CASE 1188 Published on 18.07.2001
0

Post-contrast FLAIR imaging in meningitis secondary to otitis

Section

Neuroradiology

Case Type

Clinical Cases

Authors

S.Dzelzite, A.Migals, A.A.Veinbergs, R.N.Sener

Connected authors
Patient

19 years, female

Categories
No Area of Interest ; Imaging Technique MR, MR
Download as PDF Print Show related cases Notify admin
Clinical History
Ear infection
Imaging Findings
The patient was admitted with symptoms of acute middle ear and mastoid cell infection and signs of meningitis. An MRI study was performed. MRI examination protocol included T1 and T2-weighted images, and FLAIR (fluid attenuated inversion recovery) images. After a standard dose i/v administration of Gd-DTPA 0.1mmol/kg T1-weighted and FLAIR images were repeated.
Discussion
Although T2-weighted sequences are generally not used for post-contrast examination, it has recently been recognized that FLAIR images (a T2-weighted sequence), obtained after administration of contrast medium allow excellent demonstration of meningeal pathology; that is strong enhancement of the meninges in meningitis, as well as meningeal thickening, nodules and masses due to various causes. With respect to the mechanism, previous studies with post-contrast FLAIR suggest that FLAIR could be sensitive to increases in protein concentrations in the meninges resulting in a decrease in the T1 relaxation times, hence high signal changes. Another explanation of high signal of meninges on post-contrast FLAIR is disruption of the blood- brain barrier and accumulation of gadolinium chelates with resultant high signal changes. In our patient with ear infection and consequent meningitis, post–contrast FLAIR images clearly revealed meningeal involvement , although such changes were equivocal on post-contrast T1-weighted images. Therefore, it appears that post-contrast FLAIR examination is a useful method for recognizing and determination of meningeal involvement in cases of meningitis in relatively earlier stages, especially in the posterior fossa.
Differential Diagnosis List
Meningitis shown by post-contrast FLAIR imaging
Final Diagnosis
Meningitis shown by post-contrast FLAIR imaging
Case information
URL: https://eurorad.org/case/1188
DOI: 10.1594/EURORAD/CASE.1188
ISSN: 1563-4086
Figure 1

T2, and post-contrast T1 images

T2, and post-contrast T1 images
T2-weighted image shows high-signal in the right mastoid region (arrow), consistent with infection.
T2, and post-contrast T1 images
Post–contrast T1W image reveals enchancement of venous sinuses and small vessels. Basal meningeal involvement is equivocal.
T2, and post-contrast T1 images
Post–contrast T1W image at an upper level suggests abnormal enchancement along the right part of the tentorium (arrow).
Figure 2

FLAIR, and post-contrast FLAIR images

FLAIR, and post-contrast FLAIR images
FLAIR image (without contrast medium) appears normal with respect to meningeal involvement, and it is shown for comparison with FLAIR image with contrast medium (see 2b). High-signal is seen in the right mastoid region.
FLAIR, and post-contrast FLAIR images
Post–contrast FLAIR excellently demonstrates basal meningeal involvement (arrows). Also note enhancement in the right mastoid region.
FLAIR, and post-contrast FLAIR images
Post–contrast FLAIR at upper level confirms abnormal enchancement along the right part of the tentorium (arrow), differentiating it from a vessel. Note that normally flowing vessels show flow-void, in contrast to their high signal on post-contrast T1W images.