Can Digital Breast Tomosynthesis(DBT) Perform Better than Standard Digital Mammography Workup in a Breast Cancer Assessment Clinic?

Transcription

1 Can Digital Breast Tomosynthesis(DBT) Perform Better than Standard Digital Mammography Workup in a Breast Cancer Assessment Clinic? Accepted for publication in European Radiology Authors: S Mall, J Noakes, M Kossoff, W Lee, M McKessar, A Goy, J Duncombe, M Roberts, B Giuffre, A Miller, N Bhola, C Kapoor, C Shearman, G DaCosta, S Choi, J Sterba, M Kay, K Bruderlin, N Winorta, B MacDonell-Scott, F Klijnsma, K Suzuki, P Brennan, C Mello-Thoms. Acknowledgements: A Varnava, K Donohue, A Chapman, C Skipka, S McGill, G Potts, M Connolly, C Cetinich, Data and administrative staff NSCC.

2 Study Questions Does the use of tomosynthesis improve the detection and diagnosis of breast cancer in a recall assessment clinic compared with standard mammographic workup? YES Does tomosynthesis - reduce the number of false positives in an assessment clinic? - reduce the need for performing other procedures, such as ultrasound, percutaneous biopsy, or multiple additional mammogram views? - improve confidence in diagnosis and reduce the number of patients undergoing early review, or early rescreen interval? - more accurately localise lesions that can be seen on only one mammographic view? YES YES YES YES in real life

3 Recruitment Participating clients had - routine 2D workup protocol 90 degree lateral and 2 spot mag views - 2 additional DBT views CC and 90 lateral tomosynthesis with C-view Assessment proceeded as per normal: radiologists used all images (2D and DBT) in the clinic, with US, PE and biopsy performed as per the usual decision making process. After the assessment was complete, the study component commenced. 2D Cancer 2D v DBT: note clearly visible lobulated border on tomosynthesis DBT

4 Image Reading Images were quarantined in a separate PACS. Radiologists had access only to the de-identified images provided, and the reason for recall. -small reading batches, in random order, which differed for each reading and each radiologist. -the order of reading each arm (2D or DBT first) was also randomised. Cancer 2D v DBT: note spiculation visible on tomosynthesis 2D -over 1 month separation between 2D and tomosynthesis reads DBT

5 2D Hanging DBT Hanging

6 Study design Cases were randomly assigned to silos: mulitreader multicase split plot design Silo 1 Silo 2 Silo 3 48 cases/96 reads Five radiologists 48 cases/96 reads Five radiologists 48 cases/96 reads Five radiologists Each case was hung twice in the silo: 2D / DBT All hangings in a silo were read by all radiologists - Radiologists did not read cases where they had clinical involvement - 2 radiologists in each silo read the cases within 3 months of assessment

7 Case allocation Unknown to readers: Mixture of normal, benign and cancer cases, in equal proportions. Breast density was matched for cancer, benign and normal cases. Sequential recruitment of clients with cancer diagnosis. A particular number of cancer cases was required before random allocation to silos. Once this number was achieved, normal and benign cases were randomly harvested from the immediately preceding few weeks of clients.

8 location Lesion characteristics Incidental lesions? Radiologist confidence level Severity 1-5 Is the lesion within density? Need for further workup, US, biopsy? conspicuity size

9 Collected Data - Data recorded on worksheet, and compared with assessment outcome. 144 primary lesions 30 additional lesions Low number of additional lesions (30), given the close scrutiny. - Any additional lesions found went to MDT for review as to whether additional assessment was needed. One lady recalled for additional assessment with normal outcome, and has subsequently had a normal screening round.

10 Results Diagonal average ROC curve of DBT v s 2D - Overall better diagnostic performance of DBT as a diagnostic test than 2D Trade off between sensitivity and specificity Area under the curve (AUC) is the measurement of test accuracy DBT was superior with improved AUC of 0.06.

11 Sensitivity, Specificity, PPV, NPV all lesions (primary and additional) DBT (95% CI) 2D (95% CI) Sensitivity Specificity Positive predictive value Negative predictive value DBT performed better across all parameters when compared with 2D workup. Performance was even greater for primary lesion only.

12 Reader performance Spectrum of reader experience (mean 16 years) and reader DBT-experience 93.3% (all but one reader) performed better or comparably using DBT than 2D Less experienced readers performed better with DBT

13 Ultrasound analysis - Tomosynthesis significantly reduced the recommendation for ultrasound compared with 2D workup, by 5.3% (~94% reduced to 89%). Not a statistically significant reduction specifically for nondense breasts - In dense breasts, ultrasound was required significantly less often when using tomosynthesis than when using 2D.

14 Reasons for Ultrasound * * Reassurance Lesion characterisation Biopsy Identify multifocal disease axilla Lesion localisation 2D other DBT Reasons for requesting US were similar for 2D and DBT. US is commonly used for reassurance of normality (more common in the early days of tomosynthesis), and for biopsy whenever possible. It is interesting to note that lesion characterization and lesion localization were less commonly cited as indications for US when using tomosynthesis.

15 Real life case: new posterior density on mlo. Initial US nad better targeted US

16 Percutaneous biopsy recommendation Yes No 2D DBT Radiologists were reluctant to make a decision to not biopsy without US results, and US information was not given to the readers in our study. 6.3% reduction in biopsy recommendation using tomosynthesis. Breast density had little bearing on the recommendation for biopsy.

17 Additional mammographic workup view/s required Yes, required No, not required 2D DBT The use of tomosynthesis required significantly less extra views than 2D workup (35.6% reduction, p<0.001), which is a cost saving, and a saving of radiation dose. The difference was independent of breast density. This trend has continued since, with further reduction in the need for additional views. If additional views were required when using DBT, these were most commonly magnifications views. When using 2D workup, the commonly requested additional views were DBT or an extra standard view.

18 Radiologist diagnostic confidence level Radiologists were more confident in their decisions using DBT than 2D (p<0.001). 1 = no idea = fully confident 2D DBT Particularly for non-cancer cases, reader confidence was significantly greater on DBT than 2D, enabling confident diagnosis of normality and benignity.

19 Small posterior lesion in 8cm+ compressed fatty breast. US and spot views very difficult, but lesion clearly categorised on tomo. Dx lymph node

20 Lesion conspicuity (1 5 scale) Lesion severity (1=normal; 5= malignant) Cancerous lesions were rated more severe on DBT than on 2D (p=0.02), and were more conspicuous on DBT (p=0.02). Detecting cancers is easier with DBT. Non-Cancerous lesions on DBT appeared less severe (p<0.001), and were not more conspicuous on DBT than 2D. 2D DBT Cancer: irregular spiculated border clearly visible on DBT = Grade 3 Inv NOS

21 Performance with different lesion types Case numbers were small However, there was significant better performance of DBT than 2D for nonspecific densities sensitivity on DBT was higher or equal for all lesion categories. maximum difference in sensitivity was calcs and nsd DBT>2D for all lesion categories except calcification, specificity of DBT was higher. maximum difference in specificity was for distortions DBT>2D

22 Additional lesions identified at review 30 additional lesions were detected; 10 were the same lesion on 2D and DBT 6 DBT-only lesions 14 2D-only lesions All additional lesions were benign or normal None required biopsy It is interesting that there were not an excessive number of additional lesions identified on DBT, less than on 2D.

23 Real life improvement in Assessment? Comparison 9 months Assessment outcomes pre-trial (2D workup, no DBT) (Trial ) post-trial (2 view DBT workup) MDT in place for both periods Recall lesion Tomo cancer

24 Real life improvement in Assessment? Early Review ER (6 or 12) Open Biopsy (atypias) Treatment 2D Pre-DBT (1747 cases) DBT (1728 cases) 5.5% 1.7% 9.4% 4% 2% 11% (164 cases) (190 cases) End % End 2017 <2.3% 1.9% 13% - Early Review (ER) rate has decreased, and this has converted to an increase in cancer diagnosis. - DBT treatment cases are significant cancers (only 2/190 are LGDCIS). - DBT biopsy and improved targeting has had an effect. - Trend of reducing ER s and increased cancer detection has continued.

25 Real life improvement - cases current? prior

26 ? Tomo better localises the stellate lesion on mlo and uncovers a second deeper medial stellate lesion, both Inv NOS gr2

27 Improvements from tomosynthesis in assessment Better overall performance than 2D workup: improved AUC, across different levels of reader experience Sensitivity is higher or equal across all lesion types; specificity is greater for all lesion types except calcs (still need mags) Require fewer US (and US is better targeted); fewer biopsies; and substantially fewer additional workup views (35%) More confident diagnosis with tomosynthesis, particularly with normal and benign outcomes, with confident return to rescreen Low number of additional noncancer lesions detected on DBT (less than 2D) ie. not wasting time working up incidental nothings

28 Improvements from tomosynthesis in assessment Cancers are more conspicuous on tomosynthesis; noncancerous lesions are not more conspicuous In real life, these results have translated into Decreased Early Reviews Increased cancer diagnosis at Assessment: easier to biopsy with tomosynthesis Tomosynthesis is more specific for cancer, and is finding more real cancers (not lgdcis)

29 Improved performance with tomosynthesis