Lesion quantification in oncological positron emission tomography: a maximum likelihood partial volume correction strategy.

Full Abstract

A maximum likelihood (ML) partial volume effect correction (PVEC) strategy for the quantification of uptake and volume of oncological lesions in 18F-FDG positron emission tomography is proposed. The algorithm is based on the application of ML reconstruction on volumetric regional basis functions initially defined on a smooth standard clinical image and iteratively updated in terms of their activity and volume. The volume of interest (VOI) containing a previously detected region is segmented by a k-means algorithm in three regions: A central region surrounded by a partial volume region and a spill-out region. All volume outside the VOI (background with all other structures) is handled as a unique basis function and therefore "frozen" in the reconstruction process except for a gain coefficient. The coefficients of the regional basis functions are iteratively estimated with an attenuation-weighted ordered subset expectation maximization (AWOSEM) algorithm in which a 3D, anisotropic, space variant model of point spread function (PSF) is included for resolution recovery. The reconstruction-segmentation process is iterated until convergence; at each iteration, segmentation is performed on the reconstructed image blurred by the system PSF in order to update the partial volume and spill-out regions. The developed PVEC strategy was tested on sphere phantom studies with activity contrasts of 7.5 and 4 and compared to a conventional recovery coefficient method. Improved volume and activity estimates were obtained with low computational costs, thanks to blur recovery and to a better local approximation to ML convergence.

Author information

Author/s: De Bernardi, Elisabetta (E); Faggiano, Elena (E); Zito, Felicia (F); Gerundini, Paolo (P); Baselli, Giuseppe (G);

Affiliation: Department of Bioengineering, Politecnico di Milano, Piazza Leonardo da Vinci 32, 20133 Milano, Italy. elisabetta.debernardi(-atsign-)polimi.it

Journal and publication information

Publication Type: Journal Article; Research Support, Non-U.S. Gov't

Journal: Medical physics (Med Phys), published in United States. (Language: eng)

Reference: 2009-Jul; vol 36 (issue 7) : pp 3040-9

Dates: Created 2009/08/13; Completed 2009/09/10;

PMID: 19673203, status: MEDLINE (last retrieved date: 9/10/2009)

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