Application of MRI contrast-enhanced FLAIR sequence in the evaluation of brain metastases
HUANG Haixia1,2， CHEN Jian2， DAI Rao3， SHAN Xiuhong3
（1. School of Medicine， Jiangsu University， Zhenjiang Jiangsu 212013； 2. Department of Radiology， the Fifth People′s Hospital of Zhenjiang， Zhenjiang Jiangsu 212004； 3. Department of Radiology， Affiliated People′s Hospital of Jiangsu University， Zhenjiang Jiangsu 212002， China）
Abstract： Objective： To explore the value in detecting brain metastases of contrast-enhanced fluid attenuation inversion recovery sequence （CE-T2 FLAIR） and contrast-enhanced T1WI sequence （CE-T1WI）. Methods： The MR image data of 88 patients with brain metastases admitted to Affiliated People′s Hospital of Jiangsu University from August 2021 to December 2022 with complete clinical data were retrospectively analyzed. The number, length, location, signal intensity, degree of tumor enhancement, and tumor/background ratio of brain metastases in CE-T1WI and CE-T2 FLAIR sequences were compared，and the correlation between the length of the metastases and the rate of enhancement (PI) was analyzed with Pearson correlation analysis. Results： A total of 430 lesions were detected in 88 patients with brain metastases. 340 lesions were shown in CE-T1WI and 420 lesions in CE-T2 FLAIR. There were 80 metastases shown only in the CE-T2 FLAIR sequence, of which 68 were located in the cortical or subcortical regions and 12 were located in the cerebellar hemispheres, most of which were less than 7 mm in diameter. There were 10 metastases shown only in CE-T1WI sequences. Compared with T1WI sequences, the contrast ratio (CR) and contrast signal to noise ratio (CNR) of tumorwhite matter and tumorCSF were apparently higher on T2 FLAIR plain and enhanced sequences (all P＜0.001). The percentage of tumor enhancement in T1WI was apparently higher than that in T2 FLAIR (P＜0.001). In the comparison of white and gray matter metastases at the same scan level, CE-T1WI sequences showed significantly higher PI than CE-T2 FLAIR in both white matter and gray matter (all P＜0.05), and no significant difference in CR between the two sequences. In CE-T1WI sequence, the length of metastatic tumor was significantly correlated with the PI (r=0.831, P＜0.001), but it was not significantly correlated with the PI in CE-T2 FLAIR sequence (r=0.240, P＞0.05). Conclusion： CE-T2 FLAIR sequence shows not only brain metastases shown in CE-T1WI sequence, but also micro-metastases not shown in CE-T1WI sequence, thus, CE-T2 FLAIR should be an essential sequence for MRI detection of brain metastases including micro-metastases. ［Key words］brain metastases； magnetic resonance imaging； contrast-enhanced FLAIR sequence； contrastenhanced T1WI sequence； imaging findings
