title: Adaptive Autoregressive Model for Reduction of Noise in SPECT.
abstract: This paper presents improved autoregressive modelling (AR) to reduce noise in SPECT images. An AR filter was applied to prefilter projection images and postfilter ordered subset expectation maximisation (OSEM) reconstruction images (AR-OSEM-AR method). The performance of this method was compared with filtered back projection (FBP) preceded by Butterworth filtering (BW-FBP method) and the OSEM reconstruction method followed by Butterworth filtering (OSEM-BW method). A mathematical cylinder phantom was used for the study. It consisted of hot and cold objects. The tests were performed using three simulated SPECT datasets. Image quality was assessed by means of the percentage contrast resolution (CR%) and the full width at half maximum (FWHM) of the line spread functions of the cylinders. The BW-FBP method showed the highest CR% values and the AR-OSEM-AR method gave the lowest CR% values for cold stacks. In the analysis of hot stacks, the BW-FBP method had higher CR% values than the OSEM-BW method. The BW-FBP method exhibited the lowest FWHM values for cold stacks and the AR-OSEM-AR method for hot stacks. In conclusion, the AR-OSEM-AR method is a feasible way to remove noise from SPECT images. It has good spatial resolution for hot objects.
authors.affiliation: Division of Nuclear Medicine, Department of Diagnostic Radiology, Oulu University Hospital (OYS), P.O. Box 500, 90029 Oulu, Finland.
authors.forename: Reijo
authors.initials: R
authors.lastname: Takalo
authors.affiliation: Department of Automation Science and Engineering, Tampere University of Technology, P.O. Box 692, 33101 Tampere, Finland.
authors.forename: Heli
authors.identifier: 0000-0002-7166-9399
authors.initials: H
authors.lastname: Hytti
authors.affiliation: Department of Automation Science and Engineering, Tampere University of Technology, P.O. Box 692, 33101 Tampere, Finland.
authors.forename: Heimo
authors.initials: H
authors.lastname: Ihalainen
authors.affiliation: Joint Authority for Päijät-Häme Social and Health Care, Department of Clinical Physiology and Nuclear Medicine, Keskussairaalankatu 7, 15850 Lahti, Finland.
authors.forename: Antti
authors.identifier: 0000-0002-0520-3064
authors.initials: A
authors.lastname: Sohlberg
mesh_terms: D000465:Algorithms; D019295:Computational Biology; D006801:Humans; D007089:Image Enhancement / Q000379:methods; D007091:Image Processing, Computer-Assisted / Q000379:methods; D015233:Models, Statistical; D019047:Phantoms, Imaging; D012044:Regression Analysis; D015899:Tomography, Emission-Computed, Single-Photon / Q000706:statistics & numerical data*