Optimization and assessment of quantitative 124I imaging on a Philips Gemini dual GS PET/CT system

Gregory, Rebecca; Hooker, Claire A.; Flux, Glenn

doi:10.1007/s00259-009-1099-8

Cited by 27 publications

(28 citation statements)

References 21 publications

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“…To date, the challenges of 124 I PET imaging have mainly been analyzed for clinical applications [8-10,14], and most approaches have consisted of Monte Carlo modeling of the detector [17,18]. The aim of this work was a first step to define the best experimental acquisition settings for mouse and rat phantoms for the Siemens Inveon PET system, based on the NECR figure of merit.…”

Section: Discussionmentioning

confidence: 99%

“…The easiest way to remove most of the spurious coincidences is to optimize the acquisition energy windows, and the NECR determination is the figure of merit commonly used [12,14,17,20,21]. The optimized energy window thresholds are found when the NECR reaches its maximum.…”

Section: Discussionmentioning

confidence: 99%

“…The rat and mouse phantoms were filled with 4 MBq of 124 I to determine the optimal energy window by changing the lower and upper level discriminators [LLD and ULD, respectively] [14]. For different LLD/ULD values, 1 × 10 6 prompt coincidences were recorded and NECR was calculated.…”

Section: Methodsmentioning

confidence: 99%

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dAcquisition setting optimization and quantitative imaging for 124I studies with the Inveon microPET-CT system

et al. 2012

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BackgroundNoninvasive multimodality imaging is essential for preclinical evaluation of the biodistribution and pharmacokinetics of radionuclide therapy and for monitoring tumor response. Imaging with nonstandard positron-emission tomography [PET] isotopes such as 124I is promising in that context but requires accurate activity quantification. The decay scheme of 124I implies an optimization of both acquisition settings and correction processing. The PET scanner investigated in this study was the Inveon PET/CT system dedicated to small animal imaging.MethodsThe noise equivalent count rate [NECR], the scatter fraction [SF], and the gamma-prompt fraction [GF] were used to determine the best acquisition parameters for mouse- and rat-sized phantoms filled with 124I. An image-quality phantom as specified by the National Electrical Manufacturers Association NU 4-2008 protocol was acquired and reconstructed with two-dimensional filtered back projection, 2D ordered-subset expectation maximization [2DOSEM], and 3DOSEM with maximum a posteriori [3DOSEM/MAP] algorithms, with and without attenuation correction, scatter correction, and gamma-prompt correction (weighted uniform distribution subtraction).ResultsOptimal energy windows were established for the rat phantom (390 to 550 keV) and the mouse phantom (400 to 590 keV) by combining the NECR, SF, and GF results. The coincidence time window had no significant impact regarding the NECR curve variation. Activity concentration of 124I measured in the uniform region of an image-quality phantom was underestimated by 9.9% for the 3DOSEM/MAP algorithm with attenuation and scatter corrections, and by 23% with the gamma-prompt correction. Attenuation, scatter, and gamma-prompt corrections decreased the residual signal in the cold insert.ConclusionsThe optimal energy windows were chosen with the NECR, SF, and GF evaluation. Nevertheless, an image quality and an activity quantification assessment were required to establish the most suitable reconstruction algorithm and corrections for 124I small animal imaging.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

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dAcquisition setting optimization and quantitative imaging for 124I studies with the Inveon microPET-CT system

et al. 2012

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“…Due to the specific uptake of iodine in iodine avid lesions S∶BG ratios of less than 10∶1 are very rarely observed in patients suffering from DTC. Another reason for using the specified S∶BG ratios was to provide better comparability with published data from Gregory et al [11], Jentzen et al [15], and Lubberink et al [16].…”

Section: Methodsmentioning

confidence: 99%

“…By comparing F-18, Ga-68 and I-124 differences in quantification and image quality can be better classified. In several studies PET-imaging with I-124 was studied [8], [11]–[19] comparing different parameters of I-124 PET-images with F-18, but not with Ga-68.…”

Section: Introductionmentioning

confidence: 99%

Is the Image Quality of I-124-PET Impaired by an Automatic Correction of Prompt Gammas?

et al. 2013

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ObjectivesThe aim of this study is to evaluate the quality of I-124 PET images with and without prompt gamma compensation (PGC) by comparing the recovery coefficients (RC), the signal to noise ratios (SNR) and the contrast to F-18 and Ga-68. Furthermore, the influence of the PGC on the quantification and image quality is evaluated.MethodsFor measuring the image quality the NEMA NU2-2001 PET/SPECT-Phantom was used containing 6 spheres with a diameter between 10 mm and 37 mm placed in water with different levels of background activity. Each sphere was filled with the same activity concentration measured by an independently cross-calibrated dose calibrator. The “hot” sources were acquired with a full 3D PET/CT (Biograph mCT®, Siemens Medical USA). Acquisition times were 2 min for F-18 and Ga-68, and 10 min for I-124. For reconstruction an OSEM algorithm was applied. For I-124 the images were reconstructed with and without PGC. For the calculation of the RCs the activity concentrations in each sphere were determined; in addition, the influence of the background correction was studied.ResultsThe RCs of Ga-68 are the smallest (79%). I-124 reaches similar RCs (87% with PGC, 84% without PGC) as F-18 (84%). showing that the quantification of I-124 images is similar to F-18 and slightly better than Ga-68. With background activity the contrast of the I-124 PGC images is similar to Ga-68 and F-18 scans. There was lower background activity in the I-124 images without PGC, which probably originates from an overcorrection of the scatter contribution. Consequently, the contrast without PGC was much higher than with PGC. As a consequence PGC should be used for I-124.ConclusionsFor I-124 there is only a slight influence on the quantification depending on the use of the PGC. However, there are considerable differences with respect to I-124 image quality.

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Radionuclide Therapy of Neuroendocrine Tumors

Mallia

Maccauro

Seregni

et al. 2012

Nuclear Medicine Therapy

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Optimization and assessment of quantitative 124I imaging on a Philips Gemini dual GS PET/CT system

Cited by 27 publications

References 21 publications

dAcquisition setting optimization and quantitative imaging for 124I studies with the Inveon microPET-CT system

dAcquisition setting optimization and quantitative imaging for 124I studies with the Inveon microPET-CT system

Is the Image Quality of I-124-PET Impaired by an Automatic Correction of Prompt Gammas?

Radionuclide Therapy of Neuroendocrine Tumors

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