Defining a normal finger web in children

Initial experience with an electronic radial array echoendoscope: Randomized comparison with a mechanical sector scanning echoendoscope in humans

To compare the subjective image quality of the newer generation Schick CDR detector employing complementary metal oxide semiconductor (CMOS) technology with images using the earlier generation charge-coupled device (CCD) Schick CDR detector. All radiographic images were made using the same formalin-fixed adult cadaver maxilla with surrounding natural soft tissues in place. The X-ray generator used was a Villa Sistemi Medicali Diamatic srl AP/Explor X operated at 70 kVp and 8 mA. The source-to-detector distance was set at 38 cm and an optical bench was used to ensure reproducible beam geometry. A range of exposures was applied for both detectors. A panel of nine dentists independently observed and evaluated images made at each exposure. For both detectors, the three images ranked highest were randomized for re-evaluation in panels of six images. Each image was repeated randomly a total of 10 times. Features chosen as observation points were: (1) proximal dental caries; (2) gingival soft tissues; (3) cortical bone; (4) root canal space; (5) root apices; (6) periodontal ligament space; and (7) endodontic instrument tip clarity. Comparisons were made by use of odds ratio analysis applying a 95% confidence level. Interrater and intrarater reliabilities were computed to assess consistency in observer ratings. The CMOS sensor was rated as outperforming its CCD predecessor for depiction of cortical bone and root apices; the CCD detector was only rated superior for depiction of root canal space. No significant difference was found between the two detectors in perceived depiction of proximal dental caries, gingival soft tissues, periodontal ligament space or endodontic instruments. Combining rating scores from each of the tasks, CMOS and CCD detectors had a similar proportion of image ratings of excellent, acceptable and poor. Regarding subjective image quality, the Schick CMOS and CCD detectors were perceived to produce radiographic images of similar overall quality.

Surveying and monitoring the dynamic morphology of intertidal areas is a logistically challenging and expensive task, due to their large area and complications associated with access. This thesis describes a contribution to the nearshore survey industry; an innovative methodology is developed and subsequently applied to marine radar image data in order to map topography within the intertidal area. This new method of intertidal topographical mapping has a reasonable spatial resolution (5 m) and operates over a large radial range (~4 km) with the required temporal resolution to observe both event-based and long-term morphological change (currently bi-weekly surveys). This study uses nearly three years of radar image data collected during 2006-2009 from an installation on Hilbre Island at the mouth of the Dee estuary, northwest UK. The development of the novel 'radar waterline method' builds on previous waterline techniques and improves upon them by moving the analysis from the spatial to the temporal domain, making the analysis extremely robust and more resilient to poor quality image data. Results from radar topographical surveys are compared to those of a LiDAR survey during October 2006. The differences compare favourably across large areas of the intertidal zone, within the first kilometre 97% of radar-derived elevations lie within 1 m of LiDAR estimations. Concentrations of poor estimations are seen in areas that are shown to be shadowed from the radar antenna or suffering from pooling water during the ebb tide. The full three-year dataset is used to analyse changing intertidal morphology over that time period using radar-derived surveys generated every two weeks. These surveys are used to perform an analysis of changing sediment volume and mean elevation, giving an indication of beach 'health' and revealing a seasonal trend of erosion and accretion at several sites across the Dee estuary. The ability of the developed technique to resolve morphological changes resulting from storm events is demonstrated and a quantification of that impact is provided. The application of the technique to long-range (7.5 km) marine radar data is demonstrated in an attempt to test the spatial and operational limitations of this new method. The development of a mobile radar survey platform, the Rapidar allows remote areas to be surveyed and provides a platform for potential integration with other survey instruments. A description of the potential application to coastal management and monitoring is presented. Areas of further work intended to improve vertical elevation accuracy and robustness are proposed. This contribution provides a useful tool for coastal scientists, engineers and decision-makers interested in the management of coastal areas that will form part of integrated coastal management and monitoring operations. This method presents several key advantages over traditional survey techniques including; the large area of operation and temporal resolution of repeat surveys, it is limited primarily by topographical shadowing and low wind conditions limiting data collection.

This study demonstrates a novel PROPELLER (periodically rotated overlapping parallel lines with enhanced reconstruction) pulse sequence, termed Steer-PROP, based on gradient and spin echo (GRASE), to reduce the imaging times and address phase errors inherent to GRASE. The study also illustrates the feasibility of using Steer-PROP as an alternative to single-shot echo planar imaging (SS-EPI) to produce distortion-free diffusion images in all imaging planes. Steer-PROP uses a series of blip gradient pulses to produce N (N = 3-5) adjacent k-space blades in each repetition time, where N is the number of gradient echoes in a GRASE sequence. This sampling strategy enables a phase correction algorithm to systematically address the GRASE phase errors as well as the motion-induced phase inconsistency. Steer-PROP was evaluated on phantoms and healthy human subjects at both 1.5T and 3.0T for T2 - and diffusion-weighted imaging. Steer-PROP produced similar image quality as conventional PROPELLER based on fast spin echo (FSE), while taking only a fraction (e.g., 1/3) of the scan time. The robustness against motion in Steer-PROP was comparable to that of FSE-based PROPELLER. Using Steer-PROP, high quality and distortion-free diffusion images were obtained from human subjects in all imaging planes, demonstrating a considerable advantage over SS-EPI. The proposed Steer-PROP sequence can substantially reduce the scan times compared with FSE-based PROPELLER while achieving adequate image quality. The novel k-space sampling strategy in Steer-PROP not only enables an integrated phase correction method that addresses various sources of phase errors, but also minimizes the echo spacing compared with alternative sampling strategies. Steer-PROP can also be a viable alternative to SS-EPI to decrease image distortion in all imaging planes. Magn Reson Med 79:2533-2541, 2018. © 2017 International Society for Magnetic Resonance in Medicine.

Dynamic contrast myocardial perfusion studies may benefit from methods that speed up the acquisition. Unaliasing by Fourier encoding the overlaps using the temporal dimension (UNFOLD), and a similar linear interpolation method have been shown to be effective at reducing the number of phase encodes needed for cardiac wall motion studies by using interleaved sampling and temporal filtering. Here such methods are evaluated in cardiac dynamic contrast studies, with particular regard to the effects of the choice of filter and the interframe motion. Four different filters were evaluated using a motion-free canine study. Full k-space was acquired and then downsampled to allow for a measure of truth. The different filters gave nearly equivalent images and quantitative flow estimates compared to full k-space. The effect of respiratory motion on these schemes was graphically depicted, and the performance of the four temporal filters was evaluated in seven human subjects with respiratory motion present. The four filters provided images of similar quality. However, none of the filters were effective at eliminating motion artifacts. Motion registration methods or motion-free acquisitions may be necessary to make these reduced FOV approaches clinically useful.

Adversarial learning-based camera pose-to-image mapping network for synthesizing new view in real indoor environments

The advent of large aperture arrays, such as the ones currently under construction for the SKA project, allows for observing the Universe in the radio-spectrum at unprecedented resolution and sensitivity. To process the enormous amounts of data produced by these telescopes, scalable software pipelines are required. This paper helps address this by proposing a framework that allows for decentralized radio-interferometric image reconstruction, parallelizing by spatial frequency. This is achieved by creating pseudo-full-resolution problems for each node by using the local visibilities together with previous major cycle reconstructed images from the other nodes. We apply the proposed framework to both multiscale CLEAN and sparsity regularized convex reconstruction and compare them to their serial counterparts across four different data sets of varying properties in the context of two visibility partitions. We found that the parallelization framework allows for significantly improved reconstruction times for images of similar quality. This was especially the case for our larger data sets where we were able to achieve close to the optimal 2× speedup.

A rotating multi-segment slant-hole (RMSSH) collimator is able to provide much higher (approximately 3 times for four-segment collimator with 30 degrees slant angle) sensitivity than a parallel-hole (PH) collimator with the similar spatial resolution for imaging small organs such as the heart and the breast. In this article, the authors evaluated the performance of myocardial perfusion SPECT (MPS) using a RMSSH collimator compared to MPS using the low-energy high-resolution parallel-hole collimators. The authors conducted computer simulation studies using the NURBS-based cardiac-torso phantom, receiver operative characteristic (ROC) analysis using the channelized Hotelling observer, physical phantom experiments, and pilot patient studies to evaluate the performance of MPS using a rotating four-segment slant-hole (R4SSH) collimator with respect to MPS using a PH collimator. In the simulation study, the R4SSH MPS provides images with superior contrast-noise trade-off than those of PH MPS with the same acquisition time. The defect detectability in terms of the largest area under the ROC curve for R4SSH MPS is significantly higher than those of PH MPS with p-values < 0.01. In the phantom experiments, the R4SSH MPS images with 7.5 min acquisition had similar noise level and overall image quality as those of PH MPS with 21 min acquisition. Pilot patient studies showed that with the same acquisition time, the R4SSH SPECT using a single-head camera gave images with similar quality as those of PH SPECT using a dual-head camera. The RMSSH SPECT has a potential to improve the coronary artery disease detection and workflow of SPECT imaging acquisition due to the high sensitivity property of the RMSSH collimator.

ObjectivesTo evaluate the structure and elasticity of the common carotid artery (CCA) in patients with obstructive sleep apnoea syndrome (OSAS) by ultrasound RF-data technology with Quality Intima Media Thickness (QIMT)...

OBJECTIVE: To evaluate clinical images from a prototype ultrahigh resolution (UHR) combined coronal optical coherence tomography/confocal scanning ophthalmoscope (OCT/SLO) and to compare them to standard-resolution OCT/SLO images on the same patients. DESIGN: Cross-sectional pilot-study. PARTICIPANTS: Sixty-six eyes of 42 patients with various macular pathologies, such as age-related macular degeneration, macular edema, macular hole, central serous retinopathy, epiretinal membrane and posterior vitreous traction syndrome. METHODS: Each subject was first scanned with a standard-resolution OCT/SLO that has an axial resolution of ∼10 micron. Immediately following, patients were scanned with the prototype UHR OCT/SLO device. The UHR system employs a compact super luminescent diode (SLD) with a 150 nm bandwidth centered at 890 nm, which allows imaging of the retina with an axial resolution of 3 microns. Both coronal and longitudinal OCT scans were acquired with each system, and compared side-by-side. Scan quality was assessed for the observer's ability to visualize the vitreo-retinal interface and retinal layers – in particular of the outer retina/RPE/choroidal interface, increased discrimination of pathological changes, and better signal intensity. MAIN OUTCOME MEASURES: Ultrahigh and standard-resolution coronal and longitudinal OCT/SLO images of macular pathologies. RESULTS: In the side-by-side comparison with the commercial standard-resolution OCT/SLO images, the scans in the Ultrahigh resolution OCT/SLO images were superior in 85% of cases. Relatively poor quality images were attributed to lower signal-to-noise ratio, limited focusing, or media opacities. Several images that had a better signal intensity in the standard-resolution OCT/SLO system were found to show more retinal detail in the UHR system. In general, intraretinal layers in the UHR OCT/SLO images were better delineated in both coronal and longitudinal scans. Enhanced details were also seen in the outer retina/RPE/choroidal complex. The UHR OCT/SLO system produced better definition of morphological changes in several macular pathologies. CONCLUSIONS: Broadband SLD-based UHR OCT/SLO offers a compact, efficient, and economic enhancement to the currently available clinical OCT imaging systems. UHR OCT/SLO imaging enhanced the quality of the OCT C-scans, facilitated appreciation of vitreo-retinal pathologies, and improved sensitivity to small changes in the retina, and the outer retina/RPE/choroidal interface.

Deep learning image reconstruction (DLIR) is a new reconstruction method for maintaining image quality at reduced radiation dose. The purpose of this study was to compare image quality of reduced-dose DLIR images with the standard-dose adaptive statistical iterative reconstruction (ASIR-V) images in chest CT. Our prospective study included 48 adult patients (30 women and 18 men, mean age ±SD, 49.8 ± 14.3 years) who underwent both the standard-dose CT (SDCT) and low-dose CT (LDCT) on a GE Revolution CT scanner. All patients gave written informed consent. All scans were reconstructed with ASIR-V40%. Additionally, LDCT scans were reconstructed with DLIR with high-setting (DLIR-H) and medium-setting (DLIR-M). Image noise and contrast-noise-ratio (CNR) of thoracic aorta with different reconstruction modes were measured and compared. LDCT reduced radiation dose by 96% compared with SDCT (CTDIvol: 0.54mGy vs 12.46mGy). In LDCT, DLIR significantly reduced image noise compared with the state-of-the-art ASIR-V40% with DLIR-H provided the lowest image noise and highest image quality score. In addition, the image noise, CNR of aorta and overall image quality of the low-dose DLIR-H images did not have significant difference compared with the SDCT ASIR-V40% images (all p > 0.05). DLIR significantly reduces image noise in LDCT chest scans and provides similar image quality as the SDCT ASIR-V images at 4% of the radiation dose. DLIR uses high-quality FBP data to train deep neural networks to learn how to distinguish between signal and noise, and effectively suppresses noise without affecting anatomical and pathological structures. It opens a new era of CT image reconstruction. DLIR significantly reduces image noise and improves image quality compared with ASIR-V40% under same radiation dose condition. DLIR-H achieves similar image quality at 4% radiation dose as ASIR-V40% at standard-dose level in non-contrast chest CT.

BackgroundHigh-spatial resolution magnetic resonance imaging (MRI) is essential for imaging ankle joints. However, the clinical application of fast spin-echo sequences remains limited by their lengthy acquisition time. Artificial intelligence-assisted compressed sensing (ACS) technology has been recently introduced as an integrative acceleration solution. We compared ACS-accelerated 3-T ankle MRI to conventional methods of compressed sensing (CS) and parallel imaging (PI) .MethodsWe prospectively included 2 healthy volunteers and 105 patients with ankle pain. ACS acceleration factors for ankle protocol of T1-, T2-, and proton density (PD)-weighted sequences were optimized in a pilot study on healthy volunteers (acceleration factor 3.2–3.3×). Images of patients acquired using ACS and conventional acceleration methods were compared in terms of acquisition times, signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR), subjective image quality, and diagnostic agreement. Shapiro-Wilk test, Cohen κ, intraclass correlation coefficient, and one-way ANOVA with post hoc tests (Tukey or Dunn) were used.ResultsACS acceleration reduced the acquisition times of T1-, T2-, and PD-weighted sequences by 32−43%, compared with conventional CS and PI, while maintaining image quality (mostly higher SNR with p < 0.004 and higher CNR with p < 0.047). The diagnostic agreement between ACS and conventional sequences was rated excellent (κ = 1.00).ConclusionsThe optimum ACS acceleration factors for ankle MRI were found to be 3.2–3.3× protocol. The ACS allows faster imaging, yielding similar image quality and diagnostic performance.Relevance statementAI-assisted compressed sensing significantly accelerates ankle MRI times while preserving image quality and diagnostic precision, potentially expediting patient diagnoses and improving clinical workflows.Key points• AI-assisted compressed sensing (ACS) significantly reduced scan duration for ankle MRI.• Similar image quality achieved by ACS compared to conventional acceleration methods.• A high agreement by three acceleration methods in the diagnosis of ankle lesions was observed.Graphical

Degradation of image quality caused by cardiac and respiratory motions hampers the diagnostic quality of cardiac PET. It has been shown that improved diagnostic accuracy of myocardial defect can be achieved by tagged MR (tMR) based PET motion correction using simultaneous PET-MR. However, one major hurdle for the adoption of tMR-based PET motion correction in the PET-MR routine is the long acquisition time needed for the collection of fully sampled tMR data. In this work, the authors propose an accelerated tMR acquisition strategy using parallel imaging and/or compressed sensing and assess the impact on the tMR-based motion corrected PET using phantom and patient data. Fully sampled tMR data were acquired simultaneously with PET list-mode data on two simultaneous PET-MR scanners for a cardiac phantom and a patient. Parallel imaging and compressed sensing were retrospectively performed by GRAPPA and kt-FOCUSS algorithms with various acceleration factors. Motion fields were estimated using nonrigid B-spline image registration from both the accelerated and fully sampled tMR images. The motion fields were incorporated into a motion corrected ordered subset expectation maximization reconstruction algorithm with motion-dependent attenuation correction. Although tMR acceleration introduced image artifacts into the tMR images for both phantom and patient data, motion corrected PET images yielded similar image quality as those obtained using the fully sampled tMR images for low to moderate acceleration factors (<4). Quantitative analysis of myocardial defect contrast over ten independent noise realizations showed similar results. It was further observed that although the image quality of the motion corrected PET images deteriorates for high acceleration factors, the images were still superior to the images reconstructed without motion correction. Accelerated tMR images obtained with more than 4 times acceleration can still provide relatively accurate motion fields and yield tMR-based motion corrected PET images with similar image quality as those reconstructed using fully sampled tMR data. The reduction of tMR acquisition time makes it more compatible with routine clinical cardiac PET-MR studies.

To evaluate the feasibility of three-dimensional (3D) single breath-hold late gadolinium enhancement (LGE) of the left ventricle (LV) using supplemental oxygen and hyperventilation and compressed-sensing acceleration. Breath-hold metrics [breath-hold duration, diaphragmatic/LV position drift, and maximum variation of R wave to R wave (RR) interval] without and with supplemental oxygen and hyperventilation were assessed in healthy adult subjects using a real-time single shot acquisition. Ten healthy subjects and 13 patients then underwent assessment of the proposed 3D breath-hold LGE acquisition (field of view = 320 × 320 × 100 mm(3) , resolution = 1.6 × 1.6 × 5.0 mm(3) , acceleration rate of 4) and a free-breathing acquisition with right hemidiaphragm navigator (NAV) respiratory gating. Semiquantitative grading of overall image quality, motion artifact, myocardial nulling, and diagnostic value was performed by consensus of two blinded observers. Supplemental oxygenation and hyperventilation increased the breath-hold duration (35 ± 11 s to 58 ± 21 s; P < 0.0125) without significant impact on diaphragmatic/LV position drift or maximum variation of RR interval (both P > 0.01). LGE images were of similar quality when compared with free-breathing acquisitions, but with reduced total scan time (85 ± 22 s to 35 ± 6 s; P < 0.001). Supplemental oxygenation and hyperventilation allow for prolonged breath-holding and enable single breath-hold 3D accelerated LGE with similar image quality as free breathing with NAV.

Optical remote sensing (RS) satellites perform imaging in the visible and infrared electromagnetic spectrum to collect data and analyze information on the optical characteristics of the objects of interest. However, optical RS is sensitive to illumination and atmospheric conditions, especially clouds, and multiple acquisitions are typically required to obtain an image of sufficient quality. To accurately reproduce surface information that has been contaminated by clouds, this work proposes a generative adversarial network (GAN)-based cloud removal framework using a distortion coding network combined with compound loss functions (DC-GAN-CL). A novel generator embedded with distortion coding and feature refinement mechanisms is applied to focus on cloudy regions and enhance the transmission of optical information. In addition, to achieve feature and pixel consistency, both coherent semantics and local adaptive reconstruction factors are considered in our loss functions. Extensive numerical evaluations on RICE1, RICE2, and Paris datasets are performed to validate the good performance achieved by the proposed DC-GAN-CL in both peak signal-to-noise ratio (PSNR) and visual perception. This system can thus restore images to obtain similar quality to cloud-free reference images, in a dynamic range of over 30 dB. The restoration effect on the coherence of image semantics produced by this technique is competitive compared with other methods.