Non-rigid MR-CT Image Registration

NON-RIGID MR-CT IMAGE REGISTRATION: This tutorial demonstrates how to perform MR-CT and CT-CT non-rigid registrations. In a CT-guided cryoablation of a liver tumor, we can see the tumor on the preoperative MRI but not on the intra-operative CT image (only cryoprobes visible). The non-rigid registration is used for image fusion to better visualize tumor margins and location, as shown in this figure.

PROCESS OF IMAGE REGISTRATION IN CRYOABLATION OF LIVER CASE: Registration process between MR and CT images in cryoablation of a liver case is shown. (1) A transformation matrix T1 was used to deform the pre-procedure contrast enhanced MR image on to the planning CT image. (2) T2 was used to deform the planning CT image onto the intra procedure CT image with cryoprobes. (3) The matrix T2 was combined with T1 to deform the MR image onto the CT image with cryoprobe.

Non-rigid MR-CT Image Registration Tutorial

Overview

This tutorial demonstrates how to perform a pre-operated contrast enhanced MR image to intra-procedure CT image non-rigid registration. The case study is CT-guided liver tumor cryoablation.

Clinical significants

• Non-rigid registrations desirable to compensate for liver deformation caused by patient positioning, respiratory motion, and interventional manipulation.
• A multi-modality non-rigid registration method can enhance visualization of tumor margins and location during the planning, targeting, and monitoring phases of CT imaging-guided cryoablation procedure.

Tutorial Topics / Targets

• Slicer Modules Used:
  • N41ITKBiasField Correction
  • Editor
  • BRAINSFitIGT Registration
• Image Processing Tasks Performed:
  • Intensity non-uniformly correction
  • Mask generation / segmentation
  • Inter-modality non-rigid image registration
• Image Data Used:
  • Pre-operative abdominal MR with surface coil, showing liver
  • Planning and Intra-operative CT with cryo-probe

In this tutorial, the three steps are performed as shown the figure on right side.

• (1) In the image registration between MR image and planning CT image, we can obtain the moved and deformed MR image and the Bspline transformation matrix T1 by using pre-procedure contrast enhanced MRI and mask image.
• (2) In the image registration between plannning CT image and intra-procedure CT image, we can obtain the moved and deformed planning CT image and the Bspline transformation matrix T2.
• (3) In the image registration between MR image and intra-procedure CT image, we can obtain the moved and deformed MR image by using T1 and T2 BSpline transformation matrices.

For non-rigid registration, BRAINSFitIGT and BRAINSResamle modules are used. In this tutorial, we will show that 3D Slicer with BRAINSFitIGT module allows performing non-rigid image registration and BRAINSResample module allows performing non-rigid image deformation using Bspline transform matrix. We also shows the non-rigid registration method can enhance visualization of tumor margins and location during the planning, targeting, and monitoring phases of CT imaging-guided cryoablation procedure.

Tutorials

Non-rigid MR-CT Image Registration Module tutorial : to perform MR-CT and CT-CT image registration ‏ [ppt]‏ [pdf]

Tutorial materials

Material data:

• Non-rigid_MR_CT_Image_RegistrationTutorialData_TutorialContestSummer2011.tar.gz

People

Atsushi Yamada, Ph.D. (Research Associate, Brigham and Women's Hospital and Harvard Medical School)
Dominik S. Meier, Ph.D. (Assistant Professor, Brigham and Women's Hospital and Harvard Medical School)
Nobuhiko Hata, Ph.D. (Associate Professor, Brigham and Women's Hospital and Harvard Medical School)