Simultaneous maximum a posteriori reconstruction of attenuation and activity distributions from emission sinograms

IEEE Trans Med Imaging. 1999 May;18(5):393-403. doi: 10.1109/42.774167.


In order to perform attenuation correction in emission tomography an attenuation map is required. We propose a new method to compute this map directly from the emission sinogram, eliminating the transmission scan from the acquisition protocol. The problem is formulated as an optimization task where the objective function is a combination of the likelihood and an a priori probability. The latter uses a Gibbs prior distribution to encourage local smoothness and a multimodal distribution for the attenuation coefficients. Since the attenuation process is different in positron emission tomography (PET) and single photon emission tomography (SPECT), a separate algorithm for each case is derived. The method has been tested on mathematical phantoms and on a few clinical studies. For PET, good agreement was found between the images obtained with transmission measurements and those produced by the new algorithm in an abdominal study. For SPECT, promising simulation results have been obtained for nonhomogeneous attenuation due to the presence of the lungs.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Abdomen / diagnostic imaging
  • Algorithms
  • Computer Simulation
  • Fluorodeoxyglucose F18
  • Humans
  • Leg / diagnostic imaging
  • Likelihood Functions
  • Radiopharmaceuticals
  • Technetium Tc 99m Exametazime
  • Thorax / diagnostic imaging
  • Tomography, Emission-Computed / methods*
  • Tomography, Emission-Computed / statistics & numerical data
  • Tomography, Emission-Computed, Single-Photon / methods*
  • Tomography, Emission-Computed, Single-Photon / statistics & numerical data


  • Radiopharmaceuticals
  • Fluorodeoxyglucose F18
  • Technetium Tc 99m Exametazime