Validation of volume-preserving non-rigid registration: Application to contrast-Enhanced MR-mammography

Initial validation studies have been conducted to compare the single- and multi-level registration strategies [9] and to assess the usefulness of a volume-preservation constraint [10].

METHOD

Three images pairs, where no motion was visible between pre- and post-contrast image, were selected from a large database. For each patient, four deformations were generated and target registration errors were determined as described in [7].

RESULTS

(a) (b)
(c) (d) Figure 1: Target registration error (TRE) after simulation, rigid registration and multi-resolution non-rigid registration with control point spacing of 20mm, 20mm->10mm and 20mm->10mm->5mm. TRE was evaluated over (a,b) the whole breast tissue and (c,d) the region of the enhancing lesion for (a,c) the unconstrained non-rigid registration and (b,d) the volume-preserving non-rigid registration. The graph shows the mean and standard deviation of TRE for three patients and four deformations. (from [10])

CONCLUSIONS

We found that the volume preserving non-rigid registration was more accurate than the unconstrained method. Severe local deformations were better compensated by finer control point spacing. However, the contrast enhancing lesions were more accurately aligned at a control point spacing of 20mm.

References:

[10] C. Tanner, J. A. Schnabel, A. Degenhard, A. D. Castellano-Smith, C. Hayes, M. O. Leach, D. R. Hose, D. L. G. Hill, D. J. Hawkes. Validation of volume-preserving non-rigid registration: Application to contrast-Enhanced MR-mammography. In Proc. Medical Image Computing and Computer-Assisted Interventions (MICCAI 2002), Tokyo, Japan, September 2002, vol. 2489 of Lecture Notes in Computer Science, pp. 307-314, Springer Verlag, 2002.

[9] J. A. Schnabel, C. Tanner, A. D. Castellano-Smith, A. Degenhard, C. Hayes, M. O. Leach, D. R. Hose, D. L. G. Hill, D. J. Hawkes. Finite element based validation of non-rigid registration using single- and multi-level free-form deformations: Application to contrast-enhanced MR mammography. In M. Sonka and J. M. Fitzpatrick, editors, Proc. SPIE Medical Imaging 2002: Image Processing, San Diego, CA, pp. 550-581, 2002.

[7] J. A. Schnabel, C. Tanner, A. D. Castellano-Smith, A. Degenhard, M. O. Leach, D. R. Hose, D. L. G. Hill, D. J. Hawkes. Validation of non-rigid image registration using finite element methods: Application to breast MR images. IEEE Transactions on Medical Imaging, vol. 22(1), 2003. In press.