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Quantitative cerebral water content mapping

Water content information in potentially present in any proton MR image due to the fact the magnetisation M0 induced by the main magnetic field is – by virtue of Curie’s law – proportional to the proton density (PD). However, in practice, estimating M0 necessitates a number of corrections to suppress the influence of the relaxation times T1 and T2 and to ensure that static field or RF field inhomogeneity does not bias the estimation. Two sequences where investigated for water content mapping, namely the TAPIR sequence, originally created to produce maps of the T1 relaxation time, and the QUTE sequence, designed to estimated the T2* relaxation time. The QUTE sequence, is also known today as mutli-echo gradient echo (GRE) and is provided by the manufacturer of the scanner. Those two approaches give rise to four water content protocols

  • The TAPIR water content mapping protocol
  • The M0-weighted 2D-GRE protocol
  • The T1-weigthed 2D-GRE protocol
  • The 3D-GRE protocol

The TAPIR, the M0-w. 2D-GRE and the T1-w. 2D-GRE protocols provide water content maps with an in-plane resolution of 1 mm and a slice thickness of 2 mm whereas the 3D-GRE protocol was verified to up to 1 mm isotropic resolution. However, the 3D-GRE protocol does not offer today the same accuracy as the 2D-protocols. The TAPIR protocol is well suited for high in-plane resolution (e.g., 0.7 mm) when partial brain coverage is acceptable. The 2D-GRE protocol offers the best alternative for rapid whole brain water content imaging.

Design of quantitative water content MRI protocols for 3 Tesla

Sequence Diagram of the TAPIR Sequence

Additional Information

Contact Person

Prof. N. J. Shah, PhD

Zaheer Abbas, Dipl.-Phys.

Yun Gu, MSc

Ana-Maria Oros-Peusquens, PhD