAW), and incision line (IL) for oblique lateral interbody fusion at L5-S1 (OLIF51) using computed tomography (CT). A secondary aim was to identify associations among approach characteristics and demographic and anthropometric factors. We performed a radiographic study of 50 male and 50 female subjects who received abdominal CT imaging. SAW was measured as the distance from the midline to the medial border of the iliac vessel. IL was measured at the skin surface corresponding to the distance between the center of the disc space and SAW lateral margin. OLIF51 feasibility was defined as the existence of at least a 1-cm SAW without retraction of soft tissues. For the left side, the OLIF51 SAW and IL were 12.1 ± 4.6 and 175.1 ± 55.3mm. For the right side, these measures were 10.0 ± 4.3 and 185.0 ± 52.5mm. Correlations of r = 0.648 (p < 0.001) and r = 0.656 (p < 0.001) were observed between weight and IL on the left and right sides, respectively. OLIF51 was not feasible 23% of the time. To our knowledge, this is the largest CT study to determine the feasibility of performing an OLIF51. Without the use of retraction, OLIF51 is not feasible 23% of the time. Left-sided OLIF51 allows for a larger surgical approach window and smaller incision compared to the right side. Larger incisions are required for adequate surgical exposure in patients with higher weight.

The influence of seated postures and anthropometry on lap belt fit in vehicle occupants: A 3D computed tomography study

Objective In vehicle frontal collisions, it is crucial that the lap belt is designed to engage with the anterior superior iliac spine (ASIS) of occupants for a reliable restraint. This study aims to understand the influence of different seated postures on the geometrical relationship of the seat belt and the pelvis for various occupants using 3D upright and supine computed tomography (CT) systems. Methods The 3D shapes of bones and soft tissues around the pelvis were acquired through a CT scan for 30 participants. They were seated in a rigid seat equipped with a lap belt simulating the front seat of a small car, and wore a lap belt in three seated postures: upright, slouched and reclined. Parameters related to the likelihood of submarining occurrences, such as belt-ASIS overlap (an index for assessing the potential engagement of the lap belt with the ASIS) and the belt-pelvis angle (the difference between the belt angle and the normal direction of the anterior edge of the ilium) were compared. Results It was observed that the pelvis angle tilted rearward as the hip point was positioned forward and seatback angle increased. This can be seen in the slouched and reclined posture. The belt-pelvis angle was comparable between the slouched and the reclined postures, and was closer to zero (indicating that the lap belt path is closer to perpendicular to the anterior edge of the ilium) compared to the upright posture. In contrast, the belt-ASIS overlap increased with an increasing flesh margin of the ASIS and shallower belt angle. This suggests that the belt-pelvis angle is influenced by the seated posture whereas the belt-ASIS overlap is dependent more on an individual’s anthropometry. The plot of belt-pelvis angle and belt-ASIS overlap exhibited significant variability among participants. Conclusions The belt-pelvis angle and the belt-ASIS overlap of individuals will provide valuable information for understanding the current belt-fit location and predicting submarining occurrences for individuals in various postures when designing restraint systems.

The Needle Shield Size and Applied Force of Subcutaneous Autoinjectors Significantly Influence the Injection Depth.

This study examines how shield-triggered autoinjectors (AIs), for subcutaneous drug delivery, affect injection depth. It focuses on shield size and applied force, parameters that could potentially lead to inadvertent intramuscular (IM) injections due to tissue compression. A blinded ex-vivo study was performed to assess the impact of shield size and applied force on injection depth. Shields of 15, 20, and 30 mm diameters and forces from 2 to 10 N were investigated. The study involved 55 injections in three Landrace, Yorkshire, and Duroc (LYD) pigs, with injection depths measured with computed tomography (CT). An in-vivo study, involving 20 injections in three LYD pigs, controlled the findings, using fluoroscopy (FS) videos for depth measurement. The CT study revealed that smaller shield sizes significantly increased injection depth. With a 15 mm diameter shield, 10 N applied force, and 5 mm needle protrusion, the injection depth exceeded the needle length by over 3 mm. Injection depth increased with higher applied forces until a plateau was reached around 8 N. Both applied force and size were significant factors for injection depth (analysis of variance [ANOVA], P < .05) in the CT study. The FS study confirmed the ex-vivo findings in an in-vivo setting. The study demonstrates that shield size has a greater impact on injection depth than the applied force. While conducted in porcine tissue, the study provides useful insights into the relative effects of shield size and applied force. Further investigations in humans are needed to confirm the predicted injection depths for AIs.

Assessing the Impact of the Metal Artifact Reduction Tool on Detecting Furcation Lesions in Maxillary Molars with Different Intracanal Posts: An Ex Vivo Cone-beam Computed Tomography Study

IntroductionConsidering the potential image compromise and diagnostic challenges posed by metals, this study aimed to assess the efficacy of the metal artifact reduction (MAR) tool in cone-beam computed tomography examinations for detecting furcation lesions in upper molars treated endodontically and restored with different intracanal posts. MethodsThis ex vivo study used 45 endodontically treated maxillary first molars, categorized into the following3 groups (n = 15): control (without intracanal post), metal post, and fiberglass post. Simulations were conducted in the laboratory to replicate alveolar bone, periodontal ligament, and grade I, II, and III furcation lesions. Cone-beam computed tomography scans were obtained with and without the MAR tool, and the furcation lesions were evaluated considering a 5-point Likert scale. Data were analyzed at 5%. ResultsIn the control group, there was no influence of MAR (P > .05); grade II lesions were not diagnosed, and grade III lesions were the most detected (P < .05). In the metal post group with MAR, grade III lesions were diagnosed more frequently than I and II (P < .05) and grade III without MAR (P < .05). In the fiberglass post group, the diagnosis of grade I lesions decreased with MAR (P < .05), and without MAR, grade III was most diagnosed (P < .05); grade III lesions were the most diagnosed (P < .05). ConclusionsThe MAR tool was only effective for diagnosing grade III furcation lesions, regardless of the intracanal material. Its application for grade I and II lesions did not contribute to improved diagnosis. Furthermore, in the fiberglass post group with grade I lesions, the MAR tool negatively affected the detection of the lesions.

Computed tomographic assessment of bronchoesophageal artery hypertrophy and systemic‐to‐pulmonary shunt mimicking a persistent ductus arteriosus in a French Bulldog

AbstractA 5‐year‐old, female French bulldog was evaluated for left‐sided congestive heart failure. A diagnosis of bronchoesophageal artery hypertrophy with systemic‐to‐pulmonary shunt was made. Even though Doppler echocardiographic findings were in favour of a left‐to‐right shunting patent ductus arteriosus, the exploratory thoracotomy highlighted a more complex vascular anomaly. An angiographic computed tomography study allowed to establish the final diagnosis. Bronchial‐to‐pulmonary artery shunts can mimic the presence of a patent ductus arteriosus, therefore computed tomography is considered a valuable additional tool for diagnosis and surgical planning.

Using Point-of-care Ultrasonography to Diagnose Traumatic Arthrotomy of the Knee: A Case Series.

Accurate diagnosis of traumatic arthrotomy of the knee (TAK) is critical for patients presenting to the emergency department (ED) to ensure timely treatment. Current diagnostic modalities including plain radiography, computed tomography (CT), and the saline load test (SLT) have advantages and disadvantages. Point-of-care-ultrasonography (POCUS) offers a possible timely, low-cost, and efficient alternative method of diagnosing TAK. In this case series we present three cases where POCUS was used to diagnose TAK in the ED. Three patients in their early 20s presented to the ED complaining of knee trauma with wounds in proximity to the joint. Mechanisms of injury included a gunshot wound in one case and blunt trauma (motor vehicle collision and bicycle crash) in two cases. In all three cases TAK was suggested on POCUS examinations by the presence of intra-articular hyperechoic foci consistent with air artifact. All three cases had TAK confirmed by orthopedic evaluation. Ultrasound may have utility in the evaluation of patients presenting with knee trauma where TAK is a concern. The SLT is generally considered the gold standard test for diagnosis of TAK, but it is invasive and has a wide range of diagnostic accuracy. Intra-articular air has been found to be a sensitive marker for TAK in CT studies. Thus, additional investigations into the diagnostic accuracy of POCUS for this finding should be undertaken.

A cone-beam computed tomography study of canalis sinuosus and its accessory canals in a South African population.

Canalis sinuosus (CS) is a clinically relevant structure in the anterior maxilla. The present study aimed to determine the prevalence and distribution of CS and its accessory canals (ACs) in the South African population and describe its anatomical variations. In total, 500 cone-beam computed tomography (CBCT) scans of the anterior maxilla were assessed for prevalence, sidedness, diameter, and distribution of CS. The frequency, number, diameter, configuration, and point of termination of ACs were also recorded. Statistical analysis was performed using analysis of variance, Kruskal-Wallis, chi-squared, and Fisher Exact tests with P < 0.05. CS was present in most cases (99.6%), and commonly occurred bilaterally (98.8%). The mean diameter of CS was 1.08mm (range: 0.50mm-2.39mm). Sex, population group, and age had no significant effect on the prevalence or sidedness of CS. Additionally, 535 ACs were observed in 58.8% of the sample, with 42.9% of ACs found bilaterally and 57.1% unilaterally. The mean diameter of the ACs was 0.86mm on the left and 0.87mm on the right (range; 0.50mm-1.52mm). The majority of ACs maintained a straight vertical configuration (72.3%). ACs most commonly terminated in the anterior palatal region of the maxilla (57.2%). No significant differences were found in any groups mentioned (P > 0.05). A high prevalence of CS as well as ACs were observed in thesample population. Due to their clinical significance, surgical planning with the aid of high quality CBCT scans of the anterior maxilla is advisable.

The Radiological Anatomy of the Distal Tibiofibular Joint: A Retrospective Computed Tomography Study.

Introduction Distal tibiofibular joint (DTFJ) injuries are commonly encountered in patients with ankle fractures. Achieving optimal fixation is mandatory, but it requires a thorough understanding of the local anatomical relationships. For this reason, we performed a retrospective CT study in healthy ankles to radiologically describe the normal anatomy of the DTFJ and the anatomical relationship of the fibula within the ankle joint. Materials and methods For this study, we retrospectively examined 60 CT scans of healthy, non-injured ankles in a plantigrade position. Patients with prior ankle surgery or systemic diseases with ankle involvement were excluded because we needed to describe the normal anatomy of the joint. The radiological evaluation included the position of the fibula in the fibular notch and the rotational relationship of the fibula with the talus and the medial malleolus. Results Our study included 60 healthy ankles. Thirty-three were right ankles, and 27 were left. The cohort included 36 females and 24 males with a mean age of 48.3 years old. We found that the fibular notch was retroverted on the transverse plane, with the tibiofibular engagement being 0.11 mm (SD=1.57 mm, SE=0.2 mm), at 1 cm proximally to the tibial plafond. Additionally, we observed that the fibula was internally rotated against the lateral talar facet, while the medial and lateral malleolus facets were externally rotated in between. Moreover, we found a strong positive correlation between the incisura retroversion and fibular engagement at 1 cm above the tibial plafond line (Pearson correlation=0.273, p=0.03). Conclusion Our study highlights the importance of gaining a comprehensive understanding of the inherent anatomy of the DTFJ to achieve reduction goals in ankle fractures. According to our results, in ankle fracture treatment, surgeons should aim for anatomical fracture and syndesmotic fixation, with the fibula in internal rotation against the lateral talar facet. Additionally, as normal tibiofibular engagement is borderline, we do not suggest that over-tightening the syndesmotic screws is essential. This study's findings can aid surgeons in reducing the malreduction rates in patients with ankle fractures.

Root canal morphology of anterior permanent teeth in Jordanian population using two classification systems: a cone-beam computed tomography study

BackgroundAdequate knowledge of root canal morphology and its variation is essential for success of root canal treatment and to overcome treatemnt failure. The aim of this study was to investigate the root and canal morphology of mandibular anterior teeth using 2 classification systems.Methods3342 lower anteriors were evaluated from 557 CBCT scans. The images were examined in sagittal, axial and coronal views using a CS 3D imaging software (V3.10.4, Carestream Dental). Demographic data recorded, the number of roots and canal’s morphology were described according to Vertucci and Ahmed classifications.ResultsFrequency of Type I configuration was significantly the highest in incisors and canines (76%, N = 2539), followed by Type III (20.6%, N = 687). Type II (1.1%, N = 37), IV (1.1%, N = 37), and V (0.3%, N = 11) were rarely encountered. 0.9% (N = 31) of the teeth could not be classified with the Vertucci System. The frequency of 2 roots (2MA in Ahmed classification) which has no correspondence in the Vertucci classification, was 1.1% (N = 38), it was significantly higher in canines and in females (35 canines and 3 laterals). A moderate correlation in root canal morpology was found between the left and right sides (V > 0.30). 80% (N = 2538) of the teeth did not exhibit any divergence/merging. The bifurcation level occurred mostly in the middle third of the root.ConclusionsOne fourth of anterior teeth had variation from the simple type I canal configuration and therefore requires attention during treatment. The new classification system offers a more accurate and simplified presentation of canal morphology.Clinical relevanceThe prevalence and mid root bifurcation of second canal in lower anteriors requires attention to ensure adequate quality root canal treatment without compromising the integrity of teeth.

Correlation between Tooth Position Parameters and Apical Fenestration: A Cone-Beam Computed Tomography Study.

This study aimed to assess the relationship between apical fenestration-a defect in the alveolar bone involving the root apex-and tooth position in all tooth groups, excluding the third molars, utilizing cone-beam computed tomography (CBCT) images. A total of 800 CBCT scans (400 maxillary and 400 mandibular) from patients undergoing various treatments were examined by a single professional (radiologist and endodontist). Statistical analyses, including the chi-square test or Fisher's exact test, were conducted using R software 2.7.3 (R Foundation, Vienna, Austria). Results indicated a significant association (p ≤ 0.05) between apical fenestration and tooth position. In the upper teeth, apical fenestrations were notably present in the mesio-buccal (17.17%) and disto-buccal (11.07%) roots of the first molars. Conversely, apical fenestrations in the lower teeth were relatively less frequent. The study revealed a negative correlation between apical fenestration and mesial inclination, rotation, and extrusion in the upper teeth. However, a positive correlation was observed between apical fenestration and lingual inclination in the upper teeth. In conclusion, this study illuminates the distribution of apical fenestration and its correlation with tooth positions, offering insights into factors influencing this defect in dental anatomy. The findings enhance our understanding of nuanced relationships between tooth position and apical fenestration in the upper and lower dental arches.

TomoRay: Generating Synthetic Computed Tomography of the Spine From Biplanar Radiographs.

Computed tomography (CT) imaging is a cornerstone in the assessment of patients with spinal trauma and in the planning of spinal interventions. However, CT studies are associated with logistical problems, acquisition costs, and radiation exposure. In this proof-of-concept study, the feasibility of generating synthetic spinal CT images using biplanar radiographs was explored. This could expand the potential applications of x-ray machines pre-, post-, and even intraoperatively. A cohort of 209 patients who underwent spinal CT imaging from the VerSe2020 dataset was used to train the algorithm. The model was subsequently evaluated using an internal and external validation set containing 55 from the VerSe2020 dataset and a subset of 56 images from the CTSpine1K dataset, respectively. Digitally reconstructed radiographs served as input for training and evaluation of the 2-dimensional (2D)-to-3-dimentional (3D) generative adversarial model. Model performance was assessed using peak signal to noise ratio (PSNR), structural similarity index (SSIM), and cosine similarity (CS). At external validation, the developed model achieved a PSNR of 21.139 ± 1.018 dB (mean ± standard deviation). The SSIM and CS amounted to 0.947 ± 0.010 and 0.671 ± 0.691, respectively. Generating an artificial 3D output from 2D imaging is challenging, especially for spinal imaging, where x-rays are known to deliver insufficient information frequently. Although the synthetic CT scans derived from our model do not perfectly match their ground truth CT, our proof-of-concept study warrants further exploration of the potential of this technology.

Regression of Necrotic Lesions after Methotrexate Withdrawal in Patients with Methotrexate-Associated Lymphoproliferative Disorders: A Retrospective CT Study.

This retrospective study investigated whether necrotic lesions detected on a computed tomography (CT) scan are more regressive than non-necrotic lesions after methotrexate withdrawal in patients pathologically diagnosed with methotrexate-associated lymphoproliferative disorders (MTX-LPD). In total, 89 lesions extracted from 24 patients on CT scans were included in the analysis. All patients had been evaluated for the presence of necrosis within lesions via CT scan upon first suspicion of MTX-LPD (baseline CT scan). The percentage lesion size reduction between the baseline and initial follow-up CT scan was calculated. The association between necrosis within lesions and size changes was estimated via linear regression analyses using both crude and adjusted models. Necrosis was significantly more common in extranodal lesions (27 out of 30 lesions, 90%) than in nodal lesions (9 out of 59 lesions, 15%, p<0.001). In the crude model, the regression of necrotic lesions was 58.5% greater than that of non-necrotic lesions; the difference was statistically significant (p<0.001). Additionally, the longest diameter of necrotic lesions at the baseline CT scan was significantly greater than that of non-necrotic lesions (p<0.001). Based on the adjusted model, necrotic lesions showed 49.3% greater regression than non-necrotic lesions (p=0.017). Necrosis detected on a CT scan was found to be an independent predictor of regression after MTX withdrawal in patients with MTX-LPD.

Prevalence and Association of Calcified Pulp Stones with Periodontitis: A Cone-Beam Computed Tomography Study in Saudi Arabian Population

ABSTRACT This study aimed to identify the prevalence and association of periodontitis and pulp stone (PS) along with the clinical variables. This study assessed the cone-beam computed tomography (CBCT) records to identify the presence of PS and clinical periodontitis records were used to determine the stages of periodontitis. The Chi-square test was used to evaluate the relationship between study parameters. Logistic regression was used to determine the association between PS and periodontitis. A total of 228 CBCT records were conveniently selected for this study based on the inclusion and exclusion criteria. Cohen’s kappa analysis showed near to perfect scores for both examiners. The Chi-square test showed that CBCT records from the age range 41–50 years, male patients, and stage II of periodontitis prevalently showed pulp stones; however, there were no significant differences observed between the PS and clinical variables. However, gender, involvement of tooth, and stages of periodontitis showed significant distribution of the PS. Logistic regression showed that the stages of periodontitis showed no significant association with PS in patients with periodontitis. Moreover, multivariate odds ratio adjustment did not alter the outcome. Periodontitis is not associated with the presence of PS in the current population.

Body Composition Indicators Jointly Predict Metabolic Unhealthy Phenotypes in Young and Middle-Aged Obese Individuals: A Cross-Sectional Quantitative Computed Tomography Study.

The main aim of this study is to analyze the relationship between body composition indices and metabolic unhealthy phenotypes in young and middle-aged obese patients and to assess their joint predictive ability. A cross-sectional study method was used to select 207 patients who were proposed to undergo weight loss surgery for morbid obesity from March to November 2022. Total adipose tissue (TAT), visceral adipose tissue (VAT), subcutaneous adipose tissue (SAT), liver fat content (LFC), cross-sectional area (CSAmuscle), and intermuscular adipose tissue (CSAIMAT) of paraspinal muscles were measured using quantitative computed tomography. Participants were categorized into two groups: metabolically healthy obesity (MHO) and metabolically unhealthy obesity (MUO). The receiver operating characteristic curve comprised body composition variables that correlated with MUO, and the area under the curve (AUC) was calculated to compare their prediction capacity for MUO. There were 71 patients with MHO (34.3%) and 136 patients with MUO (65.7%). The VAT, VAT/TAT ratio, LFC, and CSAmuscle was higher in MUO patients than in MHO (all P < 0.001), and SAT was lower than in MHO (P = 0.008). And all of these metrics were correlated with MUO (all P < 0.05). Inclusion of these body composition metrics in the ROC analysis showed that the AUC values for SAT, VAT, VAT/TAT ratio, LFC and CSAmuscle were 0.615, 0.663, 0.727, 0.694, 0.671, respectively, and the combination of the VAT/TAT ratio and the LFC had the ability to predict MUO best (AUC=0.746, P = 0.025). The combined use of VAT/TAT ratio and LFC is superior to the use of these two metrics alone in terms of their ability to predict the MUO, providing a more accurate approach to the management and prevention of obesity-related metabolic risk.

An evaluation of bone depth at different three-dimensional paths in infrazygomatic crest region for miniscrew insertion: A cone beam computed tomography study

ObjectiveTo investigate the difference and distribution of bone depth at different three-dimensional simulated paths to help optimize the insertion path for miniscrew placement in the infrazygomatic crest. MethodsCone beam computed tomography scans of 80 adults (38 males and 42 females; mean age, 27.0 years) were assessed. For each subject, bone depth of 81 simulated insertion paths at different insertion points and three-dimensional angulations was measured in 160 infrazygomatic crests; the differences were evaluated using the adjusted Friedman test. The bone deficiency ratio for each path was calculated. Distributions of measurements were analyzed and reported as specially designed colormaps. ResultsBone depth increased, and bone deficiency ratio reduced mesially to distally (P < 0.001), apically to coronally (P < 0.01), and at a greater gingival and distal inclination (P < 0.05). The maximum bone depth (10.72 mm) was observed 13 mm above the maxillary occlusal plane in the mesiobuccal root of the maxillary second molar. The minimum bone depth (3.4 mm) was observed 17 mm above the maxillary occlusal plane in the distobuccal root of the maxillary first molar. No bone deficiency was detected at the paths of 13 mm above the maxillary occlusal plane at a gingival inclination of 70° and distal inclination of 30° in the mesiobuccal root of the maxillary second molar. The highest bone deficiency ratio is present 17 mm above the maxillary occlusal plane at a gingival inclination of 60° and a distal inclination of 0° in the distobuccal root of the maxillary first molar (89/160). ConclusionInsertion paths located at 13 mm above the maxillary occlusal plane in the mesiobuccal root of the maxillary second molar were optimal. A gingival inclination of 70° and a distal inclination of 30° could be beneficial. The distobuccal root of the maxillary first molar region or above the 17 mm insertion plane may not be recommended.

Influence of skeletal classes and facial patterns on the positioning of the craniovertebral junction, dimensions of the pharyngeal airway space, and pre-vertebral soft tissue thickness: A cone beam computed tomography study

This study employed cone beam computed tomography (CBCT) to assess the influence of skeletal classes and facial patterns on the craniovertebral complex, pharyngeal airway space (PAS) dimensions, and pre-vertebral soft tissue thickness. The analysis of 150 CBCTs involved measurements between various vertebrae and layers of soft tissue. Significant findings included a lower odontoid process in Class II and hyperdivergent individuals, while hypodivergent subjects exhibited a larger area and volume in the PAS. A negative correlation between PAS size and pre-vertebral soft tissue thickness was observed. Gender differences were noteworthy, with males consistently displaying higher values. Significant age-related variations were also identified, with the age groups of 18-30 and 31-45 exhibiting distinct characteristics. The study underscores the impact of facial patterns and skeletal classes on the craniovertebral complex, emphasizing an inverse relationship between PAS and pre-vertebral soft tissue thickness. The intricate connections between gender and age highlight their influence on anatomical characteristics. Understanding how facial patterns and skeletal classes affect the craniovertebral complex has implications for respiratory disorders, including Obstructive Sleep Apnea and Hypopnea Syndrome (OSAHS).

Improved detection of air-filled lesions using computed tomography in dogs with recurrent spontaneous pneumothorax through reduction of pulmonary atelectasis via positive pressure ventilation.

Spontaneous pneumothorax in dogs is predominantly caused by the rupture of air-filled lesions, such as bullae or blebs. The efficacy of Computed Tomography (CT) in detecting these lesions has been deemed limited due to its reportedly low sensitivity. This retrospective, cross-sectional study investigates the utility of CT in eight dogs diagnosed with recurrent pneumothorax, all of which had surgical confirmation of the cause of the pneumothorax. Thoracic radiographs were obtained before and the day following the CT studies. Initially, a CT study was conducted without positive pressure ventilation (pre-PPV CT). Subsequent CT studies were performed post-evacuation of pneumothorax and with positive pressure ventilation of 15 cmH2O until lung atelectasis was resolved (post-PPV CT). The pre-PPV CT and post-PPV CT images were anonymized and reviewed by two board-certified radiologists. The presence and morphology of air-filled lesions were evaluated on all images. Surgical findings were recorded and compared to the CT findings. Air-filled lesions were detected in 5 out of 8 dogs in the pre-PPV CT studies and in all 8 dogs in the post-PPV CT studies. The CT findings of air-filled lesions were consistent with surgical findings. None of the dogs showed increased severity of pneumothorax in radiographs taken the day following the CT studies. The study concludes that the resolution of lung atelectasis by evacuation of pneumothorax and positive pressure ventilation during CT studies is feasible and enhances the detection of air-filled lesions in dogs with recurrent spontaneous pneumothorax. This could potentially aid in improving surgical planning.

Estimation of Cochlear Implant Insertion Depth Using 2D-3D Registration of Postoperative X-Ray and Preoperative CT Images.

To improve estimation of cochlear implant (CI) insertion depth in postoperative skull x-rays using synthesized information from preoperative CT scans. Retrospective cohort. Tertiary referral center. Ten adult cochlear implant recipients with preoperative and postoperative temporal bone computed tomography (CT)scans and postoperative skull x-ray imaging. Postoperative x-rays and digitally reconstructed radiographs (DRR) from preoperative CTs were registered using 3D Slicer and MATLAB to enhance localization of the round window and modiolus. Angular insertion depth (AID) was estimated in unmodified and registration-enhanced x-rays and DRRs in the cochlear view. Linear insertion depth (LID) was estimated in registered images by two methods that localized the proximal CI electrode or segmented the cochlea. Ground truth assessments were made in postoperative CTs. Errors of insertion depth estimates were calculated relative to ground truth measurements and compared with paired t t ests. Pearson correlation coefficient was used to assess inter-rater reliability of two reviewer's measurements of AID in unmodified x-rays. In postoperative x-rays, AID estimation errors were similar with and without registration enhancement (-1.3 ± 20.7° and -4.8 ± 24.9°, respectively; mean ± SD; p = 0.6). AID estimation in unmodified x-rays demonstrated strong interrater agreement (ρ = 0.79, p < 0.05) and interrater differences (-15.0 ± 35.3°) comparable to estimate errors. Registering images allowed measurement of AID in the cochlear view with estimation errors of 14.6 ± 30.6° and measurement of LID, with estimate errors that were similar between proximal electrode localization and cochlear segmentation methods (-0.9 ± 2.2 mm and -2.1 ± 2.7 mm, respectively; p = 0.3). 2D-3D image registration allows measurement of AID in the cochlear view and LID using postoperative x-rays and preoperative CT imaging. The use of this technique may reduce the need for postimplantation CT studies to assess these metrics of CI electrode position. Further work is needed to improve the accuracy of AID assessment in the postoperative x-ray view with registered images compared with established methods.

The impact of heterogeneity and pore network characteristics on single and multi-phase fluid propagation in complex porous media: An X-ray computed tomography study

This study investigates the impact of pore network characteristics on fluid flow through complex and heterogeneous porous media, providing insights into the factors affecting fluid propagation in such systems. Specifically, high-resolution or micro X-ray computed tomography (CT) imaging techniques were utilized to examine outcrop stromatolite samples of the Lagoa Salgada, considered flow analogous to the Brazilian Pre-salt carbonate reservoirs. The petrophysical results comprised two distinct stromatolite depositional facies, the columnar and the fine-grained facies. By generating pore network model (PNM), the study quantified the relationship between key features of the porous system, including pore and throat radius, throat length, coordination number, shape factor, and pore volume. The study found that the less dense pore network of the columnar sample is typically characterized by larger pores and wider and longer throats but with a weaker connection of throats to pores. Both facies exhibited less variability in the radius of the pores and throats in comparison to throat length. Additionally, a series of core flooding experiments coupled with medical CT scanning was designed and conducted in the plug samples to assess flow propagation and saturation fields. The study revealed that the heterogeneity and presence of disconnected or dead-end pores significantly impacted the flow patterns and saturation. Two-phase flow patterns and oil saturation distribution reveal a preferential and heterogeneous displacement that mainly swept displaced fluid in some regions of plugs and bypassed it in others. The relation between saturation profiles, porosity profiles, and the number of fluid flow patterns for the samples was evident. Only for the columnar plug sample was the enhancement in recovery factor after shifting to lower salinity water injection (SB) observed.