Relaxation effects of clustered particles

Akihiro Tanimoto, Koichi Oshio, Makoto Suematsu, Daniel Pouliquen, David D. Stark

Research output: Contribution to journalArticlepeer-review

107 Citations (Scopus)


Relations between spatial distribution of superparamagnetic iron oxide (SPIO) particles and the image contrast caused by SPIO were investigated. Actual clustering pattern of particles was measured in the liver and spleen of animals using intravital laser confocal microscopy. SPIO-doped phantoms with and without Sephadex beads were made to simulate these patterns, and relaxation parameters were measured using a 1.5-T clinical scanner. Finally, these results were compared to clinical image data using SPIO particulate agent. Intravital microscopy indicated that the clustering of latex beads was more predominant in hepatic Kupffer cells than in splenic macrophages (P < 0.001). Phantoms without Sephadex beads showed an approximately linear increase of 1/T1 (R1), 1/T2 (R2) and 1/T2* (R2*) values with increasing SPIO concentration. However, with Sephadex beads, R1 and R2 showed little change with increasing SPIO concentration, while R2* showed the same linear increase with SPIO. Also, the R2* values were higher with Sephadex beads. These results were consistent with the clinical imaging data, where signal reduction was significantly smaller in the spleen (-0.4% ± 27.4%) than in the liver (50.4% ± 16.8%, P < 0.00001) on T2*-weighted images, but the reduction in the spleen (47.2% ± 16.1%) was equivalent to the liver (38.8% ± 26.0%) on T2-weighted images.

Original languageEnglish
Pages (from-to)72-77
Number of pages6
JournalJournal of Magnetic Resonance Imaging
Issue number1
Publication statusPublished - 2001 Jul 10


  • Agar
  • Contrast media
  • Iron
  • Liver
  • Magnetic resonance imaging
  • Phantoms
  • Sephadex
  • Spleen

ASJC Scopus subject areas

  • Radiology Nuclear Medicine and imaging


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