Correction for scatter in 3D brain PET using a dual energy window method

Grootoonk, S.; Spinks, T.J.; Sashin, Donald; Spyrou, N. M.; Jones, Terry

doi:10.1088/0031-9155/41/12/013

Cited by 113 publications

(66 citation statements)

References 22 publications

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“…For conventional PET systems, a scatter sinogram can be estimated using the convolution method [4], the hardware dual energy windows method [8], the Monte Carlo simulation method [9], and analytical methods [10,11]. Among these methods, the Monte Carlo simulation can model multiple scatters and various effects in the photon detection process.…”

Section: Estimate Mean Scatter Sinogram Using Monte Carlo Simulationmentioning

confidence: 99%

Scatter correction for positron emission mammography

Huesman

2002

Phys. Med. Biol.

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Abstract. In this paper we present a scatter correction method for a regularized list mode maximum likelihood reconstruction algorithm for the positron emission mammograph (PEM) that is being developed at our laboratory. The scatter events inside the object are modeled as additive Poisson random variables in the forward model of the reconstruction algorithm. The mean scatter sinogram is estimated using a Monte Carlo simulation program. With the assumption that the background activity is nearly uniform, the Monte Carlo scatter simulation only needs to run once for each PEM configuration. This saves computational time. The crystal scatters are modeled as a shift-invariant blurring in image domain because they are more localized. Thus, the useful information in the crystal scatters can be deconvolved in high-resolution reconstructions. The propagation of the noise from the estimated scatter sinogram into the reconstruction is analyzed theoretically. The results provide an easy way to calculate the required number of events in the Monte Carlo scatter simulation for a given noise level in the image. The analysis is also applicable to other scatter estimation methods, provided that the covariance of the estimated scatter sinogram is available.

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Section: Estimate Mean Scatter Sinogram Using Monte Carlo Simulationmentioning

confidence: 99%

Scatter correction for positron emission mammography

Huesman

2002

Phys. Med. Biol.

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“…PET scans were performed on an ECAT 953B PET camera (CTI/Siemens, Knoxville, TN, USA) (Spinks et al 1992) in three-dimensional mode with dual window scatter correction (Grootoonk et al 1996). [ 11 C]WAY-100635 was prepared at the Cyclotron Unit by 11 C-carboxylation of a Grignard reagent .…”

Section: Pet Scan Acquisitionmentioning

confidence: 99%

β-blocker Binding to Human 5-HT1A Receptors in vivo and in vitro Implications for Antidepressant Therapy

Rabiner

2000

Neuropsychopharmacology

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A novel strategy for improving the treatment of depressive illness is augmentation of antidepressants with a 5-HT1SSRIs are increasingly used in the pharmacological treatment of depression. SSRIs specifically block 5-HT reuptake sites leading to an eventual increase of 5-HT in terminal synapses; an effect considered to be an important component of antidepressant action ). SSRIs are better tolerated than less selective agents such as tricyclic antidepressants (TCAs) (Anderson 1997), however, their efficacy is no greater (Rudorfer and Potter 1989) ( ≅ 70% of patients respond), and at least 2-3 weeks of treatment is required for the appearance of meaningful therapeutic response (Paykel and Priest 1992).Preclinical studies suggest the inhibition of 5-HT reuptake by SSRIs, does not lead to increased 5-HT levels in terminal synapses until an adaptive desensitization of inhibitory 5-HT 1A autoreceptors has occurred (Blier et al. NO . 3 1990;Chaput et al. 1986;Chaput et al. 1991;de Montigny et al. 1990;Hjorth and Auerbach 1994). These autoreceptors, located on 5-HT neuronal cell bodies in the raphe nuclei, inhibit 5-HT neurone firing, and hence 5-HT release in terminal synapses (VanderMaelen et al. 1986;Adell and Artigas 1991;Invernizzi et al. 1992;Sharp et al. 1989). Thus, indirect 5-HT 1A autoreceptor activation by SSRIs (via elevated 5-HT in the raphe nuclei) may impair the drug's therapeutic efficacy until desensitization has occurred. Theoretically, co-administration of 5-HT 1A autoreceptor antagonists (blocking the tonic inhibitory effect of 5-HT on the autoreceptor), together with SSRIs, may decrease the time needed to achieve clinical benefit and lead to a greater therapeutic effect (Hjorth 1993; Artigas 1993). In the absence of selective 5-HT 1A receptor antagonists for human use, therapeutic trials have been conducted with pindolol, a ␤ -blocker with nanomolar affinity for the human 5-HT 1A receptor in transfected cells in culture (Newman-Tancredi et al. 1998). Controlled clinical trials have produced mixed results. Four studies demonstrated a beneficial effect of pindolol augmentation of SSRI treatment (Zanardi et al. 1997;Perez et al. 1997;Bordet et al. 1998;Maes et al. 1996), one study showed a mixed response (Tome et al. 1997), while three studies failed to demonstrate any antidepressant benefit (Moreno et al. 1997;Berman et al. 1997;Perez et al. 1999).The equivocal results of clinical studies raise several questions about pindolol's proposed mechanism of action. Firstly it is not clear whether the dose of pindolol used clinically (typically 2.5 mg thrice daily (tds)), achieves a significant occupancy of 5-HT 1A receptors in the living human brain. Secondly, emergent evidence from preclinical studies indicates that pindolol, unlike certain other ␤ -blockers, may have 5-HT 1A partial agonist properties (Hjorth and Carlsson 1986;Newman-Tancredi et al. 1998;Clifford et al. 1998;Gartside et al. 1999). Partial agonism could lead to an activation of 5-HT 1A autoreceptors with subsequent decrease in 5-HT rele...

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“…The development of the 3D acquisition mode in PET and improvements in the detector energy resolution have allowed the implementation of scatter correction based on the analysis of energy spectra. Several groups have investigated the potential of acquiring data in two [3,4], three [5] and multiple [23] energy windows to develop corrections for scattering in 3D PET. The DEW algorithm used in this work is based on an implementation by the MRC PET methodology group at Hammersmith Hospital (UK) on the ECAT 953B scanner [4].…”

Section: The Dual-energy Window Methods (Dew)mentioning

confidence: 99%

“…For the 3D Hoffman brain phantom, the activity recovery coefficients, defined as the percentage ratio of events in an ROI in the corrected images to events in the same ROI in the ideal images, were calculated according to: (4) where N ROI is the count density in the ROI. Figure 3 illustrates the clinical cerebral study, showing a representative slice of the original reconstructed radioactivity distribution and segmented transmission image together with the corresponding reconstructed image of the Monte Carlo simulated data and the normalised difference between the original and the Monte Carlo reconstructed image.…”

Section: Comparative Assessmentmentioning

confidence: 99%

“…Increasingly sophisticated scatter correction procedures are under investigation, particularly those based on accurate scatter models and iterative reconstruction-based scatter compensation approaches. Most of the methods proposed so far attempt to estimate the scatter contamination and then remove it using either subtraction [3,4,5] or convolution/deconvolution techniques [6,7,8,9]. An alternative to these methods would be to estimate the scatter component directly from the emission and transmission data [10,11].…”

Section: Introductionmentioning

confidence: 99%

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Comparative evaluation of scatter correction techniques in 3D positron emission tomography

Zaidi

2000

Eur J Nucl Med

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Abstract. Much research and development has been concentrated on the scatter compensation required for quantitative 3D positron emission tomography (PET). Increasingly sophisticated scatter correction procedures are under investigation, particularly those based on accurate scatter models and iterative reconstruction-based scatter compensation approaches. The main difference among the correction methods is the way in which the scatter component in the selected energy window is estimated. Monte Carlo methods provide further insight and might in themselves offer a possible correction procedure. Five scatter correction methods were compared in this study where applicable: the dual-energy window (DEW) technique, the convolution-subtraction (CVS) method, two variants of the Monte Carlo-based scatter correction technique (MCBSC1 and MCBSC2) and our newly developed statistical reconstruction-based scatter correction (SRBSC) method. These scatter correction techniques were evaluated using Monte Carlo simulation studies, experimental phantom measurements and clinical studies. Accurate Monte Carlo modelling is still the gold standard since it allows the separation of scattered and unscattered events and comparison of the estimated and true unscattered component. In this study, our modified version of Monte Carlo-based scatter correction (MCBSC2) provided a good contrast recovery on the simulated Utah phantom, while the DEW method was found to be clearly superior for the experimental phantom studies in terms of quantitative accuracy at the expense of a significant deterioration in the signal-to-noise ratio. On the other hand, the immunity to noise in emission data of statistical reconstruction-based scatter correction methods makes them particularly applicable to low-count emission studies. All scatter correction methods gave very good activity recovery values for the simulated 3D Hoffman brain phantom, which averaged within 3%. The CVS and MCBSC1 techniques tended to overcorrect while SRBSC undercorrected for scatter in most regions of this phantom. It was concluded that all correction methods significantly improve the image quality and contrast compared to the case where no correction is applied. Generally, it was shown that the differences in the estimated scatter distributions did not have a significant impact on the final quantitative results. The DEW method showed the best compromise between ease of implementation and quantitative accuracy, but entailed a significant deterioration in the signal-to-noise ratio.

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Correction for scatter in 3D brain PET using a dual energy window method

Cited by 113 publications

References 22 publications

Scatter correction for positron emission mammography

Scatter correction for positron emission mammography

β-blocker Binding to Human 5-HT1A Receptors in vivo and in vitro Implications for Antidepressant Therapy

Comparative evaluation of scatter correction techniques in 3D positron emission tomography

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