1. 53th Annual meeting of the American Society of Neuroradiology Poster #: EP-30
Usefulness of Gd-enhanced 3D T2 fluid-attenuated inversion recovery imaging in various infectious meningitis
Keiko Toyoda, Takahiro Haruyama, Hiroshi Oba, Tomonori Kanda, Megumi Matsuda, Marie Osawa, Shigeru Furui Department of Radiology Teikyo University School of Medicine
April 2015
Chicago

2. No disclosure

3. Background and purpose
T2-FLAIR imaging with Gd administration is useful for detecting superficial abnormalities, e.g. “sulcal hyperintensity” however,
CSF pulsation artifacts and flow artifacts can be problematic.
lesions may be somewhat difficult to detect in the CSF spaces.
3D T2-FLAIR imaging on 3 Tesla MR systems
can be acquired in a clinically acceptable scan time.
can obtain 3D volume data with fewer partial volume artifacts.
can eliminate or suppress flow artifacts.
can better suppress signals from the cerebrospinal fluid.
The purpose of this study is
To compared (CE) 3D T2-FLAIR with CE T1WI in the depiction of abnormal leptomeningeal hyperintensities and enhancement in cases with leptomeningitis, and
To determine the usefulness of contrast-enhanced 3D T2-FLAIR.

4. Materials and Methods The subjects
35 consecutive cases diagnosed with acute meningitis or meningoencephalitis based on clinical symptoms and spinal fluid findings
17 y.o y.o. 21 male 14 female
Gd-enhanced T1-weighted & Gd-enhanced 3D FLAIR images obtained in the same examination
Between April 2010 and September 2014
Types of infection
Bacterial cases (including: those suspected by polynucleosis in CSF; excluding tuberculosis)
Streptococcus pneumoniae 6
Others
Tuberculous （adenosine deaminase (ADA) ↑） 8
Viral （including aseptic; mononucleosis (CSF)) 11
Others （SLE, autoimmune, unknown）

5. MR Protocol for Meningitis
MRI machine: 3T GE Signa HDxt
Enhancement studies {A) & B)} with injection of Gd-DTPA 0.1mmol/kg BW
3D T2 FLAIR image “Cube” all cases TR 8000; TE ; Inversion time 2200; ETL 150; Slice thickness 1.4mm; Matrix 256x192; FOV 24cm; Acquisition time 5m55s
T1-weighted imaging: Performed one of the following two techniques B)-1　SPGR (3D GRE) / 35 cases Spoiled Gradient Recalled Echo (SPGR) TR 6.9–7.0; TE 3.15 ; Slice thickness 1.4mm; Matrix 352x256; FOV 22cm; Acquisition time　3m51s B)-2 T1 3D Cube (3D TSE) 4 / 35 cases TR 600; TE 10.9; ETL 28; Slice thickness 1.4mm; Matrix 352x256; FOV 22cm; Arc 2; Acquisition time 3m45s
Sequence of the two enhancement studies:
B)　⇒　A): 16/35 cases; A)　⇒　B): 19/35 cases
Other sequences: T2WI: TR 6200; TE 84; ETL14;　512x320; FOV 22cm 　 EPI DWI: TR 8000; 128x192; FOV 24cm or
SPGR spoiled GRASS

6. Evaluation Abnormal findings in leptomeningens:
Comparison of: Post-contrast 3D T2-FLAIR (CE 3D T2-FLAIR), and Post-contrast T1WIs (CE T1-WI) on meningeal findings
Abnormal findings in leptomeningens:
CE 3D T2-FLAIR: abnormal hyperintensity (or enhancement) in sulci cistern
CE T1WI: abnormal enhancement in sulci or cistern
Divided cistern and sulci: Each CSF space was visually evaluated on both CE 3D T2-FLAIR and CE T1WI in same slices, side by side, by two experienced neuroradiologists
Determined the better sequence for depicting abnormal findings in each cistern and sulcus
Cistern: 1. medullary cistern; 2. prepontine cistern; interpeduncular cistern; 4. suprasellar cistern;
Sulcus: 5. Sylvian fissure; 6. cerebellar hemisphere; 7. frontal lobe; occipital lobe; 9. parietal lobe; 10. temporal lobe
Other findings: Subdural space; Ventricular wall; White and Gray matter
Axial images mainly used; and coronal or sagittal images.

7. Results
Of 35 cases 5 cases No abnormal findings on both CE T2 FLAIR and CE T1WI.
These included one case of bacterial meningitis, and 4 cases of aseptic meningitis.
30 cases some hyperintensities (or enhancement) in sulci or cistern on CE 3D T2 FLAIR.
In almost all cases, these hyperintensities (or enhancement) were easier to appreciate on 3D CE T2 FLAIR than on 3D T1WI; Lesions were better depicted on CE 3D T2 FLAIR.
In bacterial meningitis, including pneumococcal, scattered nodular hyperitensities were seen on the brain surface particularly in the deep portion of cistern or sulci (interpeducular cistern, Sylvian fissure, or sulci)
Viral meningitis ( total 11 cases) was mostly of the pial-subarachinoid type, with a thin enhancement effect when there were abnormal findings. On CE 3D T2 FLAIR, cerebral fissure enhancement was seen to be diffuse, being especially prominent in the cerebral sulci of the parietal and occipital lobes. On the contrary, in 4 out of 11 cases no abnormal enhancement effect was present in the sulci or cistern.
In tuberculous meningitis (total 8 cases), diagnosed on the basis of positive ADA, CE 3D T2 FLAIR showed diffuse high signal intensity in the cerebral cistern and sulci in almost all cases.

8. Results
Cases of positive abnormal findings (depicting possible abnormalities) in each cistern or sulci, and these are more visible or equal on T2 FLAIR than on T1WI
Cistern
sulcus
Medullary
Cis.
Prepontine
Inter-pedunculear
Suprasellar
Sylvian
Fis.
Cerebelllum
Frontal
Lobe
Temporal
Occipital
Parietal
Stre.Pneumo.
(Total 6 cases)
1/6 cases
0/6
5/6
3/6
1/6
4/6
2/6
Other bacterial
(7 cases)
1/7cases
0/7
1/7
3/7
2/7
1case　SP>FL
Tuberculous
(8 cases)
7/8cases /8
7/8
4/8
6/8
8/8
Viral
(11 cases)
7/11cases
4/11
2/11
6/11
5/11
7/11

9. 52 y.o. male with bacterial meningitis (Strept. Pneumoniae)
CE T2 FLAIR
CE SPGR

10. DWI
DWI
CE 3D T2 FLAIR shows scattered small or nodular hyperintensities in interpeduncular cistern and Sylvian fissure, with corresponding hyperintensities on DWI.
Localized dural thickening and enhancement effect in frontal subdural space.
These lesions are not depicted on CE SPGR.
Sagittal CE 3D T2 FLAIR also shows hyperintensity in interpeduncular cistern.

11. 81y.o. female with bacterial meningitis (Strep. Pneumoniae)
CE T2 FLAIR
CE 3D T2 FLAIR shows scattered small or nodular hyperintensities in interpeduncular cistern and Sylvian fissure, frontal and temporal sulci, corresponding to hyperintense lesions on DWI. These lesions are not depicted on CE SPGR (Not shown).
DWI

12. 46 y.o. male with tuberculous meningitis
CE T2 FLAIR
CE 3D T2 FLAIR shows diffuse high signal intensity along the cerebral cistern and sulci. Medullary and prepontine cisterns are involved.
Miwa Kazuya
CE SPGR

13. 27 y.o. female with tuberculous meningitis
CE T2 FLAIR
CE 3D T2 FLAIR shows diffuse high signal intensity along the cerebral cistern and sulci. Prepotine and interpeduncular cistern are involved.
CE T1Cube

14. 79 y.o. female with aseptic meningitis (viral S/O)
CE T2 FLAIR
CE 3D T2 FLAIR shows pial-subarachinoidal hyperitensity in cerebellar, temporal and occipital sulci, especially on the left side.
CE SPGR v

15. 44 y.o. male with viral meningitis
CE T2 FLAIR
CE 3D T2 FLAIR shows diffuse, thin pial-subarachinoid hyperintensity, especially in occipital to parietal lobes. Hyperitensity is also noted in splenium of corpus callosum.
CE SPGR
Tanaka Itaru

16. Discussion　 　　　　1/4
Contrast-enhanced FLAIR imaging has been reported as having higher sensitivity for detecting leptomeningeal disease compared with contrast-enhanced T1-WI imaging. However, concerns regarding its utility have been raised. CSF pulsation artifacts on 2D T2-FLAIR images may render the detection of lesions in the CSF spaces difficult. In a large series by Singh et al, they reviewed 74 MR images of suspected leptomeningeal metastases. Results proved that fast FLAIR was less sensitive than standard T1-WI spin-echo sequences for detecting contrast enhancement of neoplastic leptomeningeal disease (2002). Galassi et al also reported that CE T1-WI MR imaging with FS is superior to contrast-enhanced FLAIR imaging in most cases for depicting a variety of meningeal diseases (infections, meningitis or leptomeningeal metastasis). The contrast between the enhancing lesions and non-enhancing tissue was greater on CE T1WI (2005). These studies used 2D techniques on 1.5 T MR systems.

17. Discussion 2/4
Recently, Three-dimensional (3D) T2-FLAIR sequences can be acquired in a clinically acceptable scan time on 3 Tesla MR systems. 3D imaging techniques produce 3D volume data with less partial volume artifacts. With the FLAIR method as a 3D method flow artifacts disappear, and the signals from the cerebrospinal fluid are better suppressed. Fukuoka and Hirai et al have reported that CE 3D T2 FLAIR provides more additional information than CE GRE (MPRAGE) T1WI. Leptomeningeal enhancement on postcontrast 3D T2-FLAIR images may indicate true leptomeningeal enhancement. In our study, we focused on non-tumorous, infectious meningitis, and found CE 3D T2 FLAIR was superior to CE 3D T1WIs in depicting leptomeningeal lesions. We evaluated meningeal lesions in cistern and sulci, classified the lesions according to the region and showed there to be some tendency depending on the organism (next slide). Factor of hyperintensity on CE 3D T2 FLAIR: leakage of contrast material to CSF by increased permeability of vessels or inflammation in leptomeningens

18. Discussion 3/4 Bacterial meningitis, including pneumococcal;
35 consecutive cases diagnosed with acute meningitis or meningoencephalitis based on clinical symptoms and spinal fluid findings.
scattered nodular enhancement on the brain surface particularly in the deep regions
high intensity on DWI possibly indicating an accumulation of pus
associated with dural enhancement which can be better detected on CE 3D T2-FLAIR, compared to on CE T1WI.
Viral meningitis;
mostly of the pial-subarachinoid-type enhancement effect, thin enhancement effect and seen to be diffuse.
parenchymal change
no abnormal enhancement effect in half of the cases
Tuberculous meningitis;
diffuse hyperintensity in the cerebral fissure in almost all cases.
Basal cisterns (prepontine and interpeduncular cistern)

19. Study limitations Discussion4/4 Small number of cases
Few cases with radiologically severe meningitis
No comparable precontrast 3D T2 FLAIR
On CE 3D T2 FLAIR, “hyperintensity” is not exactly the same as “contrast enhancement effect,”  possibly due to pus or dirty CSF.
Further study is needed with a detailed comparison of DWI, and patient follow up.

20. Conclusion
In this study Gd-enhanced 3D T2 FLAIR imaging provided more information, compared to Gd enhanced T1-weighted imaging in cases with infectious meningitis. Further, Gd-enhanced 3D T2 FLAIR imaging plays an important role as a postcontrast study in the diagnosis of meningitis.

21. References
Tsuchiya K et al. FLAIR MR imaging for diagnosing intracranial
meningeal carcinomatosis. AJR 2001;176:
2)　Griffiths PD et al: Contrast-enhanced fluid-attenuated inversion recovery imaging for leptomeningeal disease in children. AJNR 2003;24:
3). Singh SK et al. Intracranial leptomeningeal metastases: comparison of depiction at FLAIR and contrast-enhanced MR imaging. Radiology Oct;217(1):50-3.
4) Galassi W et al. Intracranial meningeal disease: comparison of contrast-enhanced MR imaging with fluid-attenuated inversion recovery and fat-suppressed T1-weighted sequences. AJNR ;26:553-9
5) Fukuoka H, Hirai T, et al. Comparison of the added value of contrast-enhanced 3D fluid-attenuated inversion recovery and magnetization-prepared rapid acquisition of gradient echo sequences in relation to conventional postcontrast T1-weighted images for the evaluation of leptomeningeal diseases at 3T. AJNR 2010;31:
6) Oztopriak I et al. Contrast medium-enhanced MRI findings and changes over time in stage 1 tuberculosis meningitis Clincal Radiology 2007;62: