Accuracy of target delineation by positron emission tomography-based auto-segmentation methods after deformable image registration: A phantom study |
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Institution: | 1. Department of Radiation Oncology, Dana-Farber Cancer Institute and Brigham & Women’s Hospital, Harvard Medical School, Boston, Massachusetts;2. Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts;3. Department of Radiation Oncology, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts;4. Department of Medicine, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts;2. Texas Center for Proton Therapy, Irving, TX, USA;3. New York Proton Center, New York City, NY, USA;4. Emory University, Atlanta, GA, USA;1. Department of Medical Microbiology, Marmara University Pendik Training and Research Hospital, Istanbul 34899, Turkey;2. Chest Diseases Departments, Marmara University Pendik Training and Research Hospital, Istanbul, Turkey |
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Abstract: | PurposeDiagnostic positron emission tomography and computed tomography (PET/CT) images can be fused to the planning CT images by a deformable image registration (DIR). The aim of this study was to evaluate the standardized uptake value (SUV) and target delineation on deformed PET images.MethodsWe used a cylindrical phantom and removable inserts of four spheres (16–38 mm in diameter) and three ellipsoids with a volume equal to the 38-mm-diameter sphere (S38) in each. S38 was filled with 18F-fluorodeoxyglucose activity, and then PET/CT images were acquired. The contours of S38 were generated using original PET images by PET auto-segmentation (PET-AS) methods of (1) SUV2.5, (2) 40% of maximum SUV (SUV40%max), and (3) gradient-based (GB), and were deformed to the other inserts by DIR. We compared the volumes and the SUVmax with the generated contours using the deformed PET images.ResultsThe SUVmax was slightly decreased by DIR; the mean absolute difference was −0.10 ± 0.04. For SUV2.5 and SUV40%max, the differences in S38 volumes between the original and deformed PET images were less than 5%, regardless of deformation type. For the GB, the contoured volumes obtained from deformed PET images were larger than those of the original PET images for the deformation type of ellipsoids. When the S38 was deformed to the 16-mm-diameter sphere, the maximum volume difference was −22.8%.ConclusionsAlthough SUV fluctuations by DIR were negligible, the target delineation on deformed PET images by the GB should be carefully considered owing to the distortion of intensity profiles. |
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Keywords: | Deformable image registration PET auto-segmentation PET/CT Treatment planning |
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