Signal Intensity Ratio in Fluid Attenuation Inversion Recovery Sequences in Determining Cerebral Metastasis on Non-Contrast Magnetic Resonance Imaging

Abstract

Cerebral metastases are serious complications of systemic tumors. Ischemic lesions are the main differential diagnosis of cerebral metastasis. The aim of this study is to evaluate the efficiency of signal intensity ratio (SIR) in non-contrast-enhanced fluid attenuation inversion recovery (FLAIR) sequence in the detection of cerebral metastasis. Patients with brain metastasis and evaluated with brain MRI in our institution, between 2015 and 2017, were included in this study. Brain metastases were detected in contrast-enhanced fat-saturated T1-weighted images. In pre-contrast FLAIR sequences, signal intensities (SI) from metastasis, perilesional white matter, and, if present, ischemic lesion were measured. In all patients, normal white matter SI was recorded, and SI ratio (SIR = SI lesion/SI reference white matter) was calculated for standardization. A total of 59 patients with brain metastasis detected in contrast-enhanced brain MRI were included in this study. A significant difference was detected between mean metastasis SIR and mean ischemic SIR (P = 0.001); mean perilesional SIR and mean ischemic SIR (p = 0.033); minimum metastasis SIR and minimum perilesional SIR (P = 0.012); and maximum metastasis SIR and maximum ischemic SIR (p = 0.04). SIR of hyperintense lesions in FLAIR sequences may be helpful in differentiating brain metastasis from ischemic WM lesions, especially in patients contrast media is contraindicated. © 2021, The Author(s), under exclusive licence to Springer Nature Switzerland AG.