Slicer3:UIDesign:WorkingProblems:BCAnalysis:PET

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SUV Analysis for Breast Cancer

Goal

Goal is to accommodate basic RECIST assessment for cancer treatment (Response Evaluation Criteria In Solid Tumors).

Specifically for PET/CT analysis, develop appropriate visualization of PET/CT Fusion, and a module for computing Standardized Uptake Value (SUV).

PET SUV Analysis Workflow

• Segment the tumor by hand (ROI or VOI, can be simple circle or ellipsoid)
• Compute SUV of baseline
  • extract parameters from dicom header including
    • concentration
    • injected activity
    • patient weight
  • SUV = ( concentration (microcuries/cc) / injected activity (microcuries) ) - (patient weight (g))
  • use maximum value
• Compute SUV of followup
  • extract parameters from dicom header including
    • concentration
    • injected activity
    • patient weight
  • SUV = ( concentration (microcuries/cc) / injected activity (microcuries) ) - (patient weight (g))
  • use maximum value
• Normalize ROI by SUVmax
• Resport parameters of interest
  • SUVmax_baseline,
  • SUVmax_followup,
  •  % change
• For multiple tumors, report
  • sum of SUV_baselines
  • sum of SUV_followup
  • percent change

Approach

Started a PET_SUV module in Slicer that

• lets you choose a pre-treatment pet volume
• lets you choose a post-treatment CT volume (if present)
• lets you choose pre & post-treatment label maps.
• displays them in FG/BG with correct LUT
• pulls parameters of interest for SUV calculation from DICOM header
• has entry widget for parameters missing from header
• computes measures of interest as described above.
• no special viewer for now.
• ...

Resources

Display guide

case study MS PPT Slides shows tumor

MS Word document with DICOM tags for SUV

Slicer Display at present

Initial view in Slicer (w/o volume rendering)

Ron's PETCT in Slicer: GPU Raycasting (GLSL) with Gradient Magnitude Opacity Modulation

Draft module (w/o display) DICOM Tags missing?

Latest with new PET heat color LUT and SUV computation

Questions for Ron/Jeffrey

• Same case as Draft display -- same case as ppt slides?
• Check DICOM tags; not all are found for computing suv?
  • Radiopharmaceutical Start Time (0018,1072)
  • Decay Correction (0054,1102)
  • Decay Factor (0054,1321)
  • Frame Reference Time (0054,1300)
  • Radionuclide Half Life (0018,1075)
  • Series Time (0008,0032)
  • Patient Weight (0010,1030)
  • Radionuclide Total Dose (0018,1074)
  • Correction (7053,1009) (counts to Bq/cc)
  • Philips SUV Factor (7053,1000) (custom)
• Normalize ROI by SUVmax?

Approach & notes

• Fixed dicom tag reading (nuclear medicine tags are nested.)
• SUV computation:

 For each label value/color:
 create a binary volume that includes only that label
 use that binary as a stencil on the PET volume
 if the number of voxels in the stenciled image > 0
   get the maximum Cpet
   get the mean Cpet
   (no max_mean yet)
   computes SUVmax (DONE)
   computes SUVmean (DONE)
   computes SUVmin (DONE)
   updates display (DONE)

• no unit conversion yet (assumes MBq/ml) (unit conversion too, DONE)
• will work for single or multiple tumors under one label
• can be made to work for different labels, if want to assess tumors separately.
• wire up display panel inside module (create custom PETCT LUT ) (DONE)
• get good volume render for slides. (sent Questions to Yanling & Curt on 10/14/2009)
• custom LUT and scaling (created vtkMRMLPETProceduralColorNode with two types of PET (heat, which corresponds to rgb file sent from jeff, and rainbow) DONE)
• test and verify SUV calculation (jeff, see figure below -- right order of magnitude...)
• add unit correction (convert among Ci, Bq, and kg, lb, etc. DONE)
• detect vendor and use special calculations for Philips (permission from Jeff to ignore Phillips )
• improve overall usability (always, always)
• Update nuclear medicine parameters from DICOM automatically when PET volume is selected. (DONE)
• Allow manual override (manual setting) of key parameters in the computation in case PET volume is not DICOM. (DONE)

STATUS

• Module is working and checked into Slicer's svn trunk. Needs to be batted around by users (like Ron).
• Volume rendering must still be switched on -- but VR module is a moving target right now... so checkbox to turn on/off vr is disabled -- questions about how to proceed are in to Curt & Yanling.
• Need to put units (g/ml) on all SUV computation results!
• must validate with additional datasets.
• would LIKE to add opacity to the transfer function -- (sent question to Nicole about this.).
• see latest screen shots above.

KNOWN BUGS / USABILITY PROBLEMS

• Volume rendering switch currently disabled.
• propagateVolumeSelection after touching node selectors auto-fits data to win -- so annoying! must fix.
• need to add g/ml units to computation result!!!
• stupid color range slider does not initialize to span the range by default...

PPT files

Slides for Volumetric Analysis (in progress)