Motivations for the RadLex Project

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Motivations for the RadLex Project

• June 21, 2009
• Curtis P. Langlotz, MD, PhD

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Content and Clarity of Radiologists Reports

• 822 Medicare inpatients from 297 hospitals
• Admission diagnoses pneumonia, CHF, MI
• 14 different terms for interstitial
  edema/infiltrate
  
• 23 terms suggesting presence of an abnormality
• 30 terms for expressing uncertainty

Sobel et al, Acad Radiol 3709, 1996
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Alternative Terms forInterstitial
Edema/Infiltrate

• acute interstitial change
• edema along markings
• horizontal linear stranding
• increase in interstitial markings
• Kerley B lines
• linear parenchymal change
• septal fluid

• interstitial disease
• interstitial process
• interstitial changes
• interstitial prominence
• fluid
• congestion
• peribronchial cuffing
• perivascular edema
• vessel type infiltrate

Sobel et al, Acad Radiol 3709, 1996
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Alternative Terms for Presence of an Abnormality

• appears to be
• are a bit
• believe to be
• compatible with
• consistent with
• definite
• due to
• evidence for
• first consideration given to

• indicating
• most likely
• presumably representing
• representing
• seems to be
• significant
• somewhat
• suspect
• thought to be

Sobel et al, Acad Radiol 3709, 1996
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NY Cartoon
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Motivations for a Unifying Medical Imaging Lexicon

• Suboptimal clinical communication
• Fragmented educational resources for imaging
• Irreconcilable research results
• Existing lexicons incomplete or outdated

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RSNAs Medical Image Resource Center (MIRC)

• Sharing of images and information for education,
  research and clinical practice
  
• Originally conceived as a central point of
  storage (teaching file archive)
  
• Now a community of teaching files linked through
  a common index
  
• Searchable via the Internet http//mirc.rsna.org

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RadLex Use Case Examples

• Radiology educators and students
• Indexing of teaching files
• Enhanced retrieval of learning materials
• Clinical radiologists
• Structured reporting
• Clinical decision support
• Radiology researchers
• Constructing and using research databases

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Benefits of a Unified Imaging Lexicon

• Automatic indexing and retrieval of teaching
  files
  
• Point and click structured reporting systems
• Comparison or unification of disparate research
  databases
  
• Real-time clinical decision support and error
  reduction

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Medical Lexicons for Radiology

• UMLS (National Library of Medicine)
• SNOMED-RT (College of American Pathology)
• Index for Radiological Diagnoses (ACR)
• NCI Thesaurus and Common Data Elements (CDEs)
• Subspecialty lexicons ACR BI-RADSTM,
  ASSR-intervertebral disks, Fleischner, ...
  
• Coding schemes ICD, CPT, LOINC

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ACR Index Demo
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ACR Index Limitations

• Two fields Anatomy, Pathology
• Semantics embedded in identifiers
• Designed for off-line teaching files
• Coarse hierarchy
• Static categories for findings

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SNOMED-CT Demo
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Medical Lexicons Completeness for Radiology
Percent of imaging terms in lexicon
Bell Greenes, AMIA Proceedings216, 1994
Humphreys et al, JAMIA 4484, 1997.
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Shortcomings of Existing Medical Terminologies
for Imaging

• Image acquisition techniques
• MRI pulse sequences, CT parameters, imaging
  protocols
  
• Image features
• Low signal, high attenuation, hypoechoic
• Global assessments
• BI-RADS assessment categories
• Anatomy only visible on MRI or in context
• Musculoskeletal anatomy (e.g. ligaments,
  tendons)
  

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What is RadLex ?

• Joint effort with professional organizations and
  standards bodies
  
• ACR , SNOMED, DICOM
• Subspecialty organizations (e.g., SCBTMR, SGR)
• Harmonize lexicon development efforts
• Unifying framework for concepts and terms
• Common development process
• Harmonize/collaborate
• Result a freely-available resource

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Organizational Structure
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Technical Issues

• Donald Harrington, M.D.
• Professor and Chair, Department of Radiology,
• State University of New York-Stony Brook

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Definitions

• Vocabulary All the words used by or known to a
  particular person or group, or contained in a
  language as a whole
  
• Lexicon The entire stock of words belonging to a
  branch of knowledge or known by somebody
  
• Terminology The expressions and words, or a set
  of expressions and words, used by people involved
  in a specialized activity or field of work

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Definitions

• Classification
• The allocation of items to groups according to
  identified characteristics.
  
• Index
• 1. An order list of the items that make up a set
• 2. An alphabetical list, usually at the end of a
  book, of topics, giving the numbers of the pages
  on which they are mentioned

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Ciminos Desiderata

• Content, Content, Content
• SNOMED
• ACR Index
• DICOM
• Clinical experts

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Ciminos Desiderata

• Concept Orientation
• Nonvagueness Terms must have at least one
  meaning
  
• Nonambiguity Terms must have no more than one
  meaning
  
• Nonredundancy meanings correspond to no more
  than one term

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Ciminos Desiderata

• Concept permanence
• Old terms are retired but not deleted
• Nonsemantic concept identifiers
• Term IDs not assigned based on meaning

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Ciminos Desiderata

• Multiple granularities or levels of detail
• Definitions
• Reject not elsewhere classified
• Polyhierarchy

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Polyhierarchy

• Part-of (e.g., Anatomy)
• lungs
• left lung
• left upper lobe of lung
• superior division of the left upper lobe
• anterior segment of the left upper lobe
• apicoposterior segment of the left upper lobe
• lingula
• inferior segment of the lingula
• superior segment of the lingula
• left lower lobe of the lung

• Is-a (e.g., Finding)
• pneumonia
• bacterial pneumonia
• aerobic bacterial pneumonia
• gram-positive aerobic bacterial pneumonia
• gram-negative aerobic bacterial pneumonia
• anaerobic bacterial pneumonia
• mycobacterial pneumonia
• tuberculosis
• primary tuberculosis
• post-primary tuberculosis
• non-tuberculous mycobacterial pneumonia

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Chutes Framework for Health Terminology Systems

• Compositional Root concepts are combinable
  (e.g., left, anterior, diaphysis)
  
• Synonyms Explicitly represented. Likewise,
  abbreviations and non-English terms
  
• Mapping A clear relationship with other
  terminologies
  
• Uncertainty Clear and consistent expression of
  uncertainty (versus vagueness)

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Organization of RadLex

• June 21, 2009
• Curtis P. Langlotz, MD, PhD

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What is a RadLex Term?

• Unique concept
• Unique numeric ID
• Name
• Definition
• Source(s)
• Links to related terms/lexicons
• Comments
• Sample image(s)

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Term Categories

• Patient identifiers
• Clinical history
• Image acquisition, processing, and display
• Location on the image
• Image quality
• Anatomic location

• Findings
• Relationships
• Uncertainty
• Conclusions
• Recommendations
• Teaching attributes

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Demonstration of RadLex Web Site
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The Lexicon Development Process
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Lexicon Deliberation Process (1)
Primary Data Sources
Texts
Committee chairs and RSNA RadLex staff
Draft Lexicon
Informatics
Journal Articles
Imaging
Standards
Existing Lexicons And DBs
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Lexicon Development Process (2)
Final Lexicon
Lexicon Devel. Committee
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Points for Discussion

• Inaccuracies
• Gaps
• Duplication
• Need for definition
• Helpful sources

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Lexicon Development Approach

• Solution
• Synonymous terms
• Common terms
• Standard descriptors
• Adopt and link
• Publicly available

• Pitfall
• Competitive terms
• Required terms
• Clinical standards
• Reinvent
• Proprietary

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RadLex FAQs (1)

• How much detail do we need?
• Too much is better than not enough
• Refer to use cases (e.g., bone surfaces)
• Can we put the same term in two places?
• Browse vs. search
• Different hierarchies (e.g., radial artery)

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RadLex FAQs (2)

• How to deal with normal variants?
• Place with the normal anatomy
• What if there is more than one way to partition
  an organ?
  
• Include both (e.g., lung zones)
• How do we share development with another
  committee?
  
• The early bird gets the worm
• All groups will have an opportunity to
  review/revise

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Lexicographer. A writer of dictionaries a
harmless drudge. -Samuel Johnson A Dictionary
of the English Language (1755)
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The Augean O-gee-an Stables

• For the fifth labor, Eurystheus ordered Hercules
  to clean up King Augeas' stables. King Augeas was
  very rich, and he had many herds of cows, bulls,
  goats, sheep and horses. Hercules knew this job
  would mean getting dirty and smelly, but
  sometimes even a hero has to do these things.

-The Perseus Project www.perseus.tufts.edu
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Lets Get Started!
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RadLex FAQs (3)