Intracranial meningeal disease: comparison of contrast-enhanced MR imaging with fluid-attenuated inversion recovery and fat-suppressed T1-weighted sequences

Abstract

Background and purpose: Contrast-enhanced fluid-attenuated inversion recovery (FLAIR) imaging has been reported to have higher sensitivity for detecting leptomeningeal disease compared with contrast-enhanced T1-weighted MR imaging. The purpose of this study was to compare contrast-enhanced T1-weighted MR images with fat suppression to contrast-enhanced FLAIR images to determine which sequence was superior for depicting meningeal disease.

Methods: We reviewed MR images of 24 patients (35 studies) with a variety of meningeal diseases. The MR imaging protocol included contrast-enhanced T1-weighted MR images with fat suppression (FS) and contrast-enhanced fluid-attenuated inversion recovery (FLAIR) images that were reviewed by three neuroradiologists and were assigned a rating of positive, equivocal, or negative for abnormal meningeal enhancement. The two sequences were compared side by side to determine which better depicted meningeal disease.

Results: Abnormal meningeal enhancement was positive in 35 contrast-enhanced T1-weighted MR images with FS and in 33 contrast-enhanced FLAIR studies. In the first group, which had the T1-weighted sequence acquired first (21 of 33 studies), contrast-enhanced T1-weighted images with FS showed superior contrast enhancement in 11 studies (52%), inferior contrast enhancement in six studies (29%), and equal contrast enhancement in four studies (19%) compared with the contrast-enhanced FLAIR images. In the second group, which had the FLAIR sequence acquired first (12 of 33), contrast-enhanced T1-weighted images with FS showed superior contrast enhancement in seven studies (58%), inferior contrast enhancement in two studies (17%), and equal contrast enhancement in three studies (25%).

Conclusion: Contrast-enhanced T1-weighted MR imaging with FS is superior to contrast-enhanced FLAIR imaging in most cases for depicting intracranial meningeal diseases.

Fig 1.

Cryptococcal meningitis. A, Contrast-enhanced FLAIR image shows slight leptomeningeal enhancement in the right frontoparietal region (arrows). It is difficult to separate meningeal enhancement from other high signal intensity within the sulci and from adjacent parenchymal disease. B, Contrast-enhanced T1-weighted image with FS shows greater contrast between the enhancing tissue and the adjacent brain and is better for depicting enhancement within the sulci and the interhemispheric fissure (arrows). C, Contrast-enhanced FLAIR image of the same patient obtained at the level of the sylvian fissures shows subtle enhancing lesions in the basal ganglia bilaterally, but without a noncontrast FLAIR image for comparison it is not possible to distinguish enhancement from parenchymal edema. D, Contrast-enhanced T1-weighted image with FS shows multiple punctuate enhancing areas within the basal ganglia bilaterally, due to cryptococcomas within dilated Virchow-Robin spaces (arrows). The enhancement is much more conspicuous on the T1-weighted image. Additional enhancement is present in several inferior sulci in both frontal lobes.

Fig 2.

Tuberculous meningitis. A, Contrast-enhanced FLAIR image shows mildly enhancing subarachnoid space lesions in the basilar cisterns, with extension into the sylvian fissures bilaterally, right ambient cistern, and quadrigeminal cistern. B, Contrast-enhanced T1-weighted image with FS shows the enhancing lesions in the subarachnoid space more definitively (arrows). The contrast difference between the enhancing meninges and the adjacent brain is visually greater in the T1-weighted image. C, Contrast-enhanced FLAIR image of the same patient shows enhancement in the region of the right third cranial nerve, but the nerve is not clearly seen. D, The enhancement of the right third cranial nerve (arrow) is more distinct on the contrast-enhanced T1-weighted image with FS.

Fig 3.

Transitional cell carcinoma of the urinary bladder with calvarial metastases and meningeal extension. A, Contrast-enhanced FLAIR image shows localized mild pachymeningeal enhancement (arrows) adjacent to the focal destructive lesion of the right parietooccipital bone. The hyperintensity of adjacent white matter edema is clearer on contrast-enhanced FLAIR image. Note that the internal cerebral veins and cortical veins do not enhance on the FLAIR image. Similarly, the hypervascular pachymeninges (arrows) with increased blood pool does not enhance nearly as much as on the T1-weighted image in panel B. B, The pachymeningeal enhancement is more apparent and appears thicker on a contrast-enhanced T1-weighted image with FS (arrow). The enhancing cortex is distinct from the underlying hypointense edema.

Fig 4.

Tuberculous meningitis. A, Contrast-enhanced FLAIR image shows hyperintensity along the meninges and within several sulci of the left parietal lobe (arrowheads). A precontrast FLAIR image was not available to assess how much of the hyperintensity reflected T2 signal intensity and how much was true enhancement. B, Contrast-enhanced T1-weighted image with FS reveals enhancement in the same area (arrows), but the enhancement is less intense and less extensive.