breast imaging tomosynthesis l rotenberg

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7 t h t o 1 0 t h N o v 2 0 1 3

K O W L O O N S H A N G R I - L A 6 4 M o d y R o a d , T s i m S h a T s u i E a s t , K o w l o o n , H o n g K o n g

D r L i l i a n L . Y . L E O N G - H o n g K o n g P r e s i d e n t P r G i l b e r t F E R R E T T I - P r é s i d e n t F r a n ç a i s P r J e a n M i c h e l T U B I A N A - P r é s i d e n t d ’ H o n n e u r

H o n g K o n g 1 2 t h e d i t i o n

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DIGITAL BREAST TOMOSYNTHESIS

(DBT) Luc Rotenberg, Jean Guigui, Gregory Lenczner ISHH – RPO Clinique Hartmann – Ambroise Paré

Neuilly Sur Seine - France #drrotenberg

[email protected]

H o n g K o n g 1 2 t h e d i t i o n

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WHY TOMOSYNTHESIS? FFDM WAS NOT ENOUGH?

After more than 10 years from its introduction, FFDM has almost totally replaced the analogue mammography (SFM). Its superior diagnostic performances have been demonstrated by a large scale multi-center study: the DMIST

GE SIEMENS SECTRA FISCHER

HOLOGIC IMS GIOTTO

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THE SUPERIORITY OF FFDM VS. SFM HAS BEEN PROVEN!

DMIST

•  Clinical trial made in2004 – 2006 in North America •  50.000 women enrolled made both exams (FFDM/SFM) •  Preliminary results published starting from 2006 RESULTS •  For women ≤ 50 years old and/or dense breast

•  Sensitivity goes from 51% (SFM) to 70 - 78% (FFDM) •  Visualized almost 28% more breast cancers •  More than 1 over 4 cancers were not recognized:

false negatives • 

DMIST Results : Technologic or Observer Variability? Daniel B. Kopans Radiology 2008, Vol.248: 703-704 Diagnostic Accuracy of Digital versus Film Mammography: Exploratory Analysis of Selected Population Subgroups in DMIST Etta D. Pisano & coll, Radiology, 2008, Vol.246: 376-383

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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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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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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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DBT : PARAMETERS AFFECTING THE IMAGE QUALITY

The quality of the DBT images depends on several parameters, often in contrast each other

•  Scan Angle: a wide angle causes high depth resolution (the ideal angle is 360°!). •  Dose released to the patient: it must be the lowest possible. •  Number of projections: the smallest possible to decrease the time of exam. • Pixel dimension/ Binning: smaller the pixel higher the spatial resolution and visibility of details •  Tube movement: shooting while tube moves or stop at each exposure (Step & Shoot) • 3-D Reconstruction Algorithm: Better if dedicated to the specific DBT geometry.

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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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3-D RECONSTRUCTION ALGORITHM

•  The classic 3-D Algorithms are those created in the last 30 years for CT scanners or forMRI (FBP o SART) •  They have the advantage to be well known and tested, but also the defect to be designed for a different geometry: source and detectors rotating 360° around the object. •  The DBT geometry is by far different: it can go from a minimum of 15° (Hologic) to a maximum of 50° (Siemens) •  Adapting these algorithms to the DBT geometry causes streaking artifacts and worsensthe image quality. •  The Iterative algorithm is much more fit for DBT, but it is heavier and causes longer reconstruction time (to a maximum of 4 min).

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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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ALL PARAMETERS OPTIMIZED •  Wide scan angle, 40° •  Only 13 exposures •  Step & Shoot •  3-D Iterative Algorithm RESULTS: •  Increased S/N ratio •  Visibility of tiny microcalcs •  Visibility of the skin line •  Contrast and contours of the tissues

are clear and crispy

GIOTTO TOMO: ADVANCED 3-D ITERATIVE ALGORITHM

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S  Angiomammography (CEDM) based on the Dual Energy principle.

S  Automatic calculation of the breast density

S  Biopsy

NEW ADVANCED APPLICATIONS

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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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Question 1

Bi-Rads Classification?

S  1

S  2

S  3

S  4

S  5

S  0

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Localized incidences

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DBT

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Question 2

Final Birads classification ?

S  1

S  2

S  3

S  4

S  5

S  0

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Wire Marker

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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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Conclusion Take Home Messages

S  Best detection

S  Best caracterisation

S  Best localisation

S  Dose

S  Time

S  Pricing

S  National Screening Program ?

breast imaging tomosynthesis l rotenberg

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