Computerized method for nonrigid MR-to-PET breast-image registration

Abstract

Keywords:MR-to-PET nonrigid breast-image registration FEM-based soft tissue multimodality nonrigid image registration a b s t r a c tWe have developed and tested a new simple computerized finite element method (FEM) approach to MR-to-PET nonrigid breast-image registration. The method requires five-nine fiducial skin markers (FSMs) visible in MRI and PET that need to be located in the same spots on the breast and two on the flanks during both scans. Patients need to be similarly positioned prone during MRI and PET scans. This is accomplished by means of a low gamma-ray attenuation breast coil replica used as the breast support during the PET scan. We demonstrate that, under such conditions, the observed FSM displacement vectors between MR and PET images, distributed piecewise linearly over the breast volume, produce a deformed FEM mesh that reasonably approximates nonrigid deformation of the breast tissue between the MRI and PET scans. This method, which does not require a biomechanical breast tissue model, is robust and fast. Contrary to other approaches utilizing voxel intensity-based similarity measures or surface matching, our method works for matching MR with pure molecular images (i.e. PET or SPECT only). Our method does not require a good initialization and would not be trapped by local minima during registration process. All processing including FSMs detection and matching, and mesh generation can be fully automated. We tested our method on MR and PET breast images acquired for 15 subjects. The procedure yielded good quality images with an average target registration error below 4 mm (i.e. well below PET spatial resolution of 6-7 mm). Based on the results obtained for 15 subjects studied to date, we conclude that this is a very fast and a well-performing method for MR-to-PET breast-image nonrigid registration. Therefore, it is a promising approach in clinical practice. This method can be easily applied to nonrigid registration of MRI or CT of any type of soft-tissue images to their molecular counterparts such as obtained using PET and SPECT.

A review of biomechanically informed breast image registration

“…• registration of prone MRI to PET (Coman et al 2004, Unlu et al 2005, Krol et al 2006 or PET/CT (Unlu et al 2010, Dmitriev et al 2013, • registration of prone MRI to supine MRI (Carter et al 2008, Eiben et al 2013, Han et al 2014, • registration of prone MRI to supine surgical surface/depth data (Carter et al 2008, Lago et al 2012, • MRI to x-ray registration (Ruiter 2003, Ruiter et al 2006, Mertzanidou et al 2011, Hopp et al 2013a, Lee et al 2013, Mertzanidou et al 2014, Solves-Llorens et al 2014, and • registration of ultrasound CT and x-ray mammography (Hopp et al 2010, Hopp et al 2013b.…”

“…The authors highlight that no biomechanical model is required for this kind of registration. Subsequent work from this group (Unlu et al 2010) proposed an optional extension by incorporating the CT images from combined PET/CT acquisitions, if these are available. The CT image is in this case used to perform additional iterative surface matching between the MRI and the CT.…”

Identification of breast contour for nipple segmentation in breast magnetic resonance images

“…Furthermore, motion artifacts often appear above the cleavage section because an examinee might produce motion or muscle relaxation during the acquisition of the breast MR image. 26 Motion artifacts that exist between the left and right breasts increase the difficulty of their identification. Owing to the anatomical structure, it is necessary to remove the cleavage and the resulting motion artifacts above the cleavage.…”

Deformable mapping technique to correlate lesions in digital breast tomosynthesis and automated breast ultrasound images

“…In two studies of MRI/PET breast registration, ink was used to mark locations on the breast (up to nine in total). MRI visible markers were placed at those locations prior to MR imaging, and PET‐visible markers were placed at the same locations prior to PET imaging . In a study of registration between compressed and uncompressed prone MRI, four external markers were placed around the breast and on the nipple .…”