OBJECTIVES: We propose a sparse-view cone-beam CT reconstruction algorithm based on bidirectional flow field guided projection completion (BBC-Recon) to solve the ill-posed inverse problem in sparse-view cone-beam CT imaging. METHODS: The BBC-Recon method consists of two main modules: the projection completion module and the image restoration module. Based on flow field estimation, the projection completion module, through the designed bidirectional and multi-scale correlators, fully calculates the correlation information and redundant information among projections to precisely guide the generation of bidirectional flow fields and missing frames, thus achieving high-precision completion of missing projections and obtaining pseudo complete projections. The image restoration module reconstructs the obtained pseudo complete projections and then refines the image to remove the residual artifacts and further improve the image quality. RESULTS: The experimental results on the public datasets of Mayo Clinic and Guilin Medical University showed that in the case of a 4-fold sparse angle, compared with the suboptimal method, the BBC-Recon method increased the PSNR index by 1.80% and the SSIM index by 0.29%, and reduced the RMSE index by 4.12%; In the case of an 8-fold sparse angle, the BBC-Recon method increased the PSNR index by 1.43% and the SSIM index by 1.49%, and reduced the RMSE index by 0.77%. CONCLUSIONS The BBC-Recon algorithm fully exploits the correlation information between projections to allow effective removal of streak artifacts while preserving image structure information, and demonstrates significant advantages in maintaining inter-slice consistency.
Algorithms ; Cone-Beam Computed Tomography/methods* ; Image Processing, Computer-Assisted/methods* ; Humans

OBJECTIVES: We propose a segmented backprojection tensor degradation feature encoding (SBP-MAC) model for motion artifact correction in dental cone beam computed tomography (CBCT) to improve the quality of the reconstructed images. METHODS: The proposed motion artifact correction model consists of a generator and a degradation encoder. The segmented limited-angle reconstructed sub-images are stacked into the tensors and used as the model input. A degradation encoder is used to extract spatially varying motion information in the tensor, and the generator's skip connection features are adaptively modulated to guide the model for correcting artifacts caused by different motion waveforms. The artifact consistency loss function was designed to simplify the learning task of the generator. RESULTS: The proposed model could effectively remove motion artifacts and improve the quality of the reconstructed images. For simulated data, the proposed model increased the peak signal-to-noise ratio by 8.28%, increased the structural similarity index measurement by 2.29%, and decreased the root mean square error by 23.84%. For real clinical data, the proposed model achieved the highest expert score of 4.4221 (against a 5-point scale), which was significantly higher than those of all the other comparison methods. CONCLUSIONS The SBP-MAC model can effectively extract spatially varying motion information in the tensors and achieve adaptive artifact correction from the tensor domain to the image domain to improve the quality of reconstructed dental CBCT images.
Cone-Beam Computed Tomography/methods* ; Artifacts ; Humans ; Motion ; Image Processing, Computer-Assisted/methods* ; Signal-To-Noise Ratio ; Algorithms

OBJECTIVES: We propose a low-dose CT image restoration method based on central guidance and alternating optimization (FedGP). METHODS: The FedGP framework revolutionizes the traditional federated learning model by adopting a structure without a fixed central server, where each institution alternatively serves as the central server. This method uses an institution-modulated CT image restoration network as the core of client-side local training. Through a federated learning approach of central guidance and alternating optimization, the central server leverages local labeled data to guide client-side network training to enhance the generalization capability of the CT imaging model across multiple institutions. RESULTS: In the low-dose and sparse-view CT image restoration tasks, the FedGP method showed significant advantages in both visual and quantitative evaluation and achieved the highest PSNR (40.25 and 38.84), the highest SSIM (0.95 and 0.92), and the lowest RMSE (2.39 and 2.56). Ablation study of FedGP demonstrated that compared with FedGP(w/o GP) without central guidance, the FedGP method better adapted to data heterogeneity across institutions, thus ensuring robustness and generalization capability of the model in different imaging conditions. CONCLUSIONS FedGP provides a more flexible FL framework to solve the problem of CT imaging heterogeneity and well adapts to multi-institutional data characteristics to improve generalization ability of the model under diverse imaging geometric configurations.
Tomography, X-Ray Computed/methods* ; Humans ; Radiation Dosage ; Image Processing, Computer-Assisted/methods* ; Algorithms

Objective:To investigate whether brown adipose tissue-derived exosomes(BAT-exos) could ameliorate endothelial cell injury by activating Pink1-Parkin pathway-mediated mitophagy.Methods:Endothelial cell injury was induced with angiotensin Ⅱ(Ang Ⅱ) to establish a cellular injury model. Exosomes were isolated from both brown adipose tissue and white adipose tissue and characterized by transmission electron microscopy(TEM), nanoparticle tracking analysis(NTA), fluorescence labeling, and Western blot. Cell viability was assessed using the CCK-8 assay, and apoptosis rates were determined by flow cytometry. Levels of tumor necrosis factor-α(TNF-α), interleukin(IL)-6, and IL-8 were measured by ELISA. Mitochondrial autophagy was assessed by immunofluorescence colocalization, and protein expression levels of Pink1, Parkin, and LC3 Ⅱ/I were determined by Western blot.Results:Ang Ⅱ induced endothelial cell apoptosis, activated inflammatory responses, and suppressed mitophagy, as evidenced by decreased expression of mitophagy-related proteins. Following the successful characterization of BAT-exos, we found that BAT-exos activated mitophagy and alleviated endothelial cell injury, whereas white adipose tissue-derived exosomes(WAT-exos) inhibited mitophagy and exacerbated injury. Mechanistically, BAT-exos targeted the Pink1-Parkin signaling pathway to activate mitophagy.Conclusion:BAT-exos markedly improve endothelial cell injury by activating mitophagy through the Pink1-Parkin pathway, providing new insights and potential therapeutic targets for cardiovascular diseases.

Objective:To evaluate the technical feasibility and perioperative safety of pyeloplasty assis-ted by the CarinaTM modular laparoscopic surgical robotic system in patients with ureteropelvic junction obstruction(UPJO).Methods:From November to December 2024,five consecutive patients diagnosed with UPJO underwent robot-assisted pyeloplasty using the CarinaTM modular laparoscopic surgical system at Peking University First Hospital.Data on patient demographics,intraoperative parameters(including docking time,console time,and estimated blood loss),perioperative outcomes,follow-up results,and surgeons' subjective evaluations of system performance were prospectively collected.Descriptive statistics were used;continuous variables were presented as median(range),and categorical variables as frequen-cy and percentage.Results:The cohort included four females and one male.All the patients successfully completed the robotic procedure without conversion to open or conventional laparoscopic surgery.The me-dian age was 32 years(24-37 years),and the median body mass index was 21.6 kg/m2(15.8-27.3 kg/m2).The median docking time was 8 min(3-12 min),and the median console time was 91 min(71-125 min).Intraoperative blood loss was uniformly 20 mL.The median postoperative drainage du-ration was 3 d(0-4 d),and the median length of hospital stay was 4 d(4-9 d).No Clavien-Dindo grade Ⅲ or higher complications occurred.All the patients had their double-J stents removed at 2 months postoperatively,and pain in the ipsilateral flank,reported preoperatively by all the five patients,was al-leviated.The subjective surgical success rate was 100％.Surgeons reported stable system performance throughout all the procedures,with no instances of mechanical arm interference or visual drift affecting surgical fluency.Conclusion:Preliminary findings indicate that pyeloplasty using the domestically deve-loped CarinaTM modular laparoscopic robotic system is technically feasible and perioperatively safe for the treatment of UPJO.

AIM:To explore the mechanism of Salvia miltiorrhiza(Danshen)-derived exosome-like nanoparti-cles(DDN)in attenuating oxidative damage in endothelial cells through the activation of the phosphatidylinositol 3-kinase(PI3K)/protein kinase B(PKB/Akt)/endothelial nitric oxide synthase(eNOS)signaling pathway.METHODS:The DDN were characterized by transmission electron microscopy and dynamic light scattering.Fluorescence microscopy and flow cytometry were used to evaluate the uptake of DDN by human umbilical vein endothelial cells(HUVECs).The viability,migration and invasion of HUVECs were assessed using CCK8 assay,wound-healing assay and Transwell assay,respec-tively.The HUVECs were induced by angiotensin II(Ang II)for oxidative stress and intervened with DDN or LY294002(a PI3K inhibitor).The levels of reactive oxygen species were determined by flow cytometry,and intracellular nitric oxide(NO)content was measured using a biochemical assay kit.Additionally,the protein levels of NADPH oxidase 4(NOX4),NOX2,endothelial nitric oxide syntnase(eNOS),p-eNOS,Akt and p-Akt were examined by Western blot.RESULTS:(1)Transmission electron microscopy and dynamic light scattering analysis revealed that DDN had good bio-compatibility and stability.(2)According to fluorescence images and flow cytometry results,DDN were strongly taken up by HUVECs.(3)Compared with control group,DDN significantly promoted the viability,migration and invasion of HUVECs,showing a dose-dependent effect.(4)Compared with control group,DDN remarkably increased intracellular NO levels,thereby enhancing endothelial cell vasodilation via activating the PI3K/Akt/eNOS signaling pathway.(5)The PI3K/Akt/eNOS pathway played a critical role in mitigating oxidative stress and improving cellular function in response to DDN treat-ment.CONCLUSION:The DDN mediate PI3K/Akt/eNOS signaling pathway activation to significantly alleviate Ang II-induced oxidative damage in endothelial cells,suggesting a potential vascular protective effect of DDN.

Objective:To evaluate the technical feasibility and perioperative safety of pyeloplasty assis-ted by the CarinaTM modular laparoscopic surgical robotic system in patients with ureteropelvic junction obstruction(UPJO).Methods:From November to December 2024,five consecutive patients diagnosed with UPJO underwent robot-assisted pyeloplasty using the CarinaTM modular laparoscopic surgical system at Peking University First Hospital.Data on patient demographics,intraoperative parameters(including docking time,console time,and estimated blood loss),perioperative outcomes,follow-up results,and surgeons' subjective evaluations of system performance were prospectively collected.Descriptive statistics were used;continuous variables were presented as median(range),and categorical variables as frequen-cy and percentage.Results:The cohort included four females and one male.All the patients successfully completed the robotic procedure without conversion to open or conventional laparoscopic surgery.The me-dian age was 32 years(24-37 years),and the median body mass index was 21.6 kg/m2(15.8-27.3 kg/m2).The median docking time was 8 min(3-12 min),and the median console time was 91 min(71-125 min).Intraoperative blood loss was uniformly 20 mL.The median postoperative drainage du-ration was 3 d(0-4 d),and the median length of hospital stay was 4 d(4-9 d).No Clavien-Dindo grade Ⅲ or higher complications occurred.All the patients had their double-J stents removed at 2 months postoperatively,and pain in the ipsilateral flank,reported preoperatively by all the five patients,was al-leviated.The subjective surgical success rate was 100％.Surgeons reported stable system performance throughout all the procedures,with no instances of mechanical arm interference or visual drift affecting surgical fluency.Conclusion:Preliminary findings indicate that pyeloplasty using the domestically deve-loped CarinaTM modular laparoscopic robotic system is technically feasible and perioperatively safe for the treatment of UPJO.

AIM:To explore the mechanism of Salvia miltiorrhiza(Danshen)-derived exosome-like nanoparti-cles(DDN)in attenuating oxidative damage in endothelial cells through the activation of the phosphatidylinositol 3-kinase(PI3K)/protein kinase B(PKB/Akt)/endothelial nitric oxide synthase(eNOS)signaling pathway.METHODS:The DDN were characterized by transmission electron microscopy and dynamic light scattering.Fluorescence microscopy and flow cytometry were used to evaluate the uptake of DDN by human umbilical vein endothelial cells(HUVECs).The viability,migration and invasion of HUVECs were assessed using CCK8 assay,wound-healing assay and Transwell assay,respec-tively.The HUVECs were induced by angiotensin II(Ang II)for oxidative stress and intervened with DDN or LY294002(a PI3K inhibitor).The levels of reactive oxygen species were determined by flow cytometry,and intracellular nitric oxide(NO)content was measured using a biochemical assay kit.Additionally,the protein levels of NADPH oxidase 4(NOX4),NOX2,endothelial nitric oxide syntnase(eNOS),p-eNOS,Akt and p-Akt were examined by Western blot.RESULTS:(1)Transmission electron microscopy and dynamic light scattering analysis revealed that DDN had good bio-compatibility and stability.(2)According to fluorescence images and flow cytometry results,DDN were strongly taken up by HUVECs.(3)Compared with control group,DDN significantly promoted the viability,migration and invasion of HUVECs,showing a dose-dependent effect.(4)Compared with control group,DDN remarkably increased intracellular NO levels,thereby enhancing endothelial cell vasodilation via activating the PI3K/Akt/eNOS signaling pathway.(5)The PI3K/Akt/eNOS pathway played a critical role in mitigating oxidative stress and improving cellular function in response to DDN treat-ment.CONCLUSION:The DDN mediate PI3K/Akt/eNOS signaling pathway activation to significantly alleviate Ang II-induced oxidative damage in endothelial cells,suggesting a potential vascular protective effect of DDN.

Objective:To investigate whether brown adipose tissue-derived exosomes(BAT-exos) could ameliorate endothelial cell injury by activating Pink1-Parkin pathway-mediated mitophagy.Methods:Endothelial cell injury was induced with angiotensin Ⅱ(Ang Ⅱ) to establish a cellular injury model. Exosomes were isolated from both brown adipose tissue and white adipose tissue and characterized by transmission electron microscopy(TEM), nanoparticle tracking analysis(NTA), fluorescence labeling, and Western blot. Cell viability was assessed using the CCK-8 assay, and apoptosis rates were determined by flow cytometry. Levels of tumor necrosis factor-α(TNF-α), interleukin(IL)-6, and IL-8 were measured by ELISA. Mitochondrial autophagy was assessed by immunofluorescence colocalization, and protein expression levels of Pink1, Parkin, and LC3 Ⅱ/I were determined by Western blot.Results:Ang Ⅱ induced endothelial cell apoptosis, activated inflammatory responses, and suppressed mitophagy, as evidenced by decreased expression of mitophagy-related proteins. Following the successful characterization of BAT-exos, we found that BAT-exos activated mitophagy and alleviated endothelial cell injury, whereas white adipose tissue-derived exosomes(WAT-exos) inhibited mitophagy and exacerbated injury. Mechanistically, BAT-exos targeted the Pink1-Parkin signaling pathway to activate mitophagy.Conclusion:BAT-exos markedly improve endothelial cell injury by activating mitophagy through the Pink1-Parkin pathway, providing new insights and potential therapeutic targets for cardiovascular diseases.

Evaluating toxicity and decoding the underlying mechanisms of active compounds are crucial for drug development.In this study,we present an innovative,integrated approach that combines air flow-assisted desorption electrospray ionization mass spectrometry imaging(AFADESI-MSI),time-of-flight secondary ion mass spectrometry(ToF-SIMS),and spatial metabolomics to comprehensively investi-gate the nephrotoxicity and underlying mechanisms of nitidine chloride(NC),a promising anti-tumor drug candidate.Our quantitive AFADESI-MSI analysis unveiled the region specific of accumulation of NC in the kidney,particularly within the inner cortex(IC)region,following single and repeated dose of NC.High spatial resolution ToF-SIMS analysis further allowed us to precisely map the localization of NC within the renal tubule.Employing spatial metabolomics based on AFADESI-MSI,we identified over 70 discriminating endogenous metabolites associated with chronic NC exposure.These findings suggest the renal tubule as the primary target of NC toxicity and implicate renal transporters(organic cation transporters,multidrug and toxin extrusion,and organic cation transporter 2(OCT2)),metabolic en-zymes(protein arginine N-methyltransferase(PRMT)and nitric oxide synthase),mitochondria,oxidative stress,and inflammation in NC-induced nephrotoxicity.This study offers novel insights into NC-induced renal damage,representing a crucial step towards devising strategies to mitigate renal damage caused by this compound.