The massive and continuous spread of COVID-19 has motivated researchers around the world to intensely explore,understand,and develop new techniques for diagnosis and treatment.Although lung ultrasound imaging is a les...The massive and continuous spread of COVID-19 has motivated researchers around the world to intensely explore,understand,and develop new techniques for diagnosis and treatment.Although lung ultrasound imaging is a less established approach when compared to other medical imaging modalities such as X-ray and CT,multiple studies have demonstrated its promise to diagnose COVID-19 patients.At the same time,many deep learning models have been built to improve the diagnostic efficiency of medical imaging.The integration of these initially parallel efforts has led multiple researchers to report deep learning applications in medical imaging of COVID-19 patients,most of which demonstrate the outstanding potential of deep learning to aid in the diagnosis of COVID-19.This invited review is focused on deep learning applications in lung ultrasound imaging of COVID-19 and provides a comprehensive overview of ultrasound systems utilized for data acquisition,associated datasets,deep learning models,and comparative performance.展开更多
The objective of this study is to demonstrate that tensile stress resulting due to applied force on cornea can be accurately measured by using a time-domain common-path optical coherence tomography （OCT） system with...The objective of this study is to demonstrate that tensile stress resulting due to applied force on cornea can be accurately measured by using a time-domain common-path optical coherence tomography （OCT） system with an external contact reference. The unique design of the common-path OCT is utilized to set up an imaging system in which a chicken eye is placed adjacent to a glass plate serving as the external reference plane for the imaging system. As the force is applied to the chicken eye, it presses against the reference glass plate. The modified OCT image obtained is used to calculate the size of contact area, which is then used to derive the tensile stress on the cornea. The drop in signal levels upon contact of reference glass plate with the tissue are extremely sharp because of the sharp decline in reference power levels itself, thus providing us with an accurate measurement of contact area. The experimental results were in good agreement with the numerical predictions. The results of this study might be useful in providing new insights and ideas to improve the precision and safety of currently used ophthalmic surgical techniques. This research outlines a method which could be used to provide high resolution OCT images and a precise feedback of the forces applied to the cornea simultaneously.展开更多
Objective.Atherosclerosis is a leading cause of mortality and morbidity.Optical endoscopy,ultrasound,and X-ray offer minimally invasive imaging assessments but have limited sensitivity for characterizing disease and t...Objective.Atherosclerosis is a leading cause of mortality and morbidity.Optical endoscopy,ultrasound,and X-ray offer minimally invasive imaging assessments but have limited sensitivity for characterizing disease and therapeutic response.Magnetic resonance imaging(MRI)endoscopy is a newer idea employing tiny catheter-mounted detectors connected to the MRI scanner.It can see through vessel walls and provide soft-tissue sensitivity,but its slow imaging speed limits practical applications.Our goal is highresolution MRI endoscopy with real-time imaging speeds comparable to existing modalities.Methods.Intravascular(3 mm)transmit-receive MRI endoscopes were fabricated for highly undersampled radial-projection MRI in a clinical 3-tesla MRI scanner.Iterative nonlinear reconstruction was accelerated using graphics processor units connected via a single ethernet cable to achieve true real-time endoscopy visualization at the scanner.MRI endoscopy was performed at 6-10 frames/sec and 200-300μm resolution in human arterial specimens and porcine vessels ex vivo and in vivo and compared with fully sampled 0.3 frames/sec and three-dimensional reference scans using mutual information(MI)and structural similarity(3-SSIM)indices.Results.High-speed MRI endoscopy at 6-10 frames/sec was consistent with fully sampled MRI endoscopy and histology,with feasibility demonstrated in vivo in a large animal model.A 20-30-fold speed-up vs.0.3 frames/sec reference scans came at a cost of~7%in MI and~45%in 3-SSIM,with reduced motion sensitivity.Conclusion.High-resolution MRI endoscopy can now be performed at frame rates comparable to those of X-ray and optical endoscopy and could provide an alternative to existing modalities,with MRI’s advantages of soft-tissue sensitivity and lack of ionizing radiation.展开更多
White matter hyperintensities(WMHs)on fluid-attenuated inversion recovery(FLAIR)images are imaging features in various neurological diseases and essential markers for clinical impairment and disease progression.WMHs a...White matter hyperintensities(WMHs)on fluid-attenuated inversion recovery(FLAIR)images are imaging features in various neurological diseases and essential markers for clinical impairment and disease progression.WMHs are associated with brain aging and pathological changes in the human brain,such as in Alzheimer’s disease(AD)[1],Parkinson’s disease(PD)[2],cerebral small vessel disease(SVD)[3],multiple sclerosis(MS)[4].展开更多
Up-conversion photoluminescence(UCPL)refers to the elementary process where low-energy photons are converted into high-energy ones via consecutive interactions inside a medium.When additional energy is provided by int...Up-conversion photoluminescence(UCPL)refers to the elementary process where low-energy photons are converted into high-energy ones via consecutive interactions inside a medium.When additional energy is provided by intermnal thermal energy in the form of lttice vibrations(phonons),the process is called phonon-assisted UCPL.Here,we report the exceptionally large phonon-assisted energy gain of up to^8kgT(kg is Boltzmann constant,T is temperature)on all-inorganic lead halide perovskite semiconductor colloidal nanocrystals that goes beyond the maximum capabilty of only harvesting optical phonon modes.By systematic optical study in combination with a statistical probability model,we explained the nontrivial phonon-assisted UCPL process in perovskites nanocrystals,where in addition to the strong electron-phonon(light-matter)coupling,other nonlinear processes such as phonon-phonon(matter-matter)interaction also effectively boost the up-conversion efficiency.展开更多
We demonstrate Fourier domain optical coherenc tomography （FDOCT） monitoring and guiding of quantum cascade laser （QCL） therapy. The laser therapy is performed with a 6.1-tim mid-IR QCL and it involves both tissue...We demonstrate Fourier domain optical coherenc tomography （FDOCT） monitoring and guiding of quantum cascade laser （QCL） therapy. The laser therapy is performed with a 6.1-tim mid-IR QCL and it involves both tissue coagulation or ablation. FDOCT allows real-time monitoring that minimize unnecessary damage to the surrounding tissues. We perform lipid phantom tissue ablation, chicken egg yolk coagulation, and tissue and blood vessel coagulation on chicken embryo to validate the FDOCT guiding quantum cascade laser therapy.展开更多
An integrated microball lens fiber catheter probe is demonstrated, which has better lateral resolution and longer working distance than a corresponding bare fiber probe with diverging beam for Fourier domain optical c...An integrated microball lens fiber catheter probe is demonstrated, which has better lateral resolution and longer working distance than a corresponding bare fiber probe with diverging beam for Fourier domain optical coherence tomography （FDOCT）. Simulation results are shown to gain the effect of the distance between the mieroball lens and the bare fiber to the focusing plane and beam width. The freedom of modifying the working distance and lateral resolution is shown. This is achieved by changing the gap distance between the single-mode fiber and the microball lens within the packaged surgical needle catheter without using an additional beam expander having a fixed length. The probe successfully acquired crosssectional images of ocular tissues from an animal sample with the proposed miniaturized imaging probe.展开更多
We demonstrate the subsurface imaging of an articular cartilage using Fourier-domain common-path optical coherence tomography. The bare fiber probe integrated with a hypodermic needle provides the rigidness required t...We demonstrate the subsurface imaging of an articular cartilage using Fourier-domain common-path optical coherence tomography. The bare fiber probe integrated with a hypodermic needle provides the rigidness required to perform lateral scanning with less microscale bending. By submerging both the probe and the specimen into saline solution, we not only reduce the beam divergence, but also increase the signal-to-noise ratio compared with the measurement in free space. Our system can differentiate the characteristic cartilage zones and identity various micro-structured defects in an ex vivo chicken knee cartilage, thus demonstrating that it could be used to conduct early arthritis diagnosis and intraoperative endo-microscopy.展开更多
We experimentally and theoretically investigated the performance of a fiber-optic based Fourier-domain common-path optical coherence tomography （OCT）. The fiber-optic common-path OCT operated at the 840-nm center wa...We experimentally and theoretically investigated the performance of a fiber-optic based Fourier-domain common-path optical coherence tomography （OCT）. The fiber-optic common-path OCT operated at the 840-nm center wavelength. The resolution of the system was 8.8 μm （in air） and the working depth using a bare fiber probe was approximately 1.5 mm. The signal-to-noise ratio （SNR） of the system was analyzed. OCT images obtained by the system were also presented.展开更多
文摘The massive and continuous spread of COVID-19 has motivated researchers around the world to intensely explore,understand,and develop new techniques for diagnosis and treatment.Although lung ultrasound imaging is a less established approach when compared to other medical imaging modalities such as X-ray and CT,multiple studies have demonstrated its promise to diagnose COVID-19 patients.At the same time,many deep learning models have been built to improve the diagnostic efficiency of medical imaging.The integration of these initially parallel efforts has led multiple researchers to report deep learning applications in medical imaging of COVID-19 patients,most of which demonstrate the outstanding potential of deep learning to aid in the diagnosis of COVID-19.This invited review is focused on deep learning applications in lung ultrasound imaging of COVID-19 and provides a comprehensive overview of ultrasound systems utilized for data acquisition,associated datasets,deep learning models,and comparative performance.
文摘The objective of this study is to demonstrate that tensile stress resulting due to applied force on cornea can be accurately measured by using a time-domain common-path optical coherence tomography （OCT） system with an external contact reference. The unique design of the common-path OCT is utilized to set up an imaging system in which a chicken eye is placed adjacent to a glass plate serving as the external reference plane for the imaging system. As the force is applied to the chicken eye, it presses against the reference glass plate. The modified OCT image obtained is used to calculate the size of contact area, which is then used to derive the tensile stress on the cornea. The drop in signal levels upon contact of reference glass plate with the tissue are extremely sharp because of the sharp decline in reference power levels itself, thus providing us with an accurate measurement of contact area. The experimental results were in good agreement with the numerical predictions. The results of this study might be useful in providing new insights and ideas to improve the precision and safety of currently used ophthalmic surgical techniques. This research outlines a method which could be used to provide high resolution OCT images and a precise feedback of the forces applied to the cornea simultaneously.
基金supported by grants R01 EB007829 from the National Institutes of Health,Siemens Medical SystemsRussell H Morgan Professorship in Radiology。
文摘Objective.Atherosclerosis is a leading cause of mortality and morbidity.Optical endoscopy,ultrasound,and X-ray offer minimally invasive imaging assessments but have limited sensitivity for characterizing disease and therapeutic response.Magnetic resonance imaging(MRI)endoscopy is a newer idea employing tiny catheter-mounted detectors connected to the MRI scanner.It can see through vessel walls and provide soft-tissue sensitivity,but its slow imaging speed limits practical applications.Our goal is highresolution MRI endoscopy with real-time imaging speeds comparable to existing modalities.Methods.Intravascular(3 mm)transmit-receive MRI endoscopes were fabricated for highly undersampled radial-projection MRI in a clinical 3-tesla MRI scanner.Iterative nonlinear reconstruction was accelerated using graphics processor units connected via a single ethernet cable to achieve true real-time endoscopy visualization at the scanner.MRI endoscopy was performed at 6-10 frames/sec and 200-300μm resolution in human arterial specimens and porcine vessels ex vivo and in vivo and compared with fully sampled 0.3 frames/sec and three-dimensional reference scans using mutual information(MI)and structural similarity(3-SSIM)indices.Results.High-speed MRI endoscopy at 6-10 frames/sec was consistent with fully sampled MRI endoscopy and histology,with feasibility demonstrated in vivo in a large animal model.A 20-30-fold speed-up vs.0.3 frames/sec reference scans came at a cost of~7%in MI and~45%in 3-SSIM,with reduced motion sensitivity.Conclusion.High-resolution MRI endoscopy can now be performed at frame rates comparable to those of X-ray and optical endoscopy and could provide an alternative to existing modalities,with MRI’s advantages of soft-tissue sensitivity and lack of ionizing radiation.
基金supported by the Fundamental Research Funds for the Central Universities(2022CX1100)the Beijing Municipal Natural Science Foundation(JQ20035)+1 种基金the National Natural Science Foundation of China(81870958 and 81571631)the Special Fund of the Pediatric Medical Coordinated Development Center of Beijing Hospitals Authority(XTYB201831)。
文摘White matter hyperintensities(WMHs)on fluid-attenuated inversion recovery(FLAIR)images are imaging features in various neurological diseases and essential markers for clinical impairment and disease progression.WMHs are associated with brain aging and pathological changes in the human brain,such as in Alzheimer’s disease(AD)[1],Parkinson’s disease(PD)[2],cerebral small vessel disease(SVD)[3],multiple sclerosis(MS)[4].
基金the Singapore National Research Foundation through the NRF Investigatorship Award(No.NRF-NRFI2015-03)the Singapore Ministry of Education via AcRF Tier 3 Programme(No.MOE2018-T3-1-002),Tier 2 grant(No.MOE2018-T2-2-068)and Tier 1 grants(Nos.RG103/15 and RG113/16)A.G.D.A.gratefully acknowledges the financial support of the Presidential Postdoctoral Fellowship program of the Nanyang Technological University
文摘Up-conversion photoluminescence(UCPL)refers to the elementary process where low-energy photons are converted into high-energy ones via consecutive interactions inside a medium.When additional energy is provided by intermnal thermal energy in the form of lttice vibrations(phonons),the process is called phonon-assisted UCPL.Here,we report the exceptionally large phonon-assisted energy gain of up to^8kgT(kg is Boltzmann constant,T is temperature)on all-inorganic lead halide perovskite semiconductor colloidal nanocrystals that goes beyond the maximum capabilty of only harvesting optical phonon modes.By systematic optical study in combination with a statistical probability model,we explained the nontrivial phonon-assisted UCPL process in perovskites nanocrystals,where in addition to the strong electron-phonon(light-matter)coupling,other nonlinear processes such as phonon-phonon(matter-matter)interaction also effectively boost the up-conversion efficiency.
基金supported by NSF ERC(MIRTHE)partially supported by China Scholarship Council(CSC)
文摘We demonstrate Fourier domain optical coherenc tomography （FDOCT） monitoring and guiding of quantum cascade laser （QCL） therapy. The laser therapy is performed with a 6.1-tim mid-IR QCL and it involves both tissue coagulation or ablation. FDOCT allows real-time monitoring that minimize unnecessary damage to the surrounding tissues. We perform lipid phantom tissue ablation, chicken egg yolk coagulation, and tissue and blood vessel coagulation on chicken embryo to validate the FDOCT guiding quantum cascade laser therapy.
基金supported by the World Class University Program funded by the Ministry of Education, Science, and Technology through the National Research Foundation of Korea (No. R31-10008)supported in part by NIH (No. BRP 1R01 EB 007969- 01)
文摘An integrated microball lens fiber catheter probe is demonstrated, which has better lateral resolution and longer working distance than a corresponding bare fiber probe with diverging beam for Fourier domain optical coherence tomography （FDOCT）. Simulation results are shown to gain the effect of the distance between the mieroball lens and the bare fiber to the focusing plane and beam width. The freedom of modifying the working distance and lateral resolution is shown. This is achieved by changing the gap distance between the single-mode fiber and the microball lens within the packaged surgical needle catheter without using an additional beam expander having a fixed length. The probe successfully acquired crosssectional images of ocular tissues from an animal sample with the proposed miniaturized imaging probe.
基金supported by the second stage of the Brain Korea 21 Project in 2009a Korean Science and Engineering Foundation(KOSEF) grant funded by the Korea Government(MEST)(No.R01-2008-000-20089-0).
文摘We demonstrate the subsurface imaging of an articular cartilage using Fourier-domain common-path optical coherence tomography. The bare fiber probe integrated with a hypodermic needle provides the rigidness required to perform lateral scanning with less microscale bending. By submerging both the probe and the specimen into saline solution, we not only reduce the beam divergence, but also increase the signal-to-noise ratio compared with the measurement in free space. Our system can differentiate the characteristic cartilage zones and identity various micro-structured defects in an ex vivo chicken knee cartilage, thus demonstrating that it could be used to conduct early arthritis diagnosis and intraoperative endo-microscopy.
文摘We experimentally and theoretically investigated the performance of a fiber-optic based Fourier-domain common-path optical coherence tomography （OCT）. The fiber-optic common-path OCT operated at the 840-nm center wavelength. The resolution of the system was 8.8 μm （in air） and the working depth using a bare fiber probe was approximately 1.5 mm. The signal-to-noise ratio （SNR） of the system was analyzed. OCT images obtained by the system were also presented.
