Effect of respiratory gating on reducing lung motion artifacts in PET imaging of lung cancer

Abstract

Positron emission tomography (PET) has shown an increase in both sensitivity and specificity over computed tomography (CT) in lung cancer. However, motion artifacts in the 18F fluorodioxydoglucose (FDG) PET images caused by respiration persists to be an important factor in degrading PET image quality and quantification. Motion artifacts lead to two major effects: First, it affects the accuracy of quantitation, producing a reduction of the measured standard uptake value (SUV). Second, the apparent lesion volume is overestimated. Both impact upon the usage of PET images for radiation treatment planning. The first affects the visibility, or contrast, of the lesion. The second results in an increase in the planning target volume, and consequently a greater radiation dose to the normal tissues. One way to compensate for this effect is by applying a multiple-frame capture technique. The PET data are then acquired in synchronization with the respiratory motion. Reduction in smearing due to gating was investigated in both phantoms and patient studies. Phantom studies showed a dependence of the reduction in smearing on the lesion size, the motion amplitude, and the number of bins used for data acquisition. These studies also showed an improvement in the target-to-background ratio, and a more accurate measurement of the SUV. When applied to one patient, respiratory gating showed a 28% reduction in the total lesion volume, and a 56.5% increase in the SUV. This study was conducted as a proof of principle that a gating technique can effectively reduce motion artifacts in PET image acquisition.

Application of Partial Volume Effect Correction and 4D PET in the Quantification of FDG Avid Lung Lesions

“…This study showed that quantification of volumetric parameters of 4D PET/CT images using an adaptive contrastoriented thresholding algorithm and 3D lesion-based partial volume correction is feasible, and we observed only a slight increase in the quantification of metabolic activity of lung malignancies using the highest respiratory-gated versus nongated PET/CT images which is in contrast to previous respiratory-gated PET/CT studies [14,33]. Partial volume correction increased both the respiratory-gated and nongated values significantly and appears to be the dominant source of quantitative error of lung malignancies.…”

“…In phasebased respiratory gating, the respiratory cycle is divided into separate phase ranges, while amplitude gating divides the respiratory amplitude into different amplitude ranges [13]. In 2002, Nehmeh et al were the first to perform respiratory gating for PET scanning in clinical setting and found that respiratory gating decreases total lesion volume and increases measured SUV compared to non-gated images [14]. Gating has also been reported to improve the diagnosis of malignant lung lesions and the evaluation of response to radiation treatment [15][16][17][18].…”

Attenuation Correction Strategies for Positron Emission Tomography/Computed Tomography and 4-Dimensional Positron Emission Tomography/Computed Tomography

“…[66][67][68][69][70][71][72][73][74][75] One approach to improve registration between the CT and the PET data is to bring the temporal resolution of the CT images to that of the PET data. 42 Recognizing the fact that PET is averaged over many breath cycles, a CT image averaged over 1 breath cycle should improve registration between the CT and the PET data.…”

“…84 It was adopted for tumor imaging of the thorax almost a decade ago, 60,[66][67][68] about the same time when 4-dimensional CT was launched. 62,[77][78][79]85 Today, 4-dimensional CT has been accepted as a standard practice in CT imaging of tumor motion for radiation therapy.…”

Evaluation of dosimetric misrepresentations from 3D conventional planning of liver SBRT using 4D deformable dose integration

“…This could result in significant underdosing of target volumes and increased doses to healthy tissues, particularly for highly conformal techniques applied to thoracic and abdominal malignancy treatments 1 , 2 , 3 . Attempts to contend with organ deformation in image‐guided and adaptive radiotherapy often involve the implementation of deformable image registration (DIR) algorithms 4 , 5 , 6 , 7 , 8 .…”