Region-Based Partial Volume Correction Techniques for PET Imaging: Sinogram Implementation and Robustness

Mike Sattarivand,Ian Poon,Curtis Caldwell,Gregory M Szilagyi,Maggie Kusano,Jennifer Armstrong

doi:10.1155/2013/435959

Abstract

Background/Purpose. Limited spatial resolution of positron emission tomography (PET) requires partial volume correction (PVC). Region-based PVC methods are based on geometric transfer matrix implemented either in image-space (GTM) or sinogram-space (GTMo), both with similar performance. Although GTMo is slower, it more closely simulates the 3D PET image acquisition, accounts for local variations of point spread function, and can be implemented for iterative reconstructions. A recent image-based symmetric GTM (sGTM) has shown improvement in noise characteristics and robustness to misregistration over GTM. This study implements the sGTM method in sinogram space (sGTMo), validates it, and evaluates its performance. Methods. Two 3D sphere and brain digital phantoms and a physical sphere phantom were used. All four region-based PVC methods (GTM, GTMo, sGTM, and sGTMo) were implemented and their performance was evaluated. Results. All four PVC methods had similar accuracies. Both noise propagation and robustness of the sGTMo method were similar to those of sGTM method while they were better than those of GTMo method especially for smaller objects. Conclusion. The sGTMo was implemented and validated. The performance of the sGTMo in terms of noise characteristics and robustness to misregistration is similar to that of the sGTM method and improved compared to the GTMo method.

Highlights

In spite of continuous improvement in the instrumentation of positron emission tomography (PET), its spatial resolution still remains relatively low compared to anatomical imaging modalities such as magnetic resonance (MR) or computed tomography (CT)
The corrected recovery coefficient (RC) for all brain and sphere VOIs and for all four partial volume correction (PVC) methods were within 5% of the ideal value
The only exceptions were for the smallest sphere size (5 mm diameter) for 2 PVC methods (GTM and symmetric geometric transfer matrix (GTM) (sGTM)) of the physical sphere phantom, accuracy within 10% was still obtained even for this small object size

Summary

Introduction

In spite of continuous improvement in the instrumentation of positron emission tomography (PET), its spatial resolution still remains relatively low compared to anatomical imaging modalities such as magnetic resonance (MR) or computed tomography (CT). The first is the point response effect, which causes spillover between different regions This effect can be accounted for with a knowledge of the three-dimensional (3D) PET image formation processes or a measurement of the global PET point spread function (PSF). In order to perform the 3D forward projection and 3D reconstruction needed to implement the PVC methods in sinogram-space, routines from STIR release 2 [28] were used. These tasks require knowledge of the 3D PET detector geometry and STIR contains this information for a number of commercially available PET scanners including the Philips Allegro scanner used in this study. The measured sinogram data from the physical phantom scan needed to be corrected for detector gaps in the Philips Allegro scanner prior to reconstruction

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Discussion

Conclusion