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A Lexicon for UniformIndexing and Retrieval ofRadiology Information Resources
April 12, 2023
Curtis P. Langlotz, MD, PhD
Motivations for a Unifying Medical Imaging Lexicon
Tower of Babel Fragmented educational resources for
imaging Irreconcilable research results Suboptimal clinical communication Existing lexicons incomplete or outdated
Benefits of a Unified Imaging Lexicon:
Automatic indexing and retrieval of teaching files
Comparison or unification of disparate research databases
Point and click “structured” reporting systems Literature searches tailored to specific
imaging examinations or patients
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 3:709, 1996
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 3:709, 1996
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 3:709, 1996
NY Cartoon
Why Are Lexicons Important?
Donald Harrington, M.D.Professor and Chair, Department of Radiology,State University of New York-Stony Brook
The Goals of the RadLex Project
April 12, 2023
Curtis P. Langlotz, MD, PhD
RadLex
RadLex hypothetical use cases Origins: MIRC and the ACR Index Motivations: incomplete existing lexicons RadLex organizational structure
RSNA’s 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
Use Case: Teaching File Creator
Radiologist is reading an interesting case Radiologist selects case for teaching file Radiologist assigns RadLex terms to the case Radiologist makes the case publicly available All radiologists can now search for the case on
the Internet using MIRC and RadLex
Use Case: Information Seeker
Radiologist seeks optimal follow up interval for nodule on hi-res chest CT
Enters RadLex terms describing nodule and clinical history
Receives web page listing links to relevant information
Use Case: Information Seeker
Web page listing relevant: MedLine citations RSNA meeting content (refresher courses, scientific
abstracts) RSNA full-text journal articles MIRC teaching files Professional standards Relevant billing codes
Use Case: Reporting Advisor
Radiologist is using an automated reporting system to report a case
Decision support system is running in the background
Decision support system has been tracking RadLex term co-occurrence over time
Radiologist describes a lung cancer on chest X-ray using RadLex terms
Use Case: Reporting Advisor
DSS suggests features to look for in the image
DSS lists ranked differential diagnosis
Medical Lexicons for Radiology
UMLS (National Library of Medicine) SNOMED-RT (College of American
Pathology) Index for Radiological Diagnoses (ACR) NCI Common Data Elements (CDEs) Subspecialty lexicons: ACR BI-RADSTM,
ASSR-intervertebral disks, Fleischner, ... Coding schemes: ICD, CPT, LOINC
Medical Lexicons: Completeness for Radiology
0%
20%
40%
60%
80%
100%
SNOMED UMLS ACR Index LSVT
Percent of imaging terms in lexicon:
Bell & Greenes, AMIA Proceedings:216, 1994Humphreys et al, JAMIA 4:484, 1997.
ACR Index Demo
ACR Index Limitations
Two “fields”: Anatomy, Pathology Semantics embedded in identifiers Designed for “off-line” teaching files Coarse hierarchy Static categories for findings
What is RadLex ?
Joint effort with professional organizations and standards bodiesACR, Fleischner, STR, DICOM, NLM
Harmonize lexicon development effortsUnifying framework for concepts and termsCommon development processHarmonize/collaborate
Result: a freely-available resource
RSNA Organizational Structure
RadLex
Steering
Committee
RadLex
Thoracic Lexicon
Devel. Committee
Other RadLex
Lexicon Devel.
Committees
…
Collaborative ProcessTask RSNA Partner
Common lexicon framework X
Common development process X
Select committee members X X
Create draft lexicons X
Provide informatics tools X
Support meetings, conf. calls X
Review and refine lexicons X X
Establish on-line availability X
Disseminate new lexicon X X
Liaison to standards, govt. orgs. X
Desirable Properties of a Lexicon
Donald Harrington, M.D.Professor and Chair, Department of Radiology,State University of New York-Stony Brook
Organization of the RadLex System
April 12, 2023
Curtis P. Langlotz, MD, PhD
LexiconTerminologyVocabularyDictionaryGlossary
The Lexicon Development Process
Lexicon Development Process (1)
Texts
JournalArticles
ExistingLexiconsAnd DBs
Informatics
Imaging
Standards
Lexicon Steering Committee
Primary Data Sources
Draft Lexicon
Lexicon Development Process (2)
Final Lexicon
Lexicon Devel.Committee
Web-based resource
You are here.
What is a RadLex Term?
Unique concept Unique numeric ID Name Definition Sample image(s) Source(s) Links to related terms/lexicons
Term HierarchiesIs-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 …
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 …
Term Categories
1. Examination type
2. Patient identifiers
3. Clinical history
4. Technique
5. Observer context
6. Level of difficulty
7. Exam quality
8. Image location
9. Anatomic location
10. Findings
11. Uncertainty
12. Conclusions
13. Recommendations
14. Relationships
Lexicon Development Approach
Solution Synonymous terms Common terms Standard descriptors Adopt and link Publicly available
Pitfall Competitive terms Required terms Clinical standards Reinvent Proprietary
Relationship to Other Lexicons
ACR
Index
SNOMED CPT4
ICD-9-CM
RadLex
UMLS
Thesaurus
Thoracic Lexicon Efforts
Fleischner Society Glossaries NCI Common Data Elements (CDEs) NCI Lung Image Database Consortium
(LIDC) DICOM Chest CAD supplement
Fleischner Glossaries
Imaging features unique to radiology Excellent definitions No categories, hierarchies or other
framework No unique identifiers Not available in electronic form for indexing
RadLex-Fleischner Process
Use Fleischner glossary terms and definitions when possible
Note when the Fleischner glossary is a source of a RadLex term
Assign a RadLex unique identifier to each term
Place each Term in a RadLex category
Points for Discussion
Inaccuracies Gaps Duplication Need for definition Helpful sources
Lexicographer. A writer of dictionaries; a harmless drudge.
-Samuel JohnsonA Dictionary of the English Language (1755)
The Augean Stables
For the fifth labor, Eurystheus ordered Hercules to clean up King Augeas' stables. Now King Augeas owned more cattle than anyone in Greece. Some say that he was a son of one of the great gods, and others that he was a son of a mortal; whosever son he was, 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
Let’s Get Started!
Term Categories
1. Examination type
2. Patient identifiers
3. Clinical history
4. Technique
5. Observer context
6. Level of difficulty
7. Exam quality
8. Image location
9. Anatomic location
10. Findings
11. Uncertainty
12. Conclusions
13. Recommendations
14. Relationships
RadLex Term Category:Examination Type Radiograph foot CT chest MRI abdomen Ultrasound pelvis Fluoro upper GI
series
RadLex Term Category:Patient Identifiers Name Medical record number/Subject number Age Gender Ethnicity Sociodemographics (e.g., zip code)
RadLex Term Category:Clinical History Reason for exam Medical history Symptoms Medications Family history Surgical history Physical exam findings Laboratory values
RadLex Term Category:Technique Equipment (e.g. 1.5T MRI) Imaging parameters (e.g., image
weighting) Patient positioning Date/time images created Field of view Contrast agent administered, if any
RadLex Term Category:Observer Context Who viewed the images? Display medium Window/level information Reconstruction algorithm (e.g., surface
rendering) Availability of CAD or decision support
RadLex Term Category:Degree of Difficulty Layperson Medical student Junior resident Senior resident Radiologist Sub-specialist
RadLex Term Category:Image Quality Uninterpretable Non-diagnostic Limited Diagnostic Optimal
RadLex Term Category:Image Location For example
On the corner of the lateral viewOn series #1, image #5On the post contrast images
RadLex Term Category:Anatomic Location For example:
The left upper lobeThe tracheaThe right costophrenic angle
RadLex Term Category:Finding Visual features Anatomical derangements Pathologic processes Diseases Syndromes
RadLex Term Category:Uncertainty Definitely not Probably not Possibly not Uncertain Possibly Probably Definitely
RadLex Term Category:Conclusion Normal No clinically significant findings Expected findings for patient demographics
(e.g., normal for age) Probably no clinically significant findings
(confirmatory future follow-up needed) Clinically significant findings (workup should
continue) Urgent clinically significant findings (definitive
therapy required)
RadLex Term Category:Recommendation Comparison to prior exams Correlation with other patient information, such
as laboratory tests, surgical and medical history Follow up imaging, including the type of imaging
examination and the time interval Tissue sampling Definitive therapy, such as surgical excision or
medical therapy
RadLex Term Category:Relationships Spatial
(e.g., the tumor arises from the upper pole) Logical
(e.g., pneumonia and congestive heart failure) Causal
(e.g., the increased signal is due to a brain tumor)