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

Digital Mammography Mammograms are acquired digitally –Detectors do still vary: Resolution Bit depth (CR) Noise (CR)

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 cm85% 24x30 cm15%

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!

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 WITH THE EXPERIENCE OF YEARS

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

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

Computer-Aided Detection Mammography CAD first became available: –1998Film-screen mammography –2000Digital 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 SR2001

Mammography CAD SR Allows encoding of ACR’s BI-RADS TM 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 Three individual calcifications are detected in a single image Individual Calcification: –Location of center –Outline of individual calcification –Size

Inference Tree 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 Densities and other clusters are detected, some from priors Density –Center of density –Outline –Size –Description of margin

Inference Tree Densities become masses if spatially related

Inference Tree Other findings may also be spatially related

Inference Tree Calcs within a mass are related spatially

Inference Tree Objects found in priors are temporally related to currents

Inference Tree Objects can also be related contra-laterally (not shown here)

Inference Tree Individual Impressions and Recommendations are formed

Inference Tree 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 ReportSR Relevant Patient HistoryQuery

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