Patient Weight-Based Acquisition Protocols to Optimize18F-FDG PET/CT Image Quality

Nagaki, Akio; Onoguchi, Masahisa; Matsutomo, Norikazu

doi:10.2967/jnmt.110.081661

Cited by 45 publications

(29 citation statements)

References 7 publications

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“…However, the PET image quality of overweight subjects (body mass index $ 25) is degraded because of an increase in statistical noise (29)(30)(31). To obtain sufficient image quality, adjusting the injection activity or scanning time in each patient based on body weight or body mass index (29,32,33) might be required for overweight subjects (34,35). SUV was increased as a function of patient weight based on a simulation study reported by Boellaard et al (15).…”

Section: Discussionmentioning

confidence: 99%

Influence of Statistical Fluctuation on Reproducibility and Accuracy of SUV_max and SUV_peak: A Phantom Study

Akamatsu

Ikari

Nishida

et al. 2015

J. Nucl. Med. Technol.

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Standardized uptake values (SUVs) have been widely used in the diagnosis of malignant tumors and in clinical trials of tumor therapies as semiquantitative metrics of tumor 18 F-FDG uptake. However, SUVs for small lesions are liable to errors due to partialvolume effect and statistical noise. The purpose of this study was to evaluate the reproducibility and accuracy of maximum and peak SUV (SUV max and SUV peak , respectively) of small lesions in phantom experiments. Methods: We used a body phantom with 6 spheres in a quarter warm background. The PET data were acquired for 1,800 s in list-mode, from which data were extracted to generate 15 PET images for each of the 60-, 90-, 120-, 150-, and 180-s scanning times. The SUV max and SUV peak of the hot spheres in the 1,800-s scan were used as a reference (SUV ref,max and SUV ref,peak ). Coefficients of variation for both SUV max and SUV peak in hot spheres (CV max and CV peak ) were calculated to evaluate the variability of the SUVs. On the other hand, percentage differences between SUV max and SUV ref,max and between SUV peak and SUV ref,peak were calculated for evaluation of the accuracy of SUV. We additionally examined the coefficients of variation of background activity and the percentage background variability as parameters for the physical assessment of image quality. Results: Visibility of a 10-mm-diameter hot sphere was considerably different among scan frames. The CV max and CV peak increased as the sphere size became smaller and as the acquisition time became shorter. SUV max was generally overestimated as the scan time shortened and the sphere size increased. The SUV max and SUV peak of a 37-mm-diameter sphere for 60-s scans had average positive biases of 28.3% and 4.4%, compared with the reference. Conclusion: SUV max was variable and overestimated as the scan time decreased and the sphere size increased. In contrast, SUV peak was a more robust and accurate metric than SUV max . The measurements of SUV peak (or SUV peak normalized to lean body mass) in addition to SUV max are desirable for reproducible and accurate quantification in clinical situations.

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Section: Discussionmentioning

confidence: 99%

Influence of Statistical Fluctuation on Reproducibility and Accuracy of SUV_max and SUV_peak: A Phantom Study

Akamatsu

Ikari

Nishida

et al. 2015

J. Nucl. Med. Technol.

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“…NEC has been widely used as an index to evaluate the quality of the acquired PET data (29). NEC is known to be directly proportional to the SNR of the acquired data and to depend on the injected dose and patients' BMI (30,31).…”

Section: Discussionmentioning

confidence: 99%

Improvement in PET/CT Image Quality with a Combination of Point-Spread Function and Time-of-Flight in Relation to Reconstruction Parameters

et al. 2012

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The aim of this study was to investigate the effects of the pointspread function (PSF) and time-of-flight (TOF) on improving 18 F-FDG PET/CT images in relation to reconstruction parameters and noise-equivalent counts (NEC). Methods: This study consisted of a phantom study and a retrospective analysis of 39 consecutive patients who underwent clinical 18 F-FDG PET/CT. The body phantom of the National Electrical Manufacturers Association and International Electrotechnical Commission with a 10-mm-diameter sphere was filled with an 18 F-FDG solution with a 4:1 radioactivity ratio compared with the background. The PET data were reconstructed with the baseline orderedsubsets expectation maximization (OSEM) algorithm, with the OSEM1PSF model, with the OSEM1TOF model, and with the OSEM1PSF1TOF model. We evaluated image quality by visual assessment, the signal-to-noise ratio of the 10-mm sphere (SNR 10 mm ), the contrast of the 10-mm sphere, and the coefficient of variance in the phantom study and then determined the optimal reconstruction parameters. We also examined the effects of PSF and TOF on the quality of clinical images using the signal-to-noise ratio in the liver (SNR liver ) in relation to the NEC in the liver (NEC liver ). Results: In the phantom study, the SNR 10 mm was the highest for the OSEM1PSF1TOF model, and the highest value was obtained at iteration 2 for algorithms with the TOF and at iteration 3 for those without the TOF. In terms of a postsmoothing filter full width at half maximum (FWHM), the high SNR 10 mm was obtained with no filtering or was smaller than 2 mm for algorithms with PSF and was 4-6 mm for those without PSF. The balance between the contrast recovery and noise is different for algorithms with either PSF or TOF. A combination of PSF and TOF improved SNR 10 mm , contrast, and coefficient of variance, especially with a small-FWHM gaussian filter. In the clinical study, the SNR liver of the low-NEC liver group in the OSEM1PSF1TOF model was compared with that of the high-NEC liver group in conventional OSEM. The PSF1TOF improved the SNR liver by about 24.9% 6 9.81%. Conclusion: A combination of PSF and TOF clearly improves image quality, whereas optimization of the reconstruction parameters is necessary to obtain the best performance for PSF or TOF. Furthermore, this combination has the potential to provide good image quality with either lower activity or shorter acquisition time, thus improving patient comfort and reducing the radiation burden. PET/ CT with 18 F-FDG is useful for the detection and staging of various malignant tumors, monitoring of their response to therapy, and prognostic stratification (1-6). High image quality is required for an accurate diagnosis, although the spatial resolution of PET is relatively low in comparison to other imaging modalities (7). Recently, the information provided by the point-spread function (PSF) and time-of-flight (TOF) has been expected to improve the spatial resolution and signal-to-noise ratio (SNR), respectively, of PET images (8-10).A PET sca...

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“…This number of true counts is about 1−3 orders of magnitude smaller than in standard nuclear medicine imaging with injected radiotracers. 16 The number of random coincidences is found to be almost constant, as predominantly attributed to the intrinsic lutetium-oxyorthosilicate (LSO)-related random background. 17,18 The latter has been determined as 1032 ± 27 counts/s by a fit of the measured random rates in 18 different patient scans by an exponential decay plus a constant LSO background term according to Ref.…”

Section: Introductionmentioning

confidence: 99%

Investigating the limits of PET/CT imaging at very low true count rates and high random fractions in ion‐beam therapy monitoring

et al. 2015

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Under the poor statistical conditions in PET-based treatment monitoring, improved results can be achieved by considering PSF and TOF information during image reconstruction and by applying less iterations than in conventional nuclear medicine imaging. Geometrical fidelity and image noise are mainly limited by the low number of true coincidences, not the high LSO-related random background. The retrieved results might also impact other emerging PET applications at low counting statistics.

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Patient Weight-Based Acquisition Protocols to Optimize18F-FDG PET/CT Image Quality

Cited by 45 publications

References 7 publications

Influence of Statistical Fluctuation on Reproducibility and Accuracy of SUV_max and SUV_peak: A Phantom Study

Influence of Statistical Fluctuation on Reproducibility and Accuracy of SUV_max and SUV_peak: A Phantom Study

Improvement in PET/CT Image Quality with a Combination of Point-Spread Function and Time-of-Flight in Relation to Reconstruction Parameters

Investigating the limits of PET/CT imaging at very low true count rates and high random fractions in ion‐beam therapy monitoring

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Patient Weight-Based Acquisition Protocols to Optimize18F-FDG PET/CT Image Quality

Cited by 45 publications

References 7 publications

Influence of Statistical Fluctuation on Reproducibility and Accuracy of SUVmax and SUVpeak: A Phantom Study

Influence of Statistical Fluctuation on Reproducibility and Accuracy of SUVmax and SUVpeak: A Phantom Study

Improvement in PET/CT Image Quality with a Combination of Point-Spread Function and Time-of-Flight in Relation to Reconstruction Parameters

Investigating the limits of PET/CT imaging at very low true count rates and high random fractions in ion‐beam therapy monitoring

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Influence of Statistical Fluctuation on Reproducibility and Accuracy of SUV_max and SUV_peak: A Phantom Study

Influence of Statistical Fluctuation on Reproducibility and Accuracy of SUV_max and SUV_peak: A Phantom Study