Vendor DICOM Tag Reference¶
DICOM tags used by each MRI vendor for perfusion imaging parameters. These differences affect how osipy extracts metadata during data loading.
Standard DICOM Tags (All Vendors)¶
| Tag | Name | Description |
|---|---|---|
| (0008,0070) | Manufacturer | Vendor identification |
| (0008,1090) | ManufacturerModelName | Scanner model |
| (0018,0080) | RepetitionTime | TR in ms |
| (0018,0081) | EchoTime | TE in ms |
| (0018,1314) | FlipAngle | Flip angle in degrees |
| (0018,9087) | DiffusionBValue | B-value for DWI |
| (0020,0013) | InstanceNumber | Volume/slice number |
| (0020,1041) | SliceLocation | Slice position |
GE Medical Systems¶
Identification¶
- Manufacturer: "GE MEDICAL SYSTEMS"
- Private Groups: 0027, 0043, 0019
DCE-MRI Tags¶
| Tag | Name | Notes |
|---|---|---|
| (0018,0080) | RepetitionTime | Standard TR |
| (0018,0081) | EchoTime | Standard TE |
| (0018,1314) | FlipAngle | Standard |
| (0019,10a2) | NumberOfPhases | Number of dynamic timepoints |
DWI/IVIM Tags¶
| Tag | Name | Notes |
|---|---|---|
| (0043,1039) | B-value | GE private b-value array |
| (0019,10bb) | DiffusionBValue | Alternative b-value location |
| (0019,10bc) | DiffusionDirection | Gradient direction |
ASL Tags¶
GE ASL data is typically:
- 3D spiral pCASL (product sequence)
- Parameters in BIDS sidecar after conversion
- M0Type: "Included" common (M0 in same timeseries)
Known Issues: - B-values may not populate standard DiffusionBValue tag - Must check private tags for complete diffusion info - ASL parameters often require BIDS sidecar
Siemens¶
Identification¶
- Manufacturer: "SIEMENS"
- Private Groups: 0019, 0021, 0029, 0051
CSA Headers¶
Siemens stores extended metadata in CSA (Cine Supplementary Attributes) headers:
- (0029,1010) CSA Image Header Info
- (0029,1020) CSA Series Header Info
The osipy Siemens parser extracts:
Extract metadata using Siemens parser
DCE-MRI Tags¶
| Tag | Name | Notes |
|---|---|---|
| (0018,0080) | RepetitionTime | Standard TR |
| (0018,0081) | EchoTime | Standard TE |
| (0018,1314) | FlipAngle | Standard |
| (0051,100c) | NumberOfImages | May indicate timepoints |
| CSA Header | MrPhoenixProtocol | Detailed sequence parameters |
DWI/IVIM Tags¶
| Tag | Name | Notes |
|---|---|---|
| (0019,100c) | DiffusionBValue | Siemens private b-value |
| (0019,100d) | DiffusionDirection | Gradient direction (x) |
| (0019,100e) | DiffusionDirection | Gradient direction (y) |
| (0019,100f) | DiffusionDirection | Gradient direction (z) |
| CSA Header | B_value | B-value from CSA |
ASL Tags¶
Siemens ASL sequences include: - WIP pCASL: 3D GRASE readout - PASL/FAIR: Bremen sequence (multi-PLD) - 2D EPI: Research sequences
| Parameter | Source | Notes |
|---|---|---|
| ArterialSpinLabelingType | BIDS sidecar | PASL, PCASL |
| PostLabelingDelay | BIDS sidecar | May be array for multi-PLD |
| BolusCutOffFlag | BIDS sidecar | Q2TIPS for PASL |
| BolusCutOffDelayTime | BIDS sidecar | Q2TIPS timing |
| BolusCutOffTechnique | BIDS sidecar | "Q2TIPS" |
Known Issues: - Multi-PLD data has array of PLDs (not single value) - CSA header parsing may fail on some sequences - Research sequences may have non-standard parameters
Philips¶
Identification¶
- Manufacturer: "Philips Medical Systems" or "Philips"
- Private Groups: 2001, 2005
Enhanced DICOM¶
Philips commonly uses Enhanced Multi-frame DICOM: - Single file contains all slices/timepoints - Nested sequences for per-frame metadata - Use dcm2niix for reliable conversion
DCE-MRI Tags¶
| Tag | Name | Notes |
|---|---|---|
| (0018,0080) | RepetitionTime | Standard TR |
| (0018,0081) | EchoTime | Standard TE |
| (0018,1314) | FlipAngle | Standard |
| (2005,1030) | PrivateRepetitionTime | May differ from standard |
| (2001,1023) | NumberOfDynamics | Number of timepoints |
DWI/IVIM Tags¶
| Tag | Name | Notes |
|---|---|---|
| (2001,1003) | DiffusionBValue | Philips private b-value |
| (2001,1004) | DiffusionDirection | Gradient direction |
| (0018,9087) | DiffusionBValue | May also be populated |
ASL Tags¶
Philips ASL typically uses 2D EPI pCASL:
| Parameter | Source | Notes |
|---|---|---|
| ArterialSpinLabelingType | BIDS sidecar | Usually "PCASL" |
| PostLabelingDelay | BIDS sidecar | Single value typically |
| LabelingDuration | BIDS sidecar | Required for quantification |
| BackgroundSuppression | BIDS sidecar | Usually true |
Known Issues: - DICOM headers often lack complete ASL parameters - Control/label order not specified in headers - Must document settings at acquisition time - LabelingDuration may be missing
Parameter Extraction Priority¶
The osipy metadata mapper uses this priority:
1. BIDS sidecar JSON
└─ Highest confidence, standardized format
2. Vendor private tags
└─ Parsed by vendor-specific parser
3. Standard DICOM tags
└─ (0018,xxxx) series
4. User-provided values
└─ Via function parameters
5. Modality defaults
└─ Reasonable assumptions per modality
Verification Checklist¶
When loading multi-vendor data, verify:
DCE¶
- [ ] TR is in expected range (typically 2-10 ms for fast DCE)
- [ ] Flip angle(s) recorded
- [ ] Number of timepoints matches expectation
- [ ] Temporal resolution calculated correctly
DSC¶
- [ ] TE is appropriate (typically 25-50 ms for gradient echo)
- [ ] TR is in expected range (typically 1-2 s)
- [ ] Number of baseline volumes known
ASL¶
- [ ] Labeling type identified (PCASL, PASL, CASL)
- [ ] PLD specified (or array for multi-PLD)
- [ ] Labeling duration specified (for pCASL/CASL)
- [ ] Control/label order known (from aslcontext.tsv)
- [ ] M0 type identified (Separate, Included, Absent)
IVIM¶
- [ ] B-values extracted correctly
- [ ] B=0 acquisition present
- [ ] Sufficient b-values for IVIM (≥4, ideally 6+)
- [ ] Low b-values present (<200 s/mm²)