Soft-Copy Reading of Digital Chest Radiographs

Ambient light intensity affecting ultrasound operator detection of liver lesions in cine-clips

INTRODUCTION

Ambient light (AL) is an important factor to improve ultrasound pathology detection. However, there are no established room AL levels recommended during an ultrasound examination. We aim to examine the diagnostic accuracy using different intensity of AL for the detection of liver lesions in anonymised pre-recorded cine-clips.

METHODS

Eight ultrasound operators with 5-14 years' professional experiences were prospectively recruited to evaluate 51 randomised cine-clips directly from one ultrasound machine. These 15-s clips of the right lobe of the liver in longitudinal and transverse planes were meant to simulate the ultrasound examination. Operators reviewed all cine-clips and responded to two questions per cine-clip regarding their detection performance under 3 AL settings; 3, 15 and 25 lux, at one lighting per visit. A repeat visit under each AL was performed to assess for intra-operator variability. Each operator completed six visits in total, with at least a 2-day washout period. The operators' performance was compared against imaging reference standards from contrast CT/MRI for cine-clips with lesion and serial US for those without.

RESULTS

AL with highest degree of diagnostic accuracy was found to be at 25 lux. Results from 8 operators revealed sensitivity ranged from 79% to 100%, specificity ranged from 94% to 100%. Positive and negative predictive values were up to 100% with AL at 25 lux. Both intra-and interrater reliability were excellent at 0.85-1.0 (0.79-0.98) and 0.98 (0.97, 0.99) respectively, with AL at 25 lux.

CONCLUSION

This study proved that ambient light intensity affects the ultrasound operator detection of liver lesions on cine-clips.

IMPLICATIONS FOR PRACTICE

Identifying suitable AL levels will influence future ultrasound room construct.

Guidelines for reporting on CBCT scans

The aim of a radiographic report is to provide an accurate interpretation of images to facilitate the diagnostic process, and when indicated prompt the appropriate management for the patient. It is part of the patient's clinical records. This paper describes the imaging chain involved in the cone beam computed tomography (CBCT) workflow from referring to reporting on a CBCT scan. It provides guidelines on the essential information required before and immediately after a CBCT scan is taken, and optimizing the viewing conditions. Finally, it describes a framework for a systematic, comprehensive and tailored CBCT radiographic report. It is aimed at endodontists, clinicians and radiologists reporting on CBCT scans of the dentoalveolar region.

Breast screen new South wales generally demonstrates good radiologic viewing conditions

This study measured reading workstation monitors and the viewing environment currently available within BreastScreen New South Wales (BSNSW) centres to determine levels of adherence to national and international guidelines. Thirteen workstations from four BSNSW service centres were assessed using the American Association of Physicists in Medicine Task Group 18 Quality Control test pattern. Reading workstation monitor performance and ambient light levels when interpreting screening mammographic images were assessed using spectroradiometer CS-2000 and chroma meter CL-200. Overall, radiologic monitors within BSNSW were operating at good acceptable levels. Some non-adherence to published guidelines included the percentage difference in maximum luminance between pairs of primary monitors at individual workstations (61.5 % or 30.8 % of workstations depending on specific guidelines), maximum luminance (23.1 % of workstations), luminance non-uniformity (11.5 % of workstations) and minimum luminance (3.8 % of workstations). A number of ambient light measurements did not comply with the only available evidence-based guideline relevant to the methodology used in this study. Larger ambient light variations across sites are shown when monitors were switched off, suggesting that differences in ambient lighting between sites can be masked when a standard mammogram is displayed for photometric measurements. Overall, BSNSW demonstrated good adherence to available guidelines, although some non-compliance has been shown. Recently updated United Kingdom and Australian guidelines should help reduce confusion generated by the plethora and sometimes dated nature of currently available recommendations.

Human contrast-detail performance with declining contrast

PURPOSE

How do display settings and ambient lighting affect contrast detection thresholds for human observers? Can recalibrating a display for high ambient lighting improve object detection?

METHODS

Contrast∕detail (CD) threshold detection performance was measured for observers using four color displays with varying overall contrast (e.g., differing maximum luminance and ambient lighting conditions). Detailed mapping of contrast detection performance (for fixed object size) was tracked as a function of: display maximum luminance, ambient lighting changes (with and without recalibrating for the higher ambience), and the performance of radiologists vs. nonradiologists.

RESULTS

The initial phase was analyzed with a hierarchical linear model of observer performance using: background gray level, maximum display luminance, and radiologist vs. nonradiologist. The only statistically significant finding was a maximum luminance of 100 cd∕m(2) display performing worse than a baseline peak of 400 cd∕m(2). The second phase examined ambient lighting effects on detection thresholds. Background gray level and maximum display luminance were examined coupled with ambient lighting for: baseline at 30, 435 uncorrected, and 435 lx with display recalibration for the ambient conditions. Results showed ambient correction improved sensitivity for small background digital driving level, but not at higher luminance backgrounds.

CONCLUSIONS

For CD study, nonradiologist observers can be used without loss of applicability. Contrast detection thresholds improved significantly between displays with peak luminance from 100 cd∕m(2) to 200 cd∕m(2), but improvement beyond that was not statistically significant for contrast detection thresholds in a reading room environment. Applying a calibration correction at high ambience (435 lx) improved detection tasks primarily in the darker background regions.

Expert interpretation compensates for reduced image quality of camera-digitized images referred to radiologists

We compared the accuracy of five veterinary radiologists when reading 20 radiographic cases on both analog film and in camera-digitized format. In addition, we compared the ability of five veterinary radiologists vs. 10 private practice veterinarians to interpret the analog images. Interpretation accuracy was compared using receiver operating characteristic curve analysis. Veterinary radiologists' accuracy did not significantly differ between analog vs. camera-digitized images (P = 0.13) although sensitivity was higher for analog images. Radiologists' interpretation of both digital and analog images was significantly better compared with the private veterinarians (P < 0.05).

Image Quality, lesion detection, and diagnostic efficacy in digital mammography: Full-field digital mammography versus computed radiography-based mammography using digital storage phosphor plates

OBJECTIVE

To compare image quality, the lesion detection, and the diagnostic efficacy of full-field digital mammography (FFDM) and computed radiography-based mammography using digital storage phosphor plates (DSPM) in the evaluation of breast lesions.

MATERIALS AND METHODS

In this prospective study, 150 patients with suspicious breast lesions underwent FFDM and DSPM. Nine aspects of image quality (brightness, contrast, sharpness, noise, artifacts, and the detection of anatomic structures, i.e., skin, retromamillary space, glandular tissue, and calcifications) were evaluated by five radiologists. In addition, the detection of breast lesions and the diagnostic efficacy, based on the BI-RADS classification, were evaluated with histologic and follow-up correlation.

RESULTS

For contrast, sharpness, and the detection of all anatomic structures, FFDM was rated significantly better (p<0.05). Mass lesions were equally detected, whereas FFDM detected more lesions consisting of calcifications (85 versus 75). DSPM yielded two false-negative results. Both lesions were rated BI-RADS 4 with FFDM, but BI-RADS 2 with DSPM. Both were invasive carcinoma at histology. The sensitivity, specificity, PPV, NPV, and accuracy of FFDM were 1.0, 0.397, 0.636, 1.0, and 0.707, compared to 0.974, 0.397, 0.630, 0.935, and 0.693 of DSPM.

CONCLUSION

Based on image quality parameters, FFDM is, in part, significantly better than DSPM. Furthermore, the detection of breast lesions with calcifications is favorable with FFDM. However, the diagnostic efficacy of FFDM and DSPM was equal. The interpretation of the false-negative results suggests that the perception and characterization of breast lesions is not defined solely by the digital mammography system but is strongly influenced by the radiologist, who is one of the determinants in the interpretation of breast imaging.

The impact of acoustic noise found within clinical departments on radiology performance

RATIONALE AND OBJECTIVES

In recent years, there has been increasing interest in the impact of environmental factors such as ambient light on radiologist performance. One commonly encountered distractor found within all clinical departments that has received little or no attention is acoustic noise.

MATERIALS AND METHODS

The present work records the level of noises encountered within environments where radiologic images are viewed and establishes the impact of a clinically relevant level of noise on the ability of radiologists to perform a typical diagnostic task. Noise levels were recorded 10 times within each of 14 environments, 11 of which were locations where radiologic images are judged. Thirty chest images were then presented to 26 senior radiologists, who were asked to detect up to three nodular lesions within 30 posteroanterior chest x-ray images in the absence and presence of noise at an amplitude demonstrated in the clinical environment. Jackknife free-response receiver-operating characteristic analyses was performed on the free-response data.

RESULTS

The results demonstrated that noise amplitudes rarely exceeded that encountered with normal conversation with the maximum mean value for an image-viewing environment being 56.1 dB. This level of noise had no impact on the ability of radiologists to identify chest lesions with figure of merits of 0.68, 0.69, and 0.68 with noise and 0.65, 0.68, and 0.67 without noise for chest radiologists, nonchest radiologists, and all radiologists, respectively. Equally, no differences were seen for false-positive and false-negative scores or on the time required to judge the images.

CONCLUSION

These findings suggest that noise at levels encountered within areas where radiologic images are viewed is not a major distractor within the reporting environment, but the need for further work has been identified.

Optimization of region of interest luminances may enhance radiologists' light adaptation

RATIONALE AND OBJECTIVES

Radiologic image details are best discriminated at luminance levels to which the eye is adapted. Recommendations that ambient light conditions are matched to overall monitor luminance to encourage appropriate adaptation are based on an assumption that clinically significant regions within the image match average monitor luminance. The current work examines this assumption.

MATERIALS AND METHODS

Three image types were considered: posteroanterior (PA) chest; PA wrist; and computed tomography (CT) head. Luminance at clinically significant regions was measured at hilar region and peripheral lung (chest), distal radius (wrist), and supraventricular white matter (head). Average monitor luminances were calculated from measurements at 16 regions of the display face plate. Three ambient light levels-30, 100 and 400 lux-were employed. Thirty samples of each image type were used.

RESULTS

Statistically significant differences were noted between average monitor luminances and clinically important regions of interest of up to a factor of 3.8, 2, and 6.3 for chest, wrist, and CT head images respectively (P < .0001). Values for the hilum of the chest and distal radius were higher than average monitor levels, whereas the reverse was observed for the peripheral lung and CT brain. Increasing ambient light had no impact on results.

CONCLUSIONS

Clinically important radiologic information for common radiologic examinations is not being presented to observers in a way that facilitates optimized adaptation. This may have a significant impact on the ability of the observer to identify details with low contrast discriminability. The importance of image-processing algorithms focussing on clinically significant abnormalities rather than anatomic regions is highlighted.

Ambient Lighting: Effect of Illumination on Soft-Copy Viewing of Radiographs of the Wrist

OBJECTIVE

The aim of the work was to establish optimum ambient light conditions for viewing radiologic images of the wrist on liquid crystal display monitors.

MATERIALS AND METHODS

Five ambient light levels were investigated: 480, 100, 40, 25, and 7 lux. Seventy-nine experienced radiologists were asked to examine 30 posteroanterior wrist images and decide whether a fracture was present. All images were displayed on liquid crystal display monitors. Receiver operating characteristic analysis was performed, and the numbers of false-positive and false-negative findings were recorded.

RESULTS

For all the radiologists, greater area under the receiver operating characteristic curve and lower numbers of false-positive and false-negative findings were recorded at 40 and 25 lux compared with 480 and 100 lux. At 7 lux, the results were generally similar to those at 480 and 100 lux. The experience and knowledge of radiologists specializing in imaging of musculoskeletal trauma appeared to compensate in part for inappropriate lighting levels.

CONCLUSION

Typical office lighting and current recommendations on ambient lighting can reduce diagnostic efficacy compared with lower levels of ambient lighting. If, however, no light other than that of the monitor is used, results are similar to those with excessive levels of lighting. Careful control of ambient lighting is therefore required to ensure that diagnostic accuracy is maximized, particularly for clinicians not expert in interpreting posteroanterior wrist images.

Recent Advances in Chest Radiography

There have been many remarkable advances in conventional thoracic imaging over the past decade. Perhaps the most remarkable is the rapid conversion from film-based to digital radiographic systems. Computed radiography is now the preferred imaging modality for bedside chest imaging. Direct radiography is rapidly replacing film-based chest units for in-department posteroanterior and lateral examinations. An exciting aspect of the conversion to digital radiography is the ability to enhance the diagnostic capabilities and influence of chest radiography. Opportunities for direct computer-aided detection of various lesions may enhance the radiologist's accuracy and improve efficiency. Newer techniques such as dual-energy and temporal subtraction radiography show promise for improved detection of subtle and often obscured or overlooked lung lesions. Digital tomosynthesis is a particularly promising technique that allows reconstruction of multisection images from a short acquisition at very low patient dose. Preliminary data suggest that, compared with conventional radiography, tomosynthesis may also improve detection of subtle lung lesions. The ultimate influence of these new technologies will, of course, depend on the outcome of rigorous scientific validation.

An indicator device for monitoring of room illuminance level in the radiological image viewing environment

Illuminance level in the softcopy image viewing room is a very important factor to optimize productivity in radiological diagnosis. In today's radiological environment, the illuminance measurements are normally done during the quality control procedure and performed annually. Although the room is equipped with dimmer switches, radiologists are not able to decide the level of illuminance according to the standards. The aim of this study is to develop a simple real-time illuminance detector system to assist the radiologists in deciding an adequate illuminance level during radiological image viewing. The system indicates illuminance in a very simple visual form by using light emitting diodes. By employing the device in the viewing room, illuminance level can be monitored and adjusted effectively.

Portable Flat-Panel Detector for Low-Dose Imaging in a Pediatric Intensive Care Unit

OBJECTIVE

We sought to evaluate the diagnostic performance of a portable indirect flat-panel detector for low-dose imaging as compared with an asymmetric film-screen system in a pediatric intensive care unit.

MATERIALS AND METHODS

A total of 120 neonates underwent chest radiographs using a portable flat-panel detector (digital speed 800) and an asymmetric film-screen system (400 speed). Four readers evaluated the detection of 11 anatomic and 5 pathologic landmarks and 4 support devices. Statistical analysis was performed using repeated analysis of variance. The level of statistical significance was P = 0.05.

RESULTS

The detection of 4 anatomic/4 pathologic landmarks and 2 support devices was significantly better using the flat-panel detector as compared with the asymmetric film-screen system (P < 0.05). Another 8 anatomic and one pathologic landmarks were detected equally well or slightly better with the flat-panel detector (P > 0.05).

CONCLUSIONS

The portable flat-panel detector offers the potential of a 50% dose reduction with equal or significantly better detection of clinically important structures.