Purpose: To determine the impact of Breast Screen Reader Assessment Strategy (BREAST) over time in improving radiologists’ breast cancer detection performance, and to identify the group of radiologists that benefit the most by using BREAST as a training tool. Materials and Methods: Thirty-six radiologists who completed three case-sets offered by BREAST were included in this study. The case-sets were arranged in radiologists’ chronological order of completion and five performance measures (sensitivity, specificity, location sensitivity, receiver operating characteristics area under the curve (ROC AUC) and jackknife alternative free-response receiver operating characteristic (JAFROC) figure–of-merit (FOM)), available from BREAST, were compared between case-sets to determine the level of improvement achieved. The radiologists were then grouped based on their characteristics and the above performance measures between the case-sets were compared. Paired t-tests or Wilcoxon signed-rank tests with statistical significance set at p < 0.05 were used to compare the performance measures. Results: Significant improvement was demonstrated in radiologists’ case-set performance in terms of location sensitivity and JAFROC FOM over the years, and radiologists’ location sensitivity and JAFROC FOM showed significant improvement irrespective of their characteristics. In terms of ROC AUC, significant improvement was shown for radiologists who were reading screen mammograms for more than 7 years and spent more than 9 hours per week reading mammograms. Conclusion: Engaging with case-sets appears to enhance radiologists’ performance suggesting the important value of initiatives such as BREAST. However, such performance enhancement was not shown for everyone, highlighting the need to tailor the BREAST platform to benefit all radiologists.
To evaluate the radiation dose derived from digital mammography (DM) and digital breast tomosynthesis (DBT) at
different tube current-exposure time product (mAs) and at 6 phantom thicknesses from 10 to 60 mm.
Materials and Methods
A total of 240 DM and DBT cranio-caudal (CC) phantom images were acquired at each thickness and at four exposure
levels (the baseline mAs, 50%, 25% and 12.5% the baseline mAs). The incident Air Kerma (K) at the surface of the
phantoms was measured using a solid state dosimeter. Mean Glandular Doses (MGD) were calculated for both
modalities (DM and DBT).
DBT dose was greater than that of DM for all mAs at each phantom thickness. For a breast thickness of 50 mm (close to
average sized breast), the dose for DBT (2.32 mGy) was 13% higher than that for DM (2.05 mGy). The results also show
that the difference in MGD between DM and DBT was less for the thicker compared with the thinner phantom, this
difference being approximately a factor of 2.58 at 10 mm compared with a factor of 1.08 at 60 mm. While the MGD
increased with increasing phantom thickness for both modalities, the dose increase with DBT was less than for DM, with
the difference between 10 and 60 mm being a factor of 7 for DM and 3 for DBT.
The radiation dose from DBT was higher than that of DM and the difference in dose between DM and DBT decreases as
phantom thickness increases.
To compare radiologists’ confidence in assessing breast cancer using combined digital mammography (DM) and digital breast tomosynthesis (DBT) compared with DM alone as a function of previous experience with DBT.
Materials and Methods
Institutional ethics approval was obtained. Twenty-three experienced breast radiologists reviewed 50 cases in two modes, DM alone and DM+DBT. Twenty-seven cases presented with breast cancer. Each radiologist was asked to detect breast lesions and give a confidence score of 1-5 (1- Normal, 2- Benign, 3- Equivocal, 4- Suspicious, 5- Malignant). Radiologists were divided into three sub-groups according to their prior experience with DBT (none, workshop experience, and clinical experience). Confidence scores using DM+DBT were compared with DM alone for all readers combined and for each DBT experience subgroup. Statistical analyses, using GraphPad Prism 5, were carried out using the Wilcoxon signed-rank test with statistical significance set at p< 0.05.
Confidence scores were higher for true positive cancer cases using DM+DBT compared with DM alone for all readers (p < 0.0001). Confidence scores for normal cases were lower (indicating greater confidence in the non-cancer diagnosis) with DM+DBT compared with DM alone for all readers (p= 0.018) and readers with no prior DBT experience (p= 0.035).
Addition of DBT to DM increases the confidence level of radiologists in scoring cancer and normal/benign cases. This finding appears to apply across radiologists with varying levels of DBT experience, however further work involving greater numbers of radiologists is required.
This study investigates the impact of breast density on visual searching pattern. A set of 74 one-view malignancy containing mammographic images were examined by 7 radiologists. Eye position was recorded and visual search parameters such as total time examining a case, time to hit the lesion, dwell time and number of hits per area were collected. Fixations were calculated in 3 areas of interests: background breast parenchyma, dense areas of parenchyma and lesion. Significant increases in dwell time and number of hits in dense areas of parenchyma were noted for highcompared to low- mammographic density images when the lesion overlay the fibroglandular tissue (p<0.01). When the lesion was outside the fibroglandular tissue, significant increase in dwell time and number of hits in dense areas of parenchyma in high- compared to low- mammographic density images were observed (p<0.01). No significant differences have been found in total time examining a case, time to first fixate the lesion, dwell time and number of hits in background breast parenchyma and lesion areas. In conclusion, our data suggests that dense areas of breast parenchyma attract radiologists’ visual attention. Lesions overlaying the fibroglandular tissue were detected faster, therefore lesion location, whether overlaying or outside the fibroglandular tissue, appeared to have an impact on radiologists' visual searching pattern.
Purpose: To compare the diagnostic performance of digital breast tomosynthesis (DBT) in combination with digital mammography (DM) with that of digital mammography alone.
Materials and Methods: Twenty six experienced radiologists who specialized in breast imaging read 50 cases (27 cancers and 23 non-cancer cases) of patients who underwent DM and DBT. Both exams included the craniocaudal (CC) and mediolateral oblique (MLO) views. Histopathologic examination established truth in all lesions. Each case was interpreted in two modes, once with DM alone followed by DM+DBT, and the observers were asked to mark the location of any lesions, if present, and give it a score based on a five-category assessment by the Royal Australian and New Zealand College of Radiologists (RANZCR). The diagnostic performance of DM compared with that of DM+DBT was evaluated in terms of the difference between areas under receiver-operating characteristic curves (AUCs), Jackknife free-response receiver operator characteristics (JAFROC) figure-of-merit, sensitivity, location sensitivity and specificity.
Results: Average AUC and JAFROC for DM versus DM+DBT was significantly different (AUCs 0.690 vs 0.781, p=< 0.0001), (JAFROC 0.618 vs. 0.732, p=< 0.0001) respectively. In addition, the use of DM+DBT resulted in an improvement in sensitivity (0.629 vs. 0.701, p=0.0011), location sensitivity (0.548 vs. 0.690, p=< 0.0001) and specificity (0.656 vs. 0.758, p=0.0015) when compared to DM alone.
Conclusion: Adding DBT to the standard DM significantly improved radiologists’ performance in terms of AUCs, JAFROC figure of merit, sensitivity, location sensitivity and specificity values.