Enhanced 3D PET OSEM reconstruction using inter-update metz filtering

M. Jacobson, R. Levkovitz, A. Ben-Tal, K. Thielemans, T. Spinks, D. Belluzzo, E. Pagani, V. Bettinardi, M. C. Gilardi, A. Zverovich, G. Mitra

Research output: Contribution to journalArticlepeer-review

47 Scopus citations


We present an enhancement of the OSEM (ordered set expectation maximization) algorithm for 3D PET reconstruction, which we call the inter-update Metz filtered OSEM (IMF-OSEM). The IMF-OSEM algorithm incorporates filtering action into the image updating process in order to improve the quality of the reconstruction. With this technique, the multiplicative correction image - ordinarily used to update image estimates in plain OSEM - is applied to a Metz-filtered version of the image estimate at certain intervals. In addition, we present a software implementation that employs several high-speed features to accelerate reconstruction. These features include, firstly, forward and back projection functions which make full use of symmetry as well as a fast incremental computation technique. Secondly, the software has the capability of running in parallel mode on several processors. The parallelization approach employed yields a significant speed-up, which is nearly independent of the amount of data. Together, these features lead to reasonable reconstruction times even when using large image arrays and non-axially compressed projection data. The performance of IMF-OSEM was tested on phantom data acquired on the GE Advance scanner. Our results demonstrate that an appropriate choice of Metz filter parameters can improve the contrast-noise balance of certain regions of interest relative to both plain and post-filtered OSEM, and to the GE commercial reprojection algorithm software.

Original languageEnglish (US)
Pages (from-to)2417-2439
Number of pages23
JournalPhysics in medicine and biology
Issue number8
StatePublished - 2000
Externally publishedYes

ASJC Scopus subject areas

  • Radiological and Ultrasound Technology
  • Radiology Nuclear Medicine and imaging


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