Information regarding the R.I.R.E project


Details on MP-RAGE

MP-RAGE (Magnetization Prepared RApid Gradient Echo) is a rapid gradient-echo technique in which a preparation pulse (or pulses) is applied before the acquisition sequence to enhance contrast. [John P. Mugler III and James R. Brookeman, “Three-Dimensional Magnetization-Prepared Rapid Gradient-Echo Imaging (3D MP RAGE)�?, Magnetic Resonance in Medicine 15, pp. 152--157 (1990)]

In our sequence a single inversion pulse is followed by a 400 ms delay time. As a result our MP-RAGE images are T1-weighted. The excitation pulse has a 10 degree flip angle, TE is 4 ms, and TR is 10 ms. The resolution is 128 x 256 x 256.

The corresponding dimensions are approximately 160 mm by 250 mm by 250 mm. (The precise voxel dimensions for each volume are, as always, included in the corresponding header.ascii file). There is one acquisition. Total acquisition time is 8 minutes and 55 seconds.

Converting to our coordinate system

The recipe is as follows for CT-to-MR transformations:

- T_ct = translation that brings our CT coordinate system into your CT coordinate system
- T_mr = translation that brings our MR coordinate system into your MR coordinate system
- R_ctmr = transformation that registers CT to MR in your coordinate systems

To transform for a point measured in our CT coordinate system into its registered position, measured in our MR coordinate system:

1) Apply T_ct to .
2) Apply R_ctmr to the result of step 1.
3) Apply the inverse of T_mr (n.b., NOT the inverse of T_ct) to the result of step 2.

Sample acknowledgments

The images and the standard transformation(s) were provided as part of the project,

“Retrospective Image Registration Evaluation�?,
National Institutes of Health,
Project Number 8R01EB002124-03,
Principal Investigator, J. Michael Fitzpatrick,
Vanderbilt University, Nashville, TN.