Segmental acquisition method for rectal cancer in FDG-PET/CT tests: Analysis of 20 patients

Objectives We previously showed that the application of the segmental acquisition method to FDG-PET/CT scans is particularly advantageous. This study evaluated the utility of the segmental acquisition method over the continuous method in clinical FDG-PET/CT tests for 20 patients with rectal cancer.

Methods Twenty-three malignant lesions, 20 primary tumors and three lymph node metastases in 20 rectal cancer patients were investigated. The FDG-PET/CT assessments involved continuous imaging of the pelvic areas using both the continuous and segmental acquisition modes. The acquisition time was set to 3 minutes for the continuous method, and an acquisition time of 15 seconds was repeated 12 times for the segmental method. The acquired image data were reconstructed using FORE+OSEM algorithms. Segmental images were obtained by superimposing 12 reconstructed images. All images were investigated visually and quantitatively; quantitative assessment involved calculation of maximum SUV, contrast ratio, contrast-to-noise ratio (CNR), and coefficient of variation (CV), after setting regions of interest on the lesions.

Results Visual assessment revealed that the segmental method allowed for better detection of lesions and evaluation of image quality than did the continuous method. Quantitative assessment showed that the CNR and CV were 64% and 34% higher, respectively, in the segmental method than in the continuous method, while the maximum SUV and contrast ratios were similar when comparing the two acquisition methods.

Conclusions These data indicate that the segmental method allowed for better detection of lesions and image quality in rectal cancer patients when compared with the conventional continuous method. This segmental acquisition method could also be applied to clinical FDG-PET/CT tests.

Research Support This work was supported by the Grant-in-Aid for Young Scientists (B) (No. 23791474) from Japan Society for the Promotion of Science. This work was supported in part by Foundation for Promotion of Cancer Research in Japan. This work was partially supported by the Health and Labor Sciences Research Grants for Third Term Comprehensive 10-year Strategy for Cancer Control.