Challenges and current methods for attenuation correction in PET/MR

  • Vincent KeeremanEmail author
  • Pieter Mollet
  • Yannick Berker
  • Volkmar Schulz
  • Stefaan Vandenberghe
Review Article


Quantitative PET imaging requires an attenuation map to correct for attenuation. In stand-alone PET or PET/CT, the attenuation map is usually derived from a transmission scan or CT image, respectively. In PET/MR, these methods will most likely not be used. Therefore, attenuation correction has long been regarded as one of the major challenges in the development of PET/MR. In the past few years, much progress has been made in this field. In this review, the challenges faced in attenuation correction for PET/MR are discussed. Different methods have been proposed to overcome these challenges. An overview of the MR-based (template-based and voxel-based), transmission-based and emission-based methods and the results that have been obtained is provided. Although several methods show promising results, no single method fulfils all of the requirements for the ideal attenuation correction method for PET/MR. Therefore, more work is still necessary in this field. To allow implementation in routine clinical practice, extensive evaluation of the proposed methods is necessary to demonstrate robustness and automation.


PET/MR Attenuation correction Template UTE Transmission Emission 



This research was supported by the European Union FP7 projects HYPERimage (Grant 201651) and SUBLIMA (Grant 241711).


  1. 1.
    Grazioso R, Ladebeck R, Schmand M (2005) APD-based PET for combined MR-PET imaging. In: Proceedings of the 13th scientific meeting, international society for magnetic resonance in medicine, Miami Beach, p 408Google Scholar
  2. 2.
    Pichler BJ, Judenhofer MS, Catana C (2006) Performance test of an LSO-APD detector in a 7-T MRI scanner for simultaneous PET/MRI. J Nucl Med 47:639–647PubMedGoogle Scholar
  3. 3.
    Judenhofer MS, Catana C, Swann BK, Siegel SB, Jung WI, Nutt RE, Cherry SR, Claussen CD, Pichler BJ (2007) PET/MR images acquired with a compact MR- compatible PET detector in a 7-T magnet. Radiology 244:807–814PubMedCrossRefGoogle Scholar
  4. 4.
    Schulz V, Solf T, Weissler B, Gebhardt P, Fischer P, Ritzert M, Mlotok V, Piemonte C, Zorzi N, Melchiorri M, Vandenberghe S, Keereman V, Schaeffter T, Marsden P (2009) A preclinical PET/MR insert for a human 3T MR scanner. IEEE Nucl Sci Conf R 2577–2579Google Scholar
  5. 5.
    Solf T, Schulz V, Weissler B, Thon A, Fischer P, Ritzert M, Mlotok V, Piemonte C, Zorzi N (2009) Solid-state detector stack for ToF-PET/MR. IEEE Nucl Sci Conf R 2798–2799Google Scholar
  6. 6.
    Lalush D, Wernick M (2004) Iterative image reconstruction. In: Wernick M, Aarsvold J (eds) Emission tomography: the fundamentals of PET and SPECT. Elsevier Academic Press, San DiegoGoogle Scholar
  7. 7.
    Zaidi H (2007) Is MR-guided attenuation correction a viable option for dual-modality PET/MR Imaging? Radiology 244:639–642PubMedCrossRefGoogle Scholar
  8. 8.
    Hubbel J (1969) Photon cross sections, attenuation coefficients, and energy absorption coefficients from 10 keV to 100 GeV. NSRDS-NBS 29. National Bureau of Standards, Washington, DCGoogle Scholar
  9. 9.
    International Commission on Radiation Units and Measurements (ICRU) (1989) Tissue substitutes in radiation, dosimetry and measurement. ICRU Report 44. ICRU, Bethesda, MDGoogle Scholar
  10. 10.
    Bailey D, Townsend D, Valk P, Maisey M (eds) (2005) Positron emission tomography: basic sciences. Springer, LondonGoogle Scholar
  11. 11.
    Keereman V, Van Holen R, Mollet P, Vandenberghe S (2011) The effect of errors in segmented attenuation maps on PET quantification. Med Phys 38:6010–6019PubMedCrossRefGoogle Scholar
  12. 12.
    Dahlbom M, Hoffman E (1987) Problems in signal-to-noise ratio for attenuation correction in high resolution PET. IEEE T Nucl Sci 34:288–293CrossRefGoogle Scholar
  13. 13.
    deKemp RA, Nahmias C (1994) Attenuation correction in PET using single photon transmission measurement. Med Phys 21:771–778PubMedCrossRefGoogle Scholar
  14. 14.
    Beyer T, Townsend D, Brun T (2000) A combined PET/CT scanner for clinical oncology. J Nucl Med 41:1369–1379PubMedGoogle Scholar
  15. 15.
    Kinahan P, Townsend D, Beyer T, Sashin D (1998) Attenuation correction for a combined 3D PET/CT scanner. Med Phys 25:2046–2053PubMedCrossRefGoogle Scholar
  16. 16.
    Burger C, Goerres G, Schoenes S, Buck A (2002) PET attenuation coefficients from CT images: experimental evaluation of the transformation of CT into PET 511-keV attenuation coefficients. Eur J Nucl Med 29:922–927CrossRefGoogle Scholar
  17. 17.
    Beyer T, Antoch G, Blodgett T, Freudenberg LF, Akhurst T, Mueller S (2003) Dual- modality PET/CT imaging: the effect of respiratory motion on combined image quality in clinical oncology. Eur J Nucl Med Mol Imaging 30:588–596PubMedCrossRefGoogle Scholar
  18. 18.
    Goerres G, Burger C, Kamel E, Seifert B, Kaim A, Buck A, Buehler T, Schulthess G (2003) Respiration-induced attenuation artifact at PET/CT: technical considerations. Radiology 226:906–910PubMedCrossRefGoogle Scholar
  19. 19.
    Delso G, Ziegler S (2009) PET/MRI system design. Eur J Nucl Med Mol Imaging 36(Suppl 1):S86–S92PubMedCrossRefGoogle Scholar
  20. 20.
    Delso G, Martinez-Moller A, Bundschuh R, Ladebeck R, Candidus Y, Faul D, Ziegler S (2010) Evaluation of the attenuation properties of MR equipment for its use in a whole-body PET/MR scanner. Phys Med Biol 55:4361–4374PubMedCrossRefGoogle Scholar
  21. 21.
    Mawlawi O, Erasmus JJ, Pan T, Cody DD, Campbell R, Lonn AH, Kohlmyer S, Macapinlac HA, Podoloff DA (2006) Truncation artifact on PET/CT: impact on measurements of activity concentration and assessment of a correction algorithm. Am J Roentgenol 186:1458–1467CrossRefGoogle Scholar
  22. 22.
    Beyer T, Bockisch A, Kühl H, Martinez MJ (2006) Whole-body 18F-FDG PET/CT in the presence of truncation artifacts. J Nucl Med 47:91–99PubMedGoogle Scholar
  23. 23.
    Berker Y, Franke J, Salomon A, Palmowski M, Donker H, Temur Y, Mottaghy F, Kuhl C, Izquierdo-Garcia D, Fayad Z, Kiessling F, Schulz V (2012) MRI-based attenuation correction for hybrid PET/MRI systems: a four-class tissue segmentation technique using a combined ultra-short echo time (UTE)/Dixon MR sequence. J Nucl Med 53:796–804PubMedCrossRefGoogle Scholar
  24. 24.
    Montandon M, Zaidi H (2005) Atlas-guided non-uniform attenuation correction in cerebral 3D PET imaging. Neuroimage 25:278–286PubMedCrossRefGoogle Scholar
  25. 25.
    Rota Kops E, Herzog H (2007) Alternative methods for attenuation correction for PET images in MR-PET scanners. IEEE Nucl Sci Conf R 4327–4330Google Scholar
  26. 26.
    Rota Kops E, Herzog H (2008) Template based attenuation correction for PET in MR-PET scanners. IEEE Nucl Sci Conf R 3786–3789Google Scholar
  27. 27.
    Hofmann M, Steinke F, Scheel V (2008) MRI-based attenuation correction for PET/MRI: a novel approach combining pattern recognition and atlas registration. J Nucl Med 49:1875–1883PubMedCrossRefGoogle Scholar
  28. 28.
    Hofmann M, Bezrukov I, Mantlik F, Aschoff P, Steinke F, Beyer T, Pichler BJ, Scholkopf B (2011) MRI-based attenuation correction for whole-body PET/MRI: quantitative evaluation of segmentation- and atlas-based methods. J Nucl Med 52:1392–1399PubMedCrossRefGoogle Scholar
  29. 29.
    Beyer T, Weigert M, Quick HH, Pietrzyk U, Vogt F, Palm C, Antoch G, Mueller S, Bockisch A (2008) MR-based attenuation correction for torso-PET/MR imaging: pitfalls in mapping MR to CT data. Eur J Nucl Med Mol Imaging 35:1142–1146PubMedCrossRefGoogle Scholar
  30. 30.
    El Fakhri G, Kijewski MF, Johnson KA, Syrkin G, Killiany RJ, Becker JA, Zimmerman RE, Albert MS (2003) MRI-guided SPECT perfusion measures and volumetric MRI in prodromal Alzheimer disease. Arch Neurol 60:1066–1072PubMedCrossRefGoogle Scholar
  31. 31.
    El Fakhri G, Kijewski MF, Moore SC (2001) Absolute activity quantitation from projections using an analytical approach: comparison with iterative methods in Tc-99 m and I-123 brain SPECT. IEEE T Nucl Sci 48:768–773CrossRefGoogle Scholar
  32. 32.
    Zaidi H, Montandon M, Slosman D (2003) Magnetic resonance imaging-guided attenuation and scatter corrections in three-dimensional brain positron emission tomography. Med Phys 30:937–948PubMedCrossRefGoogle Scholar
  33. 33.
    Zaidi H, Montandon M, Slosman D (2004) Attenuation compensation in cerebral 3D PET: effect of the attenuation map on absolute and relative quantitation. Eur J Nucl Med Mol Imaging 31:52–63PubMedCrossRefGoogle Scholar
  34. 34.
    Schlemmer H, Pichler B, Schmand M, Burbar Z, Michel C, Ladebeck R, Jattke K, Townsend D, Nahmias C, Jacob P, Heiss W, Claussen C (2008) Simultaneous MR/PET imaging of the human brain: feasibility study. Radiology 248:1028–1035PubMedCrossRefGoogle Scholar
  35. 35.
    Hu Z, Renisch S, Schweizer B, Blaffert T, Ojha N, Guo T, Tang J, Tung C, Kaste J, Schulz V, Torres I, Shao L (2010) MR-based attenuation correction for whole-body PET/MR system. IEEE Nucl Sci Conf R 2119–2122Google Scholar
  36. 36.
    Hu Z, Ojha N, Renisch S, Schulz V, Torres I, Buhl A, Pal D, Muswick G, Penatzer J, Guo T, Bönert P, Tung C, Kaste J, Morich M, Havens T, Maniawski P, Schafer W, Gu¨nther R, Krombach G, Shao L (2009) MR-based attenuation correction for a whole-body sequential PET/MR system. IEEE Nucl Sci Conf R 3508–3512Google Scholar
  37. 37.
    Rota Kops E, Wagenknecht G, Scheins J, Tellmann L, Herzog H (2009) Attenuation correction in MR-PET scanners with segmented T1-weighted MR images. IEEE Nucl Sci Conf R 2530–2533Google Scholar
  38. 38.
    Steinberg J, Jia G, Sammet S, Zhang J, Hall N, Knopp M (2010) Three-region MRI-based whole-body attenuation correction for automated PET reconstruction. Nucl Med Biol 37:227–235PubMedCrossRefGoogle Scholar
  39. 39.
    Schulz V, Torres-Espallardo I, Renisch S, Hu Z, Ojha N, Börnert P, Perkuhn M, Niendorf T, Schafer WM, Brockmann H, Krohn T, Buhl A, Günther RW, Mottaghy FM, Krombach GA (2010) Automatic, three-segment, MR-based attenuation correction for whole-body PET/MR data. Eur J Nucl Med Mol Imaging 38:138–152PubMedCrossRefGoogle Scholar
  40. 40.
    Dixon W (1984) Simple proton spectroscopic imaging. Radiology 153:189–194PubMedGoogle Scholar
  41. 41.
    Martinez-Moller A, Souvatzoglou M, Delso G, Bundschuh R, Chefd’hotel C, Ziegler S, Navab N, Schwaiger M, Nekolla S (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
  42. 42.
    Coombs B, Szumowski J, Coshow W (1997) Two-point Dixon technique for water-fat signal decomposition with B0 inhomogeneity correction. Magn Reson Med 38:884–889PubMedCrossRefGoogle Scholar
  43. 43.
    Eiber M, Martinez-Möller A, Souvatzoglou M, Holzapfel K, Pickhard A, Loffelbein D, Santi I, Rummeny E, Ziegler S, Schwaiger M, Nekolla S, Beer A (2011) Value of a Dixon-based MR/PET attenuation correction sequence for the localization and evaluation of PET-positive lesions. Eur J Nucl Med Mol Imaging 38:1691–1701PubMedCrossRefGoogle Scholar
  44. 44.
    Eiber M, Souvatzoglou M, Pickhard A, Loeffelbein D, Knopf A, Holzapfel K, Martinez-Moller A, Nekolla S, Scherer E, Schwaiger M, Rummeny E, Beer A (2011) Simulation of a MR-PET protocol for staging of head-and-neck cancer including Dixon MR for attenuation correction. Eur J Radiol. doi: 10.1016/j.ejrad.2011.10.005
  45. 45.
    Gatehouse P, Bydder G (2003) Magnetic resonance imaging of short T2 components in tissue. Clin Radiol 58:1–19PubMedCrossRefGoogle Scholar
  46. 46.
    Robson M, Gatehouse P, So P, Bell J (2004) Contrast enhancement of short T2 tissues using ultrashort TE (UTE) pulse sequences. Clin Radiol 59:720–726PubMedCrossRefGoogle Scholar
  47. 47.
    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
  48. 48.
    Catana C, Kouwe A, Benner T, Michel C, Hamm M, Fenchel M, Fischl B, Rosen B, Schmand M, Sorensen A (2010) Toward implementing an MRI-based PET attenuation-correction method for neurologic studies on the MR-PET brain proto-type. J Nucl Med 51:1431–1438PubMedCrossRefGoogle Scholar
  49. 49.
    Johansson A, Karlsson M, Nyholm T (2011) CT substitute derived from MRI sequences with ultrashort echo time. Med Phys 38:2708–2717PubMedCrossRefGoogle Scholar
  50. 50.
    Mollet P, Keereman V, Clementel E, Vandenberghe S (2012) Simultaneous MR-compatible emission and transmission imaging for PET using time-of-flight information. IEEE Trans Med Imaging. doi: 10.1109/TMI.2012.2198831
  51. 51.
    Jan S, Santin G, Strul D, Staelens S, Assie K, Autret D, Avner S, Barbier R, Bardies M, Bloomfield P, Brasse D, Breton V, Bruyndonckx P, Buvat I, Chatziioannou A, Choi Y, Chung Y, Comtat C, Donnarieix D, Ferrer L, Glick S, Groiselle C, Guez D, Honore P, Kerhoas-Cavata S, Kirov A, Kohli V, Koole M, Krieguer M, van der Laan D, Lamare F, Largeron G, Lartizien C, Lazaro D, Maas M, Maigne L, Mayet F, Melot F, Merheb C, Penacchio E, Perez J, Pietrzyk U, Rannou F, Rey M, Schaart D, Schmidtlein C, Simon L, Song T, Vieira J, Visvikis D, Van de Walle R, Wieers E, Morel C (2004) GATE: a simulation toolkit for PET and SPECT. Phys Med Biol 49:4543–4561PubMedCrossRefGoogle Scholar
  52. 52.
    Segars P (2001) Development of a new dynamic NURBS-based cardiac-torso (NCAT) phantom. PhD thesis. University of North Carolina at Chapel HillGoogle Scholar
  53. 53.
    Tai Y, Lin K, Dahlbom M, Hoffman E (1996) A hybrid attenuation correction technique to compensate for lung density in 3-D total body PET. IEEE T Nucl Sci 43:323–330CrossRefGoogle Scholar
  54. 54.
    Xu M, Cutler P, Luk W (1996) Adaptive, segmented attenuation correction for whole-body PET imaging. IEEE T Nucl Sci 43:331–336CrossRefGoogle Scholar
  55. 55.
    Censor Y, Gustafson DE, Lent A, Tuy H (1979) A new approach to the emission computerized tomography problem: simultaneous calculation of attenuation and activity coefficients. IEEE Trans Nucl Sci 26:2775–2779CrossRefGoogle Scholar
  56. 56.
    Nuyts J, Dupont P, Stroobants S, Benninck R, Mortelmans L, Suetens P (1999) Simultaneous maximum a posteriori reconstruction of attenuation and activity distributions from emission sinograms. IEEE Trans Med Imaging 18:393–403PubMedCrossRefGoogle Scholar
  57. 57.
    Dicken V (1999) A new approach towards simultaneous activity and attenuation reconstruction in emission tomography. Inverse Prob 15:931–960CrossRefGoogle Scholar
  58. 58.
    Conti M (2011) Why is TOF PET reconstruction a more robust method in the presence of inconsistent data? Phys Med Biol 56:155–168PubMedCrossRefGoogle Scholar
  59. 59.
    Defrise M, Rezzaei A, Nuyts J (2012) Time-of-flight PET data determine the attenuation sinogram up to a constant. Phys Med Biol 57:885–899PubMedCrossRefGoogle Scholar
  60. 60.
    Welch A, Campbell C, Clackdoyle R, Natterer F, Hudson M, Bromiley A, Mikecz P, Chillcot F, Dodd M, Hopwood P, Craib S, Gullberg GT, Sharp P (1998) Attenuation correction in PET using consistency information. IEEE T Nucl Sci 45:3134–3141CrossRefGoogle Scholar
  61. 61.
    Bromiley A, Welch A, Chilcott F, Waikar S, McCallum S, Dodd M, Craib S, Schweiger L, Sharp P (2001) Attenuation correction in PET using consistency conditions and a three-dimensional template. IEEE T Nucl Sci 48:1371–1377CrossRefGoogle Scholar
  62. 62.
    Salomon A, Goedicke A, Schweizer B, Aach T, Schulz V (2011) Simultaneous reconstruction of activity and attenuation for PET/MR. IEEE Trans Med Imaging 30:804–813PubMedCrossRefGoogle Scholar
  63. 63.
    Delso G, Martinez-Möller A, Bundschuh R, Nekolla S, Ziegler S (2010) The effect of limited MR field of view in MR/PET attenuation correction. Med Phys 37:2804–2812PubMedCrossRefGoogle Scholar
  64. 64.
    Marshall H, Prato F, Deans L, Théberge J, Thompson R, Stodilka R (2012) Variable lung density consideration in attenuation correction of whole-body PET/MRI. J Nucl Med 53:977–984PubMedCrossRefGoogle Scholar
  65. 65.
    Buerger C, Aitken A, Tsoumpas C, King A, Schulz V, Marsden P, Schaeffter T (2011) Investigation of 4D PET attenuation correction using Ultra-short Echo Time MR. IEEE Nucl Sci Conf R 3558–3561Google Scholar

Copyright information

© ESMRMB 2012

Authors and Affiliations

  • Vincent Keereman
    • 1
    Email author
  • Pieter Mollet
    • 1
  • Yannick Berker
    • 2
    • 3
  • Volkmar Schulz
    • 2
    • 3
  • Stefaan Vandenberghe
    • 1
  1. 1.MEDISIP, Department of Electronics and Information SystemsGhent University-IBBT-IBiTechGhentBelgium
  2. 2.Department of Experimental Molecular ImagingRWTH Aachen University HospitalAachenGermany
  3. 3.Philips Technologie GmbH Innovative Technologies, Research LaboratoriesAachenGermany

Personalised recommendations