Soft-copy Reading Research Articles

Evaluation of the effect of zoom function on lesion detection by soft-copy reading of screening mammograms.

This study aims to evaluate the effectiveness of zooming in improving screen-reader performance in reporting digital mammograms. Two experiments were conducted. In the first experiment, 5 readers were asked to report 59 two-view bilateral mammograms retrospectively with zooming function turned off. The second session was similar to the first one except that zooming was enabled. The task of readers was to assess if the mammograms were normal or abnormal and rate the confidence levels for each of the lesion they detected. The reader performances were evaluated via case sensitivity, lesion sensitivity, specificity, receiver operating characteristics (ROC) area under the curve (AUC) and jackknife free-response receiver operating characteristics (JAFROC) figure of merit (FOM). There was no significant improvement in overall reader performance in detecting abnormalities in zooming condition compared with no zooming in terms of case sensitivity (96% and 87%, P = 0.285) or lesion sensitivity (88% and 81%, P = 0.224). However, differences in ROC AUC and JAFROC FOM (P ≤ 0.05) were found in two readers when they performed the test set with zooming function. The results suggested that the use of the zooming function did improve the performance of some readers in detecting abnormal cases.

Image Evaluation Method for Digital Mammography with Soft-copy Reading Using a Digital Phantom

Image Evaluation Method for Digital Mammography with Soft-copy Reading Using a Digital Phantom

Analysis of Dominant Factors Affecting Fatigue Caused by Soft-Copy Reading

The aim of this study was to analyze the dominant factors affecting fatigue caused by soft-copy reading to identify a method for decreasing fatigue in clinical practice. Two types of fatigue-fatigue in the central nervous system and subjective visual fatigue-were evaluated using a critical fusion frequency test and a questionnaire administered to 17 male radiologists before and after soft-copy reading. Reading-induced fatigue was assumed to be affected by 20 hypothetical factors associated with personal characteristics, time required for reading, content or amount of reading, and the reading environment. We used multiple linear regression analysis with a variable selection method to detect the best combination of factors capable of expressing variations in each of the measured fatigue values. The effects of the detected (dominant) factors on fatigue were also examined based on coefficients of the dominant factors in multiple regression models. Fatigue in the central nervous system decreased with a higher corrected visual acuity and a higher ambient illuminance in the reading room and was also affected by the type of monitor used. Visual fatigue was relieved when there was a larger difference in the brightness of the monitor and the surfaces surrounding the monitor and tended to be more severe when glasses rather than contact lenses were worn. Increasing the ambient illuminance, using an appropriate type of monitor, improving the corrected visual acuity, and using contact lenses rather than eyeglasses could help decrease reading-induced fatigue in male radiologists.

A preliminary study for exploring the luminance ratio of liquid-crystal displays required for display of radiographs

Medical-grade liquid-crystal displays (LCDs) with high contrast ratio (CR) values have recently been developed and become available for soft-copy reading. When the LCD is used under ambient light conditions, the luminance ratio (LR) is a more appropriate indicator than the CR. Our aim was to explore the LR required for LCDs for soft-copy reading by comparing the effective LR values with the LR of the LCD. We defined "the luminance ratio in an image (LRimg)", the ratio of the maximum to minimum luminance in a radiograph displayed on the LCD, as the effective LR values required for the LCD. The maximum LRimg values in chest radiographs and those in mammograms ranged from 109 to 143 and 372 to 431, respectively. The LR of the LCD was higher than the LRimg values of the radiographs. Our results indicate that currently available medical-grade LCDs have enough LR for display of radiographs.

Interpretation of Digital Chest Radiographs: Comparison of Light Emitting Diode versus Cold Cathode Fluorescent Lamp Backlit Monitors

ObjectiveTo compare the diagnostic performance of light emitting diode (LED) backlight monitors and cold cathode fluorescent lamp (CCFL) monitors for the interpretation of digital chest radiographs.Materials and MethodsWe selected 130 chest radiographs from health screening patients. The soft copy image data were randomly sorted and displayed on a 3.5 M LED (2560 × 1440 pixels) monitor and a 3 M CCFL (2048 × 1536 pixels) monitor. Eight radiologists rated their confidence in detecting nodules and abnormal interstitial lung markings (ILD). Low dose chest CT images were used as a reference standard. The performance of the monitor systems was assessed by analyzing 2080 observations and comparing them by multi-reader, multi-case receiver operating characteristic analysis. The observers reported visual fatigue and a sense of heat. Radiant heat and brightness of the monitors were measured.ResultsMeasured brightness was 291 cd/m2 for the LED and 354 cd/m2 for the CCFL monitor. Area under curves for nodule detection were 0.721 ± 0.072 and 0.764 ± 0.098 for LED and CCFL (p = 0.173), whereas those for ILD were 0.871 ± 0.073 and 0.844 ± 0.068 (p = 0.145), respectively. There were no significant differences in interpretation time (p = 0.446) or fatigue score (p = 0.102) between the two monitors. Sense of heat was lower for the LED monitor (p = 0.024). The temperature elevation was 6.7℃ for LED and 12.4℃ for the CCFL monitor.ConclusionAlthough the LED monitor had lower maximum brightness compared with the CCFL monitor, soft copy reading of the digital chest radiographs on LED and CCFL showed no difference in terms of diagnostic performance. In addition, LED emitted less heat.

Comparison of recall, biopsy, and cancer detection rates in the Southern Derbyshire screening programme between 2006 and 2009 using hard-copy mammography and in 2009 to 2012 following the full introduction of soft-copy reporting

Our programme underwent phased implementation of digital mammography, commencing soft-copy reading (SCR) in April 2009. Prior to this, all mammograms -a mixture of direct digital (DDM), computed radiography (CR) or film screen (FS) - were printed and read on multiviewers with the old films. For SCR, prior screens were available to readers but not digitised or mounted. This study was performed to evaluate recall rates, cancer detection and mammographic features assessed and biopsied, before and after SCR was introduced.

Effect factors of diagnostic system efficiency as chest radiodiagnosis with soft-copy reading

Objective To investigate the effect factors and the relationship of diagnostic system efficiency as soft copy reading with medical LCD.Methods Thirty chest images were selected from PACS on-line.Three of high,mid and low-experienced radiologists interpreted the images on different types of displays independently.Design four display levels based on five factors influencing diagnostic system efficiency,including view distance (0.3 m,0.6 m,0.9 m,1.2 m),monitor resolution ( 1 MP,2 MP,3 MP,5 MP),illuminant level (50 Ix,100 Ix,200 lx,400 lx),view angle (0°,15°,30°,45°) and angle of negative effect light (0°,30°,60°,90°).Three indices of misdiagnosis frequency,diagnosis time and frequency of unable to recognize were analyzed.Orthogonal experimental design and software SPSS 13.0 were used to analyze the results.Results The indices were much different for different factors at different levels.According to the index of average misdiagnosis frequency,extreme difference value of view angle was the lowest (1.4) and angle of negative effect light was the highest (5.0).Extreme difference value of view distance,monitor resolution and illuminant level were 2.9,2.8 and 2.5,respectively.Conclusions The order of different factors influencing diagnostic system efficiency is as follows: angle of negative effect light,view distance,monitor resolution,illuminant level and view angle. Key words: Radiology information systems; Radiography, thoracic; Research design; Orthogonal test; Diagnosis

Diagnostic performance in differentiation of breast lesion on digital mammograms: comparison among hard-copy film, 3-megapixel LCD monitor, and 5-megapixel LCD monitor

We compared observer performance of digital mammography among hard-copy readings and soft-copy readings using 3-megapixel (3M) and 5-megapixel (5M) liquid crystal display (LCD) monitors. Five experienced radiologists assessed 80 mammograms of 40 cancers and 40 benign lesions. There were no significant differences among the average A z of three modalities and among the κ values for intra- and interobserver agreement. The soft-copy reading using the 3M LCD monitor took a slightly longer time, although there were no significant differences.

Investigation of optimal viewing size for detecting nodular ground-glass opacity on high-resolution computed tomography with cine-mode display

We evaluated the effect of the displayed image sizes on observers' ability to detect nodular ground-glass opacity (n-GGO) on CT and investigated the optimal viewing size for soft-copy reading at CT screening for lung cancer. A total of 46 patients' high-resolution computed tomography (HRCT) images (22 patients with one GGO; 24 without GGO) were displayed on a monochromatic liquid crystal display monitor at a resolution of 1,200 × 1,600. HRCT was presented on the screen with cine-mode display. We compared two viewing sizes (original size, i.e., the image displayed with a zoom factor of 1 in which each pixel value in the image is displayed as one pixel on the display: 13 cm × 13 cm; fit size, i.e., by zooming the captured image until it occupies the entire screen: 30 cm × 30 cm) in terms of radiologists' performance for detecting n-GGO on HRCT and the viewing times required for soft-copy reading decisions. Observer performance was analyzed in terms of the receiver operating characteristic (ROC) curve. A statistically significant improvement was found with the original size in the average area-under-the-ROC curve values for the accuracy of diagnosis and the viewing times compared to the fit size (P < 0.05). The original size with cine-mode display leads to increased lung GGO detection at CT screening for lung cancer, and the reduced time spent performing the diagnosis offers cost savings.

A comparative contrast perception phantom image of brain CT study between high-grade and low-grade liquid crystal displays (LCDs) in electronic medical charts

The purpose of this study was to clarify whether non-medical-grade liquid crystal displays (LCDs) are acceptable for the soft-copy reading of brain CTs. Four kinds of color LCDs with different image quality levels were used: medical-grade LCD, low-grade general LCD calibrated with the grayscale display function (GSDF), low-grade general LCD calibrated with gamma 2.2 and a notebook personal computer display panel. In Osirix’s standard window setting for brain CTs, the average CT values of brain parenchyma in 100 cases were correlated with a grayscale level ranging from 71 to 91 in a 256-step grayscale. At these gray levels, the image contrast on the two low-grade LCDs calibrated with gamma 2.2 was higher than that on the medical-grade LCD. Eleven healthy volunteers participated in the contrast perception study, which used electronically generated target phantom images that simulated subtle abnormalities with a low or high attenuation difference in brain parenchyma. The three low-grade LCDs showed correct response rates and reaction times that were superior to those of the medical-grade display. The grayscale calibrations, GSDF or gamma 2.2, are likely to be more critical than the display grade, suggesting that the use of a low-grade LCD may be acceptable in the image contrast of brain CT.

Current status and issues of screening digital mammography in Japan

Digital systems have replaced screen-film systems, and have already been used for a screening program. The diagnostic performance of digital systems has been compared with that of screen-film systems, as the golden standard of breast cancer screening. Several studies have demonstrated they are superior to screen-film mammography; others have shown performance is comparable. The validity of digital screening mammography has been demonstrated. Regarding the method of interpretation of digital screening mammograms, the performance of hard-copy and soft-copy reading has been reported to be comparable, although the environment of soft-copy reading was premature. Soft-copy reading seems more promising in the future as a result of the development of both hardware and software. However, many aspects of quality assurance of soft-copy reading (e.g. standard specifications of viewing workstation, contrast visibility and resolution, ambient light) which remain undetermined should be clarified in the Japanese guideline. In Japan the average glandular dose in screening digital mammography is higher than that in screen-film mammography. Most (93.2%) are under 2 mGy for each radiation exposure. The risk of breast cancer by radiation exposure is regarded as higher than before in the 2007 recommendations of the ICRP. Management of radiation exposure is a continuing challenge.

Detection of breast cancer by soft-copy reading of digital mammograms: Comparison between a routine image-processing parameter and high-contrast parameters

Recent studies have reported the clinical usefulness of the soft-copy reading of mammograms. However, image-processing parameters for soft-copy reading of digital mammograms have not been established. To compare observer performance in detecting breast cancer by soft-copy reading of digital mammograms using a routine image-processing parameter versus each of several high-contrast parameters. The mammograms of 154 breasts, including 48 abnormal breasts with breast cancer and 106 normal breasts, were examined. Cancers were classified into 34 mass-dominant cancers, 11 microcalcification-dominant cancers, two cancers showing only architectural distortion, and one cancer without abnormal findings. All mammograms were performed using a computed radiography (CR) system. Each image was processed using GA (1.2), which was the contrast parameter recommended by the manufacturer for hard-copy film, GA (1.4), GA (1.6), and GA (1.8). These images were displayed on 5-megapixel (M) liquid-crystal display monitors. Five experienced radiologists classified them into BI-RADS category 1-2 or 3-5, and were also asked to rate the images on a scale of 0 to 100 for the likelihood of the presence of masses and microcalcifications in each breast. In mass-dominant cancers of dense breast tissue, the mean sensitivities of GA (1.2), GA (1.4), GA (1.6), and GA (1.8) were 32.7, 38.2, 36.4, and 40.0, and the A(Z) values were 0.67, 0.73, 0.71, and 0.73, respectively; in microcalcification-dominant cancers, the mean sensitivities were 80.0, 74.5, 80.0, and 78.2, respectively; however, there were no significant differences among them. High-contrast parameters tended to show relatively high sensitivity and A(Z) values in the detection of masses in dense breast tissue, but relatively low sensitivity for microcalcifications.

Diagnostic digital mammography in Japan: issues to consider

Digital mammography has been proposed as an alternative to screen-film mammography. Digital mammography has many technical advantages over film mammography, including image-enhancement capability, faster image acquisition, and better storage and transmission for archiving. However, its full potential can only be achieved through soft-copy reading. Soft-copy reading in digital mammography is still a relatively new technique, and has several issues which must still be resolved. It is necessary to optimize display formats and software as soon as possible to standardize soft-copy reading in digital mammography.

Digital mammography in Japan

Digital mammography has been proposed as an alternative to screen-film mammography. Previous publications have reported the equivalent performance of digital and film mammography [1, 2], and digital mammography has some advantages over film mammography [3, 4],including many technical advantages, including image-enhancement capability, faster image acquisition, and better storage and transmission for archiving. Its full potential can only be achieved through soft-copy reading. More than 70% of the facilities in Japan have digital mammography systems. However, most of the digital mammography systems use computed radiographic mammography and only about 10% of the facilities have fullfield digital mammography systems. In addition, there are few facilities with soft-copy reading of digital mammography in Japan. This situation is remarkable, because most of the digital mammography systems worldwide are fullfield digital mammography systems with soft-copy reading. Because the soft-copy reading of digital mammography involves very complex processes, some issues have been raised. For the special articles in this issue, a group of recognized and experienced experts, based on the Mammography Subcommittee of the Japan Radiological Society, were assembled. These experts have put together a monograph on digital mammography. The special articles provide a comprehensive review and update on digital mammography, especially in Japan. They will serve as an excellent reference source for anyone interested in digital mammography.

Digital mammographic screening in Japan

We describe the current status of mammographic screening and investigate how digital mammography is used in screening in Japan. Despite the widespread use of digital mammographic equipment, the mammographic screening rate for invited women is very low. In the majority of cases, digital hard copy images are read for screening. Soft-copy reading of digital mammography is not widely used, because of the difficulty of handling large amounts of CR data, the cost of workstations with 5 M LCD monitors, and the loading of full-field digital mammography on the mobile unit. Digital mammography has a number of advantages and has increasingly replaced conventional film-screen mammography, becoming the gold standard in combination with soft-copy reading in screening settings.

汎用液晶ディスプレイモニタの臨床使用におけるグレースケール標準表示関数の適用

Interpretations of medical images have been shifting to soft-copy readings with liquid-crystal display (LCD) monitors. The display function of the medical-grade LCD monitor for soft-copy readings is recommended to calibrate the grayscale standard display function (GSDF) in accordance with the guidelines of Japan and other countries. In this study, the luminance and display function of five models of eight general purpose LCD monitors were measured to gain an understanding of their characteristics. Moreover, the display function (gamma 2.2 or gamma 1.8) of general purpose LCD monitors was converted to GSDF through the use of a look-up table, and the detectability of a simulated lung nodule in the chest x-ray image was examined. As a result, the maximum luminance, contrast ratio, and luminance uniformity of general purpose LCD monitors, except for one model of two LCD monitors, met the management grade 1 standard in the guideline JESRA X-0093-2005. In addition, the detectability of simulated lung nodule in the mediastinal space was obviously improved by converting the display function of a general purpose LCD monitor into GSDF.

Preliminary investigation of the clinical usefulness of super-high-resolution LCDs with 9 and 15 mega-sub-pixels: observation studies with phantoms

Our purpose in this study was to evaluate the preliminary clinical efficacy of soft-copy reading of digital mammography, for a 15-mega-sub-pixel (MsP) and a 9-MsP super-high-resolution liquid-crystal display (SHR-LCD) by use of an independent sub-pixel driving technology. We performed three kinds of phantom observation studies by six radiological technologists. Detectability of a contrast-detail phantom and simulated small objects (SSOs) resembling microcalcifications (MCLs), and shape discrimination ability of SSOs with round and square shapes, were examined and compared with a 5-MP conventional LCD (5-MP LCD). In each study, four types of display magnification ratio were used. The detectability and the shape discrimination ability of the 15-MsP SHR-LCD were highest among the three LCDs of most of the display magnification ratios. The 9-MsP SHR-LCD indicated a higher or equal performance as compared with the 5-MP LCD in the SSO detection and shape studies. The results of our study demonstrated that the SHR-LCDs had good potential to detect MCLs and to evaluate the shape in high-resolution digital mammography.

Effects of ambient-light correction in luminance measurements of liquid-crystal display monitors by use of a telescopic-type luminance meter

The quality control of liquid-crystal display (LCD) monitors has become one of the important topics for maintaining reliable soft-copy readings in the interpretation of diagnostic images. In this paper, the effects of correction in the luminance measurement of an LCD monitor by use of a telescopic-type luminance meter were investigated. The luminance of the LCD monitor in different ambient-lighting conditions was measured and compared to the results obtained with no ambient lighting (0 lux). The reproducibility of luminance measurements and luminance ratios without a baffled tube was lower than those measured with the baffled tube due to the effect of ambient light. These tendencies were obvious at a relatively low luminance. The correction method by subtraction of the reflected ambient light on the surface of the LCD monitor and the stray light of the telescopic-type luminance meter from the measured luminance was examined. We found that the correction was able to bring the luminance close to that measured with the baffled tube.

Lcd versus crt monitors for digital mammography: a comparison of observer performance for the detection of clustered microcalcifications and masses

There are two types of soft-copy display of digital mammograms, cathode-ray tube (CRT) and liquid-crystal display (LCD) monitors, and these present different resolutions and noise characteristics. To compare observer performances for the detection of clustered microcalcifications and masses in digital mammograms, using LCD and CRT monitors. Four radiologists evaluated 100 digital mammograms. Of these, 28 mammograms depicted clustered microcalcifications (12 benign, 16 malignant), 18 depicted masses (10 benign, eight malignant), and 54 depicted no apparent abnormality. The images were stored uncompressed as Digital Imaging and Communications in Medicine (DICOM) files and randomized for two sessions of soft-copy reading. The readers independently read all cases displayed on two 5-megapixel LCD and two CRT monitors with an interval of 3 months. Observers were asked to rate using a five-point scale the likelihoods of microcalcifications and masses independently. Receiver operating characteristic analysis was used to analyze results. For the LCD and CRT monitors, average area-under-the-curve (A(z)) values for microcalcification detection were 0.977 (0.976, 0.970, 0.980, and 0.983 for the four readers) and 0.958 (0.910, 0.990, 0.976, 0.956), respectively. Corresponding A(z) values for masses were 0.971 (0.955, 0.990, 0.949, 0.989) and 0.944 (0.928, 0.966, 0.955, 0.925). No statistically significant difference was detected between the two monitor types (P>0.05). The LCD and CRT monitors are comparable in terms of detecting clustered microcalcifications and masses in digital mammograms.

Comparison of paper print and soft copy reading in plain paediatric radiographs

With the introduction of a Picture Archiving and Communication System, Computed (CR) and Digital Radiography (DR), reading digital images takes place from a computer screen. Laser paper print rather than laser film would be a significantly more cost-effective option for hard copy production, but would need to demonstrate acceptable diagnostic quality compared to the reference standard of screen reading. A comparative study of 51 digital paediatric CR radiographs presented in laser paper print and soft copy format to determine the diagnostic value of the paper print when compared to the reference standard of screen reading. Chest radiography had a poor sensitivity of 66.1% while musculoskeletal and abdominal radiography had acceptable sensitivities of 90% and 99%, respectively. Specificity was excellent for the different regions (98.6-99.5%). The paper print format should not be used for diagnostic purposes in paediatric chest radiography, but may still be used for demonstration when accompanied by the radiology rapport obtained from soft copy reading. Further studies would be needed to investigate the use of paper prints in abdominal and musculoskeletal radiography owing to the low number of abdominal radiographs and lack of musculoskeletal case variety in our study.