Transcript Measurements, CAD, Radiation Dose and more

DICOM INTERNATIONAL
CONFERENCE & SEMINAR
Oct 9-11, 2010
Rio de Janeiro, Brazil
DICOM Structured Reporting:
Measurements, CAD, Radiation Dose
and more
Andrei Leontiev, Harry Solomon
GE Healthcare
Structured Reporting
• DICOM Structured Reporting (SR) is an
encoding for non-imaging content:
– Observations made in an imaging-based
diagnostic or therapeutic procedure
– Analytic or diagnostic reports
– Other types of documentation
• Not limited to (clinical) “reports”
– Any type of structured data or results
When to use DICOM SR
• For structured data produced with image
acquisition or post-processing, where:
– Leveraging the DICOM infrastructure is easy and
desirable
– Results should be managed with other study
evidence
• Examples
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Sonographer measurements
Computer-aided detection results
Quality control notes about images
Radiation dose reports
Image exchange manifests
DICOM SR Document
• Each SR object represents a document
• As other DICOM objects, SR Document is
composite object fitting Patient-Study-Series
hierarchical model
– Lowest level is “Document”, rather than “Image”
• The content of a document is a tree of
Content Items connected via Relationships
– The content tree always has a single root Content
Item which serves as a container for all other items
The SR Content Tree
Standard DICOM Header
Patient
Study
Series
Document
Content Items are units of meaning …
Text, Numeric, Code, Image, Spatial
coordinates, etc.
… or units of structure
Container
Arrows are parent-child Relationships
Contains, Has properties, Inferred from, etc.
Root Content Item
Container
Content Item
Content Item
Content Item
Content Item
Content Item
Content Item
Content Item
Content Item
Content Item
Root Content Item is a Container whose
name is the name of the document
Content Tree Example
Patient Jones^Jane
Study 1.2.34.5.67.8.100
Series 1.2.34.5.67.9.10
Document Author: Smith^R^^^MD
Initial Observation Context is set by the Header:
• Subject (patient)
• Procedure
• Observer (author)
Chest X-Ray
Exam Report
Views: PA & Lat
Findings
Mass
Location =
Left lower lobe
Size = 1.3 cm
Key Images
Best Illustration:
1.2.34.5.67.1.3
Conclusions
Probable Malignancy
Relationships:
Concept Modifier
Contains
Properties
Content Items
• The Content Item is the building block of the SR
Document
• Provides a name-value pair, i.e., a Concept Name,
and a Concept Value of a particular Value Type
– Equivalent to a DICOM Data Element, at higher level of
abstraction
– Concept Name ≡ Attribute Tag
– Concept Value ≡ Data Element Value
– Value Type ≡ Value Representation
• Concept Name is drawn from a coded controlled
vocabulary system
– Nomenclature, lexicon, terminology, classification
Content Item Value Types
• Container (document section, group of other items)
– [Social History] CONTAINER
• Text (words, sentences or paragraphs)
– [Recommendation] TEXT “Follow up in three months with …”
• Numeric (measurements)
– [Left Ventricular Ejection Fraction] NUM 45%
• Code (qualitative or categorical concepts)
– [Breast Composition] CODE [Heterogeneously dense]
• Date, time
– [Prior Myocardial Infarction] DATE 2005-11-17
• Person Name
– [X-Ray Technician] PNAME Levin^Henry^^^RT
• Reference to images and other objects
– [Best Illustration of Finding] IMAGE <SOPClassUID,SOPInstanceUID>
• Spatial and time coordinates (within referenced images)
– [Area of measurement] SCOORD <coordinates> selected from IMAGE
Coded Values
• SR leverages coded values from controlled vocabulary systems
– For both Concept Names and CODE Concept Values
• Vocabulary systems used include:
– SNOMED (Systematized Nomenclature of Medicine)
• T-11501 “Cervical spine”
– LOINC (Logical Observation Identifier Names and Codes)
• 8462-4 “Intravascular diastolic blood pressure”
– UCUM (Unified Code for Units of Measure)
• mg/ml
– DICOM Content Mapping Resource (DICOM-specific concepts)
• 113040 “Lossy Compression”
– IEEE 11073 (Point-of-Care Medical Device Nomenclature)
• 2:16164 “QTc interval global”
– IETF RFC3066 (Identification of Languages)
• pt-BR “Portuguese, Brazil”
Relationships
• Relationships are the glue between the
Content Item building blocks
• Relationship types include:
– Containment (in a container)
– Modification/qualification of the Concept Name
• Allows “post-coordination” construction of complex concepts
– Observation Context
• Identifying the subject or the author of the observation
– Inference
• Content of one Item derived from other item(s)
– Properties of the parent observation
OB-GYN SR
Example
Encoded with
DICOM attributes
Hierarchical tree structure
of Content Items and
Relationships
External codes
(LOINC)
Measurements with
related method and
statistical properties
The Problem of SR Flexibility
• DICOM SR is very powerful –
a document creator can record
any content in a variety of structures
• A document reader must handle
every possible document
• Need to constrain the SR structure and
content to enable meaningful receiving
applications
• This is purpose of Templates
Templates
• DICOM defines Templates to standardize appropriate
structure and content for specialized applications
– Often developed in collaboration with a professional society
• Templates are similar to DICOM Information Object
Definitions and Modules
– Define Content Items as required/optional, and allowed values
– Specify hierarchical structure of sections and subsections
– Templates may be extensible (allow additional information
beyond what is defined in the template), or non-extensible
• Context Groups are sets of coded values used in the
templates
Standard Templates
• DICOM Part 16 has over 250 defined Templates, and over 800
associated value sets (Context Groups). Examples:
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TID 2000 Basic Diagnostic Imaging Report
TID 2010 Key Object Selection
TID 2100 Macular Grid Thickness and Volume Report
TID 3001 Cardiac Cath Procedure Log
TID 3300 Cardiac Stress Testing Report
TID 3900 CT/MR Cardiovascular Analysis
TID 4000 Mammography CAD
TID 4120 Colon CAD
TID 5000 OB-GYN Ultrasound Procedure Report
TID 5100 Vascular Ultrasound Report
TID 10001 Projection X-Ray Radiation Dose
TID 10011 CT Radiation Dose
Typical Top Level Template
Structure
CONTAINER
Document Title
…
Template specified title
OB-GYN, Adult Echo, IVUS
Ultrasound Vascular, Cath/Hemo …
CONTAINER
Patient
Characteristics
CONTAINER
Procedure
Context
CONTAINER
Summary
CONTAINER
CONTAINER
CONTAINER
Findings
Heading
Finding
FindingHeading
Heading
…
…
…
…
TID 1002
Observation
Context
Vital Signs,
Presentation
Procedure
Method
Summary
Findings
Findings,
Measurements
DICOM SR SOP Classes
• Basic Text, Enhanced and Comprehensive - General use
– Text, coded content, numeric measurements, spatial and temporal
ROI references (any template)
• CAD - Automated analysis results
– SOP Class per CAD template (TID 4000 Mammo, TID 4100 Chest,
TID 4120 Colon)
• Key Object Selection - Flags one or more images
– Purpose (“for referring physician”, “for surgery”, …) and textual note
(TID 2010 only)
• Procedure Log
– Time-based event log for extended duration procedures (TID 3001)
• Radiation Dose Report - Projection X-ray; CT
– TID 10001 Projection X-Ray, TID 10011 CT Radiation Dose
SR in workflows
• We know how to use images in radiology
workflows – it is not so obvious how to
effectively use SR
• Integrating the Healthcare Enterprise (IHE) is
developing use-case based workflow profiles
– IHE is a professional-industry collaboration that
includes the DICOM Standards Committee
– Workflows tested at IHE Connect-a-thons
– Request IHE workflow profiles in your
equipment purchases / upgrades
Post-Processing Results
• Measurements and coded data created at either
acquisition modality or workstation
– OB-GYN, Vascular, Cardiac Ultrasound Measurements
– Mammo, Chest, Colon CAD
– Cardiovascular CT/MR Measurements
• Stored in PACS with other study data (images)
as “evidence documents”
• Interpreted along with the images
– Significant observations copied into clinical report
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Evidence Documents Profile
Key Object Selection
Documents
• Conveys a list of DICOM Composite Objects grouped
together for a stated purpose
– Intent of selection is in SR Title; also includes simple textual note
– Non-extensible template TID 2010 – keep it simple!
– Identified by its own SOP Class UID, and its own modality “KO”
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Use Cases
– Technologist Note – comment to radiologist, electronic equivalent of
Post-It™ on film jacket (KIN Profile)
– Radiologist Key Image Note – list of key images for report or
consultation to PACS (KIN Profile)
– Quality Control Note – identify images to not be used, e.g., from
mammo QC workstation (MAWF Profile)
– Study Content Manifest – list of images available for sharing through
a Health Information Exchange (XDS-I Profile)
– Export List – list of images for export to teaching file or clinical trial
(TCE Profile)
Radiation Dose Report
• Radiation Dose Report is an SR Document
– Created by a modality to record the Radiation Dose delivered to
a patient during imaging procedure; stored to the PACS
– Provides more comprehensive information than attributes in an
image header or in the MPPS
– Encoded with specific SOP Class UID to allow easy access by
dose management applications
• Workflow specified in IHE Radiation Exposure
Management (REM) Profile
– New workflow actor: Dose Information Reporter for analysis and
management (“dashboard”)
• DICOM Radiation Dose Report may soon be required
by regulation in some countries
Radiation Dose Report
Content
• Specific templates for different Modalities:
Projection X-Ray (XA, CR, DX, MG) or CT
• Conveys cumulative dose information as well as
details of each irradiation event
• The irradiation event is the “smallest” information
entity recorded in the realm of Radiation Dose
reporting
– For example, a CT irradiation event is one continuous irradiation
procedure (scan) with consistent acquisition parameters
• Content Items allow aggregation for comparative
statistics by device, operator, protocol, etc.
Diagnostic Reports
• SR infrastructure supports creation and interchange
of diagnostic report documents
– Simple structure of section headings and paragraphs
– Measurements and coded content items on different levels to
support data mining and statistical analysis
– Robust image references
– Storable in PACS with study
– IHE Simple Image and Numeric Report Profile
• But needs transcoding/rendering to a displayable
format for non-DICOM access
– E.g., HL7 Clinical Document Architecture XML
Putting DICOM SR into
Practice
• DICOM SR is a potentially powerful addition to the
interoperability environment
• Use IHE use case driven profiles as basis for
requests for information (RFI) from vendors
– Start with your high priority issues, e.g., radiation dose, or
sonographer worksheet measurements
• Many profiles have implementation in some
workflow actors, but not a full end-to-end capability
– Evidence Documents widely implemented in new ultrasound
systems, but not in ultrasound analysis and reporting
applications
– Radiation Dose Reports are being implemented in modalities,
but still need the analysis and management applications
– Vendors will respond to customer requests – ask for this from the
missing link systems