Respiratory Gated ¹⁸F-FDG PET/CT Imaging Clinical Application Study Of Pulmonary Nodules

The accurate location and quantitative detection of the tumor lesions play an important role in early diagnosis, treatment and efficacy assessment of the tumor. In line with this purpose, this paper discusses the value of the application of the respiratory gating in 18F-FDG PET/CT imaging in the diagnosis and radiotherapy location of lung tumor.Objective:The purpose of this paper is to study the role of the respiratory gating in F-FDG PET/CT imaging over the qualitative, quantitative and location diagnosis of lung nodules and its application in radiotherapy location. Methods:24 cases with 30 lesions that have been diagnosed with pulmonary bump and nodules with the help of CT and suspected with lung cancer or diagnosed with lung cancer have been selected. The patients' nodules in lungs, with the help of CT, are suspected to have been metastasized. A respiratory gating check equipped with real-time position management, (RPM) and a non-respiratory gating check under calm breathing are conducted respectively by the same nuclear physician who is responsible for measuring the volumes of the lesions and SUV. First of all, the physician compares the sizes and the volumes of the lesions and the change of SUVmean and SUVmax. Secondly, images in each respiratory cycle are divided into ten breath phases, from 0% to 90%. Among them,0% corresponds to the end of inhalation and 50% the end of exhalation. The change of SUVmax of the 30 lesions in each phase of respiratory gating is to be detected. Thirdly, by means of ROI (region of interest), the nuclear physician is to calculate the volume of the lesions in PET, CT and the integrated imaging and compare the degrees of fusion of the lesions under the circumstances of respiratory gating and non-respiratory gating. Results:(1) By comparison, we find that the size of the lesions, SUVmean and SUVmax experience an obvious change:the volume of the lesions have become smaller, while SUVmean and SUVmax have been raised by 27.16% and 26.09%. (2) Even the same lesion changes within one respiratory cycle. In other words, the value of SUV changes in different breath phases. The SUVmax reaches its climax at the end of exhalation. (3) By comparing the precise degree of fusion of the 30 lesions on respiratory gating and non-respiratory gating imaging, we can see easily that PET imaging and CT imaging of the lesions have fused well with respiratory gating device. And the degrees of fusion of the lesions increase 14.1%,21.7% and 50.3% respectively in the upper lung, middle lung and lower lung. The pulmonary lesion of the lower lung fuses obviously better than that in the middle-upper lung. Conclusion:The application of respiratory gating device on PET/CT can enhance the lesion detection and increase the value of SUV. The integrated imaging can better reflect the combination of metabolism with anatomy and provide more help for clinical diagnosis and treatment of tumor.