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

Abstract

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.

Task Group 174 Report: Utilization of [18F]Fluorodeoxyglucose Positron Emission Tomography ([18F]FDG‐PET) in Radiation Therapy

“…The PET datasets corresponding to each individual interval or bin are noisier because of the lower counts per bin. The use of internal target volumes (ITVs) defined from respiratory‐gated PET/CT ITVs from amplitude binning has been shown to be larger and more accurate than those from phase binning . Amplitude and phase binning are achieved by subdividing a respiratory signal that is typically obtained from external hardware attached to the patient .…”

“…The use of internal target volumes (ITVs) defined from respiratorygated PET/CT ITVs from amplitude binning has been shown to be larger and more accurate than those from phase binning. 117 Amplitude and phase binning are achieved by subdividing a respiratory signal that is typically obtained from external hardware attached to the patient. 118 However, the respiratory signal may also be generated using a datadriven approach, from motion information contained in the PET/CT data.…”

Impact of Respiratory-Gated FMISO-PET/CT for the Quantitative Evaluation of Hypoxia in Non-small Cell Lung Cancer

“…Internal organ movement has a degrading effect on image quality and quantitative values in terms of spatial resolution and contrast [6]. Respiratory gating is a technique for improving the measurement of lesion uptake and tumor volume in PET/CT [7]. Motion management is becoming an important issue in both diagnostic and therapeutic applications.…”

Application of Three-Dimensional Motion Tracking of Low-Activity Fiducial Positron-Emitting Markers in Radiation Therapy and Positron Emission Tomography

“…terns are a common occurrence in PET imaging. [80,111,[136][137][138] Others also report that this may cause errors when binning the data into the appropriate respiratory gate. [138] PeTrack has an advantage over the RPM system with respect to its robustness to baseline shifts.…”

“…It has been shown that this type of gating performs worse than amplitude based gating. [111,137,138] administration (see Figure 5.5(a)). A case study such as Anon4886 might prove more challenging due to the smaller amplitude of motion.…”