Purpose Increase in FLAIR signal of the fluid within the resection cavity is described as a highly specific and early sign for tumor recurrence in gliomas. The aim of this study was to assess the prognostic value of FLAIR signal increase in partially or completely resected brain metastases. Materials and Methods 209 cases of surgery for brain metastases were assessed. 41 cases with at least two follow-up MRIs were retrospectively included in this study. Quantitative and qualitative assessment of the FLAIR signal intensity of the fluid within the resection cavity was performed in the MRI examination at recurrent disease/last contact and in the previous MRI examination. Results 3 of 6 cases with local tumor recurrence showed a FLAIR signal increase (sensitivity 50.0 %, specificity 100.0 %). In one case, this sign was observed even about 3 months before tumor recurrence. The specificity of FLAIR signal increase for overall tumor recurrence (local and distant) was also 100.0 %, but with a lower sensitivity of 13.0 %. Quantitative analysis showed significant differences for signal intensity of the resection cavity as well as for the change of signal intensity of the resection cavity in cases with or without local tumor recurrence. Conclusion An increase in FLAIR signal of the fluid within the resection cavity might be a highly specific and early sign of local tumor recurrence/tumor progression also for brain metastases. Key points: · An increase in FLAIR signal intensity of the fluid within the resection cavity is also observed in previously resected brain metastases.. · The pathophysiology of this sign might be due to a cell-proliferative process.. Citation Format · Bette S, Gempt J, Wiestler B et al. Increase of the FLAIR Signal of the Fluid within the Resection Cavity as Early Recurrence Marker: Also Valid for Brain Metastases?. Fortschr Röntgenstr 2017; 189: 63 - 70.     «

Purpose Increase in FLAIR signal of the fluid within the resection cavity is described as a highly specific and early sign for tumor recurrence in gliomas. The aim of this study was to assess the prognostic value of FLAIR signal increase in partially or completely resected brain metastases. Materials and Methods 209 cases of surgery for brain metastases were assessed. 41 cases with at least two follow-up MRIs were retrospectively included in this study. Quantitative and qualitative assessment of...     »