The Ontology of the Radiographic Image:

The Ontology of the Radiographic Image: From RadLex to RadiO

What do these two things have in common?

What do these two things have in common? Both of these two things are images…

What is RadLex? • RadLex is a controlled vocabulary for reporting radiographic image observations – RadLex is notan ontology (includes term categories such as uncertainty and teaching attributes). • It’s purpose: „to provide a uniform structure for capturing, indexing, and retrieving a variety of radiology information sources, such as teaching files, research data, and radiology reports. RadLex will unify and supplement radiology terms in other lexicons, such as the ACR Index, SNOMED, the Unified Medical Language System, the Fleischner Society Glossaries, and DICOM.“ • In keeping with this statement of purpose, we aim to expand this web and further supplement RadLex: • Foundational Model of Anatomy • Ontology of Biomedical Reality

What is RadiO? • Ontologically sound framework for electronic radiology reporting • Interfaces RadLex, via an intermediary ontology of the image, to the FMA (achieved), and the Ontology of Biomedical Reality (planned). • For any application ontology dealing with imaging techniques, it is important that bodily entities and their appearances are kept in separate (but interrelated) ontological domains. • Not all pathologies are susceptible to imaging, thus the assertions in radiology reports refer primarily to the images themselves and not the organs that these images are images of (think of cancer on the cellular level) • Aim: to build a knowledge base of imaging ‘findings’ and their use to form concrete diagnoses.

What is RadiO? • The application ontology is implemented in Protégé and currently consists of three layers: • 1. an electronic reporting layer, • 2. an upper-level imaging domain ontology, and • 3. the FMA, for anatomical references (w/ OBR, for pathological references).

Aligning RadLex Upper-Level Term Categories to The Domain of the Body, via the Imaging Domain Upper-Level RadLex Term Categories Medical Image Domain Ontology Biomedical Domain Image Entity Foundational Model of Anatomy Anatomic Location is_a Anatomical Image Entity Findings is_a is_a Visual Features Image Feature Ontology of Biomedical Reality is_a Diagnoses and Etiologies is_a Pathological Image Entity is_a Morphologic and Physiologic Processes term_for image_of

Anatomic Location • RadLex Documentation: • “This category specifies the body part or other anatomic region… [and] are arranged hierarchically according to sub-part relationships.”

Anatomic Location • The posterior wall of the trachea (T) and the anterior wall of the esophagus (E) almost contact and, because they contain air and the space between them does not, form the posterior tracheal stripe (arrow) in the lateral view. • There are four essential elements here: • the posterior wall of the tracheal, • the anterior wall of the esophagus, • the space between them, • and the lateral view (since it is only from this view that the various anatomical entities are superimposed (or in this case, not superimposed, since the esophagus is behind the trachea from the front view) in such a way to produce it.) • NO FMA CORRELATE!! • Not a genuine universal (like the thing of which my left arm, this table and my favourite restaurant are parts)

Visual Features • RadLex Documentation: “There terms describe features on the image that can be described without reference to specific physical, anatomic, or pathological processes or structures. • These refer only to the image!

Visual Features • Image feature includes image entity attributes such as: • shape, • size, • density, • as well as patterns that have no direct correlate on the side of the patient, such as image artifacts. CT of the liver, demonstrating intense focal enhancement CT of the head, showing a star-like artifact

Morphologic and Physiologic Processes/Diagnoses and Etiologies RadLex Documentation: • Morphologic and Physiologic Processes: “These terms describe gross morphologic and physiologic processes, but which do not relate directly to specific physical structures or proven diagnoses.” • Diagnoses and Etiologies: • Inferred causes • Proven causes i.e., specific structures

The Natural Question: What‘s the difference between terms of the category morphologic and physiologic processes and diagnoses and etiologies? The Difficult Answer: No hard and fast rule… but consider the following…

Morphologic and Physiologic Processes/Diagnoses and Etiologies Ontology of Biomedical Reality

RadLex to Ontology of Biomedical Reality Upper-Level RadLex Term Categories Medical Image Domain Ontology Findings bronchioaveolar carcinoma Diagnoses and Etiologies Pathological Image Entity Morphologic and Physiologic Processes tumour term_for image_of

Thank You

The Ontology of the Radiographic Image: