Mammography and DICOM Adapting an Analog Modality to the Digital World Julian Marshall R2...

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!