Objective: The purpose of this study was to evaluate the clinical feasibility of a simple image fusion technique with PET and CT images acquired separately using a vacuum cushion as a fixation device.
Subjects and methods: Forty-four patients underwent whole-body PET using 18F-fluoro-2-deoxy-D-glucose (FDG) followed by CT with IV contrast material. The patients were carefully fixed in an individually molded cushion to provide the same positioning for both examinations. The PET and CT images were fused on a workstation by using the lower margin of the urinary bladder as a reference. The degree of misregistration was evaluated for the physiologic uptake of the liver and kidneys and for the pathologic uptake of lesions.
Results: The average deviation of the center point of the liver between the two images was 6.6 +/- 8.7 (SD) mm in the craniocaudal direction, 1.9 +/- 5.1 mm in the anteroposterior direction, and 2.3 +/- 7.0 mm in the right-left direction. This value in the craniocaudal direction was 4.7 +/- 8.7 mm in the right kidney and 4.0 +/- 8.8 mm in the left kidney. Above the diaphragm, the deviations of the center point of movable and static lesions were 11.7 +/- 3.4 mm and 10.4 +/- 5.3 mm, respectively. Below the diaphragm, those of movable and static lesions were 9.7 +/- 2.5 mm and 6.9 +/- 2.9 mm, respectively.
Conclusion: Our preliminary data indicate that this technique is a simple and practical method for manual image fusion that may be acceptable in clinical settings.