Accuracy of delayed post-contrast flair MR imaging for the diagnosis of leptomeningeal infectious or tumoral diseases

Differentiation of Leptomeningeal and Vascular Enhancement on Post-contrast FLAIR MRI Sequence: Role in Early Detection of Infectious Meningitis

“…In concordance with a previous report by Kremer et al, [12], we have also used qualitative accuracy as a statistical parameter to compare the FLAIR and T1W sequences in detection of infectious meningitis. The sensitivity and specificity was not estimated as the CSF culture is not possible in some cases of viral meningitis.…”

“…We further observed that meningeal enhancement in cases of tubercular and pyogenic meningitis was appreciated readily on both PCFLAIR (100%) and PCTIW (76.2%) especially in region of basal cisterns. However, the SI from enhancing meninges in sulcal spaces along cerebral convexities is not unequivocally distinguishable from vascular enhancement on PCT1W, leading to the lower accuracy of PCT1W as also seen in other previous studies [3,12]. Better accuracy of PCFLAIR in infectious meningitis can further be explained by increased leakage of contrast from pial vessels into adjacent CSF from acutely inflamed meninges.…”

“…Splendiani et al, [11] found the overall sensitivity of enhanced FLAIR sequence to be 100% while Parmar et al, [13] found it to be 85%. In the study by Kremer et al, [12], the accuracy in various leptomeningeal diseases including meningitis was 90%. Singh et al, [16] and Galassi et al, [18] have reported contrast enhanced PCTW1 with FS to be superior to contrast enhanced FLAIR imaging in leptomeningeal diseases.…”

“…These agents predominantly work by shortening the T1 relaxation time of protons located nearby which leads to enhancement of tissues. Other sequences have also been attempted to detect contrast enhancement in various meningeal pathologies like Proton density, T1-weighted sequence with MT saturation, T1-weighted with fat suppression and FLAIR including 3D FLAIR sequence [3,[4][5][6][7][8][9][10][11][12][13][14][15][16][17][18]. Sequences based on T1-weighting have various limitations like too much vascular enhancement, flat images, and inflow effects [19].…”

“…However, in the last decade, post-contrast Fluid Attenuated Inversion Recovery (PCFLAIR) has emerged as a useful sequence to evaluate leptomeningeal pathologies [4][5][6][7][8][9][10][11][12][13][14][15][16]. The nullification of CSF signal, inconspicuous vascular enhancement as compared to T1-weighted imaging (T1WI) and some degree of T1 relaxivity effect makes meningeal enhancement easily discernible on PCFLAIR images [7,[11][12][13][14]. Despite its utility in leptomeningeal diseases, there have been controversies regarding the routine use of PCFLAIR in MR practice and its relative advantage over post contrast T1WI (PCT1W) with or without fat suppression (FS) [15][16][17][18].…”