European Radiology

, Volume 22, Issue 8, pp 1776–1788 | Cite as

Technical performance evaluation of a human brain PET/MRI system

  • Armin Kolb
  • Hans F. Wehrl
  • Matthias Hofmann
  • Martin S. Judenhofer
  • Lars Eriksson
  • Ralf Ladebeck
  • Matthias P. Lichy
  • Larry Byars
  • Christian Michel
  • Heinz-Peter Schlemmer
  • Matthias Schmand
  • Claus D. Claussen
  • Vesna Sossi
  • Bernd J. PichlerEmail author
Molecular Imaging



Technical performance evaluation of a human brain PET/MRI system.


The magnetic field compatible positron emission tomography (PET) insert is based on avalanche photodiode (APD) arrays coupled with lutetium oxyorthosilicate (LSO) crystals and slip-fits into a slightly modified clinical 3-T MRI system. The mutual interference between the two imaging techniques was minimised by the careful design of the hardware to maintain the quality of the B 0 and B 1 field homogeneity.


The signal-to-noise ratio (SNR) and the homogeneity of the MR images were minimally influenced by the presence of the PET. Measurements according to the Function Biomedical Informatics Research Network (FBIRN) protocol proved the combined system’s ability to perform functional MRI (fMRI). The performance of the PET insert was evaluated according to the National Electrical Manufacturers Association (NEMA) standard. The noise equivalent count rate (NEC) peaked at 30.7 × 103 counts/s at 7.3 kBq/mL. The point source sensitivity was greater than 7 %. The spatial resolution in the centre field of view was less than 3 mm. Patient data sets clearly revealed a noticeably good PET and MR image quality.


PET and MRI phantom tests and first patient data exhibit the device’s potential for simultaneous multiparametric imaging.

Key Points

Combination of PET and MRI is a new emerging imaging technology.

Evaluated brain PET/MRI enables uncompromised imaging performance.

PET/MRI aims to provide multiparametric imaging allowing acquisition of morphology and metabolism.


PET/MRI MR-PET Brain PET/MRI Multimodality imaging Multiparametric imaging 



attenuation correction


T1w flash sequence for attenuation correction


avalanche photodiode


main magnetic field


radiofrequency field


blood oxygen level-dependent


constant fraction discriminator


chemical shift imaging sequence


circular polarised


echo planar imaging


EPI BOLD sequence


difference between echo times


Function Biomedical Informatics Research Network


fast low angle shot


full width at half maximum


full width at tenth maximum


Geiger mode avalanche photodiode


gyromagnetic ratio


gradient echo map


lutetium oxyorthosilicate


magnetic resonance spectroscopy


National Electrical Manufacturers Association


noise equivalent count rate


normal spin echo


ordinary Poisson ordered subset expectation maximisation


phase map with echo time of 10 ms


phase map with echo time of 20 ms


radius of decorrelation


B 1 mapping service sequence


manufacturer service sequence


root mean square


spin echo sequence


noise signal


maximal signal intensity


minimal signal intensity


signal to fluctuation noise ratio


signal to noise ratio


stimulated echo


single voxel press spectroscopy sequence


T1w flash sequence


T2w turbo spin echo sequence


time of flight




ultra short echo time sequence



The authors thank Andreas Schmid and Johannes Breuer for their helpful advice on programming the software for the data analysis. We thank the Radiopharmacy of the University Hospital Tübingen for providing the radiotracers as well as Andreas Boss for helpful discussions.

The authors also appreciate the discussions within the Brain PET insert partners at MGH, Boston Massachusetts, USA, the Research Center Jülich, Germany, and Emory University, Atlanta, Georgia, USA.

Financial support from the German Research Association (DFG) was provided through grants PI771/1-1, PI771/3-1, PI771/5-1.

Supplementary material

330_2012_2415_MOESM1_ESM.doc (440 kb)
ESM 1 Electronic supplementary material. (DOC 440 kb)


  1. 1.
    Schlemmer HP, Pichler BJ, Schmand M et al (2008) Simultaneous MR/PET imaging of the human brain: feasibility study. Radiology 248:1028–1035PubMedCrossRefGoogle Scholar
  2. 2.
    Pichler BJ, Kolb A, Nagele T, Schlemmer HP (2010) PET/MRI: paving the way for the next generation of clinical multimodality imaging applications. J Nucl Med 51:333–336PubMedCrossRefGoogle Scholar
  3. 3.
    Marsden PK, Strul D, Keevil SF, Williams SC, Cash D (2002) Simultaneous PET and NMR. Br J Radiol 75:S53–59Google Scholar
  4. 4.
    Judenhofer MS, Wehrl HF, Newport DF et al (2008) Simultaneous PET-MRI: a new approach for functional and morphological imaging. Nat Med 14:459–465PubMedCrossRefGoogle Scholar
  5. 5.
    Catana C, Procissi D, Wu Y et al (2008) Simultaneous in vivo positron emission tomography and magnetic resonance imaging. Proc Natl Acad Sci U S A 105:3705–3710PubMedCrossRefGoogle Scholar
  6. 6.
    Raylman RR, Majewski S, Lemieux SK et al (2006) Simultaneous MRI and PET imaging of a rat brain. Phys Med Biol 51:6371PubMedCrossRefGoogle Scholar
  7. 7.
    Catana C, Wu Y, Judenhofer MS, Qi J, Pichler BJ, Cherry SR (2006) Simultaneous acquisition of multislice PET and MR images: initial results with a MR-compatible PET scanner. J Nucl Med 47:1968–1976PubMedGoogle Scholar
  8. 8.
    Raylman RR, Majewski S, Velan SS, et al (2007) Simultaneous acquisition of magnetic resonance spectroscopy (MRS) data and positron emission tomography (PET) images with a prototype MR-compatible, small animal PET imager. J Magn Res 186:305–310Google Scholar
  9. 9.
    Heiss WD (2009) The potential of PET/MR for brain imaging. Eur J Nucl Med Mol Imaging 36(Suppl 1):105–112CrossRefGoogle Scholar
  10. 10.
    Antoch G, Bockisch A (2009) Combined PET/MRI: a new dimension in whole-body oncology imaging? Eur J Nucl Med Mol Imaging 36(Suppl 1):113–120CrossRefGoogle Scholar
  11. 11.
    Nekolla SG, Martinez-Moeller A, Saraste A (2009) PET and MRI in cardiac imaging: from validation studies to integrated applications. Eur J Nucl Med Mol Imaging 36(Suppl 1):121–130CrossRefGoogle Scholar
  12. 12.
    Brix G, Lechel U, Glatting G et al (2005) Radiation exposure of patients undergoing whole-body dual-modality 18F-FDG PET/CT examinations. J Nucl Med 46(4):608–613PubMedGoogle Scholar
  13. 13.
    Buscher K, Judenhofer MS, Kuhlmann MT et al (2010) Isochronous assessment of cardiac metabolism and function in mice using hybrid PET/MRI. J Nucl Med 51:1277–1284PubMedCrossRefGoogle Scholar
  14. 14.
    Hofmann M, Steinke F, Scheel V et al (2008) MRI-based attenuation correction for PET/MRI: a novel approach combining pattern recognition and atlas registration. J Nucl Med 49:1875–1883PubMedCrossRefGoogle Scholar
  15. 15.
    Martinez-Moller A, Souvatzoglou M, Delso G et al (2009) Tissue classification as a potential approach for attenuation correction in whole-body PET/MRI: evaluation with PET/CT data. J Nucl Med 50:520–526PubMedCrossRefGoogle Scholar
  16. 16.
    Catana C, van der Kouwe A, Benner T et al (2010) Toward implementing an MRI-based PET attenuation-correction method for neurologic studies on the MR-PET brain prototype. J Nucl Med 51:1431–1438PubMedCrossRefGoogle Scholar
  17. 17.
    Keereman V, Fierens Y, Broux T, De Deene Y, Lonneux M, Vandenberghe S (2010) MRI-based attenuation correction for PET/MRI using ultrashort echo time sequences. J Nucl Med 51:812–818PubMedCrossRefGoogle Scholar
  18. 18.
    Watson C, Byars L, Michel C, Rothfuss H (2008) Scatter/trues detection efficiency compensation in scatter correction of PET emission data. IEEE Nucl Sci Symp Conf Rec 5493–5497Google Scholar
  19. 19.
    Witoszynskyj S, Rauscher A, JrR R, Barth M (2009) Phase unwrapping of MR images using ΦUN – a fast and robust region growing algorithm. Med Image Anal 13:257–268PubMedCrossRefGoogle Scholar
  20. 20.
    Jiru F, Klose U (2006) Fast 3D radiofrequency field mapping using echo-planar imaging. Magn Reson Med 56(6):1375–1379PubMedCrossRefGoogle Scholar
  21. 21.
    Wehrl HF, Judenhofer MS, Thielscher A, Martirosian P, Schick F, Pichler BJ (2011) Assessment of MR compatibility of a PET insert developed for simultaneous multiparametric PET/MR imaging on an animal system operating at 7 T. Magn Reson Med 65:269–279PubMedCrossRefGoogle Scholar
  22. 22.
    Friedman L, Glover GH (2006) Report on a multicenter fMRI quality assurance protocol. J Magn Reson Imaging 23(6):827–839PubMedCrossRefGoogle Scholar
  23. 23.
    Kaufman L, Kramer DM, Crooks LE, Ortendahl DA (1989) Measuring signal-to-noise ratios in MR imaging. Radiology 173:265–267PubMedGoogle Scholar
  24. 24.
    Byars LG, Sibomana M, Burbar Z, et al (2005) Variance reduction on randoms from coincidence histograms for the HRRT. IEEE Nucl Sci Symp Conf Rec 2622–2626Google Scholar
  25. 25.
    Hong IK, Chung ST, Kim HK, Kim YB, Son YD, Cho ZH (2007) Ultra fast symmetry and SIMD-based projection-backprojection (SSP) algorithm for 3-D PET image reconstruction. IEEE Trans Med Imaging 26:789–803PubMedCrossRefGoogle Scholar
  26. 26.
    Zaidi H, Hasegawa B (2003) Determination of the attenuation map in emission tomography. J Nucl Med 44:291–315PubMedGoogle Scholar
  27. 27.
    Hofmann M, Pichler B, Scholkopf B, Beyer T (2009) Towards quantitative PET/MRI: a review of MR-based attenuation correction techniques. Eur J Nucl Med Mol Imaging 36(Suppl 1):93–104CrossRefGoogle Scholar
  28. 28.
    Kolb A, Lorenz E, Judenhofer MS, Renker D, Lankes K, Pichler BJ (2010) Evaluation of Geiger-mode APDs for PET block detector designs. Phys Med Biol 55(7):1815–1832PubMedCrossRefGoogle Scholar
  29. 29.
    de Jong HW, van Velden FH, Kloet RW, Buijs FL, Boellaard R, Lammertsma AA (2007) Performance evaluation of the ECAT HRRT: an LSO-LYSO double layer high resolution, high sensitivity scanner. Phys Med Biol 52:1505–1526PubMedCrossRefGoogle Scholar
  30. 30.
    Boss A, Kolb A, Hofmann M et al (2010) Diffusion tensor imaging in a human PET/MR hybrid system. Invest Radiol 45:270–274PubMedCrossRefGoogle Scholar
  31. 31.
    Boss A, Bisdas S, Kolb A et al (2010) Hybrid PET/MRI of intracranial masses: initial experiences and comparison to PET/CT. J Nucl Med 51:1198–1205PubMedCrossRefGoogle Scholar

Copyright information

© European Society of Radiology 2012

Authors and Affiliations

  • Armin Kolb
    • 1
  • Hans F. Wehrl
    • 1
  • Matthias Hofmann
    • 1
    • 2
  • Martin S. Judenhofer
    • 1
  • Lars Eriksson
    • 4
  • Ralf Ladebeck
    • 4
  • Matthias P. Lichy
    • 3
    • 5
  • Larry Byars
    • 4
  • Christian Michel
    • 4
  • Heinz-Peter Schlemmer
    • 3
  • Matthias Schmand
    • 4
  • Claus D. Claussen
    • 3
  • Vesna Sossi
    • 6
  • Bernd J. Pichler
    • 1
    Email author
  1. 1.Department of Preclinical Imaging and RadiopharmacyEberhard Karls UniversityTübingenGermany
  2. 2.Max Planck Institute for Biological CyberneticsTübingenGermany
  3. 3.Department of Diagnostic and Interventional Radiology, Department of RadiologyEberhard Karls UniversityTübingenGermany
  4. 4.Siemens HealthcareKnoxvilleUSA
  5. 5.Siemens HealthcareErlangenGermany
  6. 6.University of British ColumbiaVancouverCanada

Personalised recommendations