Determination of Bone SPECT Image Reconstruction Conditions in the Head and Neck Region

Abstract

Quantitative analysis using a standardized uptake value (SUV) has become possible for singlephoton emission computed tomography-computed tomography (SPECT-CT) of bone. However, previous research was targeted to the trunk area, and there are few studies for the head and neck region. Therefore, the purpose of this study was to determine the optimal image reconstruction conditions for bone SPECT of the head and neck using a phantom study. Method: The radioactivity concentration of the 99m Tc solution enclosed in the cylindrical phantom was set to the same count rate as in clinical cases, and six hot spheres (10, 13, 17, 22, 28, 37 mm) with four times the concentration were placed within it. The image reconstruction was 3D-OSEM, and the reconstruction conditions were varied by the number of iterative updates and the width of the Gaussian filter. Quantitative evaluations of the image quality were performed using the % contrast, background variability, and SUV for the hot spheres and background. A visual evaluation was performed by four observers to determine the optimal image reconstruction conditions for bone SPECT of the head and neck region. Result: The concentration of the 99m Tc solution enclosed in the phantom was 6.95 (kBq/ml). Based on the results of the quantitative and visual evaluations, the optimal image reconstruction conditions were iterative updates=60 (subset: 10, iteration: 6) and a Gaussian filter of 7.8 mm. Conclusion:The optimal image reconstruction conditions were subset=10, iterations=6, and a Gaussian filter of 7.8 mm.

Improvement of Quantitative Single-Photon Emission Computed Tomography Image Quality by the New Step-and-Shoot Scan Mode

“…Using RAVAT 1.0 image analysis software, a circular ROI was drawn on each hot sphere and BG region of the slice where the 10-mm sphere was most clearly visible [5,7,8]. The ROI size of each hot sphere was set to 70% of its size, and the BG region was placed with 12 circular ROIs of 26 mm diameter on the edge of the phantom (Figure 1).…”