Luc Rotenberg : Digital Breast Tomosynthesis

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DIGITAL BREAST TOMOSYNTHESIS

(DBT)

Luc Rotenberg, Gregory Lenczner, Henri Ouazan ISHH – RPO Clinique Hartmann – Ambroise Paré

Neuilly Sur Seine - France #drrotenberg

[email protected]

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As a matter of fact we know:

•  Breast screening target is EARLY DIAGNOSIS OF BREAST CANCER

•  In most of the cases Screening reaches the

goal

•  almost 10 – 15% of the found late cancers is originated in regularly screened women

•  FFDM is “blind” under some particular

circumstances : •  dense breasts •  dense tissues overlapping lesions

FFDM: SUPERIOR TECHNIQUE, BUT NOT PERFECT

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The challenge of tomosynthesis

An efficient DBT system should accomplish some basic requirements:

•  The total released dose should be lower than the one released during an FFDM exam and the closest possible to a 2-D FFDM projection •  The image quality should be same as the 2-D, but it has to provide much more clinical information. •  The exam has to be the shortest possible (fast scan). •  The scan angle should be large enough to provide an adequate depth (3-D) resolution.

DOSE 3-D circa = DOSE 2-D

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SCAN ANGLE– PROS & CONS

Wide angle:

+ It provides superior depth resolution: ideal 360° (CT) - It causes mechanical movement complexities - It causes longer scan time

Small angle:

+ More simple design / construction mechanics + Shorter scan time - Lower Depth resolution. Loss of details perception

15° (±7,5°)

(Hologic Dimensions)

40° 50°

(GE Essential-Siemens Inspiration)

GIOTTO: 40°

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NUMBER OF PROJECTIONS PROS & CONS

Large Number:

+ Better reconstruction because more data to the 3-D algorithm

- Lower S/N per projection because the total dose is unchanged = Low Image Quality

- Longer scan time

Small Number:

- Less data for the 3-D algorithm

+ Higher S/N per projection = Improved I.Q.

+ Faster scan

•  Hologic Dimensions: 15 exp. •  GE Essential: 9 exp (or 15?) •  Siemens Inspiration: 25 exp. •  Giotto Tomo: 13 exp with variable

angles

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-20° +20°

Compression plate

Breast

Digital detector

�  The tube moves rapidly along an arc stopping at each exposure for a fraction of a second

�  The images are

shown as 1mm “slices” or more (slab)

Giotto:13 Projections

STEP & SHOOT

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CONTINUOUS AND STEPPING MOVEMENT: PROS & CONS

Continuous + It is faster = Faster scan time + Much simpler mechanics to design and to build

- The exposures during the tube’s movement create anyway a “blurring” effect so causing the loss of “crispy” contours of the details, especially of the

tiny microcalcifications

Step & Shoot

- More complex mechanics to avoid vibrations due to variations of speed + The images made in “frozen” conditions are clear and “crispy”. No detail is lost.

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PIXEL DIMENSION/ BINNING

Binning: Virtual combination of two or more pixels of the detector matrix. Usually 4.

+ The total number of pixel decreases 75% shortening the detector reading, decreasing the weight of the file and the 3-D recon time

- The spatial resolution decreases dramatically with loss of details that, if simultaneously the tube movement is continuous, causes an important decrease of micro calcifications visibility.

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•  Non CT style, but DBT dedicated

•  Low number of artifacts

•  Better micro calcifications visualization •  Better visualization of the skin line

•  Better S/N ratio

•  It requires less projections

•  The projections can be further apart

ADVANCED 3-D ITERATIVE ALGORITHM

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Pooled BI-RADS–based ROC curves for diagnostic assessment of conventional diagnostic views and tomosynthesis views

Zuley M L et al. Radiology 2013;266:89-95, Pittsburgh

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DBT

ROC curves for average probability of malignancy as assessed by using conventional supplemental diagnostic views and tomosynthesis views.

Zuley M L et al. Radiology 2013;266:89-95

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Pooled ROC curves for reader studies 1 and 2 using probability of malignancy scores; curves represent average ROC performance

for 12 readers in study 1 and 15 in study 2.

Rafferty E A et al. Radiology 2013;266:104-113

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Assessing Radiologist Performance Using Combined Digital Mammography and Breast Tomosynthesis Compared with Digital Mammography Alone: Results of a Multicenter, Multireader Trial

Diagnostic Sensitivity, Specificity, and Positive and Negative Predictive Values

Rafferty E A et al. Radiology 2013;266:104-113, Boston

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Applications

1.  Detection « screening » 2.  Caracterisation 3.  localisation

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Detection

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Applications

1.  Detection « screening » 2.  Caracterisation 3.  localisation

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Mme P.

S  National Screening program

S  68 y

S  No history

S  Clin examination normal

S  P2,G2

S  Menauposal, No hormonal traitment

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2D Digital Mammography

Right CC Left CC

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Right AXIL Left AXIL

2D Digital Mammography

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Localized incidences

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DBT

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Wire Marker

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43 y, screening

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Applications

1.  Detection « screening » 2.  Caracterisation 3.  Localisation

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Breast US diagnostic & balistic

IDC grade 2, RH+, Her2 -

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US Biopsy & Wire Marking

IDC grade 2, RH+, Her2 -

Large core 16g Biopsy Wire marker

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Dose ?

Full Field Digital Mammogram + Digital Breast Tomosynthesis FFDM + DBT = dose x 2

Two-dimensional Synthesized Mammograms + DBT

2D SM + DBT = dose x 1 Hologic C-View*

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FFDM SM Margarita L. Zuley; Radiology 2014, Ahead of Print.

Comparison of Two-dimensional Synthesized Mammograms versus Original Digital Mammograms Alone and in Combination with Tomosynthesis Images

123 patients

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Margarita L. Zuley; Radiology Ahead of Print DOI: 10.1148/radiol.13131530, 2014 by the Radiological Society of North America, Inc.


Overall ROC curves based on probability of malignancy ratings for individual breasts. FPF = false-positive fraction, TOMO = tomosynthesis, TPF = true-positive fraction.

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Margarita L. Zuley; Radiology Ahead of Print DOI: 10.1148/radiol.13131530, 2014 by the Radiological Society of North America, Inc.


Overall breast-based ROC curves for forced BI-RADs ratings. FPF = false-positive finding, TOMO = tomosynthesis, TPF = true-positive finding.

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S  The use of SM in lieu of FFDM, whether alone or in combination with tomosynthesis , does not result in any clinically meaningful differences in diagnostic accuracy

S  Two-dimensional SM can be used as an acceptable replacement for directly acquired mammograms in tomosynthesis-based evaluations.

S  The use of SM reduces radiation dose to patients undergoing tomosynthesis-based screening mammography.

Margarita L. Zuley; Radiology 2014, Ahead of Print.


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Two-View Digital Breast Tomosynthesis Screening with Synthetically Reconstructed Projection Images: Comparison with Digital Breast Tomosynthesis with Full-Field Digital Mammographic Images Per Skaane & all. Oslo, Norway. Radiology 2014, Ahead of Print.

S  12 270 women were compared in terms of cancer detection and false-positive rates with the reconstructed 2D images / FFDM plus DBT interpretations (2012 january-december)

S  Cancer detection rates were 7.8, and 7.7 per 1000 screening examinations for FFDM plus DBT and reconstructed 2D images plus DBT.

S  False-positive scores were 4.6%, and 4.5%, respectively. S  Corresponding reader-adjusted paired comparisons of false-positive scores

revealed no significant differences (ratio = 0.99; 95% confidence interval: 0.88, 1.11; P = .85).

S  Conclusion : combination of reconstructed 2D images and DBT performed comparably to FFDM plus DBT is adequate for routine clinical use when interpreting screening mammograms.

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Mediolateral oblique images in 61-year-old woman with 12-mm invasive lobular carcinoma in the right breast. Left: FFDM image. Middle: Current synthesized 2D image. Right: DBT image. The region of interest is magnified for each image. Reader scores for the study were 1 for FFDM, 3 for FFDM plus DBT, and 4 for synthesized 2D images plus DBT. Radiology, Skaane; Andriy I. Bandos; Ellen B. Eben; Ingvild N. Jebsen; Mona Krager; Unni Haakenaasen; Ulrika Ekseth; Mina Izadi; Solveig Hofvind; Randi Gullien; Radiology Ahead of Print DOI: 10.1148/radiol.13131391

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Conclusion Take Home Messages

S  Best detection

S  Best caracterisation

S  Best localisation

S  Dose : SM +++

S  Time

S  Pricing

S  National Screening Program ?

Luc Rotenberg : Digital Breast Tomosynthesis

Health & Medicine

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