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Breast imaging tomosynthesis l rotenberg
1. H o n g
K o n g
1 2th e d i t i o n
D r L i l i a n L . Y. L E O N G - Hong Kong President
Pr Gilbert FERRETTI - Président Français
Pr Jean Michel TUBIANA - Président d’Honneur
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2. DIGITAL BREAST
TOMOSYNTHESIS
(DBT)
Luc Rotenberg, Jean Guigui, Gregory Lenczner
ISHH – RPO Clinique Hartmann – Ambroise Paré
Neuilly Sur Seine - France
#drrotenberg
dr.rotenberg@radiologieparisouest.com
H o n g
12
!
th
K o n g
edition
3. 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 multicenter study: the DMIST
!
GE
HOLOGIC
SIEMENS
SECTRA
IMS
GIOTTO
FISCHER
4. 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
THE SUPERIORITY OF FFDM VS. SFM HAS BEEN PROVEN!
!
5. FFDM: SUPERIOR TECHNIQUE, BUT NOT PERFECT
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
!
6. 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
!
7. 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
!
8. 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
!
9. 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
!
10. 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 2D, 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
11. 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.
!
12. SCAN ANGLE– PROS & CONS
Wide angle:
+ It provides superior depth resolution: ideal
360° (CT)
- It causes mechanical movement
complexities
- It causes longer scan time
40° 50°
(GE Essential-Siemens
Inspiration)
GIOTTO: 40°
Small angle:
+ More simple design / construction mechanics
+ Shorter scan time
- Lower Depth resolution. Loss of details
perception
!
15° (±7,5°)
(Hologic Dimensions)
13. NUMBER OF PROJECTIONS
PROS & CONS
Large Number:
+
Better reconstruction because more data to the 3D 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
14. STEP & SHOOT
—
—
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)
-20°
+20°
Compression plate
Breast
Digital
detector
Giotto:13 Projections
!
15. 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.
!
16. 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.
!
17. 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).
!
18. ADVANCED 3-D ITERATIVE ALGORITHM
• 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
!
19. GIOTTO TOMO: ADVANCED 3-D
ITERATIVE ALGORITHM
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
!
20. NEW ADVANCED APPLICATIONS
S Angiomammography (CEDM) based on
the Dual Energy principle.
S Automatic calculation of the breast
density
S Biopsy
!
51. US Biopsy & Wire Marking
Large core 16g Biopsy
IDC grade 2, RH+, Her2 -
!
Wire marker
52. Conclusion
Take Home Messages
S Best detection
S Dose
S Best caracterisation
S Time
S Best localisation
S Pricing
S National Screening Program ?
!
24/11/2013
