Liver 4DMRI: A retrospective image-based sorting method

Chiara Paganelli, Paul Summers, Massimo Bellomi, Guido Baroni, Marco Riboldi

Research output: Contribution to journalArticlepeer-review


Purpose: Four-dimensional magnetic resonance imaging (4DMRI) is an emerging technique in radiotherapy treatment planning for organ motion quantification. In this paper, the authors present a novel 4DMRI retrospective image-based sorting method, providing reduced motion artifacts than using a standard monodimensional external respiratory surrogate. Methods: Serial interleaved 2D multislice MRI data were acquired from 24 liver cases (6 volunteers + 18 patients) to test the proposed 4DMRI sorting. Image similarity based on mutual information was applied to automatically identify a stable reference phase and sort the image sequence retrospectively, without the use of additional image or surrogate data to describe breathing motion. Results: The image-based 4DMRI provided a smoother liver profile than that obtained from standard resorting based on an external surrogate. Reduced motion artifacts were observed in image-based 4DMRI datasets with a fitting error of the liver profile measuring 1.2±0.9 mm (median ± interquartile range) vs 2.1±1.7 mm of the standard method. Conclusions: The authors present a novel methodology to derive a patient-specific 4DMRI model to describe organ motion due to breathing, with improved image quality in 4D reconstruction.

Original languageEnglish
Pages (from-to)4814-4821
Number of pages8
JournalMedical Physics
Issue number8
Publication statusPublished - Aug 1 2015


  • 4DMRI
  • radiotherapy
  • retrospective sorting
  • time-resolved imaging
  • treatment planning

ASJC Scopus subject areas

  • Biophysics
  • Radiology Nuclear Medicine and imaging


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