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SU‐E‐I‐84: Comparing the Accuracy of the Bilateral Filter and Gaussian Filter for PET Image Post‐Processing Through a Phantom Study
Author(s) -
Wu X,
Jani S,
Dahlbom M,
Low D,
Lamb J
Publication year - 2013
Publication title -
medical physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.473
H-Index - 180
eISSN - 2473-4209
pISSN - 0094-2405
DOI - 10.1118/1.4814195
Subject(s) - imaging phantom , gaussian filter , filter (signal processing) , gaussian , mathematics , nuclear medicine , pixel , biomedical engineering , physics , optics , medicine , computer science , computer vision , quantum mechanics
Purpose: To compare the accuracy of an edge‐preserving filter to the standard Gaussian filter for PET image post‐processing through a phantom study. Methods: A phantom was used, consisting of four different spheres (diameter 1–4 cm, filled with a solution of 11‐C) that were mounted inside an acrylic cylinder (filled with a solution of 18‐FDG) to generate a time‐varying signal to background ratio (SBR). To mimic lung and liver lesions, SBRs were chosen to range from 2 to 30 and 2 to 5, respectively. The edge‐preserving filter used was the bilateral filter, which weights pixels based on both spatial distance and intensity difference. Reconstructed 3D‐PET images were separately smoothed with the bilateral filter and Gaussian filter. A commercially available gradient‐based technique was used to segment images and measure sphere volumes. Results were evaluated by the ratio of measured to true volume (RMT) of spheres. Paired two‐tailed t‐tests were applied to test for statistical significance. Results: In the lung case, RMT differences were not statistically significant across all sphere sizes. In the liver case, statistically significant differences were obtained for the 3 cm and 4 cm spheres, with average RMTs of 1.14 (bilateral) and 1.11 (Gaussian). However, these differences did not amount to a clinically significant level. For the 2 cm sphere, the differences were not statistically significant; for the 1 cm sphere, RMT differences were statistically, and potentially clinically, significant: 0.66 (bilateral) vs. 1.31 (Gaussian). However, it should be noted that volume segmentation of the 1 cm sphere was not fully reproducible on a case‐by‐case basis. Conclusion: This work indicates that the bilateral filter has a comparable accuracy to the Gaussian filter in volume measurements of 3D‐PET images. The commercially available gradient‐based segmentation algorithm is reasonably correct for spheres greater than 2 cm, but further studies are needed for smaller spheres. NIH R01 CA096679