The impact of data selection and fitting on SAR estimation for magnetic nanoparticle heating

Hattie L Ring, Anirudh Sharma, Robert Ivkov, John C. Bischof

Research output: Contribution to journalArticlepeer-review

17 Scopus citations


Background: Magnetic fluid heating has great potential in the fields of thermal medicine and cryopreservation. However, variations among experimental parameters, analysis methods and experimental uncertainty make quantitative comparisons of results among laboratories difficult. Herein, we focus on the impact of calculating the specific absorption rate (SAR) using Time-Rise and Box-Lucas fitting. Time-Rise assumes adiabatic conditions, which is experimentally unachievable, but can be reasonably assumed (quasi-adiabatic) only for specific and limited evaluation times when heat loss is negligible compared to measured heating rate. Box-Lucas, on the other hand, accounts for heat losses but requires longer heating. Methods: Through retrospective analysis of data obtained from two laboratories, we demonstrate measurement time is a critical parameter to consider when calculating SAR. Volumetric SAR were calculated using the two methods and compared across multiple iron-oxide nanoparticles. Results: We observed the lowest volumetric SAR variation from both fitting methods between 1–10 W/mL, indicating an ideal SAR range for heating measurements. Furthermore, our analysis demonstrates that poorly chosen fitting method can generate reproducible but inaccurate SAR. Conclusion: We provide recommendations to select measurement time for data analysis with either Modified Time-Rise or Box-Lucas method, and suggestions to enhance experimental precision and accuracy when conducting heating experiments.

Original languageEnglish (US)
Pages (from-to)100-107
Number of pages8
JournalInternational Journal of Hyperthermia
Issue number3
StatePublished - 2020

Bibliographical note

Publisher Copyright:
© 2021 The Author(s). Published with license by Taylor & Francis Group, LLC.


  • Magnetic iron oxide nanoparticles
  • data analysis
  • magnetic fluid hyperthermia
  • nanowarming
  • specific absorption rate calculation

Center for Magnetic Resonance Research (CMRR) tags

  • MRE


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