Intravoxel Incoherent Motion at 7 Tesla to quantify human spinal cord perfusion: limitations and promises.

Autor: Lévy S; Aix-Marseille Univ, CNRS, CRMBM, Marseille, France.; APHM, Hopital Universitaire Timone, CEMEREM, Marseille, France.; Aix-Marseille Univ, IFSTTAR, LBA, Marseille, France.; iLab-Spine International Associated Laboratory, Marseille-Montreal, France-Canada., Rapacchi S; Aix-Marseille Univ, CNRS, CRMBM, Marseille, France.; APHM, Hopital Universitaire Timone, CEMEREM, Marseille, France., Massire A; Aix-Marseille Univ, CNRS, CRMBM, Marseille, France.; APHM, Hopital Universitaire Timone, CEMEREM, Marseille, France.; iLab-Spine International Associated Laboratory, Marseille-Montreal, France-Canada., Troalen T; Siemens Healthcare SAS, Saint-Denis, France., Feiweier T; Siemens Healthcare GmbH, Erlangen, Germany., Guye M; Aix-Marseille Univ, CNRS, CRMBM, Marseille, France.; APHM, Hopital Universitaire Timone, CEMEREM, Marseille, France., Callot V; Aix-Marseille Univ, CNRS, CRMBM, Marseille, France.; APHM, Hopital Universitaire Timone, CEMEREM, Marseille, France.; iLab-Spine International Associated Laboratory, Marseille-Montreal, France-Canada.
Jazyk: angličtina
Zdroj: Magnetic resonance in medicine [Magn Reson Med] 2020 Sep; Vol. 84 (3), pp. 1198-1217. Date of Electronic Publication: 2020 Feb 14.
DOI: 10.1002/mrm.28195
Abstrakt: Purpose: To develop a noninvasive technique to map human spinal cord (SC) perfusion in vivo. More specifically, to implement an intravoxel incoherent motion (IVIM) protocol at ultrahigh field for the human SC and assess parameters estimation errors.
Methods: Monte-Carlo simulations were conducted to assess estimation errors of 2 standard IVIM fitting approaches (two-step versus one-step fit) over the range of IVIM values reported for the human brain and for typical SC diffusivities. Required signal-to-noise ratio (SNR) was inferred for estimation of the parameters product, f IVIM D* (microvascular fraction times pseudo-diffusion coefficient), within 10% error margins. In-vivo IVIM imaging of the SC was performed at 7T in 6 volunteers. An image processing pipeline is proposed to generate IVIM maps and register them for an atlas-based region-wise analysis.
Results: Required b = 0 SNRs for 10% error estimation on f IVIM D* with the one-step fit were 159 and 185 for diffusion-encoding perpendicular and parallel to the SC axis, respectively. Average in vivo b = 0 SNR within cord was 141 ± 79, corresponding to estimation errors of 12.7% and 14.7% according to numerical simulations. Slice- and group-averaging reduced noise in IVIM maps, highlighting the difference in perfusion between gray and white matter. Mean ± standard deviation f IVIM and D* values across subjects within gray (respectively white) matter were 16.0 ± 1.7 (15.0 ± 1.6)% and 11.4 ± 2.9 (11.5 ± 2.4) × 10 -3 mm 2 /s.
Conclusion: Single-subject data SNR at 7T was insufficient for reliable perfusion estimation. However, atlas-averaged IVIM maps highlighted the higher microvascular fraction of gray matter compared to white matter, providing first results of healthy human SC perfusion mapping with MRI.
(© 2020 International Society for Magnetic Resonance in Medicine.)
Databáze: MEDLINE
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