Data Classification
Introduction
Classification is the process of consistently identifying and labeling different types of data. Each modality represented in Flywheel, such as MR, PET, CT, or EEG, has its own, possibly multi-dimensional classification scheme. As a result, the first step in classifying data is to identify its modality (or instrument type), followed by its detailed classification.
Classification is typically performed by a gear (for example, File Classifier), which can be configured to automatically run based on the Gear Rules for a project. Accurate and detailed classification is key in triggering further automated data processing. This article lists the intent, measurement, and feature aspects of classifications for the MR modality as well as the ability to provide custom classifications to the File Classifier gear.
Note
Prefer videos?
We have a collection of videos showing you how to get the most out of Flywheel. See these for more information:
Instruction Steps
Modalities in Flywheel
In order to accommodate domain-specific classification of data from different modalities, Flywheel has developed an extensible, multi-dimensional classification system. We call each dimension an aspect of classification. Many data types will be classified according to just a single aspect.
The File Classifier gear uses the DICOM modality tag for classification, and all modalities in Flywheel are listed using the standard DICOM abbreviations. For example "MR" stands for magnetic resonance and "OPT" stands for ophthalmic tomography.
Classifications can be adjusted and extended on a per-site basis. Check your local site for the most accurate information.
MR Data
The ever-increasing diversity in MR data makes its classification particularly complex. MR data is currently classified according to the following aspects, which are all multi-select.
Intent
Intent refers to the overall purpose of the acquisition and allows the system to distinguish between data acquired with similar parameters that are intended for different purposes in a downstream process.
- Localizer
- Shim
- Calibration
- Fieldmap
- Structural
- Functional
- Screenshot
- Non-image
Measurement
Measurement refers to the physical MR properties being measured by the pulse sequence used.
- B0
- B1
- BOLD
- CEST
- CSI
- Diffusion
- EPSI
- Fingerprinting
- MRA
- MT
- PD
- Perfusion
- Phoenix
- Susceptibility
- SVS
- T1
- T1rho
- T2
- T2*
Feature
Features refer to the pulse sequence properties and control variable/options used at the time of scan.
- 2D
- 3D
- AAscount
- Compressed-Sensing
- Contrast-Agent
- Control
- DCE
- Derived
- DKI
- DSC
- DSI
- DTI
- EPI
- EPISTAR
- FA
- FAIR
- FAIREST
- FLAIR
- Gradient-Unwrapped
- HARDI
- In-Plane
- iVASO
- Label
- M0
- Magnitude
- MIP
- MP2RAGE
- MPRAGE
- Multi-Band
- Multi-Echo
- Multi-Flip
- Multi-Shell
- Navigator
- NODDI
- PASL
- pCASL
- Phase
- Phase-Contrast
- Phase-Reversed
- PICORE
- PRESS
- QC
- QSM
- Quantitative
- Resting-State
- RMS
- SBRef
- Singlerep
- SPGR
- Spin-Echo
- Spiral
- Steady-State
- STEAM
- SWI
- Task
- TOF
- TRACE
- Transmit-Reference
- Uniform
- VASO
- WASSR
- Water-Reference
Custom Classifications
Classification schemas can be adjusted and extended on a per-site basis. Check your local site for the most accurate information. Attempting to set a classification that does not adhere to the classification schema may cause upload errors.
The File Classifier gear comes with default profiles for Computed Tomography (CT), Magnetic Resonance (MR), Positron Emission Tomography (PT), and Mammography (MG). In cases where the default profiles are not assigning the desired classifications for acquisitions, custom classification profiles can be provided as input to the File Classifier gear.
Best Practices
DICOM classification is implemented by a set of gears: File Metadata Importer, which extracts DICOM headers and stores them as metadata on the DICOM file object, and File Classifier, which utilizes the stored metadata to assign the classification. Additional information on this workflow can be found in the Best Practices: File Metadata Importer and File Classifier guide.