Effect of Model-Based Iterative Reconstruction on Image Quality of Chest Computed Tomography for COVID-19 Pneumonia.

PURPOSE: This study aimed to compare the image quality of chest computed tomography (CT) scans for COVID-19 pneumonia using forward-projected model-based iterative reconstruction solution-LUNG (FIRST-LUNG) with filtered back projection (FBP) and hybrid iterative reconstruction (HIR). METHOD: The CT images of 44 inpatients diagnosed with COVID-19 pneumonia between December 2022 and June 2023 were retrospectively analyzed. The CT images were reconstructed using FBP, HIR, and FIRST-LUNG-MILD/STANDARD/STRONG. The CT values and noise of the lumen of the main trachea and erector spine muscle were measured for each group. Signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) were calculated. Subjective evaluations included overall image quality, noise, streak artifact, visualization of normal lung structures, and abnormal CT features. One-way analysis of variance was used to compare the objective and subjective indicators among the five groups. The task-based transfer function was derived for three distinct contrasts representing anatomical structures, lower-contrast lesion, and higher-contrast lesion. RESULTS: The results of the study demonstrated significant differences in image noise, SNR, and CNR among the five groups (P < 0.001). The FBP images exhibited the highest levels of noise and the lowest SNR and CNR among the five groups (P < 0.001). When compared to the FBP and HIR groups, the noise was lower in the FIRST-LUNG-MILD/STANDARD/STRONG group, while the SNR and CNR were higher (P < 0.001). The subjective overall image quality score of FIRST-LUNG-MILD/STANDARD was significantly better than FBP and FIRST-LUNG-STRONG (P < 0.001). FIRST-LUNG-MILD was superior to FBP, HIR, FIRST-LUNG-STANDARD, and FIRST-LUNG-STRONG in visualizing proximal and peripheral bronchovascular and subpleural vessels (P < 0.05). Additionally, FIRST-LUNG-MILD achieved the best scores in evaluating abnormal lung structure (P < 0.001). The overall interobserver agreement was substantial (intraclass correlation coefficient = 0.891). The task-based transfer function 50% values of FIRST reconstructions are consistently higher compared to FBP and HIR. CONCLUSIONS: The FIRST-LUNG-MILD/STANDARD algorithm can enhance the image quality of chest CT in patients with COVID-19 pneumonia, while preserving important details of the lesions, better than the FBP and HIR algorithms. After evaluating various COVID-19 pneumonia lesions and considering the improvement in image quality, we recommend using the FIRST-LUNG-MILD reconstruction for diagnosing COVID-19 pneumonia.

Enhancing image quality in computed tomography angiography follow-ups after endovascular aneurysm repair: a comparative study of reconstruction techniques.

BACKGROUND: The image quality of computed tomography angiography (CTA) images following endovascular aneurysm repair (EVAR) is not satisfactory, since artifacts resulting from metallic implants obstruct the clear depiction of stent and isolation lumens, and also adjacent soft tissues. However, current techniques to reduce these artifacts still need further advancements due to higher radiation doses, longer processing times and so on. Thus, the aim of this study is to assess the impact of utilizing Single-Energy Metal Artifact Reduction (SEMAR) alongside a novel deep learning image reconstruction technique, known as the Advanced Intelligent Clear-IQ Engine (AiCE), on image quality of CTA follow-ups conducted after EVAR. MATERIALS: This retrospective study included 47 patients (mean age ± standard deviation: 68.6 ± 7.8 years; 37 males) who underwent CTA examinations following EVAR. Images were reconstructed using four different methods: hybrid iterative reconstruction (HIR), AiCE, the combination of HIR and SEMAR (HIR + SEMAR), and the combination of AiCE and SEMAR (AiCE + SEMAR). Two radiologists, blinded to the reconstruction techniques, independently evaluated the images. Quantitative assessments included measurements of image noise, signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR), the longest length of artifacts (AL), and artifact index (AI). These parameters were subsequently compared across different reconstruction methods. RESULTS: The subjective results indicated that AiCE + SEMAR performed the best in terms of image quality. The mean image noise intensity was significantly lower in the AiCE + SEMAR group (25.35 ± 6.51 HU) than in the HIR (47.77 ± 8.76 HU), AiCE (42.93 ± 10.61 HU), and HIR + SEMAR (30.34 ± 4.87 HU) groups (p < 0.001). Additionally, AiCE + SEMAR exhibited the highest SNRs and CNRs, as well as the lowest AIs and ALs. Importantly, endoleaks and thrombi were most clearly visualized using AiCE + SEMAR. CONCLUSIONS: In comparison to other reconstruction methods, the combination of AiCE + SEMAR demonstrates superior image quality, thereby enhancing the detection capabilities and diagnostic confidence of potential complications such as early minor endleaks and thrombi following EVAR. This improvement in image quality could lead to more accurate diagnoses and better patient outcomes.

Amlodipine suppresses Ang-II-induced endothelium dysfunction by diminishing ROCK1 expression.

OBJECTIVE: To investigate the effects and mechanisms of amlodipine therapy on endothelium dysfunction induced by angiotensin-II (Ang-II) stimulation. METHODS: Human umbilical vein endothelial cells (HUVECs) were used and divided into five groups: Blank control, Ang-II (10(-6 )mol/L), levorotatory amlodipine (5 × 10(-6 )mol/L) + Ang-II (10(-6 )mol/L), dextrorotatory amlodipine (5 × 10(-6 )mol/L) + Ang-II (10(-6 )mol/L) and racemic amlodipine (5 × 10(-6 )mol/L) + Ang-II (10(-6 )mol/L) groups. Twenty-four hours later, HUVECs were collected for evaluating endothelial nitric oxide synthase (eNOS), p-eNOS, rho-associated kinase 1 (ROCK1), Bcl-2 and Bax expressions. Nitric oxide (NO) concentration within endothelium was also detected. Flow cytometry was conducted to assess HUVECs apoptosis. RESULTS: With 24 hours of Ang-II stimulation, compared to blank control group, expressions of eNOS and p-eNOS and NO production were significantly reduced in Ang-II group (p < 0.05), while adding amlodipine-protected HUVECs from dysfunction induced by Ang-II. In contrast, ROCK1 expression was promoted in Ang-II group (p < 0.05). However, the expression of ROCK1 in each enantiomer of amlodipine group was significantly decreased (p < 0.05). Compared to levorotatory amlodipine group, the magnitude of ROCK1 diminishment in dextrorotatory amlodipine group was more profound (p < 0.05). The pro-survival protein (Bcl-2) was significantly upregulated, while the pro-apoptotic protein (Bax) was significantly downregulated in three amlodipine groups compared to Ang-II group. Flow cytometry revealed that amlodipine therapy could protect HUVECs from apoptosis, and no significant difference between three amlodipine groups was observed. CONCLUSION: Amlodipine could suppress Ang-II-induced endothelial dysfunction and apoptosis through diminishing ROCK1 expression.

Atorvastatin protects endothelium by decreasing asymmetric dimethylarginine in dyslipidemia rats.

BACKGROUND: Asymmetric Dimethylarginine (ADMA) is an inhibitor of endogenous nitric oxide synthase, which is the key synthase for nitric oxide (NO) production. Whether statins could protect endothelium by reducing ADMA concentration is unclear, and whether this effect is associated with the dose of statins usage is also needed further studied. METHODS: Dyslipidemia rat model was produced by giving high-fat and high-cholesterol diet for 8 weeks. Thereafter, low-dose (5 mg/kg body weight/day) and high-dose (20 mg/kg body weight/day) atorvastatin were orally prescribed for 4 weeks. Parameters of interest including lipid profiles, inflammatory and oxidative markers, NO production and plasma levels of ADMA and ADMA concentration of myocardium were evaluated. Liver enzymes and creatinine kinase (CK) were also detected for safety concern. RESULTS: At baseline, all parameters were comparable between the sham and the dyslipidemia groups. At 8 weeks of dyslipidemia establishment, as compared to the sham group, body weight and lipid profiles were significantly elevated, and plasma levels of C-reactive protein (CRP), malondialdehyde (MDA) and ADMA were concomitantly increased in accompanying with NO reduction in the dyslipidemia groups. With 4 weeks of atorvastatin therapy, as compared to the control group, lipid disorders and NO production were improved, and plasma levels of CRP, MDA and ADMA were significantly decreased in the high-dose atorvastatin group. ADMA concentration of cardiac tissues was also significantly reduced in the high-dose atorvastatin group. Notably, there was a trend to similar effects which did not reach statistical significance in the low-dose atorvastatin group when compared to the control group. Liver enzyme and CK were comparable after 4 weeks of atorvastatin therapy between groups. CONCLUSION: In rats with dyslipidemia, atorvastatin therapy could reduce plasma level of ADMA and ADMA concentration in cardiac tissues, and these effects are associated with the dose of atorvastatin therapy.

Baseline elevated Lp-PLA2 is associated with increased risk for re-stenosis after stent placement.

BACKGROUND: Lipoprotein associated phospholipase A2 (Lp-PLA2) is a novel biomarker for cardiovascular risk prediction. Whether increased Lp-PLA2 level is associated with re-stenosis after stent-placement is unclear. METHODS: Totally 326 participants eligible for stent-placement were enrolled and divided into two groups according to baseline Lp-PLA2 levels (named normal and elevated groups). Baseline characteristics and clinical outcomes were compared between normal and elevated groups. The relationships between Lp-PLA2 and other risk factors with re-stenosis were evaluated. RESULTS: Only the between-group difference of Lp-PLA2 was significant (123.2 ± 33.6 ng/mL vs 336.8 ± 85.4 ng/mL, P < 0.001) while other demographic and clinical characteristics between these two groups were comparable. Approximately 55.1% and 58.5% of participants in normal and elevated groups presented with acute coronary syndrome, and the percentage of tri-vessels stenoses was significantly higher in elevated group (40.8% vs 32.1%, P = 0.016). Nearly 96.0% and 94.0% of participants in normal and elevated Lp-PLA2 groups were placed with drug-eluting stents, and the others were with bare-metal stents. After 1 year's follow-up, the incidence of clinical end-points was comparable (13.3% vs 15.4%, P = 0.172). Nevertheless, the incidence of re-stenosis was marginally higher in elevated Lp-PLA2 group (8.5% versus 4.6%, P = 0.047). With multivariate analysis, after adjustment for other risk factors, Lp-PLA2 remained an independent predictor for re-stenosis with a hazard ratio of 1.140. No synergistic effect between Lp-PLA2 and other risk factors for re-stenosis was found. CONCLUSION: Increased Lp-PLA2 level is associated with an increased risk of re-stenosis. Lp-PLA2 assessment may be useful in predicting subjects who are at increased risk for re-stenosis.

Sulfhydryl functionalized two-dimensional Ti3C2Tx MXene for efficient removal of Hg2+ in water samples.

This study describes an adsorption method for the removal of Hg2+ from aquatic environments using sulfhydryl-functionalized Ti3C2Tx (SH-Ti3C2Tx). SH-Ti3C2Tx materials were synthesized through covalent interactions between dithiothreitol and two-dimensional Ti3C2Tx. The insertion of -SH groups increased the interlayer spacing of Ti3C2Tx, resulting in a 3-fold increase in the specific surface area of SH-Ti3C2Tx compared with the original Ti3C2Tx. The maximum Hg2+ adsorption capacity of SH-Ti3C2Tx was 3042 mg/g, which was 2.3-fold greater than that of Ti3C2Tx. After Hg2+ adsorption, SH-Ti3C2Tx was regenerated for repeated used by rinsing with HCl-thiourea. Next, SH-Ti3C2Tx was loaded onto a melamine sponge to construct SH-Ti3C2Tx adsorption columns suitable for continuous flow Hg2+ removal with extremely low flow resistance. Hg2+ removal rates exceeded 95 % when treating both high and low-concentration solutions (20 mg/L Hg2+ and 10 µg/L Hg2+). This study demonstrates the excellent adsorption-regeneration performance of SH-Ti3C2Tx, which has broad application prospects for the in-situ treatment of water contaminated with Hg2+.

Deep learning-based reconstruction improves the image quality of low-dose CT enterography in patients with inflammatory bowel disease.

PURPOSE: Lifelong re-examination of CT enterography (CTE) in patients with inflammatory bowel disease (IBD) may be necessary, and reducing radiation exposure during CT examinations is crucial. We investigated the potential application of deep learning reconstruction (DLR) in CTE to reduce radiation dose and improve image quality in IBD. METHODS: Thirty-six patients with known or suspected IBD were prospectively recruited to the low-dose CTE (LDCTE) group, while forty patients were retrospectively selected from previous clinical standard-dose CTE (STDCTE) scans as controls. STDCTE images were reconstructed with hybrid-IR (adaptive iterative dose reduction 3-dimensional [AIDR3D], standard setting); LDCTE images were reconstructed with AIDR3D and DLR (Advanced Intelligence ClearIQ Engine [AiCE], Body mild/standard/strong, Sharp Body mild/standard/strong setting). The effective radiation dose (ED), image noise, signal-to-noise ratio (SNR), overall image quality, subjective image noise, and diagnostic effectiveness were compared between the LDCTE and STDCTE groups. RESULTS: Compared with STDCTE, the ED of LDCTE was lower by 54.1% (p<0.001). Compared with STDCTE-AIDR3D, LDCTE-AIDR3D reconstruction objective image noise and SNR were greater (p<0.05), the subjective overall image quality was lower (p<0.05), and the diagnostic efficiency was lower (AUC=0.52, p<0.05). The SNRs of reconstructedimages of LDCTE-AiCE Body Strong and LDCTE-AiCE Body Sharp standard/strong groups were greater than that of STDCTE-AIDR3D group (all p<0.05), and the diagnostic performance was better than or comparable to that of STDCTE; the AUCs were 0.83, 0.76 and 0.76, respectively CONCLUSION: Compared with STDCTE with AIDR3D, LDCTE with DLR effectively reduced the radiation dose and improve image quality in IBD patients.

The diagnostic performance of ultra-low-dose 320-row detector CT with different reconstruction algorithms on limb joint fractures in the emergency department.

BACKGROUND: The aim of the study was to evaluate whether ultra-low-dose computed tomography (ULD-CT) could replace conventional-dose CT (CD-CT) for diagnosis of acute wrist, ankle, knee, and shoulder fractures in emergency departments (ED). METHODS: We developed CD-CT and ULD-CT scanning schemes for the various joints of the four limbs and scanned emergency patients prospectively. When performing CD-CT, a conventional bone reconstruction algorithm was used, while ULD-CT used both soft tissue and bone algorithms. A five-point scale was used to evaluate whether ULD-CT image quality affected surgical planning. The image quality and diagnostic performance of different types of scanned and reconstructed images for diagnosing fractures were evaluated and compared. Effective radiation dose of each group was calculated. RESULTS: Our study included 56 normal cases and 185 fracture cases. The combination of bone and soft tissue algorithms on ULD-CT can improve diagnostic performance, such that on ULD-CT, the sensitivity improved from 96.7% to 98.9%, specificity from 98.2% to 100%, positive predictive value from 99.4% to 100%, negative predictive value from 90.2% to 96.6% and diagnostic accuracy ranged from 97.5% to 99.1%. There were no statistically significant differences between ULD-CT and CD-CT on diagnostic performance (p values, 0.40-1.00). The radiation doses for ULD-CT protocols were only 3.0-7.7% of those for CD-CT protocols (all p < 0.01). CONCLUSIONS: In the emergency department, the 320-row detector ULD-CT could replace CD-CT in the diagnosis of limb joint fractures. The combination of bone algorithm with soft tissue algorithm reconstruction can further improve the image quality and diagnostic performance.

Application of ultra-low-dose CT in 3D printing of distal radial fractures.

PURPOSE: To explore the effect of ultra-low-dose computed tomography (CT) on three-dimensional (3D) printing models and the diagnosis of wrist fractures. METHOD: This study enrolled 76 patients with distal radial fractures (DRFs). All patients underwent 320-row detector CT and were divided randomly into two groups. In Group A, 38 patients were scanned with the standard-dose protocol using a tube voltage of 120 kV and current of 100 mA. In Group B, 38 patients were scanned with the ultra-low-dose protocol using a tube voltage of 80 kV and current of 10 mA. For objective image quality assessment, the noise, CT number, signal-to-noise ratio (SNR), and contrast-to-noise ratio (CNR) were measured. Subjectively, two experienced orthopaedic surgeons blinded to the scan parameters evaluated the clarity of the 3D printing model and fracture line using a 3-point scale (the diagnosis was considered acceptable with scores ≥2). The mean radiation dose was calculated. The diagnostic performances for the fractures between the two groups were compared. RESULTS: The effective radiation dose was significantly reduced by 97.1 % in Group B, compared to Group A (0.28 ± 0.05vs. 9.75 ± 2.23 µSv, respectively). Quantitative objective image quality parameters (e.g., CNR, SNR, and CT numbers) were higher in the standard-dose group (p < 0.001). However, there was no difference in subjective scoring of the 3D printing model. Although the fracture line score was higher in Group A (2.92±0.27 vs. 2.16 ± 0.37; p < 0.001), the diagnostic performance of the two groups was consistent (all scores ≥2). There were no statistically significant differences in the sensitivity, specificity or accuracy between standard-dose group and ultra-low-dose group. CONCLUSIONS: The ultra-low-dose protocol effectively reduced the radiation dose by 97.1 %, while maintaining the image quality for diagnosis of DRFs. Therefore, this protocol can meet the needs of 3D printing models for preoperative assessments.

Adverse factors on nonenhanced abdominal CT for long-term continuous ambulatory peritoneal dialysis: a comparative study between patients who withdraw from and maintain long-term peritoneal dialysis.

PURPOSE: To investigate the imaging features of patients with long-term continuous ambulatory peritoneal dialysis (CAPD) on nonenhanced abdominal CT and to identify adverse factors for long-term CAPD. METHODS: A total of 109 patients with less than 5 years of CAPD for peritoneal ultrafiltration failure who switched to hemodialysis (withdrawal group) and 23 patients with more than 10 years of CAPD (long-term group) were retrospectively enrolled. Nonenhanced CT manifestations in both groups were compared, including thickening and calcification of the parietal peritoneum, calcification of the mesangial margin and free margin of the small intestine wall, and calcification of the mesentery and abdominal aorta. A risk stratification model was proposed based on CT manifestations with statistically significant differences. RESULTS: The presence of the following CT findings was significantly different between two groups: extensive thickening of the parietal peritoneum (78.9% vs. 21.7%, P < 0.01); severe calcification of the parietal peritoneum (60.6% vs. 8.7%, P < 0.01); calcification of the mesentery (32.1% vs. 4.3%, P < 0.05); and calcification of the free margin of the small intestine wall (49.5% vs. 13.0%, P < 0.05). However, there was no significant difference in calcification of the mesangial margin of the small intestine wall (40.3% vs. 30.4%) or in abdominal aortic calcification (56.9% vs. 61.1%) (P > 0.05). The area under the receiver operating characteristic curve (AUC) was 0.906 (sensitivity 87.6% and specificity 82.6%). CONCLUSION: Extensive thickening of the parietal peritoneum, severe calcification of the parietal peritoneum, and calcification of the mesentery and the free margin of the small intestine wall are adverse factors for long-term CAPD.

Effects and potential mechanism of atorvastatin treatment on Lp-PLA2 in rats with dyslipidemia.

INTRODUCTION: The effects of statins on lipoprotein-associated phospholipase A2 (Lp-PLA2) are controversial, and the present study aimed to investigate whether atorvastatin could reduce Lp-PLA2 in rats with dyslipidemia. MATERIAL AND METHODS: A high-fat and high-cholesterol diet was prescribed to produce a dyslipidemia model. Thereafter, low-dose atorvastatin (5 mg/kg/day), high-dose atorvastatin (20 mg/kg/day) or saline (without-treatment group) was prescribed for 14 days. At 6 weeks after dyslipidemia model establishment and 14 days of atorvastatin treatment, fasting venous blood was drawn for biochemical analysis. Between-group differences and Pearson correlation analysis were conducted. RESULTS: Compared to the normal-control group, fasting plasma total cholesterol (TC) and low-density lipoprotein cholesterol (LDL-C) levels were significantly increased in dyslipidemia groups, while plasma nitric oxide (NO) levels were significantly decreased with attendant elevation of plasma C-reactive protein (CRP) and rho-associated kinase 1 (ROCK1) levels (p < 0.05). At 14 days of atorvastatin treatment, compared to the without-treatment group, plasma levels of TC and LDL-C in the high-dose group were significantly reduced (p < 0.05); and compared to low-dose and without-treatment groups, NO up-regulation (1.8 ±1.1 µmol/l), and CRP (-0.8 ±0.4 ng/ml), ROCK1 (-124 ±65 mmol/l) and Lp-PLA2 (-3.8 ±1.2 ng/ml) reduction were more significant in the high-dose group (p < 0.05). Pearson correlation analysis showed that TC (r = 0.365), LDL-C (r = 0.472), CRP (r = 0.501) and ROCK1 (r = 0.675) were positively correlated with Lp-PLA2, while NO (r = -0.378) and atorvastatin (r = -0.511) were negatively correlated with Lp-PLA2. CONCLUSIONS: Atorvastatin treatment is beneficial for reducing the Lp-PLA2 level in rats with dyslipidemia, which may be related to reduced ROCK1 expression in a dose-dependent manner.

Clopidogrel and Aspirin versus Aspirin Alone for Stroke Prevention: A Meta-Analysis.

BACKGROUND AND PURPOSE: Antiplatelet therapy is widely used for the primary or secondary prevention of stroke. Drugs like clopidogrel have emerged as alternatives for traditional antiplatelet therapy, and dual therapy with clopidogrel and aspirin is of particular interest. We conducted this meta-analysis to systematically review studies about dual therapy comparing monotherapy with aspirin alone. METHODS: Randomized controlled trials were searched in PubMed (1966-May, 2015), EMBASE (1947-May, 2015), the Cochrane Central Register of Controlled Trials (CENTRAL) (1948-May, 2015), WHO International Clinical Trial (ICTRP) (2004-May, 2015), China Biology Medicine disc (CBM disc) (1978-May, 2015) and were included into the final analysis according to the definite inclusion criteria mentioned in the study selection section. Risk ratio (RR) was pooled with 95% confidence interval (CI) for dichotomous data. The heterogeneity was considered significant if the χ2 test was significant (P value < 0.10) or the I2 > 50.00%. Subgroup analyses were carried out on the long and short time periods, the race and region. RESULTS: We included 5 studies involving 24,084 patients. A pooled analysis showed that dual therapy with clopidogrel and aspirin had a lower stroke incidence than monotherapy in both the short term and long term (RR = 0.69, 95% CI: 0.59-0.82, P <0.05; RR = 0.84, 95% CI: 0.72-0.98, P = 0.03, respectively). With regard to safety, dual therapy had a higher risk of bleeding than monotherapy for both periods (RR = 1.51, 95% CI: 1.03-2.23, P = 0.04; RR = 1.54, 95% CI: 1.32-1.79, P<0.05, respectively). CONCLUSIONS: Dual therapy with clopidogrel and aspirin could be a preferable choice to prevent stroke in patients who have had a previous stroke or transient ischemic attack, as well as those who are at high risk for stroke. And the effect of dual therapy seems to be more obvious for short-term. However, it is associated with a higher risk of bleeding.