MR-based attenuation correction for torso-PET/MR imaging: pitfalls in mapping MR to CT data

  • Thomas Beyer
  • Markus Weigert
  • Harald H. Quick
  • Uwe Pietrzyk
  • Florian Vogt
  • Christoph Palm
  • Gerald Antoch
  • Stefan P. Müller
  • Andreas Bockisch
Short Communication

Abstract

Purpose

MR-based attenuation correction (AC) will become an integral part of combined PET/MR systems. Here, we propose a toolbox to validate MR-AC of clinical PET/MRI data sets.

Methods

Torso scans of ten patients were acquired on a combined PET/CT and on a 1.5-T MRI system. MR-based attenuation data were derived from the CT following MR–CT image co-registration and subsequent histogram matching. PET images were reconstructed after CT- (PETCT) and MR-based AC (PETMRI). Lesion-to-background (L/B) ratios were estimated on PETCT and PETMRI.

Results

MR–CT histogram matching leads to a mean voxel intensity difference in the CT- and MR-based attenuation images of 12% (max). Mean differences between PETMRI and PETCT were 19% (max). L/B ratios were similar except for the lung where local misregistration and intensity transformation leads to a biased PETMRI.

Conclusion

Our toolbox can be used to study pitfalls in MR-AC. We found that co-registration accuracy and pixel value transformation determine the accuracy of PETMRI.

Keywords

PET/MRI PET/CT Attenuation correction 

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Copyright information

© Springer-Verlag 2008

Authors and Affiliations

  • Thomas Beyer
    • 1
  • Markus Weigert
    • 1
  • Harald H. Quick
    • 2
  • Uwe Pietrzyk
    • 3
    • 4
  • Florian Vogt
    • 2
  • Christoph Palm
    • 3
  • Gerald Antoch
    • 2
  • Stefan P. Müller
    • 1
  • Andreas Bockisch
    • 1
  1. 1.Department of Nuclear MedicineUniversity HospitalEssenGermany
  2. 2.Department of Diagnostic and Interventional Radiology and NeuroradiologyUniversity Hospital EssenEssenGermany
  3. 3.Institute of Neuroscience and BiophysicsResearch Centre JülichJülichGermany
  4. 4.Department of PhysicsUniversity of WuppertalWuppertalGermany

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