Capabilities of 18F-FDG PET/CT in the differential diagnosis of colorectal liver metastases
Aim. To study the capabilities of <sup>18</sup>F-FDG PET/CT in the differential diagnosis of colorectal liver metastases. Materials and methods. A retrospective analysis of <sup>18</sup>F-FDG PET/CT data of 126 patients with colorectal cancer was carried out. The final diagnosis of colorectal cancer was established based on the analysis of morphological material obtained from the primary tumor. The metastatic or benign origins of the liver foci was confirmed by histological examination or by the results of radiation examination (dynamic observation). Sensitivity and specificity of this method were determined using ROC analysis using the SUV as a numerical classifier. Results. Colorectal liver metastases were detected in 51 (40.5%) patients. Advanced extrahepatic tumor process was detected in 25 (19.8%) cases. There were no progression in 50 (39.7%) patients. Benign tumors were detected in 22 patients with colorectal cancer: in 10 cases coupled with liver metastases, in 12 - without them. Totally 166 focal liver lesions were found: 125 (75.3%) metastases and 41 (24.7%) benign tumors. According to ROC analysis, sensitivity and specificity of <sup>18</sup>F-FDG PET/CT with SUV ≥ 3.0 in the diagnosis of liver metastases were 84.8% and 97.6% respectively, the area under the ROC curve - 0.893 (95% CI 0.836-0.936 , p < 0.0001), positive predictive value and negative predictive value were - 99.1% and 67.8%, respectively. Conclusion. <sup>18</sup>F-FDG PET/CT is a highly informative imaging method in the differential diagnosis of colorectal liver metastases larger than 10 mm. The use of quantitative data processing with a threshold value SUV ≥ 3.0 allows to achieve high sensitivity and specificity of the method.