Diagnostic value of contrast-enhanced fluid-attenuated inversion recovery MR imaging of intracranial metastases.

BACKGROUND AND PURPOSE Postcontrast fluid-attenuated inversion recovery (FLAIR) imaging effectively depicts parenchymal and leptomeningeal metastases, as reported in limited patient groups. We compared postcontrast T1-weighted (T1W) and FLAIR imaging in a larger group. METHODS Sixty-nine patients with known malignancy and suspected cranial metastases underwent axial FLAIR and spin-echo T1W imaging with and then without intravenous gadopentetate dimeglumine. Postcontrast images were compared for lesion conspicuity and enhancement, number of parenchymal metastases, and extension of leptomeningeal-cisternal metastases. RESULTS Parenchymal metastases were demonstrated in 33 patients. Compared with T1W images, postcontrast FLAIR images showed more metastases in five patients, an equal number in 20, and fewer lesions in eight. Regarding lesion conspicuity, postcontrast FLAIR imaging was superior in five patients, equal in one, and inferior in 27. For enhancement, FLAIR imaging was superior in five, equal in five, and inferior in 23. Superior FLAIR results for lesion number, conspicuity, and enhancement were observed in the same five patients; in these patients, FLAIR imaging was performed as the second postcontrast sequence. Eleven patients had leptomeningeal-cisternal metastases; lesion conspicuity, extension, and enhancement were superior on postcontrast FLAIR images in eight. In five of eight patients, FLAIR imaging was performed as the second postcontrast sequence. Four patients had cranial-nerve metastases; in three, postcontrast FLAIR imaging was superior for lesion conspicuity and extension. In two of these patients, FLAIR imaging was the second postcontrast sequence. CONCLUSION Postcontrast FLAIR imaging is a valuable adjunct to postcontrast T1W imaging. Precontrast and postcontrast FLAIR imaging effectively delineates parenchymal metastases, particularly leptomeningeal-cisternal and cranial-nerve metastases.