摘要
Objective: Three-dimensional (3D) movement of a spherical liver tumor during respiration was investigated with magnetic resonance imaging (MRI) using a high-speed sequence. Methods: A marker was placed on the surface of the patient as a reference of distance. Repetition time (TR) was 7.7 ms, echo time (TE) was 4.2 ms, flip angle was 20°, section thickness was 8 mm, and a 256 x 128 matrix was used. The acquisition time was 1.0 s followed by an interval of 0.5 s. The 20 tumor contours extracted during 30 s were superimposed on sagittal and coronal MR images. Results: The maximum value of tumor edge location was 3.9 cm in the cranio-caudal direction, 2.3 cm in the ventro-dorsal direction, and 3.1 cm in the lateral direction. The mean length of tumor displacement observed was 2.1 cm in the cranio-caudal direction, 0.8 cm in the ventro-dorsal and 0.9 cm in the left-right direction, respectively. The locus of the center of the tumor contour in the sagittal cross section was inclined at 23°and in the coronal cross section was inclined at 18°to the cranio-caudal axis of body. Conclusion: In conclusion, 3D movement of a spherical liver tumor was detected using rapid MRI sequential examinations. Magnetic resonance imaging has a potential to improve the accuracy of the planning target volume of a liver tumor.