Multimodal image fusion applied to body extremities: an overview on CBCT-MRI fusion

The existing medical imaging modalities could lead physicians to incomplete or incorrect diagnosis because each technology, taken alone, cannot give a complete picture of the investigated area. The multimodal image fusion has increasingly become a very helpful tool for increasing diagnosis reliability, which consists in creating a single merged image synthesizing information extracted from two or more different imaging modalities. In this work, upper and lower body extremities multimodal imaging topic is examined, with the aim of reducing equivocal interpretations of abnormal bone conditions due to trauma, inflammation, infection, degeneration or tumor. In literature, Cone Beam Computed Tomography (CBCT) images are often combined with nuclear medicine images, with the aim of associating metabolic functionality with corresponding anatomical structures. A less common application is CBCT and Magnetic Resonance Imaging (MRI) image fusion, especially in body extremities study. This work has the aim to study the advantages of CBCT-MRI fusion, as compared to single modalities. Several methods of image co-registration are analyzed, evaluating both rigid and non-rigid transformation of investigated volumes. A suitable similarity method to be optimized must be chosen according to images contents and likeness.