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

Pathologists light level preferences using the microscope-study to guide digital pathology display use

Background

Currently, there is a paucity of guidelines relating to displays used for digital pathology making procurement decisions, and optimal display configuration, challenging.Experience suggests pathologists have personal preferences for brightness when using a conventional microscope which we hypothesized could be used as a predictor for display setup.

Methods

We conducted an online survey across six NHS hospitals, totalling 108 practicing pathologists, to capture brightness adjustment habits on both microscopes and displays.A convenience subsample of respondents was then invited to take part in a practical task to determine microscope brightness and display luminance preferences in the normal working environment. A novel adaptation for a lightmeter was developed to directly measure the light output from the microscope eyepiece.

Results

The survey (response rate 59% n=64) indicates 81% of respondents adjust the brightness on their microscope. In comparison, only 11% report adjusting their digital display. Display adjustments were more likely to be for visual comfort and ambient light compensation rather than for tissue factors, common for microscope adjustments. Part of this discrepancy relates to lack of knowledge of how to adjust displays and lack of guidance on whether this is safe; But, 66% felt that the ability to adjust the light on the display was important.Twenty consultants took part in the practical brightness assessment. Light preferences on the microscope showed no correlation with display preferences, except where a pathologist has a markedly brighter microscope light preference. All of the preferences in this cohort were for a display luminance of <500 cd/m2, with 90% preferring 350 cd/m2 or less. There was no correlation between these preferences and the ambient lighting in the room.

Conclusions

We conclude that microscope preferences can only be used to predict display luminance requirements where the microscope is being used at very high brightness levels. A display capable of a brightness of 500 cd/m2 should be suitable for almost all pathologists with 300 cd/m2 suitable for the majority. Although display luminance is not frequently changed by users, the ability to do so was felt to be important by the majority of respondents.Further work needs to be undertaken to establish the relationship between diagnostic performance, luminance preferences, and ambient lighting levels.

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.

Optimisation of exposure parameters using a phantom for thoracic spine radiographs in antero-posterior and lateral views

INTRODUCTION

To investigate the exposure parameters for thoracic spine/(TS) radiography that allows the image acquisition at the lowest dose possible, while maintaining an adequate image quality/(IQ) to identify all relevant anatomical criteria.

METHODS

An experimental phantom study was conducted, and 48 different radiographs of TS (24 AP/24 lateral) were acquired. The Automatic Exposure Control/(AEC) with the central sensor was used to select the beam intensity, while Source-to-Detector-Distance/(SDD) (AP:115/125 cm; Lateral:115/150 cm), tube potential (AP:70/81/90 kVp; Lateral: 81/90/102 kVp), use of grid/no grid and focal spot (fine/broad) were manipulated. IQ was assessed by observers with ViewDEX. Effective Dose (ED) was estimated using PCXMC2.0 software. Descriptive statistics paired with intraclass correlation coefficient (ICC) were applied to analyse data.

RESULTS

The ED increased with a greater SDD for lateral-view, presenting a significant difference (p = 0.038), however IQ was not affected. For both AP and lateral, the use of grid had a significant effect on ED (p < 0.001). Despite the images acquired without grid had lower IQ scores, the observers considered the IQ adequate for clinical use. A 20% reduction in ED (0.042mSv-0.033 mSv) was observed when increasing the beam energy from 70 to 90 kVp for AP grid in. The observers ICC ranged from moderate to good (0.5-0.75) in lateral and good to excellent (0.75-0.9) for AP views.

CONCLUSIONS

The optimised parameters in this context were 115 cm SDD, 90 kVp with grid for the best IQ and lowest ED. Further studies in clinical setting are necessary to enlarge the context and cover different body habitus and equipment.

IMPLICATIONS FOR PRACTICE

The SDD impacts on dose for TS; Higher kVp and grid are necessary to better image quality.

Thousand shades of gray - The role of imaging display in diagnosis of occult scaphoid fractures - A pilot study

Introduction

Most hospitals and clinics utilize commercial grade displays for viewing wrist radiographs. There is no evidence regarding the role of the imaging display used to evaluate the radiographs. The aim of this study was to compare the rates of scaphoid fracture diagnosis by commercial grade and medical grade displays.

Methods

Wrist radiographs of patients that had clinical signs of scaphoid fracture without findings on plain radiography (suspected scaphoid fractures) were retrospectively collected from ER department and interpreted for radiographic signs of fracture by four orthopedics seniors commercial grade and medical grade displays. The difference in fracture diagnosis rates were studied. Inter- and intra-observer variability were also studied.

Results

Study population comprised of 175 high quality wrist radiographs were interpreted. Mean 48.25 (27%) scaphoid fractures were observed on commercial grade display compared to 66 (38.2%) on medical grade display (p = 0.076). The total inter-observer agreement could be defined as a moderate agreement (κ = 0.527, Accuracy = 0.77). Total agreement between all observers were observed in 86 (49.1%) cases compared to 89 (50.9%) cases when reviewing X-rays on commercial and medical displays, respectively.

Discussion

The scaphoid fracture detection rate on medical grade display was not statistically higher compared to non-medical grade displays, but we did find a tendency toward medical grade display. We found that in a substantial number of cases, our observers recognize signs of fracture that were initially evaluated as "suspected fracture" by the ER physicians. As a pilot study, we found evidence that support the need for a prospective study designed to compare the observations to a gold standard modality, such as MRI. We believe utilizing medical grade displays can increase the rate of diagnosis in cases of clinically suspected scaphoid fractures and better manage the clinical scenario of a suspected scaphoid fracture.

Perceived contrast on displays with different luminance ranges

PURPOSE

Medical displays are fundamental in today's healthcare since they provide the link between digitally stored data and the human clinician, and it is thus important that the transfer of information is as effective and reliable as possible. Contrast perception in viewed images is complex due to the nature of the human visual system, and the luminance distribution in the viewed scene plays a major role. Standards and guidelines concerning medical displays are important as they set a baseline image quality. However, as the number of imaging applications as well as display technology has evolved rapidly during the past decades, there may be possible uses not foreseen in the current guidelines. Bright screens may perform as good in bright rooms as less bright displays do in dark rooms, but current guidelines are likely to favor dark rooms due to historical reasons. The purpose of this study was to determine the limits of contrast perception in three very different lighting conditions and relate the outcome to guideline recommendations.

METHODS

Three different display luminance settings were studied, 1-250, 6-500, and 12-750 cd/m2 with luminance ratios of 250, 85, and 62, respectively. Although the luminance ratios, black levels, and white levels were different, they all covered the same number of just noticeable differences (JNDs). By using a two-alternative forced-choice method, contrast thresholds were determined at dark, mid-gray, and bright pixel values for all luminance settings using bar patterns with two different spatial frequencies. In total, 18 contrast thresholds were determined by each of the 10 observers.

RESULTS

The contrast thresholds for the low-frequency patterns were close to 0.5 JNDs and there were no systematic differences between the three luminance conditions at any of the pixel values. The high-frequency patterns required almost 10 times higher contrast where the highest contrast threshold (worst visibility) was obtained for the luminance setting 1-250 cd/m2 at the dark pixel value.

CONCLUSIONS

The differences between the three luminance conditions were mostly minor, which indicate that display settings with low luminance ratios and high minimum luminance levels can be used without compromising displayed image contrast. The number of JNDs enclosed by the luminance range of a display is a reliable metric for global perceived contrast. Luminance ratios are limited regarding the ability to detect low contrast objects when there are large differences in luminance, although they can still be used within a relatively small range of luminance levels. Low luminance levels may cause a loss of visibility, especially for fine details, and should be avoided.

Measurement Challenges for Medical Image Display Devices

Visual information is a critical component in the evaluation and communication of patient medical information. As display technologies have evolved, the medical community has sought to take advantage of advances in wider color gamuts, greater display portability, and more immersive imagery. These image quality enhancements have shown improvements in the quality of healthcare through greater efficiency, higher diagnostic accuracy, added functionality, enhanced training, and better health records. However, the display technology advances typically introduce greater complexity in the image workflow and display evaluation. This paper highlights some of the optical measurement challenges created by these new display technologies and offers possible pathways to address them.

Evaluation of optimised 3D turbo spin echo and gradient echo MR pulse sequences of the knee at 3T and 1.5T

INTRODUCTION

To investigate the impact of parameter optimisation for novel three-dimensional 3D sequences at 1.5T and 3T on resultant image quality.

METHODS

Following institutional review board approval and acquisition of informed consent, MR phantom and knee joint imaging on healthy volunteers (n = 16) was performed with 1.5 and 3T MRI scanners, respectively incorporating 8- and 15-channel phased array knee radiofrequency coils. The MR phantom and healthy volunteers were prospectively scanned over a six-week period. Acquired sequences included standard two-dimensional (2D) turbo spin echo (TSE) and novel three-dimensional (3D) TSE PDW (SPACE) both with and without fat-suppression, and T2∗W gradient echo (TrueFISP) sequences. Signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) were measured for knee anatomical structures. Two musculoskeletal radiologists evaluated anatomical structure visualisation and image quality. Quantitative and qualitative findings were investigated for differences using Friedman tests. Inter- and intra-observer agreements were determined with κ statistics.

RESULTS

Phantom and healthy volunteer images revealed higher SNR for sequences acquired at 3T (p-value <0.05). Generally, the qualitative findings ranked images acquired at 3T higher than corresponding images acquired at 1.5T (p < 0.05). 3D image data sets demonstrated less sensitivity to partial volume averaging artefact (PVA) compared to 2D sequences. Inter- and intra-observer agreements for evaluation across all sequences ranged from 0.61 to 0.79 and 0.71 to 0.92, respectively.

CONCLUSION

Both 2D and 3D images demonstrated higher image quality at 3T than at 1.5T. Optimised 3D sequences performed better than the standard 2D PDW TSE sequence for contrast resolution between cartilage and joint fluid, with reduced PVA artefact.

IMPLICATIONS FOR PRACTICE

With rapid advances in MRI scanner technology, including hardware and software, the optimisation of 3D MR pulse sequences to reduce scan time while maintaining image quality, will improve diagnostic accuracy and patient management in musculoskeletal MRI.

Interpretative characteristics and case features associated with the performances of radiologists in reading mammograms: A study from a non-screening population in Asia

AIMS

To explore radiologist characteristics and case features associated with diagnostic performances in cancer detection on mammograms in a South East Asian population.

METHODS

Fifty-three radiologists reported 60 mammographic examinations which consisted of 40 normal and 20 cancer-containing cases at the BREAST workshops. Radiologists were asked to examine each mammogram using the BIRADS on diagnostic monitors. Differences in reader characteristics and case features between correct and incorrect decisions were assessed separately for cancer and normal cases. Univariate and multivariate logistic regressions were applied to generate odds ratios (OR) for significant factors related to correct decisions.

RESULTS

Radiologists who spent ≥10 hours/week reporting mammograms had a higher possibility of detecting cancer lesions (OR = 1.6; P = 0.01). A higher rate of accuracy in reporting negative cases was associated with female radiologists (OR = 1.4; P = 0.002), radiologists who read ≤20 mammograms per week (OR = 1.5; P < 0.0001), had completed training course (OR = 1.7; P < 0.0001) or wore eyeglasses (OR = 1.4; P = 0.01). Cancer cases with breast density >50% (OR = 2.1; P < 0.0001), having abnormal lesions ≥9 mm (OR = 1.8; P < 0.0001), or displaying calcifications, a discrete mass or nonspecific density (OR = 1.6; P < 0.0001) were recorded with a higher detection rate by radiologists than other cases. Lesions located on the right breasts (OR = 1.8; P < 0.0001) or found in the lower inner, upper outer or mixed locations (OR = 2.7; P < 0.0001) were also recorded with a better diagnostic possibility compared with other lesions.

CONCLUSION

This work identified key features related to diagnostic accuracy of breast cancer on mammograms in a nonscreening population, which is helpful for developing appropriate strategies to improve breast cancer detectability of radiologists.

Impact of time of day on radiology image interpretations

AIM

To examine the impact of the time of day on radiologists' mammography reading performance.

MATERIALS AND METHODS

Retrospective mammographic reading assessment data were collected from the BreastScreen Reader Assessment Strategy database and included timestamps of the readings and reader-specific demographic data of 197 radiologists. The radiologists performed the readings in a workshop setting with test case sets enriched with malignancies (one-third of cases were malignant). The collected data were evaluated with an analysis of covariance to determine whether time of day influenced radiologists' specificity, lesion sensitivity or the jackknife alternative free-response receiver operating characteristic (JAFROC).

RESULTS

After adjusting for radiologist experience and fellowship, specificity varied significantly by time of day (p=0.027), but there was no evidence of any significant impact on lesion sensitivity (p=0.441) or JAFROC (p=0.120). The collected data demonstrated that specificity during the late morning (10.00-12.00) was 71.7%; this was significantly lower than in the early morning (08.00-10.00) and mid-afternoon (14.00-16.00), which were 82.74% (p=0.003) and 81.39% (p=0.031), respectively. Specificity during the late afternoon (16.00-18.00) was 73.95%; this was significantly lower than in the early morning (08.00-10.00) and mid-afternoon (14.00-16.00), which were 82.74% (p=0.003) and 81.39% (p=0.031), respectively.

CONCLUSION

The results indicated that the time of day may influence radiologists' performance, specifically their ability to identify normal images correctly.

Pupil diameter differentiates expertise in dental radiography visual search

Expert behavior is characterized by rapid information processing abilities, dependent on more structured schemata in long-term memory designated for their domain-specific tasks. From this understanding, expertise can effectively reduce cognitive load on a domain-specific task. However, certain tasks could still evoke different gradations of load even for an expert, e.g., when having to detect subtle anomalies in dental radiographs. Our aim was to measure pupil diameter response to anomalies of varying levels of difficulty in expert and student dentists’ visual examination of panoramic radiographs. We found that students’ pupil diameter dilated significantly from baseline compared to experts, but anomaly difficulty had no effect on pupillary response. In contrast, experts’ pupil diameter responded to varying levels of anomaly difficulty, where more difficult anomalies evoked greater pupil dilation from baseline. Experts thus showed proportional pupillary response indicative of increasing cognitive load with increasingly difficult anomalies, whereas students showed pupillary response indicative of higher cognitive load for all anomalies when compared to experts.

Reduction of visual acuity decreases capacity to evaluate radiographic image quality

INTRODUCTION

To determine the impact of reduced visual acuity on the evaluation of a test object and appendicular radiographs.

METHODS

Visual acuity was reduced by two different magnitudes using simulation glasses and compared to normal vision (no glasses). During phase one phantom images were produced for the purpose of counting objects by 13 observers and on phase 2 image appraisal of anatomical structures was performed on anonymized radiographic images by 7 observers. The monitors were calibrated (SMPTE RP133 test pattern) and the room lighting was maintained at 7 ± 1 lux. Image display and data on grading were managed using ViewDEX (v.2.0) and the area under the visual grading characteristic (AUC_VGC) was calculated using VGC Analyzer (v1.0.2). Inferential statistics were calculated using SPSS.

RESULTS

For the evaluation of appendicular radiographs the total interpretation time was longer when visual acuity was reduced with 2 pairs of simulation glasses (15.4 versus 8.9 min). Visual grading analysis showed that observers can lose the ability to detect anatomical and contrast differences when they have a simulated visual acuity reduction, being more challenging to differentiate low contrast details. No simulation glasses, compared to 1 pair gives an AUC_VGC of 0.302 (0.280, 0.333), that decreases to 0.197 (0.175, 0.223) when using 2 pairs of glasses.

CONCLUSIONS

Reduced visual acuity has a significant negative impact on the evaluation of test objects and clinical images. Further work is required to test the impact of reduced visual acuity on visual search, technical evaluation of a wider range of images as well as pathology detection/characterization performance.

IMPLICATIONS FOR PRACTICE

It seems that visual performance needs to be considered to reduce the risks associated with incomplete or incorrect diagnosis. If employers or professional bodies were to introduce regular eye tests into health screening it may reduce the risk of misinterpretation as a result of poor vision.

Visual function assessment of diagnostic radiography students

INTRODUCTION

Deterioration of visual acuity (VA) and visual impairment has been linked to age-related subtle changes, gender, and a correlation to socioeconomic status. This study aimed to assess first-year diagnostic radiography students' visual functional abilities by applying the International Classification of Impairments, Disabilities and Handicaps (ICIDH) recommendations of functional VA screening and health-related quality of life questionnaire (HRQOL).

METHODS

The design followed the World Health Organisation (WHO) electronic VA testing of monocular sight using LogMAR charts and binocular vision using Snellen charts, and an HRQOL questionnaire assessing for reduced ability of visual-based tasks in activities of daily living (ADL). The data was evaluated in correlation to the participant's visual correction, age, gender, and socioeconomic background.

RESULTS

Seventy students were recruited, all meeting the WHO standard level for visual ability, with 100% (n = 70/70) met or achieved above normal binocular vision, correlating to expected normal population results from published studies for age. The monocular vision demonstrated 74% (n = 52/70) for the right eye, and 80% (n = 56/70) for the left eye for normal vision levels. The results did not differ significantly between each eye (p = 0.21), gender variations between the left eye (p = 0.27) and the right eye (p = 0.10) results were affected by sample ratio of females (80%; n = 56/70) to males (20%; n = 14/70), the visual correction did not impair binocular VA. The HRQOL assessment indicated no significant functional VA issues in the study sample. The study demonstrated no association between the participant's socioeconomic background that may influence their VA ability.

CONCLUSION

The results provided normative binocular and monocular data on visual function in a sample of student radiographers and indicated that their thresholds align to normal (or near-normal) VA standards.

IMPLICATIONS FOR PRACTICE

The visual health data was reviewed for subgroup comparison and trend analysis, and did not identify risk factors within this sample group that their VA and visual functioning would impact upon radiography clinical placement tasks and activities. The sample is not generalisable to the wider population; further studies are recommended.

Perceptual and Interpretive Error in Diagnostic Radiology-Causes and Potential Solutions

Interpretation of increasingly complex imaging studies involves multiple intricate tasks requiring visual evaluation, cognitive processing, and decision-making. At each stage of this process, there are opportunities for error due to human factors including perceptual and ergonomic conditions. Investigation into the root causes of interpretive error in radiology first began over a century ago. In more recent work, there has been increasing recognition of the limits of human image perception and other human factors and greater acknowledgement of the role of the radiologist's environment in increasing the risk of error. This article reviews the state of research on perceptual and interpretive error in radiology. This article focuses on avenues for further error examination, and strategies for mitigating these errors are discussed. The relationship between artificial intelligence and interpretive error is also considered.

Evaluation of unenhanced axial T1W and T2W liver MR images acquired from institutions within the Republic of Ireland and the Kingdom of Saudi Arabia

INTRODUCTION

This multi-site study evaluated two breath-hold sequences commonly utilised for liver MRI; non-enhanced T1W-3D-FS-GRE-TRA and T2W-2D-FSE-TRA sequences, using physical measurements of SNR and CNR, and observer perceptions' (Visual Grading Analysis: VGA).

METHODS

Liver MR image datasets (n = 168) from nine hospitals in the Kingdom of Saudi Arabia (KSA) and 11 hospitals in the Republic of Ireland were evaluated. Images were categorised into two groups per sequence, defined by slice thickness (T2W-2D-FSE, ≤5 mm vs ≥ 6 mm and T1W-3D-GRE-FS, ≤3 mm vs 4 mm). Images were evaluated using visual grading analysis VGA and physical measurements: SNR/CNR. Account was taken of varying patient sizes based on AP/transverse diameter measurements.

RESULTS

Physical image quality measurements (SNR/CNR) returned no significant findings across Irish and KSA hospitals, for both sequences, despite variations in acquisition parameters. Statistically significant differences were found for some scoring criteria based on the observers' perceptions including spleen parenchyma, and spatial resolution for the non-enhanced T1W-3D-FS-GRE-TRA images, with a preference for images acquired using thin slices (≤3 mm). In addition, statistically significant difference was found for the scoring criteria motion artefact for the axial T2W-2D-FSE-TRA images, with a preference for images acquired using thick slices (≥5 mm). Negligible correlation was noted between SNR/CNR and measured abdominal AP/transverse diameters.

CONCLUSION

Whilst variations in sequences rendered no statistical differences in SNR/CNR findings, significant differences in observer image criteria scores was noted. The importance of both physical measurements and observers' perceptions evaluation methods for quality assessment of MR images was demonstrated and optimisation of liver sequence parameters is warranted.

Breast lesion shape and margin evaluation: BI-RADS based metrics understate radiologists' actual levels of agreement

BACKGROUND

While there is much literature describing the radiologic detection of breast cancer, there are limited data available on the agreement between experts when delineating and classifying breast lesions. The aim of this work is to measure the level of agreement between expert radiologists when delineating and classifying breast lesions as demonstrated through Breast Imaging Reporting and Data System (BI-RADS) and quantitative shape metrics.

METHODS

Forty mammographic images, each containing a single lesion, were presented to nine expert breast radiologists using a high specification interactive digital drawing tablet with stylus. Each reader was asked to manually delineate the breast masses using the tablet and stylus and then visually classify the lesion according to the American College of Radiology (ACR) BI-RADS lexicon. The delineated lesion compactness and elongation were computed using Matlab software. Intraclass Correlation Coefficient (ICC) and Cohen's kappa were used to assess inter-observer agreement for delineation and classification outcomes, respectively.

RESULTS

Inter-observer agreement was fair for BI-RADS shape (kappa = 0.37) and moderate for margin (kappa = 0.58) assessments. Agreement for quantitative shape metrics was good for lesion elongation (ICC = 0.82) and excellent for compactness (ICC = 0.93).

CONCLUSIONS

Fair to moderate levels of agreement was shown by radiologists for shape and margin classifications of cancers using the BI-RADS lexicon. When quantitative shape metrics were used to evaluate radiologists' delineation of lesions, good to excellent inter-observer agreement was found. The results suggest that qualitative descriptors such as BI-RADS lesion shape and margin understate the actual level of expert radiologist agreement.

Systemic Error in Radiology

OBJECTIVE

Interpretive errors in diagnostic imaging result in significant patient morbidity and mortality, but the importance of errors and process failures in the imaging cycle other than during image interpretation is underappreciated. In this article, we describe these errors and potential solutions, providing a framework to improve patient safety and understand the changing roles of radiologists beyond image interpretation.

CONCLUSION

For comprehensive improvements to health care delivery, other failures in the cycle besides diagnostic interpretive error-such as ordering inappropriate studies, PACS failures, and a lack of accurate clinician contact information (with resultant communication failure)-should be recognized as contributors to patient harm because they lead to wasted resources and delayed care. By taking ownership of the entire imaging cycle, radiologists can increase their net worth to patient care and cement their roles as experts in the effective, evidence-based use of imaging technologies.

Third version of vendor-specific model-based iterativereconstruction (Veo 3.0): evaluation of CT image quality in the abdomen using new noise reduction presets and varied slice optimization

OBJECTIVE

To qualitatively and quantitatively compare abdominal CT images reconstructed with a newversion of model-based iterative reconstruction (Veo 3.0; GE Healthcare Waukesha, WI) utilizing varied presetsof resolution preference, noise reduction and slice optimization.

METHODS

This retrospective study was approved by our Institutional Review Board and was Health Insurance Portability and Accountability Act compliant. The raw datafrom 30 consecutive patients who had undergone CT abdomen scanning were used to reconstructfour clinical presets of 3.75mm axial images using Veo 3.0: 5% resolution preference (RP05n), 5%noise reduction (NR05) and 40% noise reduction (NR40) with new 3.75mm "sliceoptimization," as well as one set using RP05 with conventional 0.625mm "slice optimization" (RP05c). The images were reviewed by two independent readers in a blinded, randomized manner using a 5-point Likert scale as well as a 5-point comparative scale. Multiple two-dimensional circular regions of interest were defined for noise and contrast-to-noise ratio measurements. Line profiles were drawn across the 7 lp cm^-1 bar pattern of the Catphan 600 phantom for evaluation of spatial resolution.

RESULTS

The NR05 image set was ranked as the best series in overall image quality (mean difference inrank 0.48, 95% CI [0.081-0.88], p = 0.01) and with specific reference to liver evaluation (meandifference 0.46, 95% CI [0.030-0.89], p = 0.03), when compared with the secondbest series ineach category. RP05n was ranked as the best for bone evaluation. NR40 was ranked assignificantly inferior across all assessed categories. Although the NR05 and RP05c image setshad nearly the same contrast-to-noise ratio and spatial resolution, NR05 was generally preferred. Image noise and spatial resolution increased along a spectrum with RP05n the highest and NR40the lowest. Compared to RP05n, the average noise was 21.01% lower for NR05, 26.88%lower for RP05c and 50.86% lower for NR40.

CONCLUSION

Veo 3.0 clinical presets allow for selection of image noise and spatial resolution balance; for contrast-enhanced CT evaluation of the abdomen, the 5% noise reduction preset with 3.75 mm slice optimization (NR05) was generally ranked superior qualitatively and, relative to other series, was in the middle of the spectrum with reference to image noise and spatial resolution. Advances in knowledge: To our knowledge, this is the first study of Veo 3.0 noise reduction presets and varied slice optimization. This study provides insight into the behaviour of slice optimization and documents the degree of noise reduction and spatial resolution changes that users can expect across various Veo 3.0 clinical presets. These results provide important parameters to guide preset selection for both clinical and research purposes.

Intercountry analysis of breast density classification using visual grading

OBJECTIVE

Disagreement in mammographic breast density (MBD) assessment can impact breast cancer risk stratification, choices of further breast cancer screening intervals and pathways. This study examines whether intercountry MBD expectations and assessment approaches are associated with differences in MBD assessment.

METHODS

20 American Board of Radiology (ABR) examiners and 24 UK practitioners using the 4th edition BI-RADS^® lexicon assessed 40 mammogram cases of 20 females. 26 Royal Australian and New Zealand College of Radiologists (RANZCR) registered radiologists also assessed the same cases. Interobserver correlation and agreement were assessed using Spearman's correlation (ρ) and weighted kappa (κ_w), respectively.

RESULTS

Strong positive correlation was observed between the study cohorts on a binary scale (1-2 vs 3-4) [ABR examiners and RANZCR radiologists (ρ = 0.950); ABR examiners and UK practitioners (ρ = 0.940); and RANZCR radiologists and UK practitioners (ρ = 0.958)]. ABR and RANZCR radiologists demonstrated slight agreement [κ_w = 0.10; 95% confidence interval (CI) = -1.13-0.43], whereas ABR and UK practitioners showed a fair agreement [κ_w = 0.25; 95% CI = -0.42-0.61], and an almost perfect agreement was observed between RANZCR radiologists and UK practitioners [κ_w = 0.95; 95% CI = 0.91-0.97].

CONCLUSION

Findings demonstrate wide international and interobserver variability in MBD assessment. This level of variability underscores the need for automation and standardization of MBD assessment. Advances in knowledge: Intercountry analysis of MBD assessment shows variations, with less variation on the binary scale than on the 4-point scale. With this level of variation, automation and standardization of MBD assessment becomes more appropriate.

AN INVESTIGATION INTO CT RADIATION DOSE VARIATIONS FOR HEAD EXAMINATIONS ON MATCHED EQUIPMENT

This study investigated radiation dose and image quality differences for computed tomography (CT) head examinations across centres with matched CT equipment. Radiation dose records and imaging protocols currently employed across three European university teaching hospitals were collated, compared and coded as Centres A, B and C from specification matched CT equipment models. Patient scans (n = 40) obtained from Centres A and C were evaluated for image quality, based on the visualisation of Commission of European Community (CEC) image quality criteria using visual grading characteristic (VGC) analysis, where American Board of Radiology examiners (n = 11) stated their confidence in identifying anatomical criteria. Mean doses in terms of CT dose index (CTDI_vol-mGy) and dose length product (DLP-mGy cm) were as follows: Centre A-33.12 mGy and 461.45 mGy cm; Centre B -101 mGy (base)/32 mGy (cerebrum) and 762 mGy cm and Centre C-71.98 mGy and 1047.26 mGy cm, showing a significant difference (p ≤ 0.05) in DLP across centres. VGC analysis indicated better visualisation of CEC criteria on Centre C images (VGC_AUC 0.225). All three imaging protocols are routinely used clinically, and image quality is acceptable in each centre. Clinical centres with identical model CT scanners have variously customised their protocols achieving a range of dose savings and still resulting in clinically acceptable image quality.

Inter-observer variability in mammographic density assessment using Royal Australian and New Zealand College of Radiologists (RANZCR) synoptic scales

INTRODUCTION

The aim of this study was to evaluate observer variability in mammographic density assessment as measured using the Royal Australian and New Zealand College of Radiologists (RANZCR) synoptic scales. Visual assessment of mammographic density by radiologists is commonly used in clinical practice; however, these assessments have been shown to be more subjective than quantitative methods.

METHODS

The study included 40 cases of left cranial-caudal (CC) and mediolateral oblique (MLO) radiographs from 20 women. RANZCR-registered radiologists (n = 26) estimated mammographic breast density of the same images according to RANZCR synoptic scales 1-4. All images had their volumetric density classified using Volpara Density Grade (VDG) and Average Volumetric Breast Density percentage (AvBD%).

RESULTS

The results showed that the radiologists sampled had specialized for 17.18 years (sd 12.03) and read 2072 (sd 2441) mammograms per year on average. Inter-observer agreement using RANZCR synoptic scales had an average Kappa of 0.360; (95% CI = 0.308-0.412) and a range of 0.078-0.499. Radiologists estimated percentage density was lower by 0.37 than VDG, with their mean being 2.18 and the mean VDG was 2.55 (Z = -3.873; P < 0.001). VDG and RANZCR showed a positive strong correlation (ρ = 0.898; P < 0.001). AvBD% and RANZCR also showed a positive strong correlation (ρ = 0.904; P < 0.001).

CONCLUSION

The inter-observer agreement with RANZCR synoptic scales was fair. Wide inter-observer variability was observed. Continued research on appropriate assessment methods for mammographic density assessment is required to avoid unnecessary variations.

Development and validation of a visual grading scale for assessing image quality of AP pelvis radiographic images

OBJECTIVE

The aim of this article was to apply psychometric theory to develop and validate a visual grading scale for assessing the visual perception of digital image quality anteroposterior (AP) pelvis.

METHODS

Psychometric theory was used to guide scale development. Seven phantom and seven cadaver images of visually and objectively predetermined quality were used to help assess scale reliability and validity. 151 volunteers scored phantom images, and 184 volunteers scored cadaver images. Factor analysis and Cronbach's alpha were used to assess scale validity and reliability.

RESULTS

A 24-item scale was produced. Aggregated mean volunteer scores for each image correlated with the rank order of the visually and objectively predetermined image qualities. Scale items had good interitem correlation (≥0.2) and high factor loadings (≥0.3). Cronbach's alpha (reliability) revealed that the scale has acceptable levels of internal reliability for both phantom and cadaver images (α = 0.8 and 0.9, respectively). Factor analysis suggested that the scale is multidimensional (assessing multiple quality themes).

CONCLUSION

This study represents the first full development and validation of a visual image quality scale using psychometric theory. It is likely that this scale will have clinical, training and research applications.

ADVANCES IN KNOWLEDGE

This article presents data to create and validate visual grading scales for radiographic examinations. The visual grading scale, for AP pelvis examinations, can act as a validated tool for future research, teaching and clinical evaluations of image quality.

Mammographic Breast Density Assessment Using Automated Volumetric Software and Breast Imaging Reporting and Data System (BIRADS) Categorization by Expert Radiologists

RATIONALE AND OBJECTIVES

To investigate agreement on mammographic breast density (MD) assessment between automated volumetric software and Breast Imaging Reporting and Data System (BIRADS) categorization by expert radiologists.

MATERIALS AND METHODS

Forty cases of left craniocaudal and mediolateral oblique mammograms from 20 women were used. All images had their volumetric density classified using Volpara density grade (VDG) and average volumetric breast density percentage. The same images were then classified into BIRADS categories (I-IV) by 20 American Board of Radiology examiners.

RESULTS

The results demonstrated a moderate agreement (κ = 0.537; 95% CI = 0.234-0.699) between VDG classification and radiologists' BIRADS density assessment. Interreader agreement using BIRADS also demonstrated moderate agreement (κ = 0.565; 95% CI = 0.519-0.610) ranging from 0.328 to 0.669. Radiologists' average BIRADS was lower than average VDG scores by 0.33, with their mean being 2.13, whereas the mean VDG was 2.48 (U = -3.742; P < 0.001). VDG and BIRADS showed a very strong positive correlation (ρ = 0.91; P < 0.001) as did BIRADS and average volumetric breast density percentage (ρ = 0.94; P < 0.001).

CONCLUSIONS

Automated volumetric breast density assessment shows moderate agreement and very strong correlation with BIRADS; interreader variations still exist within BIRADS. Because of the increasing importance of MD measurement in clinical management of patients, widely accepted, reproducible, and accurate measures of MD are required.

In the digital era, architectural distortion remains a challenging radiological task

AIM

To compare readers' performance in detecting architectural distortion (AD) compared with other breast cancer types using digital mammography.

MATERIALS AND METHODS

Forty-one experienced breast screen readers (20 US and 21 Australian) were asked to read a single test set of 30 digitally acquired mammographic cases. Twenty cases had abnormal findings (10 with AD, 10 non-AD) and 10 cases were normal. Each reader was asked to locate and rate any abnormalities. Lesion and case-based performance was assessed. For each collection of readers (US; Australian; combined), jackknife free-response receiver operating characteristic (JAFROC), figure of merit (FOM), and inferred receiver operating characteristic (ROC), area under curve (Az) were calculated using JAFROC v.4.1 software. Readers' sensitivity, location sensitivity, JAFROC, FOM, ROC, Az scores were compared between cases groups using Wilcoxon's signed ranked test statistics.

RESULTS

For lesion-based analysis, significantly lower location sensitivity (p=0.001) was shown on AD cases compared with non-AD cases for all reader collections. The case-based analysis demonstrated significantly lower ROC Az values (p=0.02) for the first collection of readers, and lower sensitivity for the second collection of readers (p=0.04) and all-readers collection (p=0.008), for AD compared with non-AD cases.

CONCLUSIONS

The current work demonstrates that AD remains a challenging task for readers, even in the digital era.

The impact of pediatric-specific dose modulation curves on radiation dose and image quality in head computed tomography

BACKGROUND

The volume of CT examinations has increased with resultant increases in collective dose values over the last decade.

OBJECTIVE

To analyze the impact of the tube current and voltage modulation for dose values and image quality of pediatric head CT examinations.

MATERIALS AND METHODS

Head CT examinations were performed on anthropomorphic phantoms and four pediatric age categories before and after the introduction of dedicated pediatric curves for tube voltage and current modulation. Local diagnostic reference levels were calculated. Visual grading characteristic image quality evaluation was performed by four pediatric neuroradiologists and image noise comparisons were performed.

RESULTS

Pediatric-specific modulation curves demonstrated a 49% decrease in mean radiation dose for phantom examinations. The local diagnostic reference levels (CTDIvol) for clinical examinations decreased by 52%, 41%, 46% and 40% for newborn, 5-, 10- and 15-year-old patients, respectively. Visual grading characteristic image quality was maintained for the majority of age categorizations (area under the curve = 0.5) and image noise measurements did not change (P = 0.693).

CONCLUSION

Pediatric-specific dose modulation curves resulted in an overall mean dose reduction of 45% with no significant differences in subjective or objective image quality findings.

Visual grading characteristics and ordinal regression analysis during optimisation of CT head examinations

OBJECTIVES

To evaluate visual grading characteristics (VGC) and ordinal regression analysis during head CT optimisation as a potential alternative to visual grading assessment (VGA), traditionally employed to score anatomical visualisation.

METHODS

Patient images (n = 66) were obtained using current and optimised imaging protocols from two CT suites: a 16-slice scanner at the national Maltese centre for trauma and a 64-slice scanner in a private centre. Local resident radiologists (n = 6) performed VGA followed by VGC and ordinal regression analysis.

RESULTS

VGC alone indicated that optimised protocols had similar image quality as current protocols. Ordinal logistic regression analysis provided an in-depth evaluation, criterion by criterion allowing the selective implementation of the protocols. The local radiology review panel supported the implementation of optimised protocols for brain CT examinations (including trauma) in one centre, achieving radiation dose reductions ranging from 24 % to 36 %. In the second centre a 29 % reduction in radiation dose was achieved for follow-up cases.

CONCLUSIONS

The combined use of VGC and ordinal logistic regression analysis led to clinical decisions being taken on the implementation of the optimised protocols. This improved method of image quality analysis provided the evidence to support imaging protocol optimisation, resulting in significant radiation dose savings.

MAIN MESSAGES

• There is need for scientifically based image quality evaluation during CT optimisation. • VGC and ordinal regression analysis in combination led to better informed clinical decisions. • VGC and ordinal regression analysis led to dose reductions without compromising diagnostic efficacy.

Mammographic density measurements are not affected by mammography system

Mammographic density (MD) is a significant risk factor for breast cancer and has been shown to reduce the sensitivity of mammography screening. Knowledge of a woman's density can be used to predict her risk of developing breast cancer and personalize her imaging pathway. However, measurement of breast density has proven to be troublesome with wide variations in density recorded using radiologists' visual Breast Imaging Reporting and Data System (BIRADS). Several automated methods for assessing breast density have been proposed, each with their own source of measurement error. The use of differing mammographic imaging systems further complicates MD measurement, especially for the same women imaged over time. The purpose of this study was to investigate whether having a mammogram on differing manufacturer's equipment affects a woman's MD measurement. Raw mammographic images were acquired on two mammography imaging systems (General Electric and Hologic) one year apart and processed using VolparaDensity™ to obtain the Volpara Density Grade (VDG) and average volumetric breast density percentage (AvBD%). Visual BIRADS scores were also obtained from 20 expert readers. BIRADS scores for both systems showed strong positive correlation ([Formula: see text]; [Formula: see text]), while the VDG ([Formula: see text]; [Formula: see text]) and AvBD% ([Formula: see text]; [Formula: see text]) showed stronger positive correlations. Substantial agreement was shown between the systems for BIRADS ([Formula: see text]; [Formula: see text]), however, the systems demonstrated an almost perfect agreement for VDG ([Formula: see text]; [Formula: see text]).

A multi-phased study of optimisation methodologies and radiation dose savings for head CT examinations

The impact of optimisation methods on dose reductions for head computerised tomography was undertaken in three phases for two manufacturer models. Phase 1: a Catphan(®)600 was employed to evaluate protocols where the impact of parameter manipulation on dose and image quality was gauged by psychophysical measurements of contrast and spatial resolution in terms of contrast discs and line pairs. mA, kV and pitch were systematically altered until the optimisation threshold was identified. Phantom studies provide dose comparisons during optimisation but lack anatomical detail. Phase 2: optimised protocols were tested on a porcine model permitting further dose reductions over phantom findings providing anatomical structures for image quality evaluation using relative visual grading analysis of anatomical criteria. Phase 3: patient images using pre- and post-optimised protocols were clinically audited using visual grading characteristic analysis and ordinal regression analysis providing a robust analysis of image quality data prior to clinical implementation.

DICOM part 14: GSDF-calibrated medical grade monitor vs a DICOM part 14: GSDF-calibrated "commercial off-the-shelf" (COTS) monitor for viewing 8-bit dental images

OBJECTIVES

To investigate whether there is any difference in the presented image quality between a medical grade monitor and a "commercial off-the- shelf" (COTS) monitor when displaying an 8-bit dental image.

METHODS

The digital imaging and communications in medicine (DICOM) part 14: greyscale standard display function (GSDF) was verified for both monitors. A visual grading characteristics (VGC) curve was constructed to measure the difference in image quality between the two monitors by comparing radiological structures displayed on each monitor with a DICOM part 14: GSDF-calibrated laptop monitor as reference.

RESULTS

All of the monitors conformed to within the American Association of Physicists in Medicine Task Group 18 10% tolerance levels for the assessment of the DICOM part 14: GSDF. There was no difference in the preferred perceived visual sensation for the displayed image between the two tested monitors with the area under the VGC curve = 0.53 and 95% confidence interval = 0.47-0.59.

CONCLUSIONS

A DICOM part 14: GSDF COTS monitor is capable of displaying an image quality that is equally preferred to a DICOM part 14: GSDF medical grade monitor for an 8-bit image file.

Diagnostic sensitivity of bone scintigraphy for equine stifle disorders

Disorders of the stifle are a common cause of lameness in horses yet the accuracy of scintigraphy for diagnosis of stifle conditions is controversial. The aim of retrospective cross-sectional study was to determine the diagnostic sensitivity (Se) of bone scintigraphy in detecting stifle disease and to determine if two orthogonal scintigraphic images improve diagnostic Se. Horses that underwent scintigraphic examination during a two-year period were included. Horses were divided into two groups: group 1 (N = 23) had lameness that was localized to the stifle by intra-articular analgesia and group 2 (N = 182) had lameness that was localized to a different location. Scintigraphic studies (one image or two images) were independently and retrospectively analyzed by two radiologists (R1 and R2). Sensitivity, specificity (Sp) and predictive values (PV), and were calculated for each type of study (one image or two images) and for each radiologist (R1 or R2). The Se to detect stifle disorders varied between radiologists (29.2% and 20.8%). The Sp was 84.5% and 88.3%. When two images were evaluated a decrease in the positive PV for both readers occurred. The Cohen kappa coefficient (κ) between readers was poor when one image (0.084) or two images (0.117) were evaluated. Findings from this study indicated that bone-phase nuclear scintigraphy is reasonably specific but highly insensitive for detecting lameness originating from the stifle in a diverse population of both normal and affected horses. The addition of a caudal scintigraphic image acquisition did not improve diagnostic sensitivity.

Exposure (mAs) optimisation of a multi-detector CT protocol for hepatic lesion detection: Are thinner slices better?

INTRODUCTION

The purpose of this work was to determine the exposure-optimised slice thickness for hepatic lesion detection with CT.

METHODS

A phantom containing spheres (diameter 9.5, 4.8 and 2.4 mm) with CT density 10 HU below the background (50 HU) was scanned at 125, 100, 75 and 50 mAs. Data were reconstructed at 5-, 3- and 1-mm slice thicknesses. Noise, contrast-to-noise ratio (CNR), area under the curve (AUC) as calculated using receiver operating characteristic analysis and sensitivity representing lesion detection were calculated and compared.

RESULTS

Compared with the 125 mAs/5 mm slice thickness setting, significant reductions in AUC were found for 75 mAs (P < 0.01) and 50 mAs (P < 0.05) at 1- and 3-mm thicknesses, respectively; sensitivity for the 9.5-mm sphere was significantly reduced for 75 (P < 0.05) and 50 mAs (P < 0.01) at 1-mm thickness; sensitivity for the 4.8-mm sphere was significantly lower for 100, 75 and 50 mAs at all three slice thicknesses (P < 0.05). The 2.4-mm sphere was rarely detected. At each slice thickness, noise at 100, 75 and 50 mAs exposures was approximately 10, 30 and 50% higher, respectively, than that at 125 mAs exposure. CNRs decreased in an irregular manner with reductions in exposure and slice thickness.

CONCLUSION

This study demonstrated no advantage to using slices below 5 mm thickness, and consequently thinner slices are not necessarily better.

Human Factors and Human-Computer Considerations in Teleradiology and Telepathology

Radiology and pathology are unique among other clinical specialties that incorporate telemedicine technologies into clinical practice, as, for the most part in traditional practice, there are few or no direct patient encounters. The majority of teleradiology and telepathology involves viewing images, which is exactly what occurs without the "tele" component. The images used are generally quite large, require dedicated displays and software for viewing, and present challenges to the clinician who must navigate through the presented data to render a diagnostic decision or interpretation. This digital viewing environment is very different from the more traditional reading environment (i.e., film and microscopy), necessitating a new look at how to optimize reading environments and address human factors issues. This paper will review some of the key components that need to be optimized for effective and efficient practice of teleradiology and telepathology using traditional workstations as well as some of the newer mobile viewing applications.

Mammography test sets: reading location and prior images do not affect group performance

AIM

To examine how the location where reading takes place and the availability of prior images can affect performance in breast test-set reading.

MATERIALS AND METHODS

Under optimized viewing conditions, 10 expert screen readers each interpreted a reader-specific set of images containing 200 mammographic cases. Readers, randomly divided into two groups read images under one of two pairs of conditions: clinical read with prior images and laboratory read with prior images; laboratory read with prior images and laboratory read without prior images. Region-of-interest (ROI) figure-of-merit (FOM) was analysed using JAFROC software. Breast side-specific sensitivity and specificity were tested using Wilcoxon matched-pairs signed rank tests. Agreement between pairs of readings was measured using Kendall's coefficient of concordance.

RESULTS

Group performances between test-set readings demonstrated similar ROI FOMs, sensitivity and specificity median values, and acceptable levels of agreement between pairs of readings were shown (W = 0.75-0.79, p < 0.001) for both pairs of reading conditions. On an individual reader level, two readers demonstrated significant decreases (p < 0.05) in ROI FOMs when prior images were unavailable. Reading location had an inconsistent impact on individual performance.

CONCLUSION

Reading location and availability of prior images did not significantly alter group performance.

Quality of 'commercial-off-the-shelf' (COTS) monitors displaying dental radiographs

BACKGROUND

A computer display monitor used for interpreting dental images should have a maximum luminance of 171 cd/m(2). A monitor used for clinical review should have a maximum luminance of 100 cd/m(2).

OBJECTIVE

To compare luminance and ambient lighting measurements for a selection of computer display monitors in different locations of a dental teaching hospital to available guidelines. To assess six commercial off-the-shelf (COTS) monitors from the radiology department of the dental teaching hospital after calibration to the Digital Imaging and Communications in Medicine Part 14: Greyscale Standard Display Function (DICOM part 14: GSDF).

DESIGN

Data collection.

METHOD

Luminance and illuminance measurements were taken for a selection of monitors used for clinical applications throughout a dental teaching hospital. Conformance data were recorded for six COTS monitors from the radiology department following calibration to the DICOM part 14: GSDF. RESULTS None of the tested monitors had a maximum luminance value that was appropriate for image interpretation and the ambient lighting in the vicinity of the monitors was also set to inappropriate levels for image interpretation. The quality of conformance to the DICOM part 14: GSDF varied among the calibrated COTS monitors in the radiology department.

CONCLUSIONS

: It is important that display devices used for dental radiology are quality assured. Consideration should be given to ensure that monitors used for dental radiological interpretation have a maximum luminance that meets available guidelines. These monitors should be standardised to the DICOM part 14: GSDF and the illumination of the reporting environment should be controlled.

Analysis of dominant factors affecting fatigue caused by soft-copy reading

RATIONALE AND OBJECTIVES

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.

MATERIALS AND METHODS

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.

RESULTS

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.

CONCLUSIONS

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.

Could standardizing "commercial off-the-shelf" (COTS) monitors to the DICOM part 14: GSDF improve the presentation of dental images? A visual grading characteristics analysis

OBJECTIVES

To investigate whether standardizing commercial off-the-shelf (COTS) display devices to the digital imaging and communications in medicine part 14: greyscale standard display function (DICOM part 14: GSDF) would affect the presentation of dental images.

METHODS

Two COTS display devices from the radiology department of a dental teaching hospital and a laptop computer monitor for reference were calibrated to conform to DICOM part 14: GSDF. Four dental surgeons and two final-year students undertook a relative visual grading analysis of the two devices before and after calibration, under control of the viewing environment.

RESULTS

Calibrating COTS display devices to conform to the DICOM part 14: GSDF and viewing under reduced ambient light result in a consistent, perceived visual sensation for the presented radiological image. The area under the visual grading characteristics curve (AUCVGC) before calibration is 0.62 CI (0.56, 0.68) and AUCVGC after calibration is 0.51 CI (0.45, 0.57).

CONCLUSIONS

Standardizing COTS display devices to the DICOM part 14: GSDF can improve image presentation.

Screening mammography: test set data can reasonably describe actual clinical reporting

PURPOSE

To establish the extent to which test set reading can represent actual clinical reporting in screening mammography.

MATERIALS AND METHODS

Institutional ethics approval was granted, and informed consent was obtained from each participating screen reader. The need for informed consent with respect to the use of patient materials was waived. Two hundred mammographic examinations were selected from examinations reported by 10 individual expert screen readers, resulting in 10 reader-specific test sets. Data generated from actual clinical reports were compared with three test set conditions: clinical test set reading with prior images, laboratory test set reading with prior images, and laboratory test set reading without prior images. A further set of five expert screen readers was asked to interpret a common set of images in two identical test set conditions to establish a baseline for intraobserver variability. Confidence scores (from 1 to 4) were assigned to the respective decisions made by readers. Region-of-interest (ROI) figures of merit (FOMs) and side-specific sensitivity and specificity were described for the actual clinical reporting of each reader-specific test set and were compared with those for the three test set conditions. Agreement between pairs of readings was performed by using the Kendall coefficient of concordance.

RESULTS

Moderate or acceptable levels of agreement were evident (W = 0.69-0.73, P < .01) when describing group performance between actual clinical reporting and test set conditions that were reasonably close to the established baseline (W = 0.77, P < .01) and were lowest when prior images were excluded. Higher median values for ROI FOMs were demonstrated for the test set conditions than for the actual clinical reporting values; this was possibly linked to changes in sensitivity.

CONCLUSION

Reasonable levels of agreement between actual clinical reporting and test set conditions can be achieved, although inflated sensitivity may be evident with test set conditions.