P15.12.A BIUX2X2

Abstract

Abstract BACKGROUND Brain metastases occur in 20-40% of cancer patients. In connection with the development of radiosurgical treatment, the problem of differential diagnosis of continued tumor growth and post-radiation changes becomes relevant. The main method of radiosurgical treatment of secondary lesions is the Gamma-Knife. Positron emission tomography with 11C-Meth and 18F-FET is an important method in monitoring the treatment of patients with secondary brain tumors. MATERIAL AND METHODS We examined 73 patients with brain metastases. Of these, 36.36% were patients with breast cancer, 39.39% were patients with lung cancer, 9.00% were patients with melanoma, 6.06% were patients with kidney cancer, 9.09% were other nosology, which corresponds to the data on the frequency of metastasis to the brain of various types of cancers. All patients underwent MRI with standard sequences (T1, T2, FLAIR, T1+C) and PET-CT with 18F-FET. PET-CT was performed according to the standard protocol: scanning 20 minutes after the INTRODUCTION of the radiopharmaceutical, scanning time 20 minutes. The evaluation of PET images was carried out by a semi-quantitative method - TBR max. RESULTS The mean age of patients with breast cancer was 54.5 ± 10.4, which significantly differs from the mean age of patients with lung cancer (65.9 ± 8.7) and the mean age of patients with other primary cancers (62.8 ± 8, 8) (Kruskal-Wallis test: H(2, N=66)=13.99052 p=.0009). Differences in TBR max and the number of metastases in these groups are not significant, as well as, according to the Kaplan-Meier analysis, differences in the duration of the relapse-free period. However, differences in the duration of the relapse-free period in the groups after a single ( Median, Q1; Q3) (12.9, 10.5; 24.4) or multiple (7.5, 3.5; 10.5) radiosurgical treatment are significant ( Gehan's Wilcoxon Test, Test statistic = 2.063905 p = .03903). Based on the analysis of the data obtained, it was found that the threshold value TBR max >=2.8 in 100% of cases indicates progression, TBR max <=1.7 indicates a stable course. Whereas TBR max in the range from 1.7 to 2.8 (in 33 people from the examined group, i.e. in 50% of all cases) may indicate both progression and post-radiation changes, as well as confirmed positive dynamics. CONCLUSION Thus, we confirmed that the numerical value of TBR max is a relative indicator. And when interpreting PET data, we cannot rely only on the TBR max value in the range from 1.7 to 2.8 for a confident judgment about the genesis of increased RP uptake in tumors. In the absence of other markers of the development of progression (for example, the appearance of new pathological foci), to assess the dynamics and confidently identify post-radiation changes, a repeat PET study should be prescribed after 2-3 months with a preliminary MRI with contrast enhancement.