An edge-preserving anatomical-based regularization term for the NAS-RIF restoration of spect images

Nowadays, brain 3D SPECT is a well established functional imaging method that is widely used in clinical settings for the assessment of neurological and cerebrovascular diseases. However, due to the scattering of the emitted photons, inherent to this imaging process, brain 3D SPECT images exhibit poor spatial and inter-slice resolution. More precisely, SPECT images are blurred, leading to substantial errors in measurement of regional brain activity and making difficult and subjective, a reliable and accurate diagnosis by the nuclear physician. In order to improve the resolution of these images and then to facilitate their interpretation, we herein propose an original extension of the NAS-RIF deconvolution technique of Kundur and Hatzinakos [1]. The proposed extension has two interesting properties; it allows to exploit or fuse anatomical and geometrical information extracted from a high resolution anatomical magnetic resonance (MR) image and also to efficiently incorporate, into the NAS-RIF method, a regularization term to stabilize the inverse solution. In our application, this anatomical-based regularization term exploits the result of an unsupervised Markovian segmentation obtained after a preliminary registration step between the MR and SPECT data volume coming from a same patient. This method has been successfully tested on numerous pairs of brain MR and SPECT images of different patients, yielding very promising restoration results.