Theoretical and experimental evaluation of phase-dispersion effects caused by brain motion in diffusion and perfusion MR imaging

Summary, in English

We investigated intravoxel phase dispersion caused by pulsatile brain motion in diffusion spin-echo pulse sequences. Mathematical models were used to describe the spatial and temporal velocity distributions of human brain motion. The spatial distribution of brain-tissue velocity introduces a phase spread over one voxel, leading to signal loss. This signal loss was estimated theoretically, and effects on observed diffusion coefficient and perfused capillary fraction were assessed. When parameters from a diffusion pulse sequence without motion compensation were used, and ECG triggering with inappropriate delay times was assumed, the maximal signal loss caused by brain-motion-induced phase dispersion was predicted to be 21%. This corresponds to a 95% overestimation of the diffusion coefficient, and the perfusion-fraction error was small. Corresponding calculations for motion-compensated pulse sequences predicted a 1% to 1.5% signal loss due to undesired phase dispersion, whereas experimental results indicated a signal loss related to brain motion of 4%.

• Författare: Ronnie Wirestam; Dan Greitz; Carsten Thomsen; Sara Brockstedt; Magnus B. E. Olsson; Freddy Ståhlberg
• Avdelning/ar: Medicinsk strålningsfysik, Lund; Diagnostisk radiologi, Lund
• Publiceringsår: 1996
• Språk: Engelska
• Sidor: 348-355
• Publikation/Tidskrift/Serie: Journal of Magnetic Resonance Imaging
• Volym: 6
• Issue: 2
• Länkar: http://dx.doi.org/10.1002/jmri.1880060215
• Dokumenttyp: Artikel i tidskrift
• Förlag: John Wiley & Sons Inc.
• Ämne: Radiology, Nuclear Medicine and Medical Imaging
• Nyckelord: Magnetic resonance; MR imaging; Diffusion; Brain motion; Phase dispersion; Perfusion
• Aktiv: Published
• ISBN/ISSN/Övrigt: ISSN: 1522-2586