Hepatocellular carcinoma Liver Imaging Reporting and Data Systems treatment response assessment: Lessons learned and future directions

Hepatocellular carcinoma(HCC)is a leading cause of morbidity and mortality worldwide,with rising clinical and economic burden as incidence increases.There are a multitude of evolving treatment options,including locoregional therapies which can be used alone,in combination with each other,or in combination with systemic therapy.These treatment options have shown to be effective in achieving remission,controlling tumor progression,improving disease free and overall survival in patients who cannot undergo resection and providing a bridge to transplant by debulking tumor burden to downstage patients.Following locoregional therapy(LRT),it is crucial to provide treatment response assessment to guide management and liver transplant candidacy.Therefore,Liver Imaging Reporting and Data Systems(LI-RADS)Treatment Response Algorithm(TRA)was created to provide a standardized assessment of HCC following LRT.LIRADS TRA provides a step by step approach to evaluate each lesion independently for accurate tumor assessment.In this review,we provide an overview of different locoregional therapies for HCC,describe the expected post treatment imaging appearance following treatment,and review the LI-RADS TRA with guidance for its application in clinical practice.Unique to other publications,we will also review emerging literature supporting the use of LI-RADS for assessment of HCC treatment response after LRT.

Smartphone microendoscopy for high resolution fluorescence imaging

High resolution optical endoscopes are increasingly used in diagnosis of various medical condi-tions of internal organs,such as the cervix and gastrointestinal(GI)tracts,but they are too expensive for use in resource poor settings.On the other hand,smartphones with high resolution cameras and Internet access have become more affordable,enabling them to difuse into most rural areas and developing countries in the past decade.In this paper,we describe a smartphone microendoscope that can take fuorescence images with a spatial resolution of 3.1 pum.Images collected from ex vivo,in vnitro and in vivo samples using the device are also presented.The compact and cost-effective smart phone microendosoope may be envisaged as a powerful tool for detecting pre cancerous lesions of internal organs in low and middle income countries(LMICs).

Passive ranging and a three-dimensional imaging system through wavefront coding

A single-image passive ranging and three-dimensional（3 D） imaging system with chiral phase encoding was proposed in 2011 [Opt. Lett. 36, 115（2011）]. A new theoretical analysis of the system in space domain is presented in this paper. We deduce the analytic relationships between the object distance and the point spread function, and between the object distance and the encoded image, respectively. Both the point spread function and the processed spectrum of the encoded image have two spots, which will rotate with the variation of the object distance. Then the depth map is extracted from the encoded image and it can be used to set up 3 D images. The theoretical analysis is verified by a wavefront coding system with a chiral phase which is generated by a phase-only liquid-crystal spatial light modulator. The phase generated by the liquid-crystal spatial light modulator is more flexible than the fixed phase mask and can be adjusted in real time. It is especially suitable for observing the object with a large depth of field.

Optimization method to suppress background for imaging multiple planes

3D live imaging is important for better understanding of biological processes.To obtain biological dynamic process,high imaging speed is required.In order to improve speed in 3D live imaging,simultaneous imaging of multiple planes throughout a 3D volume has been proposed.However,a main disadvantage of this method is the cross-talk from neighboring imaging planes.In this paper,we propose an optimization method to suppress background from neighboring imaging planes.A D-aperture is used to generate multiple light sheets.An optimization method to suppress background is presented.The simulation results demonstrated that the proposed method can be used to suppress the effectiveness of background from neighboring light sheets.

NEAR-INFRARED IMAGING SENSOR WITH IMPROVED HANDLING AND DIRECT LOCALIZATION IN SIMULTANEOUS MAGNETIC RESONANCE IMAGING MEASUREMENTS

We present a novel optical sensor to acquire simultaneously functional near-infrared imaging(fNIRI)and functional magnetic resonance imaging(fMRI)data with an improved handling and direct localization in the MRI compared to available sensors.Quantitative phantom and interference measurements showed that both methods can be combined without reciprocal adverse effects.The direct localization of the optical sensor on MR images acquired with a T1-weighted echo sequence simplifies the co-registration of NIRI and MRI data.In addition,the optical sensor is simple to attach,which is crucial for measurements on vulnerable subjects.The fNIRI and T2^(*)-weighted fMRI data of a cerebral activation were simultaneously acquired proving the practicability of the setup.

Characteristics of the CsI:Tl Scintillator Crystal for X-Ray Imaging Applications

Scintillators are high-density luminescent materials that convert X-rays to visible light. Thallium doped cesium iodide (CsI:Tl) scintillation materials are widely used as converters for X-rays into visible light, with very high conversion efficiency of 64.000 optical photons/MeV. CsI:Tl crystals are commercially available, but, the possibility of developing these crystals into different geometric shapes, meeting the need for coupling the photosensor and reducing cost, makes this material very attractive for scientific research. The objective of this work was to study the feasibility of using radiation sensors, scintillators type, developed for use in imaging systems for X-rays. In this paper, the CsI:Tl scintillator crystal with nominal concentration of the 10-3 M was grown by the vertical Bridgman technique. The imaging performance of CsI:Tl scintillator was studied as a function of the design type and thickness, since it interferes with the light scattering and, hence, the detection efficiency plus final image resolution. The result of the diffraction X-ray analysis in the grown crystals was consistent with the pattern of a face-centered cubic (fcc) crystal structure. Slices 25 × 2 × 3 mm3 (length, thickness, height) of the crystal and mini crystals of 1 × 2 × 3 mm3 (length, thickness, height) were used for comparison in the imaging systems for X-rays. With these crystals scintillators, images of undesirable elements, such as metals in food packaging, were obtained. One-dimensional array of photodiodes and the photosensor CCD (Coupled Charge Device) component were used. In order to determine the ideal thickness of the slices of the scintillator crystal CsI:Tl, Monte Carlo method was used.

Depth perception on fundus images using a single-channel stereomicroscopy

Typical fundus photography produces a two-dimensional image.This makes it difficult to observe the microvascular and neural abnormalities,because the depth of the image is missing.To provide depth appreciation,we develop a single-channel stereoscopic fundus video imaging sys-tem based on a rotating refractor.With respect to the pupil center,the rotating refractor laterally displaces the optical path and the illumination.This allows standard monocular fundus cameras to generate stereo-parallax and image disparity through sequential image acquisition.We opti-mize our imaging system,characterize the stereo-base,and image an eyeball model and a rabbit eye.When virtual realities are considered,our imaging system can be a simple yet efficient technique to provide depth perception in a virtual space that allows users to perceive abnor-malities in the eye fundus.

IMAGE IMPROVEMENT IN THE WAVELET DOMAIN FOR OPTICAL COHERENCE TOMOGRAMS

In this paper,an image processing method for improving the quality of optical coherence tomography(OCT)images is proposed.Wavelet denoising based on context modeling and contrast enhancement by means of the contrast measure in the wavelet domain is carried out on the OCT images in succession.Three parameters are selected to assess the effectiveness of the method.It is shown from the results that the proposed method can not only enhance the contrast of images,but also improve signal-to-noise ratio.Compared with two other typical algorithms,it has the best visual effect.

Biomedical applications of Jones-matrix tomography to polycrystalline films of biological fuids

Algorithms for reconstruction of linear and circular birefringence-dichroism of optically thin anisotropic biological layers are presented.The technique of Jones matrix tomography of poly-crystalline films of biological fuids of various human organs has been developed and experimentally tested.The coordinate distributions of phase and amplitude anisotropy of bile films and synovial fuid taken from the knee joint are determined and statistically analyzed.Criteria(statistical moments of 3rd and 4th orders)of differential diagnostics of early stages of cholelithiasis and septic arthritis of the knee joint with excellent balanced accuracy were determined.Data on the diagnostic fficiency of the Jones matrix tomography method for polyerystalline plasma(liver disease),urine(albuminuria)and cytological smears(cervical cancer)are presented.

X-ray photon counting detectors for preclinical and clinical applications

Photon counting detectors(PCDs) have attained w ide use in X-ray imaging for various preclinical and clinical applications in the past decade. This paper briefly review s the preclinical and clinical applications of PCDs based X-ray imaging systems.Starting with an introduction of X-ray single photon detection mechanism,the brief review first describes tw o major advantages of utilizing PCDs: photon energy resolving capability and electronic noise elimination. Compared to energy integrating detectors(EIDs),the aforementioned advantages make PCDs more favorable in X-ray imaging with profound benefits such as enhanced tissue contrast,decreased image noise,increased signal to noise ratio,decreased radiation dose to the small animals and patients,and more accurate material decomposition. The utilizations of PCDs in X-ray projection radiography and computed tomography(CT)including micro-CT,dedicated breast CT,K-edge CT,and clinical CT are then review ed for the imaging applications ranging from phantoms to small animals and humans. In addition,optimization methods aiming to improve the imaging performance using PCDs are briefly review ed. PCDs are not flaw less though,and their limitations are also discussed in this review. Nevertheless,PCDs may continuously contribute to the advancement of X-ray imaging techniques in future preclinical and clinical applications.

An image compression method for space multispectral time delay and integration charge coupled device camera

Multispectral time delay and integration charge coupled device （TDICCD） image compression requires a low- complexity encoder because it is usually completed on board where the energy and memory are limited. The Consultative Committee for Space Data Systems （CCSDS） has proposed an image data compression （CCSDS-IDC） algorithm which is so far most widely implemented in hardware. However, it cannot reduce spectral redundancy in mukispectral images. In this paper, we propose a low-complexity improved CCSDS-IDC （ICCSDS-IDC）-based distributed source coding （DSC） scheme for multispectral TDICCD image consisting of a few bands. Our scheme is based on an ICCSDS-IDC approach that uses a bit plane extractor to parse the differences in the original image and its wavelet transformed coefficient. The output of bit plane extractor will be encoded by a first order entropy coder. Low-density parity-check-based Slepian-Wolf （SW） coder is adopted to implement the DSC strategy. Experimental results on space multispectral TDICCD images show that the proposed scheme significantly outperforms the CCSDS-IDC-based coder in each band.

Three-dimensional imaging interferometric synthetic aperture ladar

A monostatic strip-map mode interferometric synthetic aperture ladar （SAL） is reported. Using a chirped laser of about 5 mW at 1550 nm wavelength as the illumination source and two cross-track receiving apertures with a baseline of 1.6 mm, the ladar can generate both well-focused two-dimensional SAL images without adopting phase error removing techniques and three-dimensional images by interferometric SAL techniques. Detailed results are illustrated for retro-reflective or diffusive targets at a distance of 2.4 m.

Sub-pixel processing for super-resolution scanning imaging system with fiber bundle coupling

A multilayer fiber bundle is used to couple the image in a remote sensing imaging system. The object image passes through all layers of the fiber bundle in micro-scanning mode. The malposition of adjacent layers arranged in a hexagonal pattern is at sub-pixel scale. Therefore, sub-pixel processing can be applied to improve the spatial resolution. The images coupled by the adjacent layer fibers are separated, and subsequently, the intermediate image is obtained by histogram matching based on one of the separated image called base image. Finally, the intermediate and base images are processed in the frequency domain. The malposition of the adjacent layer fiber is converted to the phase difference in Fourier transform. Considering the limited sensitivity of the experimental instruments and human sight, the image is set as a band-limited signal and the interpolation function of image fusion is found. The results indicate that a super-resolution image with ultra-high spatial resolution is obtained.

A Novel Imaging Algorithm for Airborne Bistatic Squint SAR with Unparallel Trajectories

A novel analytical imaging algorithm is proposed for the strip-map mode of airborne bistatic squint SAR with unparallel trajectories. The algorithm derives the two-dimensional （2D） spectrum formula of the point target echo by using the contribution ratios of Doppler frequency modulation ratios of the transmitter and receiver as the weighting coefficients. Through decoupling the target position against the tracks of the transmitter and receiver, the range parameter and the azimuth one in the spectrum formula are separated. In 2D frequency domain, 2D Chirp-Z transform （2D-CZT） is applied to correcting the migrations of the echo along the range and azimuth after the bistatic deformation term has been compensated, so the target image is precisely focused. The advantage of the algorithm is easy to be expanded to the virtual wide swath by blocking the radar data along the range and azimuth to limit the 2D residual migrations. Simulation results confirm the validity of the 2D-CZT algorithm.

Control and image processing for streak tube imaging lidar based on VB and MATLAB

In this letter, we develope a control and image processing system for Streak Tube Imaging Lidar （STIL）. In the system, the data acquisition card control and the software interface are programmed in Visual Basic （VB） while the image processing is finished by MATLAB. A STIL imaging experiment is carried out in the laboratory. We obtained the intensity and range images of targets with pseudo color by image processing and reconstruction for a set of raw streak images of targets at different distances acquired by STIL. The range resolution is better than 2 centimeters.

Wide field-of-view foveated imaging system

We have designed and demonstrated a simple, wide field-of-view （FOV = 60°） foveated imaging system utilizing a deformable mirror. The deformable mirror is used to dynamically correct the off-axis aberrations that limit the useful FOV of the system. The system mimics the operation of human eye through creating an image with variable spatial resolution and can be made significantly smaller and more compact than a conventional wide FOV system. Experiments show that this system can be used in many areas where size, weight, and data transmission bandwidth are critical.

Design of a freeform,dual fields-of-view,dual focal lengths,off-axis three-mirror imaging system with a point-by-point construction-iteration process

In this Letter, we propose a novel configuration and design method of freeform, dual fields-of-view （FOVs）, dual focal lengths, off-axis three-mirror zoom imaging systems. The switch of the two zooms is achieved by rotating a single mirror element. The design of a freeform, dual focal lengths zoom system is realized by a point-by-point design approach for the first time to our knowledge. This method enables the direct design of freeform surfaces from initial planes using given system specifications and configuration, and the designed system can be taken as a good starting point for further optimization. A freeform, dual FOVs, dual focal lengths, off-axis three-mirror zoom system is demonstrated. The F-numbers of the two zooms are 2 and 2.4. The dual FOVs are 3° × 3° and 2.5° × 2.5°. After final o^timization, both of the zooms achieve high performances.

Investigations of range accuracy for long-range three-dimensional active imaging

Distance resolutions and noises are analyzed experimentally for long-range three-dimensional （3D） active imaging systems that have signal-to-noise ratios （SNRs） more optimal than 30：1. Findings indicate that the photon shot noise primarily determines the SNR. However, the active imaging method, which has a relatively low SNR, generates a relatively high distance resolution. To explain this phenomenon, a theory in which the distance resolution of 3D active imaging systems is determined by both the photon shot noise and the subinterval width is developed. Theoretical and experimental results differ by less than 4%.

Analytical and experimental demonstration of depth of field extension for incoherent imaging system with a standard sinusoidal phase mask

The wavefront coding technique is used to enlarge the depth of field（DOF）of incoherent imaging systems. The key to wavefront coding lies in the design of suitable phase masks.To date,numerous kinds of phase masks are proposed.However,further understanding is needed regarding phase mask with its phase function being in a standard sinusoidal form.Therefore,the characteristics of such a phase mask are studied in this letter.Deriving the defocused optical transfer function（OTF）analytically proves that the standard sinusoidal phase mask is effective in extending the DOF,and actual experiments confirm the numerical results.At the same time,with the Fisher information as a criterion,the standard sinusoidal phase mask shows a higher tolerance to focus errors（especially severe focus errors）than the classical cubic phase mask.

Power efficiency of time-stretch imaging system by using parallel interleaving detection

A 38.88 MHz time-stretch line-scan imaging system with parallel interleaving detection is experimentally dem- onstrated. Since only half-chromatic dispersion is used to stretch optical pulses for wavelength-to-time mapping, the power efficiency is significantly improved by 6.5 dB. Furthermore, the theoretical analysis indicates that the power loss can be efficiently reduced for scan rates less than 100 MHz. In addition, a mathematical model for signal-to-noise evaluation is derived, including amplified spontaneous emission noise in the power compensation. Thanks to the improvement of the power efficiency by using parallel interleaving detection, the signal quality is enhanced.