PET/CT 검사에서 확대된 표시시야가 표준섭취계수에 미치는 영향 평가

The Evaluation of the Difference of the SUV Caused by DFOV Change in PET/CT

Purpose: The limited FOV(Field of View) of CT (Computed Tomography) can cause truncation artifact at external DFOV (Display Field of View) in PET/CT image. In our study, we measured the difference of SUV and compared the influence affecting to the image reconstructed with the extended DFOV. Materials and Methods: NEMA 1994 PET Phantom was filled with ¹⁸F(FDG) of 5.3 kBq/mL and placed at the center of FOV. Phantom images were acquired through emission scan. Shift the phantom's location to the external edge of DFOV and images were acquired with same method. All of acquired data through each experiment were reconstructed with same method, DFOV was applied 50 cm and 70 cm respectively. Then ROI was set up on the emission image, performed the comparative analysis SUV. In the clinical test, patient group shown truncation artifact was selected. ROI was set up at the liver of patient's image and performed the comparative analysis SUV according to the change of DFOV. Results: The pixel size was increase from 3.91 mm to 5.47 mm according to the DFOV increment in the centered location phantom study. When extended DFOV was applied, maxSUV of ROI was decreased from 1.49 to 1.35. In case of shifted the center of phantom location study, maxSUV was decreased from 1.30 to 1.20. The maxSUV was 1.51 at the truncated region in the extended DFOV. The difference of the maxSUV was 25.9% higher at the outside of the truncated region than inside. When the extended DFOV was applied, maxSUV was decreased from 3.38 to 3.13. Conclusion: When the extended DFOV was applied, maxSUV decreasing phenomenon can cause pixel to pixel noise by increasing of pixel size. In this reason, maxSUV was underestimated. Therefore, We should consider the underestimation of quantitative result in the whole image plane in case of patient study applied extended DFOV protocol. Consequently, the result of the quantitative analysis may show more higher than inside at the truncated region.