Mohammad A. Rawashdeh

Quantitative measures confirm the inverse relationship between lesion spiculation and detection of breast masses.

OBJECTIVE To identify specific mammographic appearances that reduce the mammographic detection of breast cancer. MATERIALS AND METHODS This study received institutional board review approval and all readers gave informed consent. A set of 60 mammograms each consisting of craniocaudal and mediolateral oblique projections were presented to 129 mammogram Breastscreen readers. The images consisted of 20 positive cases with single and multicentric masses in 16 and 4 cases, respectively (resulting in a total of 24 cancers), and readers were asked to identify and locate the lesions. Each lesion was then ranked according to a detectability rating (ie, the number of observers who correctly located the lesion divided by the total number of observers), and this was correlated with breast density, lesion size, and various descriptors of lesion shape and texture. RESULTS Negative and positive correlations between lesion detection and density (r = -0.64, P = .007) and size (r = 0.65, P = .005), respectively, were demonstrated. In terms of lesion size and shape, there were significant correlations between the probability of detection and area (r = 0.43, P = .04), perimeter (r = 0.66, P = .0004), lesion elongation (r = 0.49, P = .02), and lesion nonspiculation (r = 0.78, P < .0001). CONCLUSIONS The results of this study have identified specific lesion characteristics associated with shape that may contribute to reduced cancer detection. Mammographic sensitivity may be adversely affected without appropriate attention to spiculation.

The impact of using a JAFROC or ROC approach on the conclusions of a typical observer performance study

Purpose: The current study aims to compare ROC with JAFROC methodologies to investigate how the choice of available analytical approaches in observer studies can impact upon study conclusions. Methods and materials: A total of 129 readers independently reviewed 60 mammographic cases, 20 of which were biopsy proven cases (abnormal) and 40 were normal. Each case consisted of the four standard cranio-caudal (CC) and medio-lateral oblique (MLO) projections. Readers were asked to interpret and locate any presence of cancer, and levels of confidence were scored on a scale of 1-5. Radiology workstations supporting 5MP diagnostic monitors and with full image manipulation tools were used to display all images. JAFROC and ROC methodologies were used and figures of merit and Az values respectively were correlated against key reader characteristics such as experience, qualifications, breast reading practices and physical characteristics using Spearman techniques. Results: Correlation analysis between reader characteristics and JAFROC analysis demonstrated that four key characteristics were linked to performance: years of qualification as a radiologist (p=0.05, r= 0.18), years reading mammograms (p=0.01, r=0.24), number of mammograms read per year (p=0.001, r=0.24), and hours reading mammogram per week (p=0.04, r= 0.19). The ROC method indicated that determinants of performance were confined to years reading mammograms (p=0.02, r = 0.2), and number of mammograms read per year (p=0.04, r=0.23). Conclusion: This work demonstrates the practical impact on study conclusions when different methodologies are used. The location sensitivity approach employed and statistical power with JAFROC, would suggest that the findings from this approach should be prioritized.

Impact of Breast Reader Assessment Strategy on mammographic radiologists' test reading performance.

The detection of breast cancer is somewhat limited by human factors, and thus there is a need to improve reader performance. This study assesses whether radiologists who regularly undertake the education in the form of the Breast Reader Assessment Strategy (BREAST) demonstrate any changes in mammography interpretation performance over time.

Experience in reading digital images may decrease observer accuracy in mammography

Rationale and Objectives: To identify parameters linked to higher levels of performance in screening mammography. In particular we explored whether experience in reading digital cases enhances radiologists’ performance. Methods: A total of 60 cases were presented to the readers, of which 20 contained cancers and 40 showed no abnormality. Each case comprised of four images and 129 breast readers participated in the study. Each reader was asked to identify and locate any malignancies using a 1-5 confidence scale. All images were displayed using 5MP monitors, supported by radiology workstations with full image manipulation capabilities. A jack-knife free-response receiver operating characteristic, figure of merit (JAFROC, FOM) methodology was employed to assess reader performance. Details were obtained from each reader regarding their experience, qualifications and breast reading activities. Spearman and Mann Whitney U techniques were used for statistical analysis. Results: Higher performance was positively related to numbers of years professionally qualified (r= 0.18; P<0.05), number of years reading breast images (r= 0.24; P<0.01), number of mammography images read per year (r= 0.28; P<0.001) and number of hours reading mammographic images per week (r= 0.19; P<0.04). Unexpectedly, higher performance was inversely linked to previous experience with digital images (r= - 0.17; p<0.05) and further analysis, demonstrated that this finding was due to changes in specificity. Conclusion: This study suggests suggestion that readers with experience in digital images reporting may exhibit a reduced ability to correctly identify normal appearances requires further investigation. Higher performance is linked to number of cases read per year.

Measurement of breast lesion display luminance and overall image display luminance relative to optimum luminance for contrast perception

Introduction: To minimize fatigue due to eye adaptation and maximize contrast perception, it has been suggested that lesion luminance be matched to overall image luminance to perceive the greatest number of grey level differences. This work examines whether lesion display luminance matches the overall image and breast tissue display luminance and whether these factors are positioned within the optimum luminance for maximal contrast sensitivity. Methods: A set of 42 mammograms, collected from 21 patients and containing 15 malignant and 6 benign lesions, was used to assess overall image luminance. Each image displayed on the monitor was divided into 16 equal regions. The luminance at the midpoint of each region was measured using a calibrated photometer and the overall image luminance was calculated. Average breast tissue display luminance was calculated from the subset of regions containing of only breast tissue. Lesion display luminance was compared with both overall image display luminance and average breast tissue display luminance. Results: Statistically significant differences (p<0.0001) were noted between overall image display luminance (4.3±0.7 cd/m2) and lesion display luminance (15.0±6.8 cd/m2); and between average breast tissue display luminance (6.8±1.3 cd/m2) and lesion display luminance (p<0.002). Conclusions: Lesion luminance was significantly higher than the overall image and breast tissue luminance. Luminance of lesions and general breast tissue fell below the optimum luminance range for contrast perception. Breast lesion detection sensitivity and specificity may be enhanced by use of brighter monitor displays.

Assessment of Jordanian Radiologist Performance in the Detection of Breast Cancers

This study aims to monitor diagnostic accuracy amongst Jordanian mammography readers and identify parameters linked to higher levels of performance. In this study, we have used the Breast Screen Reader Assessment Strategy (BREAST) platform to facilitate 27 radiologists in reading a case set of 60 digital mammograms, 20 of which included cancers. Each case consisted of the four standard cranio-caudal (CC) and medio-lateral oblique (MLO) projections. All radiologists were registered to read mammograms at their workplace by the Jordanian Ministry of Health. Each reader was asked to locate any malignancies, provide a confidence rating using a scale of 1 - 5, and identify the type of appearance. All images were displayed using 8 MP monitor, supported by radiology workstations with full image manipulation facilities. Results were evaluated using Jackknife Alternative Free-Response Receiver Operating Characteristic (JAFROC). Demographics obtained from each radiologist regarding their experience, qualifications and breast-reading activities were correlated against JAFROC scores using Spearman techniques. The results showed that the mean JAFROC score was 0. 52 (95% confidence interval (CI): 0.46, 0.58); location sensitivity score was 0. 41 (95% CI: 0.41, 0.56); specificity score was 0.73 (95% CI: 0.68, 0.83). Higher performance in term of JAFROC scores was directly related to number of years since professional qualification (r = 0.433; p = 0.024), number of years reading breast images (r = 0.62; r = 0.001) and number of mammography images read per year (r = 0.69; p = 0.001). On the other hand, higher performance was inversely linked to the frequency of reading other modalities per week (r = -0.48; p = 0.010). No other statistical differences were significant. Finally, higher radiologists’ performance in cancer detection is correlated with increasing the number of mammograms reads per week.

Knowledge and practice of computed tomography exposure parameters amongst radiographers in Jordan

OBJECTIVE To investigate the knowledge and practice of computed tomography (CT) radiographers working in Jordan. MATERIALS AND METHODS This Institutional Review Board (IRB) approved study disseminated a questionnaire via social media and recruited 54 Jordanian CT radiographers. The questionnaire comprised 36 questions divided into four sections: demographics; an evaluation of knowledge regarding CT exposure; modifications to CT exposure for paediatric patients; dose units and diagnostic reference levels (DRLs). Descriptive and inferential statistics including Chi-square tests, Mann-Whitney U tests, independent samples t-tests and Kruskal-Wallis H tests were employed. Statistical significance was considered below p < 0.05. RESULTS The 54 participants had various qualifications, with the majority holding a Bachelors degree (n = 35, 64.8%) and the rest holding a Diploma (n = 19, 35.2%). In order to pass the questionnaire, participants needed to score 13 correct answers. The overall number of radiographers who correctly passed the questionnaire was 48 (88.9%). None of the participants correctly stated all the DRL values for chest, abdomen and brain CT. However, four out of 54 respondents (7.4%) knew the chest DRL value, three (5.6%) participants correctly estimated the abdominal DRL value but only two (3.7%) knew the DRL for the brain. CONCLUSION Good general knowledge was found amongst radiographers regarding the relationship of each exposure parameter to the image quality and patient dose. However, there was poor knowledge of diagnostic reference levels and the order of the organ radiation sensitivity. The need for CT radiographers to undertake further education that focuses on radiation exposure in CT is highlighted.

Classification of normal screening mammograms is strongly influenced by perceived mammographic breast density

To investigate how breast screen readers classify normal screening cases using descriptors of normal mammographic features and to assess test cases for suitability for a single reading strategy.

Investigating the link between the radiological experience and the allocation of an 'equivocal finding'

Rationale and Objectives: This study will investigate the link between radiologists’ experience in reporting mammograms, their caseloads and the decision to give a classification of Royal Australian and New Zealand College of Radiologists (RANZCR) category ‘3’ (indeterminate or equivocal finding). Methods: A test set of 60 mammograms comprising of 20 abnormal and 40 normal cases were shown to 92 radiologists. Each radiologist was asked to identify and localize abnormalities and provide a RANZCR assessment category. Details were obtained from each reader regarding their experience, qualifications and breast reading activities. ‘Equivocal fractions’ were calculated by dividing the number of ‘equivocal findings’ given by each radiologist in the abnormal and normal cases by the total number of cases analyzed: 20 and 40 respectively. The ‘equivocal fractions’ for each of the groups (normal vs abnormal) were calculated and independently correlated with age, number of years since qualification as a radiologist, number of years reading mammograms, number of mammograms read per year, number of hours reading mammograms per week and number of mammograms read over lifetime (the number of years reading mammograms multiplied by the number of mammograms read per year). The non-parametric Spearman test was used. Results: Statistically negative correlations were noted between ‘equivocal fractions’ for the following groups: • For abnormal cases: hours per week (r= -0.38 P= 0.0001) • For normal cases: total number of mammograms read per year (r= -0.29, P= 0.006); number of mammograms read over lifetime (r= -0.21, P= 0.049)); hours reading mammograms per week (r= - 0.20, P= 0.05). Conclusion: Radiologists with greater reading experience assign fewer RANZCR category 3 or equivocal classifications. The findings have implications for screening program efficacy and recall rates. This work is still in progress and further data will be presented at the conference.

Mammography: Radiologist and Image Characteristics That Determine the Accuracy of Breast Cancer Diagnosis

Variations in the performance of breast readers are well reported, but key lesion and reader parameters explaining such variations are not fully explored. This large study aims to: 1) measure diagnostic accuracy of breast radiologists, 2) identify parameters linked to higher levels of performance, and 3) establish the key morphological descriptors that impact detection of breast cancer. Methods: Sixty cases, 20 containing cancer, were shown to 129 radiologists. Each reader was asked to locate any malignancies and provide a confidence rating using a scale of 1-5. Details were obtained from each radiologist regarding experience and training and were correlated with jackknifing free response operating characteristic (JAFROC) figure of merit. Cancers were ranked according to the “detectability rating” that is, the number of readers who accurately detected and located the lesion divided by the total number of readers, and this was correlated with various mathematical lesion descriptors. Results: Higher reader performance was positively correlated with number of years reading mammograms (r=0.24, p=0.01), number of mammogram readings per year (r=0.28, p=0.001), and hours reading mammogram per week (r=0.19, p=0.04). For image features and lesion descriptors there was correlation between “detectability rating” and lesion size (r=0.65, p=0.005), breast density (r=-0.64, p=0.007), perimeter (r=0.66, p=0.0004), eccentricity (r= 0.49, p=0.02), and solidity (r=0.78, p< 0.0001). Radiologist experience and lesion morphology may contribute significantly to reduce cancer detection.