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Mapping of the prostate in endorectal coil‐based MRI/MRSI and CT: A deformable registration and validation study
Author(s) -
Lian J.,
Xing L.,
Hunjan S.,
Dumoulin C.,
Levin J.,
Lo A.,
Watkins R.,
Rohling K.,
Giaquinto R.,
Kim D.,
Spielman D.,
Daniel B.
Publication year - 2004
Publication title -
medical physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.473
H-Index - 180
eISSN - 2473-4209
pISSN - 0094-2405
DOI - 10.1118/1.1806292
Subject(s) - imaging phantom , fiducial marker , image registration , voxel , image quality , nuclear medicine , magnetic resonance imaging , artificial intelligence , electromagnetic coil , computer vision , medicine , computer science , radiology , physics , image (mathematics) , quantum mechanics
The endorectal coil is being increasingly used in magnetic resonance imaging (MRI) and MR spectroscopic imaging (MRSI) to obtain anatomic and metabolic images of the prostate with high signal‐to‐noise ratio (SNR). In practice, however, the use of endorectal probe inevitably distorts the prostate and other soft tissue organs, making the analysis and the use of the acquired image data in treatment planning difficult. The purpose of this work is to develop a deformable image registration algorithm to map the MRI/MRSI information obtained using an endorectal probe onto CT images and to verify the accuracy of the registration by phantom and patient studies. A mapping procedure involved using a thin plate spline (TPS) transformation was implemented to establish voxel‐to‐voxel correspondence between a reference image and a floating image with deformation. An elastic phantom with a number of implanted fiducial markers was designed for the validation of the quality of the registration. Radiographic images of the phantom were obtained before and after a series of intentionally introduced distortions. After mapping the distorted phantom to the original one, the displacements of the implanted markers were measured with respect to their ideal positions and the mean error was calculated. In patient studies, CT images of three prostate patients were acquired, followed by 3 Tesla( 3 T ) MR images with a rigid endorectal coil. Registration quality was estimated by the centroid position displacement and image coincidence index (CI). Phantom and patient studies show that TPS‐based registration has achieved significantly higher accuracy than the previously reported method based on a rigid‐body transformation and scaling. The technique should be useful to map the MR spectroscopic dataset acquired with ER probe onto the treatment planning CT dataset to guide radiotherapy planning.