Average Image Quality Research Articles

Effectiveness of an additively manufactured porous layer in dissimilar solid-state bulk joining of additively manufactured maraging steel and conventional AISI410 steel

Solid-state bulk joining of additively manufactured maraging steel and commercially available martensitic stainless steel (AISI410) specimens in a cylindrical shape is accomplished through electrically assisted pressure joining (EAPJ). The cylindrical maraging steel specimen is fabricated to have a porous layer on the joining side by selective laser melting additive manufacturing. During EAPJ, the porous layer, which serves as an interlayer with locally increased electrical resistance due to geometrically induced defects (pores), significantly and locally increases the maximum temperature while the joining load is dramatically decreased. The microstructure evolution suggests that grain refinement occurs on both the maraging steel and AISI410 sides due to recrystallization. The high residual stress induced during additive manufacturing of maraging steel specimens is significantly released during EAPJ. Martensite formation in the AISI410 steel and the reverted austenite in the maraging steel are characterized by the grain average image quality. Tensile tests show that the fracture always occurs in the transition region between the heat-affected region and the unaffected base metal region. The present study demonstrates that bulk joining of additively manufactured components and conventional components can be more easily and effectively achieved with the use of an additively manufactured porous layer, even for dissimilar material combinations. • AMed maraging steel and conventional AISI410 steel were solid-state joined. • The temperature was locally controlled by the AMed porous layer. • The high residual stress of AMed maraging steel was released during joining. • Microstructure evolution during joining was characterized by EBSD. • Base metal fracture in AISI410 side occurred during tension test.

Usefulness of Silent MRA for Evaluation of Aneurysm after Stent-Assisted Coil Embolization.

ObjectiveTo determine the usefulness of Silent MR angiography (MRA) for evaluating intracranial aneurysms treated with stent-assisted coil embolization.Materials and MethodsNinety-nine patients (101 aneurysms) treated with stent-assisted coil embolization (Neuroform atlas, 71 cases; Enterprise, 17; LVIS Jr, 9; and Solitaire AB, 4 cases) underwent time-of-flight (TOF) MRA and Silent MRA in the same session using a 3T MRI system within 24 hours of embolization. Two radiologists independently interpreted both MRA images retrospectively and rated the image quality using a 5-point Likert scale. The image quality and diagnostic accuracy of the two modalities in the detection of aneurysm occlusion were further compared based on the stent design and the site of aneurysm.ResultsThe average image quality scores of the Silent MRA and TOF MRA were 4.38 ± 0.83 and 2.78 ± 1.04, respectively (p < 0.001), with an almost perfect interobserver agreement. Silent MRA had a significantly higher image quality score than TOF MRA at the distal internal carotid artery (n = 57, 4.25 ± 0.91 vs. 3.05 ± 1.16, p < 0.001), middle cerebral artery (n = 21, 4.57 ± 0.75 vs. 2.19 ± 0.68, p < 0.001), anterior cerebral artery (n = 13, 4.54 ± 0.66 vs. 2.46 ± 0.66, p < 0.001), and posterior circulation artery (n = 10, 4.50 ± 0.71 vs. 2.90 ± 0.74, p = 0.013). Silent MRA had superior image quality score to TOF MRA in the stented arteries when using Neuroform atlas (4.66 ± 0.53 vs. 3.21 ± 0.84, p < 0.001), Enterprise (3.29 ± 1.59 vs. 1.59 ± 0.51, p = 0.003), LVIS Jr (4.33 ± 1.89 vs. 1.89 ± 0.78, p = 0.033), and Solitaire AB stents (4.00 ± 2.25 vs. 2.25 ± 0.96, p = 0.356). The interpretation of the status of aneurysm occlusion exhibited significantly higher sensitivity with Silent MRA than with TOF MRA when using the Neuroform Atlas stent (96.4% vs. 14.3%, respectively, p < 0.001) and LVIS Jr stent (100% vs. 20%, respectively, p = 0.046).ConclusionSilent MRA can be useful to evaluate aneurysms treated with stent-assisted coil embolization, regardless of the aneurysm location and type of stent used.

Microstructural evolution and fatigue performance of dissimilar solid-state joints of SUS316L and SUS410

Dissimilar stainless steels 316L (SUS316L) and SUS410 in a cylindrical butt configuration are solid-state joined along the cylinder axis by electrically assisted pressure joining (EAPJ). In EAPJ, different electric current densities are applied during compressive plastic deformation to investigate the effect of electric current density on joint performance. The microstructure analysis confirms that solid-state joints without macro- and micro-defects are fabricated through elemental diffusion and recrystallization during EAPJ. The effect of electric current density on the formation of martensite and subsequently on the variation of hardness is revealed by the grain average image quality maps and their relevant area distribution. The results of quasi-static tensile tests show that the fracture behavior of the joint is strongly affected by the applied electric current density. The fatigue behavior of joints with a higher tensile strength (SUS410 base metal fracture) is also evaluated by the S–N curve under a certain confidence level using two-parameter Weibull distribution. Finally, the fracture mechanism is investigated by examining the fracture surfaces from fatigue failure. The fracture morphology under high stress level exhibits a mixed fracture mode of base metal and interface fracture, while the fracture under low stress level exhibits interface fracture.

Results of a study of remote reporting over virtual applications and using visually calibrated monitors

Background and Objectives The purpose of this study is to examine differences in image quality, discrepancy rates, productivity and user experience between remote reporting over Virtual Application (VA) using visually calibrated monitors, and reporting using diagnostic grade workstations in hospital premises. Methods Three specialist accredited radiologists examined and provisionally reported outpatient CT and MR studies over PACS delivered as a VA, using visually calibrated monitors from their homes. They then proceeded to view the same studies within hospital premises and issue a final report. Surveys were filled out for each imaging study. Discrepancies were reviewed and assigned RADPEER scores. Results A total of 51 outpatient CT and MRIs were read. Relative to hospital premise reporting, on a Likert scale of 5 (the higher the better), average image quality was 3.9, speed of loading and image manipulation was 4.4 and productivity was 4.1. Remote reporting user experience did not differ significantly between CT versus MRI studies. Complete concordance rate was 80.4% (41/51) and only one of the studies had a significant discrepancy, which may have been due to extra time given to interpretation. All three radiologists reported factors influencing image display and quality as the top factor impacting remote reporting throughput. Conclusions Remote reporting over VA with visually calibrated monitors for CT and MR can be useful in periods of staffing difficulty to augment on-site radiologists, though attention must be paid to its limitations and policies defined by local leadership with reference to relevant national position

Surface imaging of breast implants using modern high-frequency ultrasound technology in comparison to high-end sonography with power analyses for B-scan optimization1.

This study aims to evaluate optimized breast implant surface-structure analysis by comparing high-end ultrasound technology with a new high frequency technique. This comparative study used new breast implants with different surfaces in an in vitro setting. Nine idle silicon or polyurethane (PU) breast implants were examined by two investigators in an experimental in vitro study using two high-end ultrasound devices with multi-frequency transducers (6-15 MHz, 9-16 MHz, 12.5-33 MHz).The ultrasound B-Mode was optimized using tissue harmonic imaging (THI), speckle reduction imaging (SRI, level 0-5), cross beam (high, medium, low) and photopic.Using a standardized ultrasound protocol, the implants were examined in the middle (point of highest projection) and lateral, by two independent examiners.Image evaluation was performed on anonymized digital images in the PACS. The aim was to achieve an artifact-free recording of the surface structure, the surface coating, the total image structures and, as far as possible, an artifact-free internal representation of the implants.For independent surface evaluation a score was used (0 = undetectability of surface structures, rich in artifacts, 5 = best possible, artifact free image quality). The quality of ultrasound imaging of breast implant surfaces after the optimization of B-Scan differed significantly comparing high-end ultrasound technology with modern high-frequency ultrasound technology (p < 0,05).The following setting has been found to be the best setting with the highest image quality:B-Mode, SRI value 3, Crossbeam high level with color coded imaging for B- mode. In the total examined frequency range of 6-33 MHz, the highest image quality was found in the average frequency range of 12.5-33 MHz at both measured points. For both devices, device 1 (high-end) and device 2 (high frequency) ultrasound, the image quality was in the12.5-33 MHz frequency range with an average image quality of 3.236. It was significantly higher, than in the lower frequency ranges and the same frequency range with THI. (p < 0,05). The image quality of the high-end sonography device was superior to the conventional high-frequency ultrasound device in all frequency ranges. High-end ultrasound imaging technology was superior in the quality of implant surface evaluation in comparison to high-frequency ultrasound sonography. The gained knowledge can serve as a basis for further multicenter clinical application and studies with the aim to develop an objective, precise tool to evaluate the implant and the surrounding tissue with ultrasound.

Image quality in liver CT: low-dose deep learning vs standard-dose model-based iterative reconstructions

To compare the overall image quality and detectability of significant (malignant and pre-malignant) liver lesions of low-dose liver CT (LDCT, 33.3% dose) using deep learning denoising (DLD) to standard-dose CT (SDCT, 100% dose) using model-based iterative reconstruction (MBIR). In this retrospective study, CT images of 80 patients with hepatic focal lesions were included. For noninferiority analysis of overall image quality, a margin of - 0.5 points (scored in a 5-point scale) for the difference between scan protocols was pre-defined. Other quantitative or qualitative image quality assessments were performed. Additionally, detectability of significant liver lesions was compared, with 64 pairs of CT, using the jackknife alternative free-response ROC analysis, with noninferior margin defined by the lower limit of 95% confidence interval (CI) of the difference of figure-of-merit less than - 0.1. The mean overall image quality scores with LDCT and SDCT were 3.77 ± 0.38 and 3.94 ± 0.34, respectively, demonstrating a difference of - 0.17 (95% CI: - 0.21 to - 0.12), which did not cross the predefined noninferiority margin of - 0.5. Furthermore, LDCT showed significantly superior quantitative results of liver lesion contrast to noise ratio (p < 0.05). However, although LDCT scored higher than the average score in qualitative image quality assessments, they were significantly lower than those of SDCT (p < 0.05). Figure-of-merit for lesion detection was 0.859 for LDCT and 0.878 for SDCT, showing noninferiority (difference: - 0.019, 95% CI: - 0.058 to 0.021). LDCT using DLD with 67% radiation dose reduction showed non-inferior overall image quality and lesion detectability, compared to SDCT. • Low-dose liver CT using deep learning denoising (DLD), at 67% dose reduction, provided non-inferior overall image quality compared to standard-dose CT using model-based iterative reconstruction (MBIR). • Low-dose CT using DLD showed significantly less noise and higher CNR lesion to liver than standard-dose CT using MBIR and demonstrated at least average image quality score among all readers, albeit with lower scores than standard-dose CT using MBIR. • Low-dose liver CT showed noninferior detectability for malignant and pre-malignant liver lesions, compared to standard-dose CT.

Evaluation of complex congenital heart disease with prospective ECG-gated cardiac CT in a single heartbeat at low tube voltage (70kV) and adaptive statistical iterative reconstruction in infants: a single center experience.

The purpose of this study is to evaluate the radiation dose, image quality, and diagnostic accuracy of prospective ECG-gated cardiac CT at 70kV and adaptive statistical iterative reconstruction (ASIR), with a single source, 512 slice MDCT in the diagnosis of complex congenital heart disease in infants. We retrospectively evaluated 47 infants (ages 1day to 353days) with prospective ECG-gated cardiac CT that was performed on a single source 512 slice CT at low tube voltage (70kV) using a wide detector aperture, adaptive statistical iterative reconstruction algorithm (ASIR), and specific reconstruction software reducing coronary motion artifacts (SnapShot Freeze). All cardiac images were obtained during the first pass of contrast material through the anatomic structures of interest and the targets for the center of the acquisition window were set 45% of the R-R interval during one cardiac cycle without sedation and breath-hold. The median effective dose measured in our study was 0.64 ± 0.16mSv. The average subjective overall image quality score was 4.34 ± 0.31 (range 3-5). For the determination of objective image quality, Mean Noise (HU), SNR, and CNR values ​​emerged as 20.8, 28.7(for pulmonary artery), and 27.1, respectively. Diagnostic accuracy was 100% for the main purposes for the main clinical indication. During cardiac CT examination, pathologies in addition to cardiac anomalies were found in 9/47 of cases (7 severe airway obstructions,1 posterior diaphragmatic hernia, 1 vertebral anomaly).Prospective ECG-gated cardiac CT scan at 70kV and ASIR in infants with complex CHD provides low radiation dose (submillisievert) in a single heartbeat with a good objective and subjective image quality. It also provides important benefits in the diagnosis of additional pathology.

The Role of Four-Dimensional Automatic Right Ventricular Quantification Technology to Determine RV Function and Hemodynamics in Patients With Pulmonary Hypertension Compared With Right Heart Catheterization.

Background: Four-dimensional automatic right ventricular quantification technology (4D auto-RVQ) is a new method that can simultaneously measure right ventricular (RV) structure and strain. The role of 4D auto-RVQ in determining RV function and hemodynamics is not clear. The role of 4D auto-RVQ in determining RV function and hemodynamics is not clear. We assessed the 4D auto-RVQ to measure right heart structure, function, and hemodynamics in patients with pulmonary hypertension (PHTN) correlated with right heart catheterization (RHC).Methods: We enrolled a prospective cohort of 103 patients with PHTN and 25 healthy controls between September 2017 and December 2018. All patients with PHTN underwent echocardiography and RHC. Patients were included if they underwent two-dimensional (2D) and 4D auto-RVQ echocardiographic sequences on the same day as RHC. We analyzed RV functional indices using 2D and 4D auto-RVQ analyses. We divided patients with PHTN into three groups according to echocardiographic image quality as follows: high (n = 24), average (n = 48), and poor (n = 4). Hemodynamic parameters were measured using RHC, including mean right atrial pressure, mean pulmonary arterial pressure, RV cardiac index (RV-CI), and pulmonary vascular resistance.Results: There were significant differences in most 2D and 4D auto-RVQ parameters between patients with PHTN and healthy controls. Interobserver variability showed significant agreement with 4D auto-RVQ for most measurements except for 4D end-diastolic volume. Indices measured by auto 4D-RVQ in the high-quality image group had a good correlation with RHC but not in the average- and poor-quality image group. Mid-RV diameter showed the best predictive power for the right RV-CI [area under the curve (AUC) 0.935; 95% confidence interval (CI), 0.714–0.997; p < 0.001]. RV end-systolic volume >121.50 mL had a 71.43% sensitivity and a 100% specificity to predict right RV-CI (AUC, 0.890; 95% CI, 0.654–0.986; p < 0.001).Conclusions: 4D auto-RVQ may be used to estimate RV function and some hemodynamic changes compared with RHC in PHTN patients with high image quality. Furthermore, a large sample of the study is needed to evaluate RV function by 4D auto-RVQ in PHTN patients with average image quality.

Correlations between two EBSD-based metrics Kernel Average Misorientation and Image Quality on indicating dislocations of near-failure low alloy steels induced by tensile and cyclic deformations

Two metrics Kernel Average Misorientation (KAM) and Image Quality (IQ) widely used in Electron Back-Scatter Diffraction (EBSD) mapping are compared with each other on indicating the dislocations of type 40Cr low alloy steel induced by tensile and cyclic deformations approaching failure limits respectively. The tensile deformation up to 12 % just before necking increased the KAM and decreased the IQ obviously, thus a negative correlation was established between KAM and normalized IQ in this case. In contrast, the cyclic deformation with small strain amplitudes (±0.4 % and ±0.7 %) until fatigue failure only decreased the IQ obviously but almost produced no effect on KAM, thus the above negative correlation no longer existed in this case. The different correlations between KAM and normalized IQ in tensile and cyclic cases were attributed to the different ratios between Geometrically Necessary Dislocations (GNDs) and Statistically Storage Dislocations (SSDs). GNDs contribute to not only the lattice distortion that can be indicated by IQ mapping, but also the lattice curvature that can be indicated by KAM mapping, while SSDs only contribute to the lattice distortion. In tensile case, GNDs occupy the major part of total dislocations, thus KAM and IQ indicate the similar dislocations distribution. In cyclic case with the applied strain amplitude lower than ±0.7 %, SSDs play a leading role, thus KAM and IQ disagree with each other on indicating the dislocations distribution.

A 5G-powered robot-assisted teleultrasound diagnostic system in an intensive care unit

BackgroundTeleultrasound provides an effective solution to problems that arise from limited medical resources, a lack of local expertise, and scenarios where the risk of infection is high. This study aims to explore the feasibility of the application of a 5G-powered robot-assisted teleultrasound diagnostic system in an intensive care unit.MethodsIn this study, the robot-assisted teleultrasound diagnostic system MGIUS-R3 was used. Using 5G network technology, the doctor manipulates the robotic arm to perform teleultrasound examination. The doctor can adjust parameters via the teleultrasound control panel, and real-time transmission of audio, video and ultrasound images can facilitate simultaneous communication between both parties. All patients underwent robot-assisted teleultrasound examination and bedside ultrasound examination of the liver, gallbladder, pancreas, spleen, kidney, as well as assessment for pleural effusion and abdominal effusion. We evaluated the feasibility of the application of the robot-assisted teleultrasound diagnosis system in the intensive care unit in terms of consultation duration, image quality, and safety. We also compared diagnostic consistency and differences.ResultsApart from one patient who was excluded due to severe intestinal gas interference and poor image quality, a total of 32 patients were included in this study. Every patient completed all relevant examinations. Among them, 20 patients were male; 12 were female. The average age of the patients was 61 ± 20 years. The average duration of teleultrasound diagnosis was 17 ± 7 min. Of the 32 patients, 26 had positive results, 6 had negative results, and 5 had inconsistent diagnoses. The overall diagnostic results were basically the same, and there were no differences in diagnostic levels between the two. The overall average image quality score was 4.73 points, which represented a high-quality image. After robot-assisted teleultrasound examination, no significant changes were observed in the vital signs of patients as compared to before examination, and no examination-related complications were found.ConclusionThe 5G-powered robot-assisted teleultrasound diagnostic system was associated with the benefits of clear images, simple operation, relatively high levels of consistency in terms of diagnostic results, higher levels of safety, and has considerable application value in the intensive care unit.

Fuzzy logic-based moving average filters for reducing noise from Tc-99m-sestamibi parathyroid images.

The objective of the study was to use fuzzy logic-based moving average filters for reducing noise from Tc-99m-sestamibi parathyroid images and to compare its performance with classical moving average filters. Sixty-eight Tc-99m-sestamibi parathyroid images (33 image zoom 1.0, 35 images zoom 2.0) were filtered using symmetric triangular fuzzy filters with the moving average (TMAV), asymmetric triangular fuzzy filters with the moving average (ATMAV) and classical moving average filter (MAV) with moving average within a square window of dimension N × N pixels (N=3,5,7,9,11). The relative filtering performance was compared both objectively (using Brisque score) and subjectively [by two nuclear medicine physicians on a 4-point scale (1 = nondiagnostic; 2 = diagnostic; 3 = good; and 4 = excellent image quality)]. The nonparametric two-sample Kolmogorov-Smirnov test was applied to find the statistically significant difference between the quality of input and their corresponding filtered images. The Brisque score assigned to MAV filtered zoom 2.0 images (MAV_3, median = -0.61) were significantly smaller than that of their input images (median = 53.84, at P = 1) and fuzzy filtered images (TMAV_3, median = 0.44, at P = 0.89 and ATMAV_3, median =8.26, at P = 0.97). The sum of average subjective image quality score for input, MAV_3, TMAV_3, TMAV_5, ATMAV_3, and ATMAV_5 were 148, 221, 221.5, 198,171,253 and 237.5, respectively. On the basis of subjective assessment, the performance of ATMAV_3 fuzzy filter was found to be better compared to the classical moving average filter in reducing noise from Tc-99m-sestambi parathyroid images.

Measuring myocardial extracellular volume of the right ventricle in patients with congenital heart disease

The right ventricle´s (RV) characteristics—thin walls and trabeculation—make it challenging to evaluate extracellular volume (ECV). We aimed to assess the feasibility of RV ECV measurements in congenital heart disease (CHD), and to introduce a novel ECV analysis tool. Patients (n = 39) and healthy controls (n = 17) underwent cardiovascular magnetic resonance T1 mapping in midventricular short axis (SAX) and transverse orientation (TRANS). Regions of interest (ROIs) were evaluated with regard to image quality and maximum RV wall thickness per ROI in pixels. ECV from plane ROIs was compared with values obtained with a custom-made tool that derives the mean T1 values from a “line of interest” (LOI) centered in the RV wall. In CHD, average image quality was good (no artifacts in the RV, good contrast between blood/myocardium), and RV wall thickness was 1–2 pixels. RV ECV was not quantifiable in 4/39 patients due to insufficient contrast or wall thickness < 1 pixel. RV myocardium tended to be more clearly delineated in SAX than TRANS. ECV from ROIs and corresponding LOIs correlated strongly in both directions (SAX/TRANS: r = 0.97/0.87, p < 0.001, respectively). In conclusion, RV ECV can be assessed if image quality allows sufficient distinction between myocardium and blood, and RV wall thickness per ROI is ≥ 1 pixel. T1 maps in SAX are recommended for RV ECV analysis. LOI application simplifies RV ECV measurements.

Retrospective respiratory motion correction in cardiac cine MRI reconstruction using adversarial autoencoder and unsupervised learning.

The aim of this study was to develop a deep neural network for respiratory motion compensation in free-breathing cine MRI and evaluate its performance. An adversarial autoencoder network was trained using unpaired training data from healthy volunteers and patients who underwent clinically indicated cardiac MRI examinations. A U-net structure was used for the encoder and decoder parts of the network and the code space was regularized by an adversarial objective. The autoencoder learns the identity map for the free-breathing motion-corrupted images and preserves the structural content of the images, while the discriminator, which interacts with the output of the encoder, forces the encoder to remove motion artifacts. The network was first evaluated based on data that were artificially corrupted with simulated rigid motion with regard to motion-correction accuracy and the presence of any artificially created structures. Subsequently, to demonstrate the feasibility of the proposed approach in vivo, our network was trained on respiratory motion-corrupted images in an unpaired manner and was tested on volunteer and patient data. In the simulation study, mean structural similarity index scores for the synthesized motion-corrupted images and motion-corrected images were 0.76 and 0.93 (out of 1), respectively. The proposed method increased the Tenengrad focus measure of the motion-corrupted images by 12% in the simulation study and by 7% in the in vivo study. The average overall subjective image quality scores for the motion-corrupted images, motion-corrected images and breath-held images were 2.5, 3.5 and 4.1 (out of 5.0), respectively. Nonparametric-paired comparisons showed that there was significant difference between the image quality scores of the motion-corrupted and breath-held images (P < .05); however, after correction there was no significant difference between the image quality scores of the motion-corrected and breath-held images. This feasibility study demonstrates the potential of an adversarial autoencoder network for correcting respiratory motion-related image artifacts without requiring paired data.

Developing and Evaluating a Remote Quality Assurance System for Point-of-Care Ultrasound for an Internal Medicine Residency Global Health Track.

Background: A quality assurance system is vital when using point-of-care ultrasound (POCUS) to ensure safe and effective ultrasound use. There are many barriers to implementing a quality assurance system including need for costly software, faculty time, and extra work to log images. Methods: With minimal funding or protected faculty time, we successfully developed an effective remote quality assurance system between residents rotating internationally and faculty in the US. Results: 270 total exams were logged using this system (41 per resident over a 7 week period). Over the course of the implementation period, a significant increase was seen in average image quality (p = 0.030) and percent agreement with reviewer (p = 0.021). No significant increase was seen for percent images with quality rating 5/5 (p = 0.068) or for studies per resident per week (p = 0.30). Discussion/Conclusions: A quality assurance system for remote review and feedback of POCUS exams was successfully developed with limited available funding, using consumer-level software and an educational collaboration. Residents used the system regularly and demonstrated improvement in reviewer-rated image acquisition and interpretation skills. A similar system can be applied for physicians in any geographic area looking to learn POCUS, in partnership with local or international POCUS mentors. We detail a step-by-step approach, challenges encountered, and lessons learned, to help guide others seeking to implement similar programs.

Predictive dual-scale finite element simulation for hole expansion failure of ferrite-bainite steel

A dual-scale finite element model is proposed to investigate the failure of ferrite-bainite (FB) dual-phase steel in the hole expansion test. The first level simulation solves the elastic-plastic deformation behavior with phenomenological isotropic elastic-anisotropic plastic constitutive models, and its resulting local deformation histories are supplied to the second level simulation as boundary conditions. In the second level simulation, the local microstructure evolution is solved and provides the dislocation densities, equivalent plastic strains, and stress triaxiality that measure the local fracture in grain scale. A special formulation for calculating the dislocation density distribution in the form of dislocation pile-up at grain boundary areas is highlighted as the microscale level constitutive law. The microstructural information is provided from image analyses based on grain average image quality (GavgIQ) and grain average misorientation (GAM) values observed using electron backscatter diffraction (EBSD). The data were used to identify the constituent phases of the FB steel as the major input for the microstructure-based representative volume element (RVE). Nanoindentation tests are employed to validate the identified phase and to extract the phase-level mechanical properties. The onset of failure at the hole edge during the hole expansion test is simulated by the proposed dual-scale numerical approach. Thus, both the hole expansion ratio (HER) and the location of failure can be successfully predicted. The example clarifies that the present approach based on local deformation histories and the resultant microstructure evolution with grain-level deformation inhomogeneity can be utilized for understanding the deformation and fracture of multi-phase steels.

The effect of contact lens wear on retinal spectral domain optical coherence tomography

BackgroundThis study assessed the impact of contact lens wear on retinal spectral domain optical coherence tomography (SD‐OCT) image quality and macular thickness measurements, among subjects with myopia.MethodsThis was a prospective study including 34 subjects (26.59 ± 3.19-years) with myopia or myopic astigmatism. Twelve were imaged wearing spherical soft contact lenses, eight non‐contact lens wearers were imaged with a plano soft contact lens, and 14 with significant astigmatism were fitted with a rigid gas permeable (RGP) contact lens. For each group of contact lens types, the average image quality index (Q‐index), and the average macular thickness measurements were compared between macular OCT scans obtained from the same eyes with and without a contact lens.ResultsAmong the subjects assessed with their habitual spherical soft lenses, the average Q‐index was similar for scans acquired with and without a contact lens (30.10 ± 1.94 versus 31.03 ± 2.55; p = 0.18). Among non‐contact lens wearers, the average Q‐index was slightly higher for scans acquired without a contact lens, compared to scans with a plano contact lens (31.99 ± 2.06 versus 29.51 ± 1.56; p = 0.006). Among 14 subjects imaged wearing a fitted RGP contact lens, the Q‐index was similar for scans acquired with and without a contact lens (29.04 ± 2.73 versus 28.75 ± 2.86; p = 0.78). In all groups, there were no correlations between the power of the sphere and change in the Q‐index (that is, post‐ minus pre‐contact lens Q‐index), and no differences were found between OCT‐derived macular thickness measurements from scans with and without a contact lens. The magnitude of cylinder was not correlated with the change in the Q‐index in the habitual and RGP contact lens groups. However, an inverse correlation between cylinder power and change in the Q‐index was found in the plano contact lens group.ConclusionIn low to intermediate levels of myopia, with or without regular astigmatism, macular SD‐OCT imaging does not merit placement of a soft or rigid contact lens, nor is there an added benefit from removing a habitual spherical soft lens prior to scanning.

Impact of Healthy Volunteer MR-Linac Imaging on Clinical Implementation of Stereotactic MR-Guided Online Adaptive Radiotherapy

Stereotactic magnetic resonance (MR)-guided online adaptive radiotherapy (SMART) combines real-time MR imaging with RT delivery, allowing for online adaptive planning and continuous motion management. However, uncertainty remains in optimal patient positioning, image quality standards, and contouring guidelines for SMART. To determine the optimal combination of MR sequence parameters, coil and patient positioning, and treatment immobilization, we conducted a healthy volunteer (HV) study utilizing a 0.35T MR-Linac (MRL). We hypothesized that with optimization of these parameters, image quality and SMART workflows for HVs would be acceptable across a range of clinically relevant organs, facilitating subsequent patient imaging. The HV study was approved by the IRB. Adults of all races and genders were included. MR simulation and simulated SMART were performed in HVs on an MRL. For each scan, the following parameters were assessed on a scale from 1-5 (5 = extremely high, 1 = extremely poor): visibility of target, visibility of nearby normal organs, and overall image quality. Adaptive recontouring time was recorded. With IRB approval, we retrospectively reviewed recontouring times for the first fraction for the first 18 patients treated clinically with SMART. HV and clinical times were compared with a t-test (alpha = 0.05). 46 HVs consented to the study. 18 underwent simulated treatments that included simulation of all aspects of SMART clinical workflow, except RT delivery, and targeted the following organs: adrenal, prostate, pancreas, lung, kidney, and brain. Average visibility of target and nearby organs were 4.58 and 4.62, respectively, and average overall image quality was 4.62 with a range of 4-5 for all measures. The average recontouring time was 15 minutes (range 4-35) in the HVs, comparable to an average of 16.1 minutes (range 7-33) in patients (p = 0.886). The clinical cases targeted adrenal, prostate, pancreas, lung, and pelvic and abdominal nodes. HV scanning on an MRL resulted in acceptable image quality and target visibility for a range of organs. Contouring time, the longest step in our workflow, was well-simulated in HVs, with similar times achieved clinically. The organs targeted in HVs correlated well with the organs treated clinically. The HV study provided a non-clinical environment to optimize all aspects of SMART, except for RT delivery. Further study is needed to determine the optimal number of HV scans required to prepare for clinical implementation of SMART.

Retinal Imaging Using a Confocal Scanning Laser Ophthalmoscope-Based High-Magnification Module

To evaluate the usefulness of a high-magnification module (HMM) lens to visualize retinal photoreceptors, retinal nerve fiber layer (RNFL), and superficial retinal vasculature in physiologic and pathologic retinal conditions. Observational descriptive study. Thirty-two participants with normal and pathologic retina examination results. Normal and pathologic maculae were imaged invivo using still and video HMM lens modes, with fixation and contrast adjustments to enhance visualization. The HMM images were classified qualitatively based on structures identified as either good (photoreceptors seen), average (photoreceptor mosaic cannot be visualized clearly, retinal vessels and other retinal changes can be seen), or poor (no identifiable structures). Selected eyes were imaged with fundus photography, OCT, OCT angiography, indocyanine green angiography, and fluorescein angiography for comparison with the pathologic maculae. Description of HMM module-obtained macula images. From 32 eyes imaged (16 normal and 16 pathologic retinas), 12 of 16 normal and 11 of 16 pathologic retinas demonstrated at least average image quality, in which retinal vasculature and landmarks could be visualized. The mosaic pattern of hexagonal shapes representing photoreceptors could not be resolved in most pathologic retinas. For the retinas in which the photoreceptor mosaics were visualized (12 of 16 normal and 2 of 16 pathologic retinas), parafoveal mosaic patterns appeared denser with better image quality for all participants compared with foveal photoreceptors. Difficulty in resolving the photoreceptors in the umbo, fovea, and perifovea was encountered, similar to what has been reported with adaptive optics devices. The RNFL was seen as arcuate hyperreflective bundles. Flow was observed in the macular microvasculature. Poorly resolved photoreceptors and scattered hyperreflective foci were correlated with changes in the retinal pigment epithelium in eyes with age-related macular degeneration or central serous chorioretinopathy. Macular striae were seen in eyes with epiretinal membrane. In most eyes, regardless of whether retinal pathologic features were present, it was challenging to obtain average quality (or better) images. In the few participants with good-quality imaging, the parafoveal photoreceptor mosaic, vascular flow, and various features of pathologic eyes could be visualized.

Video Images Enhanced by using Sigmoid-Logarithm Transform

It is challenging to enhance contrast in video images, because of the irregularity of contrast and lightness in each frame, and the long processing time to improve. In this research, we suggested a new method relied on sigmoid logarithm transform (SLT). In the video image, the SLT used to enhance lighting component in the HSV color space. To know the ability of enhancement the proposed method was compared with other methods as histogram equalization (HE), Multi Scale Retenix with Color Restoration (MSRCR) and non-traditional as Fusion at Weakly Illuminated Images (FWII), Depending on the average Natural Image Quality Evaluator (NIQE), Mean Squared Error for Hue (MSEH), Mean Squared Error for Saturation (MSES) for each video. By analyzing the results, it was found that the proposed algorithm has good results in the contrast and lightness enhancement.

Rosette Trajectories Enable Ungated, Motion-Robust, Simultaneous Cardiac and Liver T2 * Iron Assessment.

Quantitative T2 * MRI is the standard of care for the assessment of iron overload. However, patient motion corrupts T2 * estimates. To develop and evaluate a motion-robust, simultaneous cardiac and liver T2 * imaging approach using non-Cartesian, rosette sampling and a model-based reconstruction as compared to clinical-standard Cartesian MRI. Prospective. Six ferumoxytol-containing phantoms (26-288 μg/mL). Eight healthy subjects and 18 patients referred for clinically indicated iron overload assessment. 1.5T, 2D Cartesian and rosette gradient echo (GRE) ASSESSMENT: GRE T2 * values were validated in ferumoxytol phantoms. In healthy subjects, test-retest and spatial coefficient of variation (CoV) analysis was performed during three breathing conditions. Cartesian and rosette T2 * were compared using correlation and Bland-Altman analysis. Images were rated by three experienced radiologists on a 5-point scale. Linear regression, analysis of variance (ANOVA), and paired Student's t-testing were used to compare reproducibility and variability metrics in Cartesian and rosette scans. The Wilcoxon rank test was used to assess reader score comparisons and reader reliability was measured using intraclass correlation analysis. Rosette R2* (1/T2 *) was linearly correlated with ferumoxytol concentration (r2 = 1.00) and not significantly different than Cartesian values (P = 0.16). During breath-holding, ungated rosette liver and heart T2 * had lower spatial CoV (liver: 18.4 ± 9.3% Cartesian, 8.8% ± 3.4% rosette, P = 0.02, heart: 37.7% ± 14.3% Cartesian, 13.4% ± 1.7% rosette, P = 0.001) and higher-quality scores (liver: 3.3 [3.0-3.6] Cartesian, 4.7 [4.1-4.9] rosette, P = 0.005, heart: 3.0 [2.3-3] Cartesian, 4.5 [3.8-5.0] rosette, P = 0.005) compared to Cartesian values. During free-breathing and failed breath-holding, Cartesian images had very poor to average image quality with significant artifacts, whereas rosette remained very good, with minimal artifacts (P = 0.001). Rosette k-sampling with a model-based reconstruction offers a clinically useful motion-robust T2 * mapping approach for iron quantification. J. MAGN. RESON. IMAGING 2020;52:1688-1698.