Portable Chest Radiography Through Glass During COVID-19 Pandemic-Initial Experience in a Tertiary Care Center.

BACKGROUND: Portable chest radiograph for COVID-19 positive patients and persons under investigation can be acquired through glass doors or walls of isolation rooms to limit exposure to the pathogen and conserve resources. PURPOSE: To report our initial experience with acquiring portable chest radiographs through glass doors of isolation rooms. METHODS: Only 1 of 2 radiology technologist team members donned personal protective equipment and stayed inside the isolation room, while the second technologist and the radiography unit remained outside during the procedure. First hundred radiographs acquired through glass at the emergency department of our institute formed the "through glass radiograph" group. Hundred consecutive portable chest radiographs performed in a conventional manner formed the "conventional radiograph" group for comparison. Imaging database and feedback from operations leader were used to identify occurrences of a failed procedure. Suggestion of repeating the study and comments related to quality of the study were recorded from the reports of the staff radiologist. RESULTS: There was no instance of failed acquisition, nondiagnostic examination, or suggestion of repetition in both groups. No significant difference in the number of reports with quality related remarks (P > .05) was found between the 2 groups. Radiography through glass doors was associated with increased suboptimal positioning related remarks in radiology reports (P < .05). No significant association was identified among other comments about image quality. CONCLUSION: Our initial clinical experience suggests that the acquisition of portable chest radiographs through the glass doors of isolation rooms is technically feasible and results in diagnostic quality studies.

Including mRECIST in the Metroticket 2.0 criteria improves prediction of hepatocellular carcinoma-related death after liver transplant.

BACKGROUND & AIMS: In the context of liver transplantation (LT) for hepatocellular carcinoma (HCC), prediction models are used to ensure that the risk of post-LT recurrence is acceptably low. However, the weighting that 'response to neoadjuvant therapies' should have in such models remains unclear. Herein, we aimed to incorporate radiological response into the Metroticket 2.0 model for post-LT prediction of "HCC-related death", to improve its clinical utility. METHODS: Data from 859 transplanted patients (2000-2015) who received neoadjuvant therapies were included. The last radiological assessment before LT was reviewed according to the modified RECIST criteria. Competing-risk analysis was applied. The added value of including radiological response into the Metroticket 2.0 was explored through category-based net reclassification improvement (NRI) analysis. RESULTS: At last radiological assessment prior to LT, complete response (CR) was diagnosed in 41.3%, partial response/stable disease (PR/SD) in 24.9% and progressive disease (PD) in 33.8% of patients. The 5-year rates of "HCC-related death" were 3.1%, 9.6% and 13.4% in those with CR, PR/SD, or PD, respectively (p <0.001). Log10AFP (p <0.001) and the sum of number and diameter of the tumour/s (p <0.05) were determinants of "HCC-related death" for PR/SD and PD patients. To maintain the post-LT 5-year incidence of "HCC-related death" <30%, the Metroticket 2.0 criteria were restricted in some cases of PR/SD and in all cases with PD, correctly reclassifying 9.4% of patients with "HCC-related death", at the expense of 3.5% of patients who did not have the event. The overall/net NRI was 5.8. CONCLUSION: Incorporating the modified RECIST criteria into the Metroticket 2.0 framework can improve its predictive ability. The additional information provided can be used to better judge the suitability of candidates for LT following neoadjuvant therapies. LAY SUMMARY: In the context of liver transplantation for patients with hepatocellular carcinoma, prediction models are used to ensure that the risk of recurrence after transplantation is acceptably low. The Metroticket 2.0 model has been proposed as an accurate predictor of "tumour-related death" after liver transplantation. In the present study, we show that its accuracy can be improved by incorporating information relating to the radiological responses of patients to neoadjuvant therapies.

Web-Based Technology for Remote Viewing of Radiological Images: App Validation.

BACKGROUND: Internet technologies can create advanced and rich web-based apps that allow radiologists to easily access teleradiology systems and remotely view medical images. However, each technology has its own drawbacks. It is difficult to balance the advantages and disadvantages of these internet technologies and identify an optimal solution for the development of medical imaging apps. OBJECTIVE: This study aimed to compare different internet platform technologies for remotely viewing radiological images and analyze their advantages and disadvantages. METHODS: Oracle Java, Adobe Flash, and HTML5 were each used to develop a comprehensive web-based medical imaging app that connected to a medical image server and provided several required functions for radiological interpretation (eg, navigation, magnification, windowing, and fly-through). Java-, Flash-, and HTML5-based medical imaging apps were tested on different operating systems over a local area network and a wide area network. Three computed tomography colonography data sets and 2 ordinary personal computers were used in the experiment. RESULTS: The experimental results demonstrated that Java-, Flash-, and HTML5-based apps had the ability to provide real-time 2D functions. However, for 3D, performances differed between the 3 apps. The Java-based app had the highest frame rate of volume rendering. However, it required the longest time for surface rendering and failed to run surface rendering in macOS. The HTML5-based app had the fastest surface rendering and the highest speed for fly-through without platform dependence. Volume rendering, surface rendering, and fly-through performances of the Flash-based app were significantly worse than those of the other 2 apps. CONCLUSIONS: Oracle Java, Adobe Flash, and HTML5 have individual strengths in the development of remote access medical imaging apps. However, HTML5 is a promising technology for remote viewing of radiological images and can provide excellent performance without requiring any plug-ins.

Radioanalytical Techniques to Quantitatively Assess the Biological Uptake and In Vivo Behavior of Hazardous Substances.

Concern about environmental exposure to hazardous substances has grown over the past several decades, because these substances have adverse effects on human health. Methods used to monitor the biological uptake of hazardous substances and their spatiotemporal behavior in vivo must be accurate and reliable. Recent advances in radiolabeling chemistry and radioanalytical methodologies have facilitated the quantitative analysis of toxic substances, and whole-body imaging can be achieved using nuclear imaging instruments. Herein, we review recent literature on the radioanalytical methods used to study the biological distribution, changes in the uptake and accumulation of hazardous substances, including industrial chemicals, nanomaterials, and microorganisms. We begin with an overview of the radioisotopes used to prepare radiotracers for in vivo experiments. We then summarize the results of molecular imaging studies involving radiolabeled toxins and their quantitative assessment. We conclude the review with perspectives on the use of radioanalytical methods for future environmental research.

Dual-energy CT: theoretical principles and clinical applications.

The physical principles of dual-energy computed tomography (DECT) are as old as computed tomography (CT) itself. To understand the strengths and the limits of this technology, a brief overview of theoretical basis of DECT will be provided. Specific attention will be focused on the interaction of X-rays with matter, on the principles of attenuation of X-rays in CT toward the intrinsic limits of conventional CT, on the material decomposition algorithms (two- and three-basis-material decomposition algorithms) and on effective Rho-Z methods. The progresses in material decomposition algorithms, in computational power of computers and in CT hardware, lead to the development of different technological solutions for DECT in clinical practice. The clinical applications of DECT are briefly reviewed in relation to the specific algorithms.

2016 New Horizons Lecture: Beyond Imaging-Radiology of Tomorrow.

This article is based on the New Horizons lecture delivered at the 2016 Radiological Society of North America Annual Meeting. It addresses looming changes for radiology, many of which stem from the disruptive effects of the Fourth Industrial Revolution. This is an emerging era of unprecedented rapid innovation marked by the integration of diverse disciplines and technologies, including data science, machine learning, and artificial intelligence-technologies that narrow the gap between man and machine. Technologic advances and the convergence of life sciences, physical sciences, and bioengineering are creating extraordinary opportunities in diagnostic radiology, image-guided therapy, targeted radionuclide therapy, and radiology informatics, including radiologic image analysis. This article uses the example of oncology to make the case that, if members in the field of radiology continue to be innovative and continuously reinvent themselves, radiology can play an ever-increasing role in both precision medicine and value-driven health care. © RSNA, 2018.

Measuring and correcting wobble in large-scale transmission radiography.

BACKGROUND: Large-scale transmission radiography scanners are used to image vehicles and cargo containers. Acquired images are inspected for threats by a human operator or a computer algorithm. To make accurate detections, it is important that image values are precise. However, due to the scale (∼5 m tall) of such systems, they can be mechanically unstable, causing the imaging array to wobble during a scan. This leads to an effective loss of precision in the captured image. OBJECTIVE: We consider the measurement of wobble and amelioration of the consequent loss of image precision. METHODS: Following our previous work, we use Beam Position Detectors (BPDs) to measure the cross-sectional profile of the X-ray beam, allowing for estimation, and thus correction, of wobble. We propose: (i) a model of image formation with a wobbling detector array; (ii) a method of wobble correction derived from this model; (iii) methods for calibrating sensor sensitivities and relative offsets; (iv) a Random Regression Forest based method for instantaneous estimation of detector wobble; and (v) using these estimates to apply corrections to captured images of difficult scenes. RESULTS: We show that these methods are able to correct for 87% of image error due wobble, and when applied to difficult images, a significant visible improvement in the intensity-windowed image quality is observed. CONCLUSIONS: The method improves the precision of wobble affected images, which should help improve detection of threats and the identification of different materials in the image.

Fundamental Study of Three-dimensional Fast Spin-echo Imaging with Spoiled Equilibrium Pulse.

Three-dimensional fast spin-echo (3D FSE) imaging with variable refocusing flip angle has been recently applied to pre- or post-enhanced T1-weighted imaging. To reduce the acquisition time, this sequence requires higher echo train length (ETL), which potentially causes decreased T1 contrast. Spoiled equilibrium (SpE) pulse consists of a resonant +90° radiofrequency (RF) pulse and is applied at the end of the echo train. This +90° RF pulse brings residual transverse magnetization to the negative longitudinal axis, which makes it possible to increase T1 contrast. The purpose of our present study was to examine factors that influence the effect of spoiled equilibrium pulse and the relationship between T1 contrast improvement and imaging parameters and to understand the characteristics of spoiled equilibrium pulse. Phantom studies were conducted using an magnetic resonance imaging (MRI) phantom made of polyvinyl alcohol gel. To evaluate the effect of spoiled equilibrium pulse with changes in repetition time (TR), ETL, and refocusing flip angle, we measured the signal-to-noise ratio and contrast-to-noise ratio (CNR). The effect of spoiled equilibrium pulse was evaluated by calculating the enhancement rate of CNR. The factors that influence the effect of spoiled equilibrium pulse are TR, ETL, and relaxation time of tissues. Spoiled equilibrium pulse is effective with increasing TR and decreasing ETL. The shorter the T1 value, the better the spoiled equilibrium pulse functions. However, for tissues in which the T1 value is long (>600 ms), at a TR of 600 ms, improvement in T1 contrast by applying spoiled equilibrium pulse cannot be expected.

Comparison of Analytical Values in Diffusion Kurtosis Imaging among Different MRI Units.

Diffusion kurtosis imaging (DKI) is a method of analyzing restricted diffusion. Mean kurtosis (MK) is obtained from DKI. It is not known how different MRI scanners and coil systems will change MK when the same imaging parameters are used. The purpose of this study is to identify tendencies in MK when using various MRI scanners and coil systems. A total of 27 healthy volunteers were enrolled in this study. DKI was performed on the brain for each volunteer on five MRI scanner/coil system combinations using the same scan parameters. MK of 10 anatomical areas of the brain were compared, and the signal-noise ratios (SNRs) of b-2000 s/mm2 images were measured in identical areas. There were no significant differences among MKs from multi transmit (MT) MRI systems, but MK was significantly lower on the single transmit MRI system because of pepper artifact caused by low SNR. In conclusion, we found no significant differences in MK among MT systems, and MK was significantly lower without MT.

Optimization of exposure in panoramic radiography while maintaining image quality using adaptive filtering.

Objective The purpose of the present study was to investigate the potential of using advanced external adaptive image processing for maintaining image quality while reducing exposure in dental panoramic storage phosphor plate (SPP) radiography. Materials and methods Thirty-seven SPP radiographs of a skull phantom were acquired using a Scanora panoramic X-ray machine with various tube load, tube voltage, SPP sensitivity and filtration settings. The radiographs were processed using General Operator Processor (GOP) technology. Fifteen dentists, all within the dental radiology field, compared the structural image quality of each radiograph with a reference image on a 5-point rating scale in a visual grading characteristics (VGC) study. The reference image was acquired with the acquisition parameters commonly used in daily operation (70 kVp, 150 mAs and sensitivity class 200) and processed using the standard process parameters supplied by the modality vendor. Results All GOP-processed images with similar (or higher) dose as the reference image resulted in higher image quality than the reference. All GOP-processed images with similar image quality as the reference image were acquired at a lower dose than the reference. This indicates that the external image processing improved the image quality compared with the standard processing. Regarding acquisition parameters, no strong dependency of the image quality on the radiation quality was seen and the image quality was mainly affected by the dose. Conclusions The present study indicates that advanced external adaptive image processing may be beneficial in panoramic radiography for increasing the image quality of SPP radiographs or for reducing the exposure while maintaining image quality.

A Lossless hybrid wavelet-fractal compression for welding radiographic images.

In this work a lossless wavelet-fractal image coder is proposed. The process starts by compressing and decompressing the original image using wavelet transformation and fractal coding algorithm. The decompressed image is removed from the original one to obtain a residual image which is coded by using Huffman algorithm. Simulation results show that with the proposed scheme, we achieve an infinite peak signal to noise ratio (PSNR) with higher compression ratio compared to typical lossless method. Moreover, the use of wavelet transform speeds up the fractal compression algorithm by reducing the size of the domain pool. The compression results of several welding radiographic images using the proposed scheme are evaluated quantitatively and compared with the results of Huffman coding algorithm.

Image enhancement for on-site X-ray nondestructive inspection of reinforced concrete structures.

The use of portable and high-energy X-ray system can provide a very promising approach for on-site nondestructive inspection of inner steel reinforcement of concrete structures. However, the noise properties and contrast of the radiographic images for thick concrete structures do often not meet the demands. To enhance the images, we present a simple and effective method for noise reduction based on a combined curvelet-wavelet transform and local contrast enhancement based on neighborhood operation. To investigate the performance of this method for our X-ray system, we have performed several experiments with using simulated and experimental data. With comparing to other traditional methods, it shows that the proposed image enhancement method has a better performance and can significantly improve the inspection performance for reinforced concrete structures.

A Novel Evaluation Method for Displacement between Carbon Beam Axis and Positioning X-ray Axis Using an Imaging Plate.

PURPOSE: We developed an evaluation method for easily calculating displacement directly between the carbon beam axis and positioning X-ray axis. METHODS: A verification image was acquired by irradiating an imaging plate with a carbon beam and X-ray. The X-ray passed through a lead plate inserted in the range compensator holder. The displacement was calculated on the verification image from the center of a wire irradiated with carbon using a multi leaf collimator (MLC) and a wire irradiated with X-ray also using MLC. The accuracy of the method was evaluated by moving the carbon beam axis, the X-ray axis, and the setup angle. The weekly changes of vertical and lateral beams in all rooms were also evaluated. RESULTS: The displacements of the carbon beam axis and the setup angle did not influence the calculation results, whereas the displacement of the X-ray axis did (R=0.999). The displacements including weekly changes were all less than 1.00 mm. CONCLUSION: An evaluation method for calculating the displacement directly and simply between the carbon beam axis and positioning X-ray axis was developed and verified. The weekly changes of displacement between axes were evaluated to be acceptable at our facility.

Evaluation of Size Correction Factor for Size-specific Dose Estimates (SSDE) Calculation.

American Association of Physicists in Medicine (AAPM) Report No.204 recommends the size-specific dose estimates (SSDE), wherein SSDE=computed tomography dose index-volume (CTDIvol )×size correction factor (SCF), as an index of the CT dose to consider patient thickness. However, the study on SSDE has not been made yet for area detector CT (ADCT) device such as a 320-row CT scanner. The purpose of this study was to evaluate the SCF values for ADCT by means of a simulation technique to look into the differences in SCF values due to beam width. In the simulation, to construct the geometry of the Aquilion ONE X-ray CT system (120 kV), the dose ratio and the effective energies were measured in the cone angle and fan angle directions, and these were incorporated into the simulation code, Electron Gamma Shower Ver.5 (EGS5). By changing the thickness of a PMMA phantom from 8 cm to 40 cm, CTDIvol and SCF were determined. The SCF values for the beam widths in conventional and volume scans were calculated. The differences among the SCF values of conventional, volume scans, and AAPM were up to 23.0%. However, when SCF values were normalized in a phantom of 16 cm diameter, the error tended to decrease for the cases of thin body thickness, such as those of children. It was concluded that even if beam width and device are different, the SCF values recommended by AAPM are useful in clinical situations.

Image Format Conversion to DICOM and Lookup Table Conversion to Presentation Value of the Japanese Society of Radiological Technology (JSRT) Standard Digital Image Database.

Japanese Society of Radiological Technology (JSRT) standard digital image database contains many useful cases of chest X-ray images, and has been used in many state-of-the-art researches. However, the pixel values of all the images are simply digitized as relative density values by utilizing a scanned film digitizer. As a result, the pixel values are completely different from the standardized display system input value of digital imaging and communications in medicine (DICOM), called presentation value (P-value), which can maintain a visual consistency when observing images using different display luminance. Therefore, we converted all the images from JSRT standard digital image database to DICOM format followed by the conversion of the pixel values to P-value using an original program developed by ourselves. Consequently, JSRT standard digital image database has been modified so that the visual consistency of images is maintained among different luminance displays.

Evaluation of Resolution Recovery for Each Collimator in Brain Perfusion Image.

PURPOSE: This study aimed to verify the resolution recovery for each collimator in the brain perfusion image. METHOD: To verify the effect of the resolution recovery for each collimator, we evaluated via the three-dimensional brain phantom (phantom) and the normal brain perfusion single photon emission computed tomography (SPECT) data. These data were reconstructed using the three-dimensional ordered subset expectation maximization method (3D-OSEM) (Evolution for boneTM) that was performed with scatter correction, attenuation correction, and resolution recovery (RR). The performance of resolution recovery was evaluated in the two collimator systems (ELEGP and MEGP) reconstruction condition via the contrast value, mean counts, normalized mean square error (NMSE), and regional brain activity. RESULT: In the "with resolution recovery (+RR)", the NMSE indicated minimum value with SI (subset×iteration) = 100, cut-off frequency (Fc) = 0.50 cycles/cm. The contrast value in the "+RR" increased 20% for the cortical region and decreased 28% and 6% at ELEGP collimator and MEGP collimator for the central region, as compared to the "without resolution recovery (-RR)". In the phantom study, the error of the brain activity using MEGP collimator at the temporal lobe and sub-lobar decreased 15%, compared with ELEGP collimator in the + RR. In the clinical study, the error of the regional brain activity using MEGP collimator in the "+RR" increased from 3% to 8%, compared with "-RR". DISCUSSION: The accurate resolution recovery was obtained at SI = 100 and Fc = 0.50 cycles/cm. The contrast value and regional brain activity at the central region decreased due to incomplete resolution recovery by use of ELEGP collimator.

Radiology and diabetes mellitus.

Diabetes mellitus (DM) is a major health concern globally, affecting almost every organ of the body. A major issue with DM is that a relatively large proportion of patients remain undiagnosed till the development of complications, many of which may cause permanent impairment. Therefore, early recognition of the radiological manifestations (of DM) is of utmost importance, so that the disease may be diagnosed and managed well in time. Some common and important radiological features encountered in practice are compiled in this article.

Guide to Digital Radiographic Imaging.

This is a resource for clinicians who are considering purchasing a digital imaging system or those already using one who want to optimize its use. It covers selected topics in digital imaging fundamentals, detector technology, image processing and quality assurance. Through a critical appraisal of the strengths and limitations of digital imaging components, the goal of this guide is to contribute to the appropriate use of these systems to maximize the health benefit for patients.

[Study on the effect of setting the region of interest for exposure index computing].

Exposure index (EI) is expected as important standard for the optimization of image quality and exposed dose in digital radiography. It is set a region of interest (ROI) in a radiograph, to obtain a histogram of pixel values within an ROI, it is computed as EI of the image representative value of the histogram. In this study, we examined the effects of setting the ROI for EI computing. We set five different ROIs in chest or cervical spine frontal radiograph, and compared the computed EI in each ROIs. From the result, in some cases, we found that EI varied greatly as those compared to the case of ROI set in full image. We should consider about setting the ROI for EI computing when we use EI as standard for optimization of image quality and exposed dose in digital radiography.

Liver masses: a clinical, radiologic, and pathologic perspective.

Liver masses present a relatively common clinical dilemma, particularly with the increasing use of various imaging modalities in the diagnosis of abdominal and other symptoms. The accurate and reliable determination of the nature of the liver mass is critical, not only to reassure individuals with benign lesions but also, and perhaps more importantly, to ensure that malignant lesions are diagnosed correctly. This avoids the devastating consequences of missed diagnosis and the delayed treatment of malignancy or the unnecessary treatment of benign lesions. With appropriate interpretation of the clinical history and physical examination, and the judicious use of laboratory and imaging studies, the majority of liver masses can be characterized noninvasively. Accurate characterization of liver masses by cross-sectional imaging is particularly dependent on an understanding of the unique phasic vascular perfusion of the liver and the characteristic behaviors of different lesions during multiphasic contrast imaging. When noninvasive characterization is indeterminate, a liver biopsy may be necessary for definitive diagnosis. Standard histologic examination usually is complemented by immunohistochemical analysis of protein biomarkers. Accurate diagnosis allows the appropriate selection of optimal management, which is frequently reassurance or intermittent follow-up evaluations for benign masses. For malignant lesions or those at risk of malignant transformation, management depends on the tumor staging, the functional status of the uninvolved liver, and technical surgical considerations. Unresectable metastatic masses require oncologic consultation and therapy. The efficient characterization and management of liver masses therefore requires a multidisciplinary collaboration between the gastroenterologist/hepatologist, radiologist, pathologist, hepatobiliary or transplant surgeon, and medical oncologist.