Mammography and DICOM Adapting an Analog Modality to the Digital World Julian Marshall R2 Technology, Inc.
Jan 16, 2016
Mammography and DICOM
Adapting an Analog Modality
to the Digital World
Julian Marshall
R2 Technology, Inc.
Mammography
• Mammography is a film-based modality– Worldwide mammo machines:
• 25,500 film-screen
• 500 digital
98.1 %
1.9 %
Reading Mammograms
• ACR position:– Radiologist must read original image
• US clinical practice:– Read film-screen mammograms on film
• Do not digitize films and read softcopy
– Priors can be read softcopy
Digitized Film
• Mammograms are digitized– Wide variation– Scanners vary:
• Resolution
• Maximum O.D.
• Noise
RCC
RCC
FILM
SCANNER
IMAGE
Digital Mammography
• Mammograms are acquired digitally– Detectors do still vary:
• Resolution
• Bit depth (CR)
• Noise (CR)
RCC
IMAGE
Mammography
• Imaging demands are extreme:– Typical resolutions:
• Film: 43 to 50 microns x 12 bits
• Digital: 50 to 100 microns x 14 bits
– Typical image sizes:• 18x24 cm 85%
• 24x30 cm 15%
Mammography
• Imaging demands are extreme:– Typical data volume:
• 4 film case: 180 MB avg
• 100 case/day: 18.0 GB/day
• 250 days/yr: 4.5 TB/year
– Film scanner will generate:• 45 MB per minute, all day long!
Mammography and PACS
• Images are recalled regularly
• Scheduled pre-fetching is easy
• But … each image is accessed each year!
RCCRCC
RCCRCC
RCCRCC
RCCRCC
RCCRCC
RCCRCC
RCCRCC
RCCRCC
RCCRCC
RCCRCC
RCCRCC
RCCRCC
RCCRCC
RCCRCC
RCCRCC
RCCRCC
RCCRCC
RCCRCC
1998 2000 2002
Computer-Aided Detection
• Use a computer to look for regions-of-interest that might be overlooked by a radiologist
• Simple example: Count the ‘F’s
Computer-Aided Detection
• Simple example: Count the ‘F’s
FINISHED FILES ARE THE RE-SULT OF YEARS OF SCIENTIF-IC STUDY COMBINED WITHTHE EXPERIENCE OF YEARS
Computer-Aided Detection
• Most people find these three
FINISHED FILES ARE THE RE-SULT OF YEARS OF SCIENTIF-IC STUDY COMBINED WITHTHE EXPERIENCE OF YEARS
Computer-Aided Detection
• Many people do not find all six!
FINISHED FILES ARE THE RE-SULT OF YEARS OF SCIENTIF-IC STUDY COMBINED WITHTHE EXPERIENCE OF YEARS
Computer-Aided Detection
• Mammography CAD first became available:– 1998 Film-screen mammography– 2000 Digital mammography
• At that time:– DICOM support for images– No DICOM support for CAD output
DICOM WG 15
• Standards development:– Digital X-ray (includes mammo)
1998– Mammography CAD SR 2001
Mammography CAD SR
• Allows encoding of ACR’s BI-RADSTM reporting structure via an inference tree
• “Simple” CAD devices can create “simple” Mammo CAD objects
• “Complex” CAD devices can create full mammography report inference tree
Mammography CAD SR
• Single image finding – found in one image
• Composite object – findings correlated in one or more images:– Temporal – comparison over time– Spatial – e.g. mass behind the nipple, or
mammo/ultrasound correlation– Contra-laterally – e.g. left/right comparison
Inference Tree
SingleImage
Finding
CompositeObject
SingleImage
Finding
CompositeObject
IndividualImpression /
RecommendationSP
T
CL
Related Spatially
Related Temporally
Related Contra-Laterally
O
I Individual
Overall
C Individual Calcification
CC Calcification Cluster
D Density
OverallImpression /
Recommendation
CC D D D D
SP SP
SP T
D
I
SP
I
O
C C C
CC
Three individual calcifications are detected in a single image
Individual Calcification:–Location of center
–Outline of individual calcification
–Size
Inference Tree
SingleImage
Finding
CompositeObject
SingleImage
Finding
CompositeObject
IndividualImpression /
RecommendationSP
T
CL
Related Spatially
Related Temporally
Related Contra-Laterally
O
I Individual
Overall
C Individual Calcification
CC Calcification Cluster
D Density
OverallImpression /
Recommendation
CC D D D D
SP SP
SP T
D
I
SP
I
O
C C C
CC
The three are grouped together as a cluster of calcifications
Calcification cluster:–Location of center
–Outline of cluster
–Size
–No. of individual calcifications
Inference Tree
SingleImage
Finding
CompositeObject
SingleImage
Finding
CompositeObject
IndividualImpression /
RecommendationSP
T
CL
Related Spatially
Related Temporally
Related Contra-Laterally
O
I Individual
Overall
C Individual Calcification
CC Calcification Cluster
D Density
OverallImpression /
Recommendation
CC D D D D
SP SP
SP T
D
I
SP
I
O
C C C
CC
Densities and other clusters are detected, some from priors
Density–Center of density
–Outline
–Size
–Description of margin
Inference Tree
SingleImage
Finding
CompositeObject
SingleImage
Finding
CompositeObject
IndividualImpression /
RecommendationSP
T
CL
Related Spatially
Related Temporally
Related Contra-Laterally
O
I Individual
Overall
C Individual Calcification
CC Calcification Cluster
D Density
OverallImpression /
Recommendation
CC D D D D
SP SP
SP T
D
I
SP
I
O
C C C
CC
Densities become masses if spatially related
Inference Tree
SingleImage
Finding
CompositeObject
SingleImage
Finding
CompositeObject
IndividualImpression /
RecommendationSP
T
CL
Related Spatially
Related Temporally
Related Contra-Laterally
O
I Individual
Overall
C Individual Calcification
CC Calcification Cluster
D Density
OverallImpression /
Recommendation
CC D D D D
SP SP
SP T
D
I
SP
I
O
C C C
CC
Other findings may also be spatially related
Inference Tree
SingleImage
Finding
CompositeObject
SingleImage
Finding
CompositeObject
IndividualImpression /
RecommendationSP
T
CL
Related Spatially
Related Temporally
Related Contra-Laterally
O
I Individual
Overall
C Individual Calcification
CC Calcification Cluster
D Density
OverallImpression /
Recommendation
CC D D D D
SP SP
SP T
D
I
SP
I
O
C C C
CC
Calcs within a mass are related spatially
Inference Tree
SingleImage
Finding
CompositeObject
SingleImage
Finding
CompositeObject
IndividualImpression /
RecommendationSP
T
CL
Related Spatially
Related Temporally
Related Contra-Laterally
O
I Individual
Overall
C Individual Calcification
CC Calcification Cluster
D Density
OverallImpression /
Recommendation
CC D D D D
SP SP
SP T
D
I
SP
I
O
C C C
CC
Objects found in priors are temporally related to currents
Inference Tree
SingleImage
Finding
CompositeObject
SingleImage
Finding
CompositeObject
IndividualImpression /
RecommendationSP
T
CL
Related Spatially
Related Temporally
Related Contra-Laterally
O
I Individual
Overall
C Individual Calcification
CC Calcification Cluster
D Density
OverallImpression /
Recommendation
CC D D D D
SP SP
SP T
D
I
SP
I
O
C C C
CC
Objects can also be related contra-laterally (not shown here)
Inference Tree
SingleImage
Finding
CompositeObject
SingleImage
Finding
CompositeObject
IndividualImpression /
RecommendationSP
T
CL
Related Spatially
Related Temporally
Related Contra-Laterally
O
I Individual
Overall
C Individual Calcification
CC Calcification Cluster
D Density
OverallImpression /
Recommendation
CC D D D D
SP SP
SP T
D
I
SP
I
O
C C C
CC
Individual Impressions and Recommendations are formed
Inference Tree
SingleImage
Finding
CompositeObject
SingleImage
Finding
CompositeObject
IndividualImpression /
RecommendationSP
T
CL
Related Spatially
Related Temporally
Related Contra-Laterally
O
I Individual
Overall
C Individual Calcification
CC Calcification Cluster
D Density
OverallImpression /
Recommendation
CC D D D D
SP SP
SP T
D
I
SP
I
O
C C C
CC
Overall Impression and Recommendation is formed
A Vast Array of Adjectives
• Every Single Image Finding and Composite Object has a set of common descriptors:– Rendering intent– Certainty of finding– Probability of cancer
• Plus a variety of context-specific descriptors:– Calcs: rod-like, pleomorphic, etc.
Other Information
• Breast outline (border)
• Pectoral muscle outline
• Nipple location
• Other findings:– BBs– J-wires
Other Information
• Image quality findings– Motion blur– Artifacts
Coming Soon
• Breast Imaging Report SR
• Relevant Patient History Query
Summary
• Mammography is almost entirely a film-based modality
• Slowly this is changing
• And with that change comes DICOM!