Image Quality Research Articles

Comparing the utility of 3D vs 2D left atrial volumes by echocardiography to predict stroke in the general population

Abstract Background Left atrial (LA) volume dilatation is associated with stroke in the general population. Two-dimensional echocardiography (2DE) is commonly used to measure LA size but is known to underestimate LA volumes compared to three-dimensional echocardiography (3DE). It is unknown whether this difference has clinical significance. Purpose We hypothesized that LA volumes by 3DE are more closely associated with stroke risk than 2DE in the general population. Methods We included 2,085 participants from a longitudinal cohort study from the general population who underwent 3DE and 2DE assessment of maximal and minimal LA volume index (LAVimax and LAVimin, respectively). After excluding participants with poor image quality, low volume rate, atrial fibrillation at baseline and non-sinus-rhythm during examination, a total of 1,956 participants were included for this analysis. The endpoint was stroke. Multivariable Cox regression models were adjusted for the CHA2DS2-VASc stroke risk score (age, sex, heart failure, hypertension, stroke, vascular disease, and diabetes). Results Mean age was 54±17 years, 43% were male, mean CHA2DS2-VASc score was 1.6±1.3. During a median follow-up of 4.8 years (interquartile range 4.3-5.5 years), 36 participants (1.8%) developed stroke. After multivariable adjustment, 2D LA volumes were not associated with stroke, whereas both 3D-LAVimax (HR 1.03 (95% CI 1.00-1.06), p=0.046, per 1 mL/m2 increase) and 3D-LAVimin (HR 1.05 (95% CI 1.02-1.08), p=0.002, per 1 mL/m2 increase) remained significantly associated with stroke (Figure 1). In addition, 3D-LAVimin showed the highest discrimination for predicting stroke with a C-statistic of 0.70 (95% CI: 0.59-0.80), which was significantly higher than 2D-LAVimax (C-statistic: 0.58 (95% CI 0.48-0.69); p=0.02), 2D-LAVimin (C-statistic: 0.54 (95% CI 0.42-0.65); p<0.001) and 3D-LAVimax (C-statistic: 0.62 (95% CI 0.52-0.73); p=0.004). 3D-LAVimin also showed incremental prognostic information when added to the CHA2DS2-VASc risk score (continuous net reclassification index 0.28±0.17; p=0.047). Conclusion Increasing 3D-LA volumes are significantly associated with higher risk of stroke in the general population which was not the case for 2D-derived LA volumes.

Radiation exposure of patients undergoing multiple-slice CT scans in Romania

Abstract Ionizing radiation is largely used in medicine due to its role in the diagnosis and treatment of patients. In the past 50 years computed tomography (CT) has become indispensable for medical practice because it offers sub-millimeter cross-sectional imaging of any region of the body. New CT scanners use thinner slices, providing more accurate results, but also an increased radiation exposure with possible long-term harmful effects for the patients. The parameter used as an indicator of radiation dose in CT is the dose-length product (DLP). The study included 4507 patients who were CT scanned using a 16, 32, 64 or 128-slice CT machine. DLP was measured for head, sinuses, thorax, abdomen, pelvis, abdomen+pelvis, and trunk scans - regions for which the health authorities have established national diagnostic reference levels (DRL - the expected radiation dose received by a patient in CT). One-way ANOVA was used to analyse data considering the use of contrast agents, the gender, age, and weight of patients. Average DLP values were higher (up to 80%) than national DRL for all regions in 64 and 128-slice scans. The highest DLP values were registered in contrast CT for all scanners (p < 0.01); the maximum average (a threefold increase compared to DRL) was measured in the 32-slice sinuses contrast CT. Average DLP correlated with patients’ gender and weight (p < 0.01), but the influence was lower compared to the use of contrast agents. In conclusion, CT scans acquired using thinner slices lead to more accurate results and high-quality images, but the study suggests an increased radiation exposure. CT has an uncontestable contribution to a precise and rapid diagnosis, but more attention must be given to the stochastic effects risks associated with the radiation dose received during a CT scan. Are all scans necessary? Do all patients really need to receive high doses? The role of the practitioner is decisive, and the justifiable process is “a must” in all radiodiagnosis practices. Key messages • CT doses must be kept “as low as reasonably achievable” while maintaining diagnostic image quality. • Justification, dose limitation, and optimisation are fundamental principles of radioprotection.

Initial Experience with the 4D Mini-TEE Probe in the Adult Population

Background: Transesophageal echocardiography (TEE) is a vital diagnostic tool in clinical practice, particularly in transcatheter interventions where it aids in both pre-operative planning and intra-operative guidance. Traditional TEE probes often require general anesthesia due to patient discomfort. However, the development of miniaturized TEE probes presents a promising alternative, enabling routine examinations and interventions with minimal sedation. This study evaluates the feasibility of performing a complete 2D/4D TEE protocol with the new 4D mini-TEE probe in the echocardiography department and its application in transcatheter interventions. Methods: This is a retrospective study that included 30 consecutive patients from two high-volume European hospitals (Interbalkan Medical Center, Thessaloniki, Greece, and Rennes University, France) that underwent TEE or transcatheter interventions. The new 4D mini-TEE 9VT-D probe (GE Healthcare) was utilized. The quality of the images and the tolerance of the probe were assessed in the cath lab during interventions and in the echocardiography department during routine TEE examinations. Results: Direct comparison of the 4D mini-TEE probe with the standard 6VT-D probe confirmed the excellent image quality of this new pediatric probe. Most of the patients required minimal sedation or local oropharyngeal anesthesia, with satisfactory tolerance reported. Most of the transcatheter procedures did not require general anesthesia and intubation, resulting in shorter procedural time. Both 2D and 4D imaging modalities offered adequate intra-operative guidance for transcatheter procedures. Conclusions: The 4D mini-TEE probe delivers exceptional imaging capabilities for routine examinations and transcatheter interventions without needing sedation. Its use reduces esophageal trauma and the need for general anesthesia, enhancing patient comfort and safety.

Atrial and ventricular mitral regurgitation in the general population

Abstract Background Functional mitral valve regurgitation (FMR) is the result of two concurrent pathomechanisms: (1) the dilatation of mitral valve annulus (atrial) or (2) remodelling of the left ventricle (ventricular) in the absence of relevant leaflet degeneration¹. Even though FMR has been reported to be the most common cause of relevant MR², there is no general accepted definition of the two subtypes, nor are there population-based data regarding their prevalence, distribution and risk profiles¹. Purpose We aimed to evaluate the prevalence of FMR and to provide an in-depth characterisation of the subtypes aFMR and vFMR in the general population. Methods The study included the first 10,000 participants of the population-based Hamburg City Health Study enrolled between 2016 and 2019. Of these, 8.543 echocardiographic samples were available for analysis. Mitral valve was assessed by two independent investigators. Isolated degenerative MRs as determined by valve mobility (prolapse or restrictive) were excluded. FMR was classified as ventricular when fulfilling one of the following criteria: history of myocardial infarction or coronary artery disease, left ventricular ejection fraction (LVEF) ≤ 40%, restrictive leaflet, tenting area ≥ 150 mm² or coaptation depth ≥ 10 mm. All FMR with LVEF > 55% were classified as atrial. Results After excluding the samples with an insufficient image quality or missing data and re-assessment by the second investigator, 216 of 282 participants with a relevant MR (i.e. moderate or severe) remained (2,6% of the total cohort, see figure 1). In the next step, 153 participants were classified as pure FMR (68.9%), the remaining were mainly functional with minor degenerative features. A total of 31 (14.4%) MRs were classified as vFMR, the remaining 185 participants had an aFMR. Female gender was significantly more common in the aFMR cohort. The remaining demographic variables (age, body mass index) as well as established cardiovascular risk factors (i.e., diabetes, smoking, hypertension) were comparable between the vFMR and aFMR cohort. However, vFMR patients had significantly higher levels of NT-proBNP or NHYA state and presented more frequently with an atrial fibrillation (see figure 2). LVEF and LV stroke volume, TAPSE, left atrial ejection fraction and E/A ratio as a parameter of diastolic dysfunction were lower in the vFMR cohort whereas tenting area and left atrial endsystolic volume was significantly increased. Conclusion In our population-based study, aFMR was found to be the predominant subtype of FMR. The established cardiovascular risk factors were comparable in the vFMR and aFMR cohort. Echocardiographic variables differed significantly and indicate more advanced heart failure and LV remodelling in the vFMR cohort. Further categorization of FMR, in particular regarding the prognostic impact and long-term outcomes, is strongly warranted to allow a clinically relevant definition of aFMR and vFMR.Figure 1:Overview of sample sizeFigure 2:Baseline characteristics

Normal reference values of left atrioventricular coupling index on two-dimensional echocardiography

Abstract Background From a physiological background, there is close relationship between left atrial (LA) and left ventricular (LV) expressed as coupling. The assessment of LA/LV coupling may reflect LV dysfunction and differentiate between normal and abnormal LV function. Aim of study The study is designed to sample normal subjects to provide the normal reference values of LA/LV coupling index (LACI) according to age and sex using 2-dimensional echocardiography (2DE). Methods 550 healthy subjects (51.9±17.8 years, 56% males) were included with good 2DE image quality enabled measurement of end-diastolic volumes of both LA and LV. LACI was defined as the ratio between LA to LV end-diastolic volumes. Results An off-line analysis of apical 4-chamber and 2-chamber views to obtain the 2DE measurements was performed within short time (1.5± 0.3 min). Measurement of LACI was obtained in all individuals. Subjects were divided into 3 age groups (G I: 18-40 years, G II: 41-65 years, and GIII: >65 years). As shown in table 1, the normal LACI values in the whole population was 0.17±0.08 with significantly higher in females (0.178±0.09) than males (0.15±0.06); P<0.02. The LACI values tends to be higher in females than males in the subdivided 3 age groups but not statistically significant. In both sexes, increasing age was associated with significant reduction of the mean LVEDV (P<0.0001), significant increase of the mean LAEDV (P= 0.004), and significant increase of LACI (P< 0.0001); especially considering the differences between the youngest and oldest age groups. Conclusions Measurement of LACI is feasible and easily obtainable using 2DE. Age and sex should be considered when defining normal reference values for LACI. The standardization of normal LACI values will help the future studies to assess the changes of these normal values in various cardiac abnormalities for prognostic risk stratification.

Impact of left atrial appendage occlusion in atrial flow evaluated through 4D flow cardiac magnetic resonance

Abstract Introduction Device-related thrombus (DRT) and peri-device leak constitute significant complications following left atrial appendage occlusion (LAAO), primarily due to its association with strokes and thromboembolic events. Patient-specific fluid simulations have been employed to explore this hypothesis(1). However, these simulations require detailed anatomical and physiological data, rely on certain assumptions when defining boundary conditions, and involve long computational times. Recently, there has been growing interest in the use of 4D flow cardiac magnetic resonance (CMR) imaging for various cardiovascular diseases, owing to its capability to reproduce blood flow. While its role in the LAAO scenario has been evaluated in silico(2), there are no reported cases of its application in patients undergoing LAAO. Purpose Our objective was to evaluate the impact of LAAO in atrial flow through 4D flow CMR. Methods Five patients undergone LAAO were included in the pilot study. A pre- and 90-days post-procedure 4D flow CMR scans were performed. One of the patients was excluded due to suboptimal image quality. To assess the impact of LAAO on atrial flow dynamics, three parameters were evaluated: a) mean velocity, b) stasis velocity ratio, and c) endothelial cell activation potential (ECAP) index — all associated with an elevated risk of thrombus formation(3,4). Results Baseline and procedural characteristics, along with imaging results, are presented in Table 1. Preprocedural 4D flow CMR for all patients revealed low velocities (Figure 1A) and a high ECAP index (Figure 2A) in the left atrial appendage, indicating flow stasis and an elevated risk of thrombus formation. Successful device implantation was performed in all cases, and no periprocedural complications were detected. Postprocedural 4D flow CMR was feasible in all cases, and no artifacts were detected despite the presence of the LAAO device. An objective increase in velocities and a decrease in the ECAP index were observed in all cases following LAAO. No DRT or ischemic events were reported during follow-up. Conclusions Our preliminary study demonstrates that 4D flow CMR provides valuable information on left atrial flow dynamics following the LAAO procedure. Further studies are warranted to evaluate this promising technique.Table 1.Patient characteristicsFigure 1 and 2.Representative example

Subclinical left ventricular dysfunction detected by speckle tracking echocardiography predicts mortality in COVID-19 patients

Abstract In COVID-19 patients, both preexisting cardiovascular disease and cardiac injury resulting from SARS-CoV-2 infection are associated with increased mortality. In this patient population the value of speckle tracking echocardiography (STE) for detecting high-risk patients has not been evaluated thoroughly. Aim The aim of study was to determine the prevalence of subclinical myocardial dysfunction revealed by STE and its association with in-hospital and two-year mortality in patients with COVID-19 and preserved left ventricular ejection fraction (LVEF). Methods The study group comprised 163 consecutive patients with preserved LVEF(>/=50%) and maintained right ventricular function evaluated by assessment of tricuspid annular plane systolic excursion (TAPSE >14 mm) hospitalized in the cardiology department due to COVID-19 in 2020 and 2021. All patients underwent transthoracic echocardiographic examination with off-line analysis using STE. Left ventricular global longitudinal strain(GLS), right ventricular global longitudinal strain (RV-GLS), right ventricular free wall strain(RV-FWS) and myocardial work parameters: global work index(GWI), global wasted work(GWW), global constructive work(GCW) and global work efficiency(GWE) were measured. The primary outcome was in-hospital and two-year mortality. Results 96 patients (mean age 66 years, 59 [61%] male) had adequate image quality to evaluate deformation-derived parameters.19 patients (19.8%) died during hospitalization and 9 (9,4%) patients died within two years after discharge. In-hospital non-survivors were older, had lower baseline oxygen saturation(SpO2) and had higher NTproBNP. In non-survivors STE revealed significant impairment of LV and RV function compared to the group of survivors(Table 1). The independent predictors of in-hospital death were: age (OR 1.1 [95% CI 1.01 – 1.19]), SpO2 on admission (OR 0.83 [95% CI 0.75 – 0.93]), NTproBNP (OR 1.0003 [95% CI 1.0001 – 1.0006]) and LV-GLS (OR 1.45 (1.06 – 1.99)]. Based on the analysis of the ROC curves, the cut-off points optimal for predicting in-hospital death were identified: age >71 years (sensitivity [sens.] 74%, specificity [spec.] 68%) , baseline SpO2 value ≤ 89% (sens. 89%, spec. 74%,) NTproBNP >951 pg/ml (sens. 79%, spec. 58%) and GLS >-16% (sens. 63%, spec. 89%). The independent predictors of two-year mortality were: age (OR 1.10 [95% CI 1.02 – 1.19]), Sp02 on admission (OR 0.82 [95% CI 0.73 – 0.91]) and NTproBNP (OR 1.0006 [95% CI 1.0001 – 1.0011]).Based on the ROC curve analysis, the cut-off points optimal for predicting death within 24 months after COVID-19 were also identified: age>71 years (sens. 71%; spec. 72%), Sp02 <89% (sens. 69%, spec. 73%), NTproBNP >520 pg/ml (sens. 89%, spec. 48%). Conclusions STE allows for the detection of subclinical myocardial dysfunction in COVID-19 patients with preserved LVEF. However, LV GLS is the only independent STE-based predictor of in-hospital mortality in this patient population.

A Lightweight underwater detector enhanced by Attention mechanism, GSConv and WIoU on YOLOv8

The underwater target detection is the most important part of monitoring for environment, ocean, and other fields. However, the detection accuracy is greatly decreased by the poor image quality resulted from the complex underwater environments. The storage and computing power of underwater equipments are not enough for complex underwater target detection technology. Therefore, many YOLO series algorithms have been applied to underwater target detection. On the basis of YOLOv8, a lightweight underwater detector enhanced by Attention mechanism, GSConv and WIoU, AGW-YOLOv8, is proposed in this paper. Firstly, by the combination of limited contrast adaptive histogram equalization and wavelet transform(LCAHE-WT), the fidelity and detail of images are improved; Secondly, by CBAM, the key channel features can be effectively extracted with retaining spatial information to improve the performance of the network when dealing with complex image tasks; Thirdly, by GSConv, composed of depth-wise separable convolution and regular convolution, the model parameters and computational complexity are reduced; Fourth, the SE attention mechanism is integrated into the C2f module of the neck, and the channel dimension is weighted to make the network more focus on important features, and to further enhance the feature extraction capability; Finally, by the dynamic nonmonotonic mechanism of WIoU, the gradient gain can be reasonably distributed, the harmful gradients of extreme samples can be reduced, and the generalization ability and overall performance of the model are improved. By the experiments on the URPC2020 data-set, it can been proved that the mAP of AGW-YOLOv8 can reaches 82.9%, is 2.5% higher than that of YOLOv8; and the parameters is 2.95M, is lower than 3.01M of YOLOv8.

Global longitudinal strain predicts clinical outcome in patients after acute ischemic stroke without left ventricular dysfunction

Abstract Background Global longitudinal strain (GLS) is a sensitive marker of myocardial dysfunction that could help predict adverse outcomes. Purpose We assessed whether GLS can help predict adverse clinical outcomes in patients after acute ischemic stroke (AIS). Methods Patients without LV dysfunction after AIS were divided into groups according to abnormal GLS (≤15.9%) or normal GLS (≥16%). Blood samples were obtained to determine levels of high-sensitive troponin I (hs-cTnI). Clinical data, functional outcome, and all-cause mortality at 1 year were compared between groups. National Institutes of Health Stroke Scale (NIHSS) at the time of admission and the modified Rankin Scale (mRS) 90 days following the patient’s discharge from the hospital were used to assess stroke severity and clinical outcome. All analyses were performed with SPSS 29.0 (SPSS Inc). Results In our study, between 8/2020-8/2022 155 enrolled patients after AIS had echocardiographic examination, due to image quality or LV dysfunction, GLS was assessed in 110 patients with normal LV function, 28 patients (25.6%) had abnormal GLS. After a year follow-up, the overall mortality was more common in patients with abnormal GLS compared to patients with normal GLS (hazard ratio [HR] 2.9610, 95% confidence interval [CI] 0.9015 to 9.7255, p =0.074) and was significant when comparing mean values (p<0.001) (Fig. 1A). The Kaplan-Meier survival curve accentuated a significantly elevated all-cause mortality among patients with abnormal GLS (Fig 2). Moreover, abnormal GLS was associated with positive hs-cTnI (Fig. 1B), and was connected with unfavorable functional outcome evaluated by mRS at 90 days (Fig. 1C). At last, severe stroke (NIHSS >15) was not significantly associated with abnormal GLS (HR 2.2121, 95% CI 0.7091 to 6.9009, p = 0.1714) Conclusion In patients after AIS, abnormal GLS could be helpful predictor for clinical events and subclinical myocardial injury.

Left atrial strain demonstrates the ability to distinguish patients with pre and post-capillary pulmonary hypertension

Abstract Background The characterization of pulmonary hypertension (PH) patients into pre or postcapillary (pcPH)phenotypes poses a challenge during screening due to the ambiguity surrounding their comorbidities. This distinction is crucial as it influences treatment decisions and prognostication. Purpose Investigating Left Atrial Strain as a Discriminant Marker for Distinguishing Pre and Post-Capillary PH. Methods Out of 164 patients exhibiting both pre- and post-capillary phenotypes, 97 had optimal left atrial 2D strain. Left atrial 2D strain was performed with a GE Vivid9 ultrasound machine equipped with dedicated software, ensuring meticulous attention to image quality and region of interest thickness restricted to a maximum of 6 mm. Subsequently, the peak left atrial strain during reservoir function was quantified as part of the investigation. To determine the optimal cut-off value, ROC curve analysis was employed. Results 60 patients had pcPH while 37 had pre-capillary PH. Mean age was 65±12y. Mean pulmonary artery pressure, wedge pressure, cardiac output and pulmonary vascular resistance averaged 40,9±10,7 mm Hg, 15,7±8,7 mm Hg, 5,9±2,0 l/min and 4,7±3,1 WU, respectively. Left atrial 2D strain ranged from +2,5% to 60%, with a mean of +18,2±11,2%. From ROC cure analysis, patients with LA 2D strain > +19,1% had a precapillary phenotype with a sensitivity and a specifity of 93% and 88% respectively (Fig 1). Left atrial 2D strain demonstrates higher sensitivity compared to various parameters, such as scores from the European Society of Respiratory Disease, left ventricular end-diastolic pressure estimation from the American Society of Echocardiography, HFA-PEFF score, and H2FPEF from the AHA. Conclusion Left atrial 2D strain demonstrates superior sensitivity in distinguishing between patients with pre and post-capillary pulmonary hypertension compared to other assessment methods.FIG 1:Left atrial 2D strainFig 2:SENS of parameters and scores

Multiple description image coding using Schur transform

A novel obvious and robust image Multiple Description Coding (MDC) using Schur transform (ST)is presented in this work. To overcome the inherent drawbacks in the discrete wavelet transform (DWT)which are the hardware implementation and computational complexityIn the MDC approach, two or more correlated descriptions of the same data aregenerated, which can be independently decoded, and yield mutually refinable information. Therefore, the quality of the recovered signal is dependent only on the number of received descriptions, and not on the specific loss pattern. The new techniquewas analyzed and compared to the conventional approach in the case of four descriptions by using multiple grayscale test images having different spectral characteristics.Theexperimental results of Schur transform (ST) compared to discrete wavelet transform (DWT)show that our method achievesbetter performance in terms of delivered peaksignal to noise ratio (PSNR) and visual image quality reconstruction.The proposed MDC has a low redundancy and outperforms the conventionalscheme for image transmission over error-prone networks.Therefore, the proposed approach provides an easier practical implementation and a better redundancy performancethan the classical approach.

3D distortion-free, reduced FOV diffusion-prepared gradient echo at 3 T.

To develop a 3D distortion-free reduced-FOV diffusion-prepared gradient-echo sequence and demonstrate its application in vivo for diffusion imaging of the spinal cord in healthy volunteers. A 3D multi-shot reduced-FOV diffusion-prepared gradient-echo acquisition is achieved using a slice-selective tip-down pulse in the phase-encoding direction in the diffusion preparation, combined with magnitude stabilizers, centric k-space encoding, and 2D phase navigators to correct for intershot phase errors. The accuracy of the ADC values obtained using the proposed approach was evaluated in a diffusion phantom and compared to the tabulated reference ADC values and to the ADC values obtained using a standard spin echo diffusion-weighted single-shot EPI sequence (DW-SS-EPI). Five healthy volunteers were scanned at 3 T using the proposed sequence, DW-SS-EPI, and a clinical diffusion-weighted multi-shot readout-segmented EPI sequence (RESOLVE) for cervical spinal cord imaging. Image quality, perceived SNR, and image distortion were assessed by two expert radiologists. ADC maps were calculated, and ADC values obtained with the proposed sequence were compared to those obtained using DW-SS-EPI and RESOLVE. Consistent ADC estimates were measured in the diffusion phantom with the proposed sequence and the conventional DW-SS-EPI sequence, and the ADC values were in close agreement with the reference values provided by the manufacturer of the phantom. In vivo, the proposed sequence demonstrated improved image quality, improved perceived SNR, and reduced perceived distortion compared to DW-SS-EPI, whereas all measures were comparable against RESOLVE. There were no significant differences in ADC values estimated in vivo for each of the sequences. 3D distortion-free diffusion-prepared imaging can be achieved using the proposed sequence.

Polarization remote sensing of ships in sea haze

ABSTRACT Sea haze reduces the visibility of ships and makes the optical imaging system blind, which increases the difficulty of ship remote sensing. In this paper, we propose a new method for polarization remote sensing of ships in sea haze. The method takes advantage of image haze removal and exposure correction to improve the visibility of ships in sea haze. Different from the existing polarization-based image haze removal methods, the proposed method does not depend on any assumptions about the polarization properties of incident light. The exposure correction method is proposed based on the Retinex model and Bayes theorem, which can improve the visibility of ships in haze removal images. To evaluate the effectiveness of the proposed method, we implemented an outdoor experiment on polarization remote sensing of ships in sea haze weather. The experimental results indicate that the method can improve the visibility of ships significantly. In addition, the method outperforms the Stokes parameter-based ship remote sensing method in terms of the image quality metric fog aware density evaluator and can be easily generalized to RGB image haze removal.

A Nighttime Driving-Scene Segmentation Method Based on Light-Enhanced Network

To solve the semantic segmentation problem of night driving-scene images, which often have low brightness, low contrast, and uneven illumination, a nighttime driving-scene segmentation method based on a light-enhanced network was proposed. Firstly, we designed a light enhancement network, which comprises two parts: a color correction module and a parameter predictor. The color correction module mitigates the impact of illumination variations on the segmentation network by adjusting the color information of the image. Meanwhile, the parameter predictor accurately predicts the parameters of the image filter through the analysis of global content, including factors such as brightness, contrast, hue, and exposure level, thereby effectively enhancing the image quality. Subsequently, the output of the light enhancement network is input into the segmentation network to obtain the final segmentation prediction. Experimental results show that the proposed method achieves mean Intersection over Union (mIoU) values of 59.4% on the Dark Zurich-test dataset, outperforming other segmentation algorithms for nighttime driving-scenes.

Usefulness of FFR-CT to exclude haemodynamically significant lesions in high-risk NSTE-ACS.

Coronary computed tomography angiography (CCTA) and fractional flow reserve (FFR) derived from CCTA (FFR-CT) may provide a means of reducing unnecessary invasive coronary angiography (ICA) in patients with suspected non-ST-elevation acute coronary syndromes (NSTE-ACS). The aim of this study was to evaluate the capacity of FFR-CT and CCTA to rule out significant lesions in high-risk NSTE-ACS patients, using ICA with invasive FFR as the gold standard. High-risk NSTE-ACS patients admitted to 4 European centres were enrolled in this single-arm, prospective core lab-adjudicated study. Patients underwent CCTA with FFR-CT analysis, followed by ICA with invasive FFR. Out of the 250 initially planned NSTE-ACS patients, 168 were included, of whom 151 (92%) had sufficient CCTA image quality to undergo CCTA and FFR-CT analysis. The median high-sensitivity troponin T level at 1 hour post-hospitalisation was 5.3 (interquartile range: 1.8-18.6) times the upper reference limit. At the patient level, the diagnostic performance of FFR-CT was numerically higher as compared to CCTA though not statistically significant (sensitivity: 94% vs 93%, specificity: 63% vs 54%, positive predictive value: 83% vs 79%, negative predictive value: 85% vs 80% and accuracy: 83% vs 79%; p=0.58), suggesting an enhanced capability to avoid unnecessary ICA. At the lesion level, the ability of FFR-CT to detect significant lesions was significantly better than that of CCTA (receiver operating characteristic curves: 0.84 vs 0.65 respectively; p<0.01). In patients with high-risk NSTE-ACS, FFR-CT offers better diagnostic accuracy - though not statistically significant - and a higher ability to rule out haemodynamically significant stenoses as compared to CCTA. This indicates that FFR-CT can reduce unnecessary invasive procedures by more accurately identifying patients requiring further intervention.

Image Quality Comparison of Three 3D Mobile X-Ray Imaging Guidance Devices Used in Spine Surgery: A Phantom Study

An image-quality CT phantom was scanned with three different 3D X-ray imaging guidance devices in the operating theatre: O-Arm, Loop-X, and Airo TruCT. Default acquisition and reconstruction parameters for lumbar spine procedures were used on each device. The tube current was set to a dose level of around 27 mGy. A task-based image quality assessment was performed by calculating the noise power spectrum (NPS) and task transfer function (TTF). A detectability index (d’) was calculated for three simulated bone lesions. The noise magnitude of the O-Arm was higher than the Airo TruCT, and the Loop-X had higher noise than the Airo TruCT. The highest average NPS frequency was for the O-Arm images, and the lowest was for the Loop-X. The TTFs at 50% values were similar for the Airo TruCT and Loop-X devices. Compared to Airo TruCT, the TTF at 50% value increased with the O-Arm by 53.12% and 41.20% for the Teflon and Delrin inserts, respectively. Compared to Airo TruCT, the d’ value was lower with Loop-X by −26.73%, −27.02%, and −23.95% for lytic lesions, sclerotic lesions, and high-density bone, respectively. Each 3D-imaging spine surgery guidance device has its own strengths and weaknesses in terms of image quality. Cone-beam CT systems apparently offer the best compromise between noise and spatial resolution for spine surgery.

WiTUnet: A U-shaped architecture integrating CNN and Transformer for improved feature alignment and local information fusion

Low-dose computed tomography (LDCT) has emerged as the preferred technology for diagnostic medical imaging due to the potential health risks associated with X-ray radiation and conventional computed tomography (CT) techniques. While LDCT utilizes a lower radiation dose compared to standard CT, it results in increased image noise, which can impair the accuracy of diagnoses. To mitigate this issue, advanced deep learning-based LDCT denoising algorithms have been developed. These primarily utilize Convolutional Neural Networks (CNNs) or Transformer Networks and often employ the Unet architecture, which enhances image detail by integrating feature maps from the encoder and decoder via skip connections. However, existing methods focus excessively on the optimization of the encoder and decoder structures while overlooking potential enhancements to the Unet architecture itself. This oversight can be problematic due to significant differences in feature map characteristics between the encoder and decoder, where simple fusion strategies may hinder effective image reconstruction. In this paper, we introduce WiTUnet, a novel LDCT image denoising method that utilizes nested, dense skip pathway in place of traditional skip connections to improve feature integration. Additionally, to address the high computational demands of conventional Transformers on large images, WiTUnet incorporates a windowed Transformer structure that processes images in smaller, non-overlapping segments, significantly reducing computational load. Moreover, our approach includes a Local Image Perception Enhancement (LiPe) module within both the encoder and decoder to replace the standard multi-layer perceptron (MLP) in Transformers, thereby improving the capture and representation of local image features. Through extensive experimental comparisons, WiTUnet has demonstrated superior performance over existing methods in critical metrics such as Peak Signal-to-Noise Ratio (PSNR), Structural Similarity (SSIM), and Root Mean Square Error (RMSE), significantly enhancing noise removal and image quality. The code is available on github https://github.com/woldier/WiTUNet.

Super-resolution reconstruction of time-resolved four-dimensional computed tomography (TR-4DCT) with multiple breathing cycles based on TR-4DMRI.

Respiratory motion irregularities in lung cancer patients are common and can be severe during multi-fractional (∼20 mins/fraction) radiotherapy. However, the current clinical standard of motion management is to use a single-breath respiratory-correlated four-dimension computed tomography (RC-4DCT or 4DCT) to estimate tumor motion to delineate the internal tumor volume (ITV), covering the trajectory of tumor motion, as a treatment target. To develop a novel multi-breath time-resolved (TR) 4DCT using the super-resolution reconstruction framework with TR 4D magnetic resonance imaging (TR-4DMRI) as guidance for patient-specific breathing irregularity assessment, overcoming the shortcomings of RC-4DCT, including binning artifacts and single-breath limitations. Six lung cancer patients participated in the IRB-approved protocol study to receive multiple T1w MRI scans, besides an RC-4DCT scan on the simulation day, including 80 low-resolution (lowR: 5×5×5mm3) free-breathing (FB) 3D cine MRFB images in 40s (2Hz) and a high-resolution (highR: 2×2×2mm3) 3D breath-hold (BH) MRBH image for each patient. A CT (1×1×3mm3) image was selected from 10-bin RC-4DCT with minimal binning artifacts and a close diaphragm match (<1cm) to the MRBH image. A mutual-information-based Freeform deformable image registration (DIR) was used to register the CT and MRBH via the opposite directions (namely F1: and F2: ) to establish CT-MR voxel correspondences. An intensity-based enhanced Demons DIR was then applied for , in which the original MRBH was used in D1: , while the deformed MRBH was used in D2: . The deformation vector fields (DVFs) obtained from each DIR were composed to apply to the deformed CT (D1) and original CT (D2) to reconstruct TR-4DCT images. A digital 4D-XCAT phantom at the end of inhalation (EOI) and end of exhalation (EOE) with 2.5cm diaphragmatic motion and three spherical targets (ϕ=2, 3, 4cm) were first tested to reconstruct TR-4DCT. For each of the six patients, TR-4DCT images at the EOI, middle (MID), and EOE were reconstructed with both D1 and D2 approaches. TR-4DCT image quality was evaluated with mean distance-to-agreement (MDA) at the diaphragm compared with MRFB, tumor volume ratio (TVR) referenced to MRBH, and tumor shape difference (DICE index) compared with the selected input CT. Additionally, differences in the tumor center of mass (|∆COMD1-D2|), together with TVR and DICE comparison, was assessed in the D1 and D2 reconstructed TR-4DCT images. In the phantom, TR-4DCT quality is assessed by MDA=2.0±0.8mm at the diaphragm, TVR=0.8±0.0 for all tumors, and DICE=0.83±0.01, 0.85±0.02, 0.88±0.01 for ϕ=2, 3, 4cm tumors, respectively. In six patients, the MDA in diaphragm match is -1.6±3.1mm (D1) and 1.0±3.9mm (D2) between the reconstructed TR-4DCT and lowR MRFB among 18 images (3 phases/patient). The tumor similarity is TVR=1.2±0.2 and DICE=0.70±0.07 for D1 and TVR=1.4±0.3 (D2) and DICE=0.73±0.07 for D2. The tumor position difference is |∆COMD1-D2|=1.2±0.8mm between D1 and D2 reconstructions. The feasibility of super-resolution reconstruction of multi-breathing-cycle TR-4DCT is demonstrated and image quality at the diaphragm and tumor is assessed in both the 4D-XCAT phantom and six lung cancer patients. The similarity of D1 and D2 reconstruction suggests consistent and reliable DIR results. Clinically, TR-4DCT has the potential for breathing irregularity assessment and dosimetry evaluation in radiotherapy.

The Effect of Tube Voltage Variations on CT Scan Image Quality at Prof. I G. N. G. Ngoerah General Hospital, Denpasar, Indonesia

Aims: Knowing the SNR and CNR values obtained from the image results that have been varied in the tube voltage. Knowing the effect of variations in the tube voltage value on the quality of the CT scan image that will be produced. Place and Duration of Study: Radiology installation of Prof. I G. N. G. Ngoerah General Hospital, Denpasar from May 2024 to August 2024. Methodology: This study used a Canon Aquilion LB CT Scanner to scan a TOS phantom containing 6 materials (polypropylene, nylon, acrylic, derlin, air, and water) with varying tube voltages (80 kV, 100 kV, 120 kV, 135 kV). The data were analyzed using PSPP and Excel to calculate SNR and CNR, and statistical tests for normality, Pearson correlation, and simple regression were performed. Results: The image data analyzed includes the average value of the object ROI, the average ROI background, and the standard deviation of the background. The data is grouped based on the variation of the tube voltage, the average value and standard deviation of the ROI on each material, and the standard deviation of the background. The results obtained for the relationship between the variation of the tube voltage and the SNR value are that the tube voltage affects the SNR value by 94,02% in polypropylene, 97,79% in nylon, 97,71% in acrylic, 96,42% in derlin, and 94,22% in air. And for the relationship between the tube voltage and the CNR value, the tube voltage affects the CNR value by 93,65% in polypropylene, 97,35% in nylon, 96,81% in acrylic, 95,62% in derlin, and 94,65% in air. Conclusion: Selecting the right tube voltage is important to optimize CT scan image quality, with 120 kV and 135 kV recommended for organs such as the kidney, liver, and lungs as they produce better SNR and CNR. Organs with significant attenuation differences show increased SNR and CNR, while soft tissues such as fat experience decreased contrast at high voltages. The use of tube voltage must be adjusted to diagnostic needs and evaluated through quality control according to BAPETEN regulation Number 2 of 2018.

Assessing the utility of computer vision for age determination of Gulf Menhaden

AbstractObjectiveIn this work, we assess the potential of computer vision techniques for age estimation of Gulf Menhaden Brevoortia patronus scales. Scales are the primary structure used for the age determination of Gulf Menhaden, and the ageing process can be labor intensive. Gulf Menhaden is the second‐largest fishery by weight in the United States, with average annual landings from 2018 to 2022 of 449,540 metric tons, and is assessed with age‐structured models that require information about the age structure of the catch and the stock.MethodsWe used convolutional neural networks and deep neural networks to classify the age from images of Gulf Menhaden scales from three different sets of images of scales. The first set of data consists of images of scales from fish at ages 0 and 1 year. The second set of data consists of images of scales from fish at ages 0–4 years. The last set of data consists of images of scales from fish of ages 0, 1, and 2 years and includes only images of scales for which there is agreement by readers of age estimates derived from analyzing sagittal otoliths and scales from the same individual.ResultThe classification of ages was best when using a convolutional neural network model on the first data set. The poorest classification was for the model using deep neural networks with the second data set.ConclusionAlthough we show that computer vision has promise for age determination from fish scale samples, our results indicate that considerable work must be done for wide adoption of the approach. With the continuous enhancements of computer vision models, improvements in the quality of scale images, and the accumulation of larger sets of scale images that can be used to train machine learning models, we believe that using computer vision can serve to reduce processing time and increase the accuracy of age estimates.