Euromedim 2006 :1st European Conference on Molecular Imaging Technology

AUTOMATIC CALCULATION OF SUV ON FDG PET-CT LUNG LESIONS

9 May 2006, 14:00

1h

Palais du Pharo, Marseille

poster • Image reconstruction and processing Poster Session :Simulation, Modeling, Reconstruction

Speaker

Mr Ismael KARIDIOULA ((1) Centre Jean Perrin, Division of Nuclear Medicine, F-63011 Clermont-Ferrand, France, (2)University of Auvergne, Faculty of Medicine, F-63000 Clermont-Ferrand, France, (3)INSERM, U484, F-63000Clermont-Ferrand, France)

Description

Aim: A new method for the automatic calculation of the mean standardized uptake value (meanSUV) in pulmonary lesions detected by FDG PET-CT has been developed and validated. Materials and methods: In PET-CT, calculation of FDG meanSUV rests on the delineation of a region of interest (ROI) around the tumor on a PET section. We propose to draw the ROI by utilizing the limits of the lesion as seen on the matched CT section. Once the tumor has been selected, a segmentation based on a fixed density threshold automatically delineates a ROI around the tumor on the CT section. This ROI is then applied to the PET image to calculate the meanSUV. This method was applied to a section passing through the center of a pulmonary masse or solitary nodule obtained in a series of 56 patients imaged with a PET/CT (Discovery ST,GE Health Care) one hour after injection of 340-440 MBq of FDG. The automatic method was compared with the manual method in which the operator manually selected the best-suited circular ROI to surround the tumour on the PET image. ROI size was also measured. All measurements were performed independently by two operators. Results: With the manual method, meanSUV and ROI size were respectively (m±sd) 3.47±1.58 and 73±54 for the first operator vs 3.83±1.61 and 64±53 (p<0.001 for both) for the second one. Between the two operators, the coefficient of correlation was 0.95 for the meanSUV and 0.96 for the ROI size. With the automatic method, the meanSUV and ROIsize found by the two operators were always the same for all the patients : they were respectively 4.40±2.22 and 65±50. In both cases, the coefficient of correlation was one. The comparison of the two methods by a same operator gave the next results : meanSUV and ROIsize were respectively 3.85±1.67 and 63±52 for the manual method versus 4.40±2.22 and 65±50 for the automatic method (p<0.001 for the meanSUV). The coefficient of correlation was 0.92 for the meanSUV and 0.93 for the ROIsize.The higher meanSUV obtained with the automatic, CT-based method can be explained by a better delineation of the tumor when compared with a circular ROI Conclusion: The use of an automatic, CT-based ROI to surround a tumour on a FDG PET image provides highly reproducible SUV values.