Slicer3:UIDesign:WorkingProblems:BCAnalysis:Volumetric

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Volumetric Tumor Analysis for Breast Cancer

Goal

Goal is to accommodate basic RECIST assessment for cancer treatment.

Specifically for volumetric analysis:

  • perform linear measurements
  • perform volumetric measurements
  • test change tracker in cases where linear measurements may not provide clear assessment.

Linear Measurements Workflow Described by Jeffrey Yapp

  • Scroll through baseline
  • Find the tumor's longest diameter (no reformat, just on orig acquisition)
  • Measure the longest diameter D1(t1)
  • Measure the orthogonal diameter D2(t1)
  • If there are multiple tumors, measure both diams in each tumor and sum to get relative D1(t1) and relative D2(t1)
  • Perform same measurements D1(t2) and D2(t2)
  • Specific results to report:
    • Percent change
    • Absolute change
    • Question: units for these values -- mm!

Approach in Slicer

  • create a subvolume of target breast for both pre and post treatment timepoints: try to make these two subvolumes match as closely as possible. Ron uses 2-fold oversampling.
  • Registration:
    • create transform node
    • perform manual,
    • then affine,
    • then B-spline (modified number of histogram bins to 20)
  • run bias field correction on both subvolumes with 10 iterations and skin mask for pre and post separately
  • mask out background
  • perform histogram matching with "threshold at mean" checked
  • Ran diffeomorphic demons on post, took 3 hours, with nice results
  • Linear Measurements:
    • scroll to slice with largest diameter Dmax
    • measure Dmax and orthogonal Dmax on both treatment timepoints using the linear measurement widget.
  • in Editor module:
    • use threshold paint to segment tumor; or
    • use fastmarching with seeds in the tumor tissue
    • erase any outlying pixels
  • in Fiducials module:
    • create two fiducials along longest axis
    • check distance measure between; or
    • eventually use nicole's measurement widget
    • move fiducials to mark orthogonal axis
    • check distance measure between;
  • Extra things to do:
    • use the editor quick model to create a model of the gland
    • use the editor to segment the skin (threshold, change island, quick model)

Ron's requests:

  • The fiducial text is too large in the fast marching display. The default text size be smaller?
  • I was not quite clear on how to create a new label map for doing the skin segmentation. I ended up reusing the fastmarchinglabel and losing that segmentation.
  • quickmodel should use the label name as default.
  • It would be nice to have short cuts to the add label tools and label statistics tools on the editor page. This would give a cue for beginners where to look for that functionality.

Volume Measurements Workflow

  • Scroll through dataset and determine tumor with largest diameter.
  • Segment largest diameter tumor in baseline Question: multiple tumors ok?
    • Manual or automatic segmentation OK
  • Segment tumor in followup Questions: Must be same tumor, or largest diameter in followup? multiple tumors ok? (same tumor)
    • Manual or automatic segmentation OK -- but use same method
  • Measure:
    • Volume(t1) and Volume(t2) Question: which is preferred, mm^3!
    • Relative % difference
    • Absolute change (same units as above)

Screenshots

Linear Measurement (from draft slides)

measuring pre-TX tumor with fiducials, longest dimension
measuring pre-TX tumor with fiducials, orthogonal dimension
measuring pre-TX tumor with MeasureWidget, orthogonal dimension
measuring pre-TX tumor with fiducials, longest dimension
measuring pre-TX tumor with fiducials, orthogonal dimension

Volumetric Measurement (from draft slides)

defining VOI for measurements
pre-TX statistics
post-TX statistics
pre- versus post-TX statistics

STATUS

  • have new Pre/Post GAD Ax case for post-treatment -- need to regenerate slides and workflow with this dataset instead of T1 for better tumor contrast (November RSNA deadline)
  • need to use dataset appropriate for ChangeTracker demonstration -- t2 for this dataset has no detectable tumor (November RSNA deadline)

PPT files

Slides for Volumetric Analysis (in progress)