Breast tomosynthesis reduces radiologist performance variability compared to digital mammography

Transcription

1 Breast tomosynthesis reduces radiologist performance variability compared to digital mammography Andrew Smith 1, Elizabeth Rafferty 2, Loren Niklason 1 1 Hologic, Inc., Bedford MA, USA 2 Massachusetts General Hospital, Boston MA, USA andrew.smith@hologic.com

2 Study Goals Measure radiologist variability of performance of 2D+3D compared to 2D: Area under ROC curve Decision to recall

3 Tomosynthesis Acquisition X-ray tube Reconstructed 1 mm planes Compression plate Breast Digital detector X-ray tube moves in an arc across the breast 11 projections over 15 Total tomo dose matched to 2D dose (FFDM) Reconstruction into 1 mm transverse slices

4 Data Collection Study tomo in screening environment patients. Diagnostic needed to enrich with cancers. Imaged using 2D (FFDM: Selenia), Imaged using 3D (Tomosynthesis prototype) Both views (CC, MLO), both breasts. Previous studies suggest both CC and MLO tomo needed for optimal performance Institution Review Board/Informed patient consent

5 Why 3D+2D, and not 3D alone? Tomosynthesis (3D) will reduce tissue overlap compared to FFDM (2D), mostly needed for masses Having 2D exam speeds up search for microcalcifications There will be a transition period when 2D is useful: comparison to priors, use of 2D as gold standard. System supports single breast compression acquisition of both 2D and 3D

6 Acquisition showing 3D followed by 2D exam

7 Reader Study Protocol ~310 patients, includes normals,, recalls, benign lesions and 51 cancers 27 readers, radiologists with range of mammography experience Readers had no prior experience with tomosynthesis Readers were trained over 2 day session

8 Assessment Methodology Read images on dedicated mammography workstation Read and score the 2D: Initial BIRADS 0, 1, or 2 Forced BIRADS (1-5) Probability of Malignancy (POM) from 0 to 100% Read 3D and score (2D+3D) using same methods Initial BIRADS 0, 1, or 2 Forced BIRADS (1-5) Probability of Malignancy (POM) from 0 to 100%

9 Data Analysis Compare 2D and (2D+3D) Compute ROC curve from Probability of Malignancy ROC analysis: Multi-reader multi-case DBM MRMC Beta 2 software

10 Examples of readers ROC curves

11 ROC Analysis: Area under ROC Curve (AUROC) AUROC of 3D+2D superior to 2D for every reader Look at radiologist variation,, i.e. standard deviation of AUROC Equality of Variance test for statistical significance

12 Radiologist Variability with 2D and 2D+3D 2D+3D 2D

13 All Cases 2D 2D+3D Mean AUROC Standard Deviation AUROC AUROC 2D+3D variability 72% of 2D, variances equal p=0.11

14 Averaged ROC Curves All cases Calcs only No calcs

15 Cases involving Calcifications 2D 2D+3D Mean AUROC Standard Deviation AUROC AUROC 2D+3D variability 93% of 2D, variances equal p=0.73

16 Cases without Calcs 2D 2D+3D Mean AUROC Standard Deviation AUROC AUROC 2D+3D variability 63% of 2D, variances equal p = 0.02

17 Decision to Recall, non-cancer cases (BIRADS 0) 2D 2D+3D Agreed on recall decision Kappa 70.9% % Kappa differences statistically significant

18 Image Examples

19 False Positive Digital Mammogram Tomosynthesis Image

20 Cancer Digital Mammogram Tomosynthesis Image

21 Conclusions Tomosynthesis previously shown to improve radiologist performance: 3D+2D compared to 2D Variability of AUROC reduced when using 3D, for cases not involving calcifications, p = 0.02 Variability unchanged for calc cases Radiologists are more accurate (AUROC) and more confident (Variances) with 3D+2D, compared to 2D for mass detection Radiologists agreed more often on decision to recall non-cancer cases with 2D+3D than 2D

22 More on the same subject Elizabeth Rafferty, MD Massachusetts General Hospital, Boston MA, USA Inter-reader reader variability: Comparing breast tomosynthesis combined with FFDM to FFDM alone Multi-center, retrospective study: Comparing breast tomosynthesis combined with FFDM to FFDM alone Sunday, March 8, 14:00-15:30 Satellite Symposium, Room F2

23 Thank you Images and data courtesy of: Massachusetts General Hospital, Boston MA USA Netherlands Cancer Institute Antoni Van Leeuwenhoek Hospital, Amsterdam Holland Centre de Radiologie et d Echographie du Docteur Joussier,, Paris France Dartmouth Hitchcock Medical Center, Lebanon NH USA Magee Women s s Hospital, Pittsburgh PA USA University of Iowa Health Care, Iowa City IA USA Yale University School of Medicine, New Haven CT USA