Increased signal intensity in FLAIR sequences in the resection cavity can predict progression and progression-free survival in gliomas

Abstract

Objective: To determine if hyperintense fluid in the postsurgical cavity on follow-up fluid-attenuated inversion recovery (FLAIR) sequences can predict progression in gliomas.

Material and methods: Observational study of magnetic resonance imaging signal of fluid within the post-surgical cavity in patients with glioma (grade II-IV), with surgery and follow-up between 2007 and 2012. Qualitative comparison between the signal of fluid in the cavity and of the ventricular cerebrospinal fluid (CSF) was performed on FLAIR sequences. Fluid in the cavity was classified as isointense or hyperintense compared to CSF. Double-blind reading was performed. The signal intensity was correlated with tumour progression, assessed using Response Assessment in Neuro-Oncology criteria.

Results: A total of 107 patients were included, of whom 90 had high-grade gliomas. Inter-rater agreement was excellent, and intra-rater complete (k=0.94 and 1, p<.001). Hyperintense fluid in the resection cavity occurred more commonly (58.9% versus 29.4%, p=.025) and earlier (mean 4.5 versus 9.9 months, p<.001) in high-grade than in low-grade gliomas. Hyperintense fluid was associated with progression in high-grade gliomas, with a sensitivity of 65.7% (95%CI, 54.3-75.6%) and a specificity of 70.6% (95%CI, 46.6-87%), and in low-grade gliomas with a sensitivity of 50% (95%CI, 18.7-81.2%), and a specificity of 81.8% (95%CI, 51.1-96%). The positive predictive value of this sign was 90.6% (95%CI, 79.3-96.3%) for high-grade gliomas, and was higher for grade IV (93.2%, 95%CI, 87.3-99.1%) and lower for grade III (77.8%, 95%CI, 59.6-96%), and low-grade gliomas (60%, 95%CI, 22.9-88.4%). False-positives were identified in 7 patients, due to bleeding or infection. Hyperintense fluid in high-grade gliomas preceded progression in 22 patients (30.1%), with a mean of 4.1 months (SD 2.1, 95% CI, 3.2-5), and associated with poorer progression-free survival (mean 6.8 versus 11.7 months, p=.004).

Conclusions: Hyperintense fluid in the resection cavity on follow-up FLAIR sequences occurs more frequently and earlier in high-grade gliomas, and is associated with poorer progression-free survival. Hyperintense fluid is associated with disease progression, and can predict the progression of resected gliomas. False-positives due to bleeding and infection can be observed, and are easily recognizable.

Keywords: FLAIR; Glioblastoma; Glioma; Magnetic resonance imaging; Progresión; Progression; Resonancia magnética.