Skip to main content

Advertisement

Cross calibration of the Siemens mMR: easily acquired accurate PET phantom measurements, long term stability and reproducibility

Article metrics

  • 554 Accesses

We present a quick and easy method to perform quantitatively accurate PET scans of typical water-filled PET plastic shell phantoms on the Siemens mMR PET/MR scanner. We perform regular cross calibrations (Xcals) of our PET scanners, including the Siemens mMR PET/MR, with a Siemens mCT water phantom. We evaluate the mMR cross calibration stability over a 3-year period. Recently, the mMR software (VB20P) offered the option of using predefined μ-maps. We evaluated this option by using either the predefined μ-map of the long mMR water phantom or a system-integrated user defined CT-based μ-map of the mCT water phantom used for Xcal. On 54 cross calibrations that were acquired over 3 years, the mMR on average underestimated the concentration by 16% due to the use of MR-based μ-maps. The mMR produced the narrowest range and lowest standard deviation of the Xcal ratios, implying it and is the most stable of the 6 scanners included in this study over a 3 year period. With correctly segmented μ-maps, the mMR produced Xcal ratios of 1.00-1.02, well within the acceptance range [0.95-1.05]. Measuring the concentration in a centrally placed cylindrical VOI allows for some robustness against misregistration of the μ-maps but it should be no more than a few millimeters in the x-y plane, while the tolerance is larger on the z-axis (when, as always with PET, keeping clear of the axial edges of the FOV). The mMR is the most stable scanner in this study and the mean underestimation is no longer an issue with the easily accessible μ-map, which in all 7 tests resulted in correct Xcal ratios. We will share the user defined μ-map of the mCT phantom and the protocol with interested mMR users.

Author information

Correspondence to Sune H Keller.

Rights and permissions

Open Access This article is distributed under the terms of the Creative Commons Attribution 4.0 International License (https://creativecommons.org/licenses/by/4.0), which permits use, duplication, adaptation, distribution, and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made.

Reprints and Permissions

About this article

Verify currency and authenticity via CrossMark

Cite this article

Keller, S.H., Jakoby, B., Hansen, A.E. et al. Cross calibration of the Siemens mMR: easily acquired accurate PET phantom measurements, long term stability and reproducibility. EJNMMI Phys 2, A28 (2015) doi:10.1186/2197-7364-2-S1-A28

Download citation

Keywords

  • Computational Mathematic
  • Technical Physic
  • Term Stability
  • Lower Standard Deviation
  • Easy Method