TY - JOUR
T1 - Comparison of two quantitative proton density mapping methods in multiple sclerosis
AU - Gracien, René Maxime
AU - Reitz, Sarah C.
AU - Wagner, Marlies
AU - Mayer, Christoph
AU - Volz, Steffen
AU - Hof, Stephanie Michelle
AU - Fleischer, Vinzenz
AU - Droby, Amgad
AU - Steinmetz, Helmuth
AU - Groppa, Sergiu
AU - Hattingen, Elke
AU - Klein, Johannes C.
AU - Deichmann, Ralf
N1 - Publisher Copyright:
© 2016, ESMRMB.
PY - 2017/2/1
Y1 - 2017/2/1
N2 - 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.
AB - 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.
KW - Fatouros equation
KW - Proton density
KW - Quantitative MRI
KW - Relapsing-remitting multiple sclerosis
UR - http://www.scopus.com/inward/record.url?scp=84982291529&partnerID=8YFLogxK
U2 - 10.1007/s10334-016-0585-9
DO - 10.1007/s10334-016-0585-9
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C2 - 27544270
AN - SCOPUS:84982291529
SN - 0968-5243
VL - 30
SP - 75
EP - 83
JO - Magnetic Resonance Materials in Physics, Biology, and Medicine
JF - Magnetic Resonance Materials in Physics, Biology, and Medicine
IS - 1
ER -