MR Imaging of Leptomeningeal Metastases: Comparison of Three Sequences

BACKGROUND AND PURPOSE: Recent work has shown that fluid-attenuated inversion re-covery (FLAIR) imaging with contrast enhancement is highly sensitive for detecting subarach-noid space disease. We hypothesized that contrast-enhanced FLAIR imaging has superior sensi-tivity to contrast-enhanced T1-weighted MR imaging in detecting leptomeningeal metastases. METHODS: Sixty-eight patients referred for suspected leptomeningeal metastases underwent 74 MR imaging studies. The patients had either temporally related cytologic proof of lepto-meningeal metastases or negative results of clinical follow-up confirming absence of leptomen-ingeal metastases. The MR imaging examinations included unenhanced and contrast-enhanced FLAIR images and contrast-enhanced T1-weighted MR images that were independently re-viewed by two neuroradiologists blinded to the results of cytology. Each of the three sequences was reviewed individually and separately and was assigned a score of positive or negative for leptomeningeal metastases. Discrepancies were settled by consensus. RESULTS: Of the 17 studies of patients with cytology-proven leptomeningeal metastases, two were positive based on unenhanced FLAIR images, seven were positive based on contrast-enhanced FLAIR images, and 10 were positive based on contrast-enhanced T1-weighted M