Mammography and DICOM

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Mammography and DICOM

• Adapting an Analog Modality
• to the Digital World
• Julian Marshall
• R2 Technology, Inc.

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Mammography

• Mammography is a film-based modality
• Worldwide mammo machines
• 25,500 film-screen
• 500 digital

98.1 1.9
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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

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Digitized Film

• Mammograms are digitized
• Wide variation
• Scanners vary
• Resolution
• Maximum O.D.
• Noise

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Digital Mammography

• Mammograms are acquired digitally
• Detectors do still vary
• Resolution
• Bit depth (CR)
• Noise (CR)

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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

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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!

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Mammography and PACS

• Images are recalled regularly
• Scheduled pre-fetching is easy
• But each image is accessed each year!

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Computer-Aided Detection

• Use a computer to look for regions-of-interest
  that might be overlooked by a radiologist
• Simple example Count the Fs

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Computer-Aided Detection

• Simple example Count the Fs

FINISHED FILES ARE THE RE- SULT OF YEARS OF
SCIENTIF- IC STUDY COMBINED WITH THE EXPERIENCE
OF YEARS
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Computer-Aided Detection

• Most people find these three

FINISHED FILES ARE THE RE- SULT OF YEARS OF
SCIENTIF- IC STUDY COMBINED WITH THE EXPERIENCE
OF YEARS
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Computer-Aided Detection

• Many people do not find all six!

FINISHED FILES ARE THE RE- SULT OF YEARS OF
SCIENTIF- IC STUDY COMBINED WITH THE EXPERIENCE
OF YEARS
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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

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DICOM WG 15

• Standards development
• Digital X-ray (includes mammo) 1998
• Mammography CAD SR 2001

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Mammography CAD SR

• Allows encoding of ACRs 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

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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

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Inference Tree

• Individual Calcification
• Location of center
• Outline of individual calcification
• Size

Three individual calcifications are detected in a
single image
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Inference Tree

• Calcification cluster
• Location of center
• Outline of cluster
• Size
• No. of individual calcifications

The three are grouped together as a cluster of
calcifications
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Inference Tree

• Density
• Center of density
• Outline
• Size
• Description of margin

Densities and other clusters are detected, some
from priors
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Inference Tree
Densities become masses if spatially related
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Inference Tree
Other findings may also be spatially related
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Inference Tree
Calcs within a mass are related spatially
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Inference Tree
Objects found in priors are temporally related to
currents
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Inference Tree
Objects can also be related contra-laterally (not
shown here)
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Inference Tree
Individual Impressions and Recommendations are
formed
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Inference Tree
Overall Impression and Recommendation is formed
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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.

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Other Information

• Breast outline (border)
• Pectoral muscle outline
• Nipple location
• Other findings
• BBs
• J-wires

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Other Information

• Image quality findings
• Motion blur
• Artifacts

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Coming Soon

• Breast Imaging Report SR
• Relevant Patient History Query

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Summary

• Mammography is almost entirely a film-based
  modality
• Slowly this is changing
• And with that change comes DICOM!