Comparison of two quantitative proton density mapping methods in multiple sclerosis

René Maxime Gracien*, Sarah C. Reitz, Marlies Wagner, Christoph Mayer, Steffen Volz, Stephanie Michelle Hof, Vinzenz Fleischer, Amgad Droby, Helmuth Steinmetz, Sergiu Groppa, Elke Hattingen, Johannes C. Klein, Ralf Deichmann

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review


Objective: Proton density (PD) mapping requires correction for the receive profile (RP), which is frequently performed via bias-field correction. An alternative RP-mapping method utilizes a comparison of uncorrected PD-maps and a value ρ(T1) directly derived from T1-maps via the Fatouros equation. This may be problematic in multiple sclerosis (MS), if respective parameters are only valid for healthy brain tissue. We aimed to investigate whether the alternative method yields correct PD values in MS patients. Materials/methods: PD mapping was performed on 27 patients with relapsing-remitting MS and 27 healthy controls, utilizing both methods, yielding reference PD values (PDref, bias-field method) and PDalt (alternative method). Results: PDalt-values closely matched PDref, both for patients and controls. In contrast, ρ(T1) differed by up to 3 % from PDref, and the voxel-wise correlation between PDref and ρ(T1) was reduced in a patient subgroup with a higher degree of disability. Still, discrepancies between ρ(T1) and PDref were almost identical across different tissue types, thus translating into a scaling factor, which cancelled out during normalization to 100 % in CSF, yielding a good agreement between PDalt and PDref. Conclusion: RP correction utilizing the auxiliary parameter ρ(T1) derived via the Fatouros equation provides accurate PD results in MS patients, in spite of discrepancies between ρ(T1) and actual PD values.

Original languageEnglish
Pages (from-to)75-83
Number of pages9
JournalMagnetic Resonance Materials in Physics, Biology, and Medicine
Issue number1
StatePublished - 1 Feb 2017
Externally publishedYes


  • Fatouros equation
  • Proton density
  • Quantitative MRI
  • Relapsing-remitting multiple sclerosis


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