Diffusion in Brain

1. Diffusion in Brain IHE use case for Enhanced MR Diffusion Use Case

2. Description • This use case refers the MR procedure of standard Diffusion Weighted Imaging (DWI) or Diffusion Tensor Imaging (DTI), in which stacks of images (slices) are generated with different meaning and derived contrast. • The images are present in different Enhanced MR SOP Instances: • There shall be a series of original images with different Diffusion b-values. There shall be a stack of images for b=0.For other b-values there may be a number of images for different diffusion gradient directions. • There shall be a series with the resulting isotropic images (at least for b=max) • If there are ADC images then there shall be a series with ADC images for each slice (at least for b=max) • The isotropic images and ADC images for b = max shall be presented in conjunction with the b=0 images for each slice. • This use case defines that non-isotropic images (which only differ by Gradient Direction) may be present, but are not of interest for standard viewing applications (these images may be specific for Diffusion postprocessing like FiberTracking). Diffusion Use Case

3. Notes • All images are related to their respective InStackPositionNumber.These numbers (and their dimension indices) are to be kept consistent over all related Enhanced MR Objects through the Dimension Organization. • b=0 Images are related to only one b-value (=0) • Isotropic images are one-to-one related to a b-value.They are the result of a postprocessing on the directional images of one slice for one b-value, these original images may or may not be present in the “original” object. • ADC images are the result of a postprocessing on the (isotropic or the original directional) images of one slice for different b-values.Reference shall be made to the source image SOP Instances. Diffusion Use Case

4. b=0 Slice 1 b=max ISO Slice 1 ADC for b=max Slice 1 b=max ISO Slice 2 b=0 Slice 2 ADC for b=max Slice 2 b=max ISO Slice 3 b=0, Slice 3 ADC for b=max Slice 3 Display example Seriesnavigation Linked by position Linked by position b=0 ISO ADC scroll Diffusion Use Case

5. Selection Criteria for the use case (all apply) • SOP CLASS UID is: Enhanced MR Image ======== • Image Type and Frame Type have: • Value 1: • ORIGINAL for b=0 and Directional • DERIVED for Isotropic and ADC • Value 2: PRIMARY • Value 3: DIFFUSION ============ • Value 4: • <empty> for “ORIGINAL” • “ISOTROPIC” for Isotropic of DW-TRACE • “ADC” for ADC maps: ADC-TRACE • For diffusion images (= all images in this use case) the “Per Frame Functional Groups Sequence” contains the “MR Diffusion Sequence”. Diffusion Use Case

6. Image Type and Frame Type Values for original images in this use case Diffusion Use Case

7. Example of Image Type and Frame Type Values for Isotropic images in this use case Diffusion Use Case

8. Example of Image Type and Frame Type Values for “ADC” images in this use case Diffusion Use Case

9. Object requirements for creators Creator provide Enhanced MR Image SOP instance with dimension indices for: • Stack ID • InStackPositionNumberremoved from proposal, replaced by selection of value:(Directionality: (new IHE Use Case Requirement: to assign a specific index)1 = NONE, 2 = ISOTROPIC, 3 = DIRECTIONAL or BMATRIX (these are DICOM mutually exclusive)) • Diffusion b-value (new IHE Use Case Requirement: to sort on increasing value)Index values according increasing b-value Diffusion Use Case

10. Object Relations • Derivation Image Sequence • Refers to the method used for derivation. • Codes to be used for Image Derivation: CID 7203 • Isotropic: Diffusion weighted : 113043 • ADC: Aparent Diffusion Coefficient: 113041 • Source Image Sequence • Refers to the SOP Instance of the source images • SOP Class UID of the source • Dimension Organization UID shall have one overall value in the use case. Diffusion Use Case

11. Functional Requirements for Display • Support Enhanced MR SOP Class. • Support the use of Derivation Image Functional Group for tracking the original images (standard DICOM). • Support the display according the Image Dimensions. • Provide (at least) one row of three viewports for the display of frames for the same InStackPositionNumber (= slice number).Minimally the frames with b=0 and an Isotropic for b=max and the ADC image for b=max should be displayed. • The frames of one InStackPositionNumber must be presented in one row.Additional rows can be used for other InStackPositionNumber-s. • Be able to filter (select) frames based on Diffusion Directionality attribute as described in the profile. • Be able to scroll the images (vertically) by InStackPositionNumber-Index. Diffusion Use Case

12. Dimension index values Display (frames#) SOP Instance 1 “originals” Example 1 stack 4 slices 2 b-values 5 directions Display Rule is: Display according dimension. Select only frames with Diffusion Directionality = NONE == Select only frames for (3rd) index (b-value index) =1 Diffusion Use Case

13. Dimension index values Display (frame#) SOP Instance 2 Isotropic SOP Instance 3 ADC Display Rule is: Display according dimension. Display the values of the dimension attributes with each frame Diffusion Use Case

14. (CLOSED) Open issues • It must be discussed in WG16 whether the Isotropic images generated in the reconstruction process can indeed still be called “ORIGINAL” images. DERIVED • It must be discussed in WG16 whether Isotropic images when called: “DERIVED”, shall have their own defined term for Frame type Value 4. “ISOTROPIC” => CP • It must be discussed in IHE, whether the allocation of certain Index Values may be prescribed for otherwise unsorted attribute values (e.g. Diffusion Directionality: DICOM allows free allocation of index values). YES Diffusion Use Case

15. End case Diffusion Use Case