ABSTRACT
It is well known in the literature that Apparent Diffusion Coefficient (ADC) obtained during diffusion-weighted MRI of brain is sensitive in detecting and differentiating low-grade and aggressive meningiomas. However, other studies establish no correlation between mean-ADC and ultimate classification as benign, atypical or malignant. We wanted to assess the correlation between, A. mean of MRI Apparent Diffusion Coefficient (mean-ADC) and B. meningioma biomarker Ki-67 proliferation index, in cases of both low-grade and aggressive meningioma. We also wanted to assess the sensitivity of mean-ADC for diagnosing an aggressive meningioma.METHODSWe analysed 66 surgically treated meningioma patients with complete histopathology report (HPR) in Government Medical College, Kozhikode during the period of study (Nov-2017-Oct-2018), also having a pre-operative mean-ADC value during Diffusion Weighted Imaging (DWI) investigation at the same centre. For the latter, a standard MRI brain protocol including diffusion imaging was conducted and ADC map was generated. Regions of interest (ROIs) were manually drawn within the tumour on ADC map and mean-ADC values were measured.RESULTSUsing Pearson correlation coefficient, we found a significant negative correlation between Ki-67 proliferation index and mean-ADC in meningioma cases. We also calculate 0.79 x 10-3 mm2/s being a reasonable mean-ADC cut-off value due to its sensitivity of 84% and specificity of 77% in differentiating between typical and atypical meningiomas.CONCLUSIONSThe non-invasive calculation of mean-ADC is a valid diagnostic tool. Further, mean ADC can be used as a good test to differentiate typical and atypical meningiomas. The latter is a particularly valid conclusion, since there were few results from conventional MRI studies to differentiate between various typical and atypical meningiomas.
ABSTRACT
Fluid Attenuated Inversion Recovery (FLAIR) MRI of brain is sensitive in detecting parenchymal lesions, extra axial lesions such as meningoencephalitis, and leptomeningeal tumoural disease. We wanted to compare gadolinium enhanced T2W FLAIR with PC-T1W (post contrast T1 weighted) MRI sequence in detection and evaluation of meningeal and parenchymal lesions. We also wanted to compare gadolinium enhanced T1W FLAIR with PC-T1W MRI sequence in detection and evaluation of meningeal and parenchymal lesions.METHODS65 patients with clinical diagnosis of cerebral meningitis or intracranial tumoural disease were scanned on 1.5 T 16 channel MRI scanner. A standard brain protocol was used, followed by PC-T1W and post contrast FLAIR, with PC-T1W MR preceding post contrast FLAIR. Images were assessed independently by 2 radiologists who marked the technique they thought had made the meningeal and parenchymal disease more conspicuous. In case of disagreement the radiologists made a consensus determination.RESULTSPC-T2 FLAIR showed better enhancement in 100% of the intra axial lesions compared to PC-T1W images. However, PC-T1 FLAIR showed better enhancement than PC-T1W images in only 81% of the same. PC-T2 FLAIR showed better enhancement in 100% of the extra-axial lesions compared to PC-T1W images. However, PC-T1 FLAIR showed less enhancement in all the extra axial lesions.CONCLUSIONSContrast enhanced T2 FLAIR MRI showed better enhancement of parenchymal and meningeal lesions. PC-T2 FLAIR detected more number of lesions when compared to PC-T1W, aided better delineation of extra-axial mass lesions due to superior enhancement, and had a better demarcated dural tail. Post-contrast T2 FLAIR images should be included in routine protocol for contrast MRI brain study.