Brain metastatic volume and white matter lesions in advanced cancer patients

Brain white matter T2 hyperintensities (WMH) are a frequent MRI finding in adults, both in asymptomatic and in cancer patients. The aim of our study is to determine the relationship between quantitative measures of the volume of WMH and the volume of brain metastatic lesions at the first MRI diagnosis of brain metastases in a population of advanced cancer patients. Brain MRI examinations of 162 consecutive patients were included and 984 brain metastases at first diagnosis were studied. Axial FLAIR images were used to visualize peri-lesional edema and to segment WMH; multiplanar contrast-enhanced T1-weighted TSE images were used to detect, count, segment and measure metastatic lesions. Segmentation of WMH on FLAIR images was performed after linear image registration to eliminate peri-lesional edema from the WMH masks. The distribution of the volumes of metastatic lesions was significantly different (ANOVA, p = 0.003) among all patients and among lung cancer patients (ANOVA, p = 0.003), with higher volumes of metastatic lesions in a higher proportion of patients when WMH were absent. There were no significant differences among groups at the 10 cc threshold of WMH. We found that volumes of brain metastases at the first MR diagnosis in a sample of advanced cancer patients and in the group of lung cancer patients were significantly lower if WMH were present; we suggest that WMH may represent a clinical MRI bio-marker of brain micro-environment resistance to the occurrence of brain metastases.