Identification of factors associated with diagnostic performance variation in reporting of mammograms: A review.

OBJECTIVES: This narrative review aims to identify what factors are linked to diagnostic performance variation for those who interpret mammograms. Identification of influential factors has potential to contribute to the optimisation of breast cancer diagnosis. PubMed, ScienceDirect and Google Scholar databases were searched using the following terms: 'Radiology', 'Radiologist', 'Radiographer', 'Radiography', 'Mammography', 'Interpret', 'read', 'observe' 'report', 'screen', 'image', 'performance' and 'characteristics.' Exclusion criteria included articles published prior to 2000 as digital mammography was introduced at this time. Non-English articles language were also excluded. 38 of 2542 studies identified were analysed. KEY FINDINGS: Influencing factors included, new technology, volume of reads, experience and training, availability of prior images, social networking, fatigue and time-of-day of interpretation. Advancements in breast imaging such as digital breast tomosynthesis and volume of mammograms are primary factors that affect performance as well as tiredness, time-of-day when images are interpreted, stages of training and years of experience. Recent studies emphasised the importance of social networking and knowledge sharing if breast cancer diagnosis is to be optimised. CONCLUSION: It was demonstrated that data on radiologist performance variability is widely available but there is a paucity of data on radiographers who interpret mammographic images. IMPLICATIONS FOR PRACTICE: This scarcity of research needs to be addressed in order to optimise radiography-led reporting and set baseline values for diagnostic efficacy.

Test-set training improves the detection rates of invasive cancer in screening mammography.

AIM: To investigate if mammographic test-set participation affects routine breast cancer screening performance. MATERIALS AND METHODS: Clinical audit data between 2008 and 2018 were collected for 35 breast screen readers who participated in the BreastScreen Reader Assessment Strategy (BREAST) and 22 readers with no history of test-set participation. For BREAST readers, the annual audit data were divided according to the year they completed their first test set, and the same years were used randomly to align and divide the data of non-BREAST readers into pre- and post-test set periods. Multiple audit parameters were inspected retrospectively for the two cohorts to identify how their reading performance has evolved in screening mammography. RESULTS: Investigating 2 calendar years before and after test-set participation, BREAST and non-BREAST readers recalled lower rates of women in the latter period (p=0.03 and p=0.02, respectively). They also improved their positive predictive value (PPV; p=0.01 and p=0.02, respectively). BREAST readers additionally improved their detection rates of invasive cancer (p=0.02) and all cancers (p=0.01). In an extended 3-year comparison, similar improvements occurred in the recall rate for BREAST (p=0.02) and non-BREAST readers (p=0.02) and in PPV (p=0.001, 0.01, respectively); however, improvements in detection rates also occurred exclusively in BREAST readers' performance for invasive cancer (p=0.04), DCIS (p=0.05), and all cancers (p=0.02); however, significant improvements in detection did not involve <15 mm invasive cancers in both periods. Meanwhile, non-BREAST readers demonstrated a decrease in sensitivity (p=0.02). CONCLUSION: Participation in test sets is linked to over-time improvements in most audit-measured cancer detection rates.

Imaging Breast Microcalcifications Using Dark-Field Signal in Propagation-Based Phase-Contrast Tomography.

Breast microcalcifications are an important primary radiological indicator of breast cancer. However, microcalcification classification and diagnosis may be still challenging for radiologists due to limitations of the standard 2D mammography technique, including spatial and contrast resolution. In this study, we propose an approach to improve the detection of microcalcifications in propagation-based phase-contrast X-ray computed tomography of breast tissues. Five fresh mastectomies containing microcalcifications were scanned at different X-ray energies and radiation doses using synchrotron radiation. Both bright-field (i.e. conventional phase-retrieved images) and dark-field images were extracted from the same data sets using different image processing methods. A quantitative analysis was performed in terms of visibility and contrast-to-noise ratio of microcalcifications. The results show that while the signal-to-noise and the contrast-to-noise ratios are lower, the visibility of the microcalcifications is more than two times higher in the dark-field images compared to the bright-field images. Dark-field images have also provided more accurate information about the size and shape of the microcalcifications.

Clinical performance progress of BREAST participants: the impact of test-set participation.

AIM: To investigate if positive changes in the clinical performance of radiologists are associated with reading mammographic test sets. MATERIALS AND METHODS: This study investigated the clinical audit history for a cohort of 39 participants in the BreastScreen Reader Assessment Strategy who have read for BreastScreen New South Wales in the period between 2010 and 2018, inclusively. Based on the year in which each radiologist completed his or her first test set, data of multiple clinical audit metrics from two calendar years before test-set reading were compared against similar data from three different periods after test-set completion. The same process was repeated after dividing radiologists into two subgroups based on their median screen-reading volume (3,688), to test if experience is a determinant of post-test set performance. RESULTS: On average, radiologists showed significant improvements (p<0.05) in the recall rate for subsequent screening rounds, in positive predictive value 1 (PPV1), and in specificity. When dividing radiologists based on their average annual reading volume, radiologists with higher reading numbers demonstrated similar significant improvements in the recall rate and in PPV1. In addition, they showed significant improvements in the detection rates of invasive breast cancer and ductal carcinoma in situ (DCIS). In contrast, the radiologists with lower reading volume indicated significant changes in the recall rate and in PPV1, both accruing in one of the three compared periods. CONCLUSION: Mammographic test-set participants improve over time in identifying normal breast screens and detecting breast cancer in association with reading higher volumes of breast screening cases.

Dark-field signal extraction in propagation-based phase-contrast imaging.

A method for extracting the dark-field signal in propagation-based phase-contrast imaging is proposed. In the case of objects consisting predominantly of a single material, or several different materials with similar ratios of the real decrement to the imaginary part of the complex refractive index, the proposed method requires a single image for extraction of the dark-field signal in two-dimensional projection imaging. In the case of three-dimensional tomographic imaging, the method needs only one image to be collected at each projection angle. Initial examples using simulated and experimental data indicate that this method can improve visualization of small sharp features inside a larger object, e.g. the visualization of microcalcifications in propagation-based x-ray breast cancer imaging. It is suggested that the proposed approach may be useful in other forms of biomedical imaging, where it can help one to obtain additional small-angle scattering information without increasing the radiation dose to the sample.

Perfecting detection through education.

INTRODUCTION: Radiologists' image reading skills vary, such variations in image interpretations can influence the effectiveness of the early treatment of disease and may have important clinical and economic implications. In screening mammography, clinical audits are used to assess radiologists' performance annually, however, the nature of these audits prevent robust data analysis due to the low prevalence of breast cancer and the long waiting periods for the audit results. Research-based evidence revealed a need for changes in the methods utilised to optimise the assessment of the efficacy of radiologists' interpretations. METHODS: A cloud-based platform was developed to assess and enhance radiologists' performance help reduce variability in medical image interpretations in a research environment; however, to address a number of limitations, the platform was commercialised to make it available worldwide. RESULTS: DetectED-X's team have been able to make their cloud-based platform available worldwide, tailored to the needs of radiologists and accredited for continuing medical/professional education; thus, changing the continuous professional development practice globally. CONCLUSION: DetectED-X's Rivelato, was developed to address a need for effective, available and affordable educational solutions for clinicians and health care workers wherever they are located. A true fusion of industry, academia, clinics and consumer to adapt to the growing needs of clinicians' around the world, the latest being COVID-19 global pandemic. DetectED-X repurposed its platform to educate physicians around the world on the appearances of COVID-19 on Lung Computed Tomography scans, introducing CovED to clinicians worldwide free of charge as a multi-national consortium of collaboration to help fight COVID-19, showing how research-based evidence can create effective and scalable change globally.

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.

The roles of clinical audit and test sets in promoting the quality of breast screening: a scoping review.

Breast screening programmes enhance the probability of early breast cancer detection in many countries worldwide; however, the success of these efforts is highly dependent on the ability of breast screen readers to detect abnormalities in the screened population, which has low prevalence. Therefore, this task can be challenging. Clinical audit is a key quality assurance measure that aims to keep the screen reading performance within acceptable standards. Auditing, nonetheless, is a lengthy process, and its accuracy is dependent on available clinical data, which often can be limited. Mammographic standardised test sets are a different screen reading evaluation approach that provides participants with instant feedback based on a simulated environment. Although a test set provides unique evaluative qualities, its ability to represent clinical performance is debated. This article describes the distinctive roles of clinical audit and test sets in measuring and improving the quality of breast screening and highlights the relationship between test sets and clinical performance.

Effects of time of day on radiological interpretation.

Accurate interpretation of radiological images involves a complex visual search that relies on several cognitive processes, including selective attention, working memory, and decision-making. Patient outcomes often depend on the accuracy of image interpretations, and yet research has revealed that conclusions vary significantly from one radiologist to another. A myriad of factors has been shown to contribute to the likelihood of interpretative errors and discrepancies, including the radiologist's level of experience and fatigue, and these factors are well reported elsewhere; however, a potentially important factor that has been given little previous consideration is how radiologists' interpretations might be impacted by the time of day at which the reading takes place, a factor that other disciplines have shown to be a determinant of competency. The available literature shows that while the time of day is known to significantly impact some cognitive functions that likely relate to reading competence, including selective visual attention and visual working memory, little is known about the impact of the time of day on radiology interpretation performance. This review explores the evidence regarding the relationship between time of day and performance, with a particular emphasis on radiological activities.

Propagation-based x-ray phase-contrast tomography of mastectomy samples using synchrotron radiation.

PURPOSE: Propagation-based phase-contrast computed tomography (PB-CT) is a method for three-dimensional x-ray imaging that utilizes refraction, as well as absorption, of x rays in the tissues to increase the signal-to-noise ratio (SNR) in the resultant images, in comparison with equivalent conventional absorption-only x-ray tomography (CT). Importantly, the higher SNR is achieved without sacrificing spatial resolution or increasing the radiation dose delivered to the imaged tissues. The present work has been carried out in the context of the current development of a breast CT imaging facility at the Australian Synchrotron. METHODS: Seven unfixed complete mastectomy samples with and without breast cancer lesions have been imaged using absorption-only CT and PB-CT techniques under controlled experimental conditions. The radiation doses delivered to the mastectomy samples during the scans were comparable to those approved for mammographic screening. Physical characteristics of the reconstructed images, such as spatial resolution and SNR, have been measured and compared with the results of the radiological quality assessment of the complete absorption CT and PB-CT image stacks. RESULTS: Despite the presence of some image artefacts, the PB-CT images have outperformed comparable absorption CT images collected at the same radiation dose, in terms of both the measured objective image characteristics and the radiological image scores. The outcomes of these experiments are shown to be consistent with predictions of the theory of PB-CT imaging and previous reported experimental studies of this imaging modality. CONCLUSIONS: The results presented in this paper demonstrate that PB-CT holds a high potential for improving on the quality and diagnostic value of images obtained using existing medical x-ray technologies, such as mammography and digital breast tomosynthesis (DBT). If implemented at suitable synchrotron imaging facilities, PB-CT can be used to complement existing imaging modalities, leading to more accurate breast cancer diagnosis.

Free propagation phase-contrast breast CT provides higher image quality than cone-beam breast-CT at low radiation doses: a feasibility study on human mastectomies.

In this study we demonstrate the first direct comparison between synchrotron x-ray propagation-based CT (PB-CT) and cone-beam breast-CT (CB-CT) on human mastectomy specimens (N = 12) including different benign and malignant lesions. The image quality and diagnostic power of the obtained data sets were compared and judged by two independent expert radiologists. Two cases are presented in detail in this paper including a comparison with the corresponding histological evaluation. Results indicate that with PB-CT it is possible to increase the level of contrast-to-noise ratio (CNR) keeping the same level of dose used for the CB-CT or achieve the same level of CNR reached by CB-CT at a lower level of dose. In other words, PB-CT can achieve a higher diagnostic potential compared to the commercial breast-CT system while also delivering a considerably lower mean glandular dose. Therefore, we believe that PB-CT technique, if translated to a clinical setting, could have a significant impact in improving breast cancer diagnosis.

Radiologist performance in the detection of lung cancer using CT.

AIM: To measure the level of radiologists' performance in lung cancer detection, and to explore radiologists' performance in cancer specialised and non-specialised centres. MATERIALS AND METHODS: Thirty radiologists read 60 chest computed tomography (CT) examinations. Thirty cases had surgically or biopsy-proven lung cancer and 30 were cancer-free cases. The cancer cases were validated by four expert radiologists who located the malignant lung nodules. Reader performance was evaluated by calculating sensitivity, location sensitivity, specificity, and area under the receiver operating characteristic (ROC) curve (AUC). In addition, sensitivity at fixed specificity (0.794) was computed from each reader's estimated ROC curve. RESULTS: The radiologists had a mean sensitivity of 0.749, sensitivity at fixed specificity of 0.744, location sensitivity of 0.666, specificity of 0.81 and AUC of 0.846. Radiologists in the specialised and non-specialised cancer centres had the following (specialised, non-specialised) pairs of values: sensitivity=(0.80, 0.719); sensitivity for fixed 0.794 specificity=(0.752, 0.740); location sensitivity=(0.712, 0.637); specificity=(0.794, 0.82) and AUC=(0.846, 0.846). CONCLUSION: The efficacy of radiologists was comparable to other studies. Furthermore, AUC outcomes were similar for specialised and non-specialised cancer centre radiologists, suggesting they have similar discriminatory ability and that the higher sensitivity and lower specificity for specialised-centre radiologists can be attributed to them being less conservative in interpreting case images.

THE IMPACT OF DIGITAL TECHNOLOGY ON DOSE REDUCTION IN PAEDIATRIC CARDIAC CATHETERISATION WITHIN A LARGE METROPOLITAN CHILDREN'S HOSPITAL.

This study examines the kerma-area product (PKA) levels from paediatric cardiac catheterisations at a major Children's Hospital over three different time periods in order to gain an understanding of the causation of dose variations over time and to present a model for dose reduction. A retrospective review of 1245 paediatric procedural records was undertaken. This cohort consisted of patients that were catheterised over a period from November 2007 to July 2009, October 2009 to November 2011 and January 2016 to December 2016. The age distribution was from newborn to 18 years. Archived (PKA) readings were retrieved and analysed. The 75th percentile PKA values for the specific age categories over time periods (1, 2, 3) were 0-30 days-(5.47, 1.37, 1.37) Gy cm2; 1-12 months-(6.42, 2.03, 1.06) Gy cm2; 1-3 years-(11.25, 3.20, 1.25) Gy cm2; 3-5 years-(12.65, 3.72, 2.88) Gy cm2; 5-10 years-(12.80, 8.53, 3.52) Gy cm2; 10-15 years-(27.92, 10.85, 2.97) Gy cm2; >15 years-(29.09, 27.81, 11.65) Gy cm2. Using newer imaging technologies, optimising dose reduction strategies and regular dose auditing can transform radiation dose delivery for paediatric x-ray examinations. Our centre provides a template for dose reduction success worldwide.

Mammographic Appearances in Mongolia: Causal Factors for Varying Densities

Objective: Mammographic density (MD) is a significant risk factor for breast cancer and an important determinant for establishing efficiency of any screening program. Currently, the distribution and influential factors of MD is unknown among Mongolian women. This work aims to characterize MD of Mongolian women. Methods: The ethical approval was obtained from Research Ethics Board of the University of Sydney (2014/973) and National Ethic Committee from Ministry of Mongolia (2015/04). We recruited 1985 women aged 16-83 from the National Cancer Center in Mongolia for whom MD and age of each woman was known. From this total group, 983 women also had additional available details on height, weight, body mass index (BMI) and area of residency. We investigated the association of each of these variables with breast density, which was assessed by using the Breast Imaging Reporting and Data System (BIRADS) lexicon. Univariate and multivariate regression analyses were conducted to explore the importance of these variables as predictors of MD. Results: Category B (33%) was the most common type of MD, whereas 25%, 18% and 24% of women belonged to the category A, C and D respectively. The univariate analysis demonstrated that, younger women had more dens breasts than their older counterparts (OR=6.8). Also, increased MD was significantly (p<0.05) associated with decreased weight (OR=4.5), increased height (OR=0.4) and lower BMI (OR=13.2). Urban women had significantly higher MD compared with rural counterparts (OR=2.2). In the multivariate analysis, 75% of variation in MD was explained by age (OR=4.5) and BMI (OR=7.3). Conclusion: A high proportion of Mongolian women have very high density breasts and age and body size are key factors determining MD among these women.

Increased image quality and reduced radiation dose and contrast media volume: a holistic approach to intracranial CTA.

AIM: To investigate the dose-length product (DLP) during intracranial computed tomography angiography (CTA) using a patient-specific contrast formula. MATERIALS AND METHODS: Intracranial CTA was performed on 120 patients using 64-channel CT. Patients were subjected in equal numbers to one of two acquisitions/contrast medium protocols. Protocol A, consisted of 80 ml contrast medium and protocol B, involved a novel contrast medium formula. In each protocol, contrast medium and saline were injected at a flow rate of 4.5 ml/s. The DLP and contrast volume (CV) were measured between each protocol and the data obtained were compared using two-tailed independent t-test. RESULTS: Mean arterial vessel attenuation was up to 56% (p<0.01) higher using protocol B compared with A. In the venous system, the mean vessel attenuation was significantly lower in protocol B than A with a maximum reduction of 93% (p<0.001). The mean CV was significantly lower in protocol B (53±10 ml) compared to A (80±1 ml, p<0.001). The scan time was equal in each protocol (B, 4.22±1.2 seconds; A, 4.01±1.3 seconds). A significant reduction in mean DLP was demonstrated in protocol B (3.99±0.22 mSv) compared to A (4.74±0.22 mSv; p=0.02). CONCLUSION: A significant reduction in CV and DLP during intracranial CTA can be achieved when employing a patient-specific contrast medium formula.

Optimization of propagation-based x-ray phase-contrast tomography for breast cancer imaging.

The aim of this study was to optimise the experimental protocol and data analysis for in-vivo breast cancer x-ray imaging. Results are presented of the experiment at the SYRMEP beamline of Elettra Synchrotron using the propagation-based phase-contrast mammographic tomography method, which incorporates not only absorption, but also x-ray phase information. In this study the images of breast tissue samples, of a size corresponding to a full human breast, with radiologically acceptable x-ray doses were obtained, and the degree of improvement of the image quality (from the diagnostic point of view) achievable using propagation-based phase-contrast image acquisition protocols with proper incorporation of x-ray phase retrieval into the reconstruction pipeline was investigated. Parameters such as the x-ray energy, sample-to-detector distance and data processing methods were tested, evaluated and optimized with respect to the estimated diagnostic value using a mastectomy sample with a malignant lesion. The results of quantitative evaluation of images were obtained by means of radiological assessment carried out by 13 experienced specialists. A comparative analysis was performed between the x-ray and the histological images of the specimen. The results of the analysis indicate that, within the investigated range of parameters, both the objective image quality characteristics and the subjective radiological scores of propagation-based phase-contrast images of breast tissues monotonically increase with the strength of phase contrast which in turn is directly proportional to the product of the radiation wavelength and the sample-to-detector distance. The outcomes of this study serve to define the practical imaging conditions and the CT reconstruction procedures appropriate for low-dose phase-contrast mammographic imaging of live patients at specially designed synchrotron beamlines.

A review of lung cancer screening and the role of computer-aided detection.

Lung cancer is the leading cause of cancer-related death worldwide; however, early diagnosis of lung cancer leads to higher survival rates. The National Lung Screening Trial (NLST) demonstrated that scanning with low-dose computed tomography (LDCT) led to a 20% reduction in mortality rate in a high-risk population. This paper covers new developments in screening eligibility criteria and the possible benefits and the harm of screening with CT. To make the screening process more feasible and help reduce the rate of missed lung nodules, computer-aided detection (CAD) has been introduced to assist radiologists in lung nodule detection. The aim of this paper is to review how CAD works, its performance in lung nodule detection, and the factors that influence its performance. This paper also aims to investigate the effect of different types of CAD on CT in lung nodule detection and the effect of CAD on radiologists' decision outcomes.

Cumulative Effective and Individual Organ Dose Levels in Paediatric Patients Undergoing Multiple Catheterisations for Congenital Heart Disease.

This study examines the cumulative radiation dose levels received by a group of children who underwent multiple cardiac catheterisation procedures during the investigation and management of congenital heart disease (CHD). The purpose is to calculate cumulative doses, identify higher dose individuals, outline the inconsistencies with risk assessment and encourage the establishment of dose databases in order to facilitate the longitudinal research necessary to better understand health risks. A retrospective review of patient records for 117 paediatric patients who have undergone two or more cardiac catheterisations for the investigation of CHD was undertaken. This cohort consisted of patients who were catheterised over a period from September 2002 to August 2014. The age distribution was from newborn to 17 y. Archived kerma-area product (PKA) and fluoroscopy time (T) readings were retrieved and analysed. Cumulative effective and individual organ doses were determined. The cumulative PKA levels ranged from 1.8 to 651.2 Gycm2, whilst cumulative effective dose levels varied from 2 to 259 mSv. The cumulative fluoroscopy time was shown to vary from 8.1 to 193.5 min. Median cumulative organ doses ranged from 3 to 94 mGy. Cumulative effective dose levels are highly variable but may exceed 250 mSv. Individual organ and effective dose measurements remain useful for comparison purposes between institutions although current methodologies used for determining lifetime risks are inadequate.

CONTEMPORARY AUSTRALIAN DOSE AREA PRODUCT LEVELS IN THE FLUOROSCOPIC INVESTIGATION OF PAEDIATRIC CONGENITAL HEART DISEASE.

This study examines radiation dose levels delivered to children from birth to 15 y of age in the investigation of congenital heart disease (CHD) at a major Sydney children's hospital. The aims are to compare values with those derived from similar studies, to provide a template for more consistent dose reporting, to establish local and national diagnostic reference levels and to contribute to the worldwide paediatric dosimetry database. A retrospective review of 1007 paediatric procedural records was undertaken. The cohort consisted of 795 patients over a period from January 2007 to December 2012 who have undergone cardiac catheterisation for the investigation of CHD. The age range included was from the day of birth to 15 y. Archived dose area product (DAP) and fluoroscopy time (FT) readings were retrieved and analysed. The mean, median, 25th and 75th percentile DAP levels were calculated for six specific age groupings. The 75th percentile DAP values for the specific age categories were as follows: 0-30 d-1.9 Gy cm2, 1-12 months-2.9 Gy cm2, 1-3 y-5.3 Gy cm2, 3-5 y-6.2 Gy cm2, 5-10 y-7.5 Gy cm2 and 10-15 y-17.3 Gy cm2. These levels were found to be lower than the values reported in comparable overseas studies. Individual year-specific levels were determined, and it is proposed that these are more useful than the common grouping method. The age-specific 75th percentile DAP levels outlined in this study can be used as baseline local diagnostic reference levels. The needs for the standardisation of DAP reporting and for a greater range of age-specific diagnostic reference levels have been highlighted. For the first time, Australian dose values for paediatric cardiac catheterisation are presented.