View source for Slicer4:Prostate mpMRI review use case

=Objective=

The purpose of this summary is to describe Slicer use scenario that is important for one of the driving biological projects of NCIGT. We are currently using Slicer3, and would be very interested to switch to Slicer4 as soon as all the needed features of our interest are available and stable. 

One of our uses of Slicer is in the review of the multiparametric MRI (mpMRI) for qualitative assessment of prostate cancer and for planning of image-guided procedures. mpMRI includes prostate gland images obtained with several sequences (T2-weighted, T1-weighted, DWI, DCE). Each of these images have to be visually reviewed and correlated with each other to improve reliability of cancer assessment. 

The primary scan used in the assessment is axial T2-weighted (anatomical) MRI. All other scans are examined in relation to this T2 scan.

In summary, our needs are the following:
* layout: ideally, we would like to have 4 or 6 axial slice viewers, no 3D viewer, all slices are in axial view mode reformatted to axial slice orientation of T2w MRI
* synchronous slice scrolling: since the images are examined one slice at a time, and for that slice each of the images needs to be reviewed, it is very helpful to scroll all slice viewers simultaneously
* Bg/Fg selection: allow changing Bg/Fg in just one slice viewer, even if the slices are locked together
* fiducials: as the tumor-suspicious regions are located, they are marked in slice with a fiducial
* speed: it is very important for the clinicians to have quick feedback as they quickly scroll through the images (preferably, using mouse wheel or arrow keys) 

=Existing review workflow: Slicer3=

* we use 4-Up layout, cannot swap 3D viewer for another slice viewer
* when slice viewers are locked and rotated to the same reformat plane, Slicer3 allows to scroll through slices synchronously
* Bg/Fg selection: tweaked local source code -- radiologists love this mode!
* fiducials are working
* speed is not quite there

[[Image:Slicer3_prostate_mpMRI_review.png|thumb|380px|]]

=Desired review workflow: Slicer4=

* layout: would like to use "3-over-3" layout; is there a plan for "2-over-2"?
* synchronous reformat slice scrolling: not available
* Bg/Fg selection: can we implement this feature as an option in Slicer4?
* fiducials: not available
* speed: cannot test in a desired configuration with slice synchronization

[[Image:Slicer4_prostate_mpMRI_review.png|thumb|380px|]]


=List of the currently missing features=
The following features prevent us from switching/testing the Slicer4 for the purposes of our application:
* fiducials
* synchronous reformat slice scrolling

The following features are highly desirable
* independent Bg/Fg selection in locked slice view mode