Edema is not a reliable diagnostic sign to exclude small brain metastases

Abstract

No prior systematic study on the extent of vasogenic edema (VE) in patients with brain metastases (BM) exists. Here, we aim to determine 1) the general volumetric relationship between BM and VE, 2) a threshold diameter above which a BM shows VE, and 3) the influence of the primary tumor and location of the BM in order to improve diagnostic processes and understanding of edema formation. This single center, retrospective study includes 173 untreated patients with histologically proven BM. Semi-manual segmentation of 1416 BM on contrast-enhanced T1-weighted images and of 865 VE on fluid-attenuated inversion recovery/T2-weighted images was conducted. Statistical analyses were performed using a paired-samples t-test, linear regression/generalized mixed-effects model, and receiver-operating characteristic (ROC) curve controlling for the possible effect of non-uniformly distributed metastases among patients. For BM with non-confluent edema (n = 545), there was a statistically significant positive correlation between the volumes of the BM and the VE (P < 0.001). The optimal threshold for edema formation was a diameter of 9.4 mm for all BM. The primary tumors as interaction term in multivariate analysis had a significant influence on VE formation whereas location had not. Hence VE development is dependent on the volume of the underlying BM and the site of the primary neoplasm, but not from the location of the BM.

Brain metastases with unusual MRI features in an infant with relapsed clear cell sarcoma of the kidney: A case report

“…Although large-sized intraparenchymal metastases of the brain mostly exhibit vasogenic edema, the presence or degree of vasogenic edema may be influenced by other factors than the lesion size, such as the primary tumor type, location of the lesion in the gray or white matter, desmoplastic effects of the chemotherapy, and the presence or absence of reactive astrogliosis around the lesion. 4,6 As the histopathological evaluation of the metastatic brain lesions in the presented case was not performed, addressing the exact cause of the absence of the peritumoral edema is not possible. A faint contrast-enhancement of the metastatic lesions, however, might be due to the lesions' poor vascularity and the signal alteration layers with T2 hypointensity and T1-FLAIR hyperintensity within the lesions might suggest the presence of relatively hypocellular fibrotic components.…”

A Critical Review of PET Tracers Used for Brain Tumor Imaging

“…This logic would have been acceptable if this phenomenon was a major drawback for FDG as a useful tracer for this purpose. Over the years, we and other groups have demonstrated that brain tumors are associated with significant edema in the surrounding white matter, which can be readily visualized by MR (83,119,120). Such edema is frequently associated with significant suppression of cortical uptake of FDG.…”

Exploratory Analysis of Qualitative MR Imaging Features for the Differentiation of Glioblastoma and Brain Metastases

“…non-enhancing tumor margin: GBMs presented with welldefined non-enhancing tumor margin more often than BMs. Previously, brain lesions have been found to show peritumoral edema if they are larger than~9.5 mm in diameter (35). GBMs are usually large at the time of diagnosis, thus typically exhibiting extensive edema with a well-defined margin.…”