Prospective data-driven respiratory gating of [68Ga]Ga-DOTATOC PET/CT

Jonathan Sigfridsson,Victor Iyer,Mark Lubberink,Anders Sundin,Elin Lindström,Irina Velikyan,Maria Holstensson

doi:10.1186/s13550-021-00775-w

Jonathan Sigfridsson, Victor Iyer + Show 5 more

Open Access

https://doi.org/10.1186/s13550-021-00775-w

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Abstract

AimThe aim of this prospective study was to evaluate a data-driven gating software’s performance, in terms of identifying the respiratory signal, comparing [68Ga]Ga-DOTATOC and [18F]FDG examinations. In addition, for the [68Ga]Ga-DOTATOC examinations, tracer uptake quantitation and liver lesion detectability were assessed.MethodsTwenty-four patients with confirmed or suspected neuroendocrine tumours underwent whole-body [68Ga]Ga-DOTATOC PET/CT examinations. Prospective DDG was applied on all bed positions and respiratory motion correction was triggered automatically when the detected respiratory signal exceeded a certain threshold (R value ≥ 15), at which point the scan time for that bed position was doubled. These bed positions were reconstructed with quiescent period gating (QPG), retaining 50% of the total coincidences. A respiratory signal evaluation regarding the software’s efficacy in detecting respiratory motion for [68Ga]Ga-DOTATOC was conducted and compared to [18F]FDG data. Measurements of SUVmax, SUVmean, and tumour volume were performed on [68Ga]Ga-DOTATOC PET and compared between gated and non-gated images.ResultsThe threshold of R ≥ 15 was exceeded and gating triggered on mean 2.1 bed positions per examination for [68Ga]Ga-DOTATOC as compared to 1.4 for [18F]FDG. In total, 34 tumours were evaluated in a quantitative analysis. An increase of 25.3% and 28.1%, respectively, for SUVmax (P < 0.0001) and SUVmean (P < 0.0001), and decrease of 21.1% in tumour volume (P < 0.0001) was found when DDG was applied.ConclusionsHigh respiratory signal was exclusively detected in bed positions where respiratory motion was expected, indicating reliable performance of the DDG software on [68Ga]Ga-DOTATOC PET/CT. DDG yielded significantly higher SUVmax and SUVmean values and smaller tumour volumes, as compared to non-gated images.

Highlights

Respiratory motion has an impact on positron emission tomography (PET) imaging of the thorax and abdomen, usually in the vicinity of the diaphragm
Data-driven gating (DDG) has previously not been available for clinical use, but recently a software based on principal component analysis (PCA) was commercially released, making it possible to apply DDG during the PET acquisition [11, 14]
By using an R = 15 threshold, gating was triggered in bed positions where respiratory motion was expected to have a large impact, indicating that DDG reliably detects the respiratory signal in the [68Ga]Ga-DOTATOC PET/CT

Summary

Introduction

Respiratory motion has an impact on positron emission tomography (PET) imaging of the thorax and abdomen, usually in the vicinity of the diaphragm. Application of respiratory gating has proven useful. Data-driven gating (DDG) constitutes a device-less alternative by which respiratory motion is derived directly from the PET-acquisition data. DDG has previously not been available for clinical use, but recently a software based on principal component analysis (PCA) was commercially released, making it possible to apply DDG during the PET acquisition [11, 14]. The respiratory signal generated with PCA-based DDG has been found to correlate well with that from devices, and showed better performance in terms of robustness, image quality, and higher standardized uptake values (SUV). Introduction of DDG into PET clinics might allow for replacement of device-based gating and make routine use of respiratory gating clinically feasible [14,15,16]

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