Number of partitions (gates) needed to obtain motion‐free images in a respiratory gated 4D‐PET/CT study as a function of the lesion size and motion displacement

Bettinardi, Valentino; Rapisarda, E.; Gilardi, M.C.

doi:10.1118/1.3254431

Cited by 26 publications

(22 citation statements)

References 12 publications

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“…Motion-specific internal target volumes were readily drawn using 4D-PET. Use of the 4D-PET MIP is a significant time-saving device, because contouring on the MIP plus end-exhale and inhale 4D-PET phases is expected to take roughly half as long as contouring on all phases of 4D-PET, since 6-8 phases are typically used in 4D-PET imaging[18,19]. We demonstrated that the 4D-PET MIP can be used in conjunction with the end-exhale and end-inhale phases of 4D-PET to construct motion-specific target volumes for malignant FDG-avid lymph nodes, and that such target volume differ at a clinically significant level from those generated by standard of care techniques (non-contrast 4D-CT and breath-hold CT in conjunction with un-gated PET).…”

Section: Discussionmentioning

confidence: 99%

Motion-specific internal target volumes for FDG-avid mediastinal and hilar lymph nodes

Lamb

Robinson

Bradley

et al. 2013

Radiotherapy and Oncology

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Background and Purpose To quantify the benefit of motion-specific internal target volumes for FDG-avid mediastinal and hilar lymph nodes generated using 4D-PET, vs. conventional internal target volumes generated using non-respiratory gated PET and 4D-CT scans. Materials and Methods Five patients with FDG-avid tumors metastatic to 11 hilar or mediastinal lymph nodes were imaged with respiratory-correlated FDG-PET (4D-PET) and 4D-CT. FDG-avid nodes were contoured by a radiation oncologist in two ways. Standard-of-care volumes were contoured using conventional un-gated PET, 4D-CT, and breath-hold CT. A second, motion-specific, set of volumes was contoured using 4D-PET. Contours based on 4D-PET corresponded directly to an internal target volume (ITV4D), whereas contours based on un-gated PET were expanded by a series of exploratory isotropic margins (from 5-13 mm) based on literature recommendations on lymph node motion to form internal target volumes (ITV3D). Results A 13 mm expansion of the un-gated PET nodal volume was needed to cover the ITV4D for 10 of 11 nodes studied. The ITV3D based on a 13 mm expansion included on average 45 cm3 of tissue that was not included in the ITV4D. Conclusions Motion-specific lymph-node internal target volumes generated from 4D-PET imaging could be used to improve accuracy and/or reduce normal-tissue irradiation compared to the standard-of-care un-gated PET based internal target volumes.

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Section: Discussionmentioning

confidence: 99%

Motion-specific internal target volumes for FDG-avid mediastinal and hilar lymph nodes

Lamb

Robinson

Bradley

et al. 2013

Radiotherapy and Oncology

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“…Dawood et al 22 demonstrated that sixphase decomposition was optimal in a single case study. Using a phantom, Bettinardi et al 23 determined that the fewer the number of phases, the lower the SUV max quantification.…”

Section: Introductionmentioning

confidence: 99%

Clinical respiratory motion correction software (reconstruct, register and averaged—RRA), for 18F-FDG-PET-CT: phantom validation, practical implications and patient evaluation

Bouyeure-Petit¹,

Chastan²,

Edet-Sanson³

et al. 2017

The British Journal of Radiology

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Objective: On fluorine-18 fludeoxyglucose ( 18 F-FDG) positron emission tomography (PET) CT of pulmonary or hepatic lesions, standard uptake value (SUV) is often underestimated due to patient breathing. The aim of this study is to validate, on phantom and patient data, a motion correction algorithm [reconstruct, register and averaged (RRA)] implemented on a PET-CT system. Methods: Three phantoms containing five spheres filled with 18 F-FDG and suspended in a water or Styrofoam® 18 F-FDG-filled tank to create different contrasts and attenuation environment were acquired on a Discovery GE710. The spheres were animated with a 2-cm longitudinal respiratory-based movement. Respiratory-gated (RRA) and ungated PET images were compared with static reference images (without movement). The optimal acquisition time, number of phases and the best phase within the respiratory cycle were investigated. The impact of irregular motion was also investigated. Quantification impact was computed on each sphere. Quantification improvement on 28 lung lesions was also investigated. Results: Phantoms: 4 min was required to obtain a stable quantification with the RRA method. The reference phase and the number of phases used for RRA did not affect the quantification which was similar on static acquisitions but different on ungated images. The results showed that the maximum standard uptake value (SUV max ) restoration is majored for the smallest spheres (#2.1 ml). Patients: SUV max on RRA and ungated acquisitions were statistically different to the SUV max on whole-body images (p 5 0.05) but not different from each other (mean SUV max : 7.0 6 7.8 vs 6.9 6 7.8, p 5 0.23 on RRA and ungated images, respectively). We observed a statistically significant correlation between SUV restoration and lesion displacement, with a real SUV quantitation improvement for lesion with movement .1.2 mm. Conclusion: According to the results obtained using phantoms, RRA method is promising, showing a real impact on the lesion quantification on phantom data. With regard to the patient study, our results showed a trend towards an increase in the SUVs and a decrease in the volume between the ungated and RRA data. We also noticed a statistically significant correlation between the quantitative restoration obtained with RRA compared with ungated data and lesion displacement, indicating that the RRA approach should be reserved to patients with small lesions or nodes moving with a displacement larger than 1.2 cm. Advances in knowledge: This article investigates the performances of motion correction software recently introduced in PET. The conclusion revealed that such respiratory motion correction approach shows a real impact on the lesion quantification but must be reserved to the patient for whom lesion displacement was confirmed and high enough to clearly impact lesion evaluation.

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“…Increasing the number of gating windows beyond 8 would be expected to increase the motion recovery of both amplitude-based and phase-based gating at the expense of increased image noise. We chose 8 gating windows because this was found to be effective in capturing motion displacement in a cardiac PET study (15) and obtaining motion-free images in a respiratory gated 4D-PET/CT study (25). In addition, only nonattenuation corrected images were examined in this study, although segmentation can also be performed on PET images with attenuation correction applied.…”

Section: Discussionmentioning

confidence: 99%

A Comparison of Amplitude-Based and Phase-Based Positron Emission Tomography Gating Algorithms for Segmentation of Internal Target Volumes of Tumors Subject to Respiratory Motion

Jani

Robinson

Dahlbom

et al. 2013

International Journal of Radiation Oncology*Biology*Physics

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Purpose To compare quantitatively the accuracy of tumor volume segmentation in amplitude-based and phase-based respiratory gating algorithms in respiratory-correlated positron emission tomography (PET). Methods and Materials List-mode fluorodeoxyglucose-PET data was acquired for 10 patients with a total of 12 fluorodeoxyglucose-avid tumors and 9 lymph nodes. Additionally, a phantom experiment was performed in which 4 acrylic spheres with inner diameters ranging from 1 to 4 cm were imaged as they underwent 1-dimensional motion based on 2 measured patient breathing trajectories. PET list-mode data were gated into 8 bins using 2 amplitude-based (equal amplitude bins [A1] and equal counts per bin [A2]) and 2 temporal phase-based gating algorithms. Gated images were segmented using a commercially available gradient-based technique and a fixed 40% threshold of maximum uptake. Internal target volumes (ITVs) were generated by taking the union of all 8 contours per gated image. Segmented phantom ITVs were compared with their respective ground-truth ITVs, defined as the volume subtended by the tumor model positions covering 99% of breathing amplitude. Superior-inferior distances between sphere centroids in the end-inhale and end-exhale phases were also calculated. Results Tumor ITVs from amplitude-based methods were significantly larger than those from temporal-based techniques (P= .002). For lymph nodes, A2 resulted in ITVs that were significantly larger than either of the temporal-based techniques (P<.0323). A1 produced the largest and most accurate ITVs for spheres with diameters of ≥2 cm (P = .002). No significant difference was shown between algorithms in the 1-cm sphere data set. For phantom spheres, amplitude-based methods recovered an average of 9.5% more motion displacement than temporal-based methods under regular breathing conditions and an average of 45.7% more in the presence of baseline drift (P<.001). Conclusions Target volumes in images generated from amplitude-based gating are larger and more accurate, at levels that are potentially clinically significant, compared with those from temporal phase-based gating.

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Number of partitions (gates) needed to obtain motion‐free images in a respiratory gated 4D‐PET/CT study as a function of the lesion size and motion displacement

Abstract: By using the 4D-PET/CT acquisition technique, it is possible to compensate for the degradation effect of lesion motion on the reconstructed PET images.

Cited by 26 publications

References 12 publications

Motion-specific internal target volumes for FDG-avid mediastinal and hilar lymph nodes

Motion-specific internal target volumes for FDG-avid mediastinal and hilar lymph nodes

Clinical respiratory motion correction software (reconstruct, register and averaged—RRA), for 18F-FDG-PET-CT: phantom validation, practical implications and patient evaluation

A Comparison of Amplitude-Based and Phase-Based Positron Emission Tomography Gating Algorithms for Segmentation of Internal Target Volumes of Tumors Subject to Respiratory Motion

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