Development of a portable reflectance confocal microscope and its application in the noninvasive in vivo evaluation of mesenchymal stem cell-promoted cutaneous wound healing

The process of wound healing is routinely evaluated by histological evaluation in the clinic,which may cause scarring and secondary injury.Reflectance confocal microscopy(RCM)represents a noninvasive,real-time imaging technique that allows in vivo evaluation of the skin.Traditional RCM was wide-probe-based,which limited its application on uneven and covered skin.In this study,we report the development of a portable reflectance confocal microscope(PRCM)in which all components were assembled in a handheld shell.Although the size and weight of the PRCM were reduced based on the use of a microelectromechanical system,the resolution was kept at 0.91μm,and the field of view of the system was 343μm×532μm.When used in vivo,the PRCM was able to visualize cellular and nuclear morphology for both mouse and human skin.PRCM evaluations were then performed on wounds after topically applied mesenchymal stem cells(MSCs)or saline treatment.The PRCM allowed visualization of the formation of collagen bundles,re-epithelization from the wound edge to the wound bed,and hair follicle regeneration,which were consistent with histological evaluations.Therefore,we offer new insights into monitoring the effects of topically applied MSCs on the process of wound healing by using PRCM.This study illustrates that the newly developed PRCM represents a promising device for real-time,noninvasive monitoring of the dynamic process of wound healing,which demonstrates its potential to diagnose,monitor,or predict disease in clinical wound therapy.

Machine learning models compared to existing criteria for noninvasive prediction of endoscopic retrograde cholangiopancreatography-confirmed choledocholithiasis

Background and aims:Noninvasive predictors of choledocholithiasis have generally exhibited marginal performance characteristics.We aimed to identify noninvasive independent predictors of endoscopic retrograde cholangiopancreatography(ERCP)-confirmed choledocholithiasis and accordingly developed predictive machine learning models(MLMs).Methods:Clinical data of consecutive patients undergoing first-ever ERCP for suspected chol-edocholithiasis from 2015 to 2019 were abstracted from a prospectively-maintained database.Multiple logistic regression was used to identify predictors of ERCP-confirmed choledocholithiasis.MLMs were then trained to predict ERCP-confirmed choledocholithiasis using pre-ERCP ultrasound(US)imaging only as well as using all available noninvasive imaging(US,computed tomography,and/or magnetic reso-nance cholangiopancreatography).The diagnostic performance of American Society for Gastrointestinal Endoscopy(ASGE)“high-likelihood”criteria was compared to MLMs.Results:We identified 270 patients(mean age 46 years,62.2%female,73.7%Hispanic/Latino,59%with noninvasive imaging positive for choledocholithiasis)with native papilla who underwent ERCP for suspected choledocholithiasis,of whom 230(85.2%)were found to have ERCP-confirmed chol-edocholithiasis.Logistic regression identified choledocholithiasis on noninvasive imaging(odds ratio(OR)¼3.045,P¼0.004)and common bile duct(CBD)diameter on noninvasive imaging(OR¼1.157,P¼0.011)as predictors of ERCP-confirmed choledocholithiasis.Among the various MLMs trained,the random forest-based MLM performed best;sensitivity was 61.4%and 77.3%and specificity was 100%and 75.0%,using US-only and using all available imaging,respectively.ASGE high-likelihood criteria demonstrated sensitivity of 90.9%and specificity of 25.0%;using cut-points achieving this specificity,MLMs achieved sensitivity up to 97.7%.Conclusions:MLMs using age,sex,race/ethnicity,presence of diabetes,fever,body mass index(BMI),total bilirubin,maximum CBD diameter,and choledocholithiasis on pre-ERCP noninvasive imaging predict ERCP-confirmed choledocholithiasis with good sensitivity and specificity and outperform the ASGE criteria for patients with suspected choledocholithiasis.

Imaging probes for non-invasive tumoral detection and functional monitoring of cancer multidrug resistance

Aim:Several cationic radiotracers originally developed as myocardial perfusion agents have shown potential for both early detection of cancer and non-invasive monitoring of multiple drug resistance(MDR)by single photon emission computed tomography.We have introduced two cationic complexes,^(99m)Tc-DMEOP[di-methoxy-tris-pyrazolyl-^(99m)Tc-(CO)_(3)]and ^(99m)Tc-TMEOP[tri-methoxy-tris-pyrazolyl-^(99m)Tc-(CO)_(3)],which showed excellent preclinical results as cardiac imaging probes,namely a persistent heart uptake with rapid blood and liver clearance.This study aimed at the evaluation of their usefulness for tumoral detection and functional assessment of MDR.Methods:The uptake and efflux kinetics of ^(99m)Tc-DMEOP and ^(99m)Tc-TMEOP were evaluated in human prostate,lung,and breast cancer cell lines,including drug-resistant cell lines that are known to overexpress the MDR P-glycoprotein(Pgp).The effects of MDR modulators were also studied.In vivo studies were performed in xenografted tumor models,and the MDR phenotype of the tumors was confirmed by Western blot.Results:The uptake kinetics of both complexes in human cancer cell lines is comparable with the one found for ^(99m)Tc-Sestamibi,increasing over time.The uptake of ^(99m)Tc-TMEOP is greatly reduced in cells overexpressing Pgp and increased in the presence of a Pgp modulator.In nude mice,the tumor uptake of ^(99m)Tc-TMEOP was higher in the MCF-7 xenografts compared with the MCF7 Pgp tumors.Conclusion:The uptake kinetics of both complexes in human cancer cell lines is comparable with the one found for ^(99m)Tc-Sestamibi,increasing over time.The uptake of ^(99m)Tc-TMEOP is greatly reduced in cells overexpressing Pgp,and increased in the presence of a Pgp modulator.In nude mice,the tumor uptake of ^(99m)Tc-TMEOP was higher in the MCF-7 xenografts compared with the MCF7 Pgp tumors.

The retinal function imager and clinical applications

Background:The Retinal Function Imager(RFI)provides in vivo and noninvasive imaging of both the retinal structure and function.Review:The RFI can create capillary perfusion maps,measure blood flow velocity,and determine metabolic function including blood oximetry.It can aid clinical diagnosis as well as assess treatment response in several retinal vascular diseases including diabetic retinopathy.Blood flow velocity abnormalities have also been implicated in disease such as age-related macular degeneration and require further investigation.Compared with optical coherence tomography angiography,the RFI produces capillary maps of comparable image quality and wider field of view but it is unable to provide depth-resolved information and has longer image acquisition time.Currently,functional imaging using blood oximetry has limited applications and additional research is required.Conclusion:The RFI offers noninvasive,high-resolution imaging of retinal microvasculature by creating capillary perfusion maps.In addition,it is capable of measuring retinal blood velocity directly and performs functional imaging with retinal blood oximetry.Its clinical applications are broad and additional research with functional imaging may potentially lead to diagnosis of diseases and their progression before anatomic abnormalities become evident,but longer image acquisition times may limit its clinical adoption.

Design and simulation of a 2-D array flexible ultrasound transducer system for tissue characterization-A pilot study

Noninvasive diagnosis of bone density and mechanical properties using non-radiation imaging modality is an emerging area with promising in early prediction of osteopenia and treatment effectiveness in the clinic and functional disuse,i.e.,long-term bedrest and space mission.Advances in quantitative ultrasound have shown advantages in measuring both bone density and mechanical strength,non-radiation,imaging capability,and easy to use.The challenge that remained is the poor penetration of ultrasound signals passing through trabecular and cortical bones and acoustic energy scattering.A new scanning confocal ultrasound technology is developed in this lab to detect the alteration of bone to provide diagnostic results in bone density and structure properties.A software-controlled flexible ultrasound system with 2-D dual array transducer is developed and proposed for the purpose of noninvasive bone density diagnosis and assessment of bone loss.Transmitting(Tx)transducer elements are divided into sub-blocks to excite the ultrasound signals in sequence to decrease the system complexity while maintaining beam pattern properties by the signal processing procedure at receiving(Rx)side.Apodization is also applied to reduce acoustic side lobes and to make the resolution in the ultrasound field of view(FOV)more uniform.This study may provide basic understanding of modulated confocal ultrasound beam forming for tissue characterization,such as trabecular bone structual and strength properties.