Comparison of post-contrast T1 and post-contrast FLAIR sequences in detecting intra-cranial pathology in paediatrics.

Abstract Background: Depending on location of the lesion, intracranial lesions can be classified into two compartments: - extra-axial: referring to intracranial structures outside the brain parenchyma, as lesions affecting the skull, meninges, pituitary gland, pineal gland or cranial nerves. Intra-axial: referring to lesions affecting the brain parenchyma itself. These can be classified into neoplastic or inflammatory. Aim of study : to assess the role of contrast enhanced (CE)-Flair versus CE-T1 sequences in evaluating different intra-cranial pathologies in paediatrics. Patients and Methods: This is a prospective analytical study (cross sectional study design) of diagnostic tests. Pre and post contrast FLAIR were compared by contrast enhanced index. Also,Contrast enhanced FLAIR and Post contrast T1 were compared by lesion to background ratio Results: This study was conducted on 37 paediatric patients ( 32 patients with intra-parenchymal lesions & 5 patients with meningeal enhancement and subependymal nodules) .There was no statistically significant difference regarding the number of detected lesions between pre and post-contrast FLAIR. However, the lesions were more obvious in CE-FLAIR,the two observers suggested that the CE-FLAIR was better than pre contrast FLAIR in 87.5 % and 81.5% ,respectively. The Contrast enhancement index was significantly higher in post-contrast FLAIR (P-value <0.001). There was no statistically significant difference regarding the number of lesions in post contrast T1 and post contrast FLAIR. however, the contrast enhancement of the lesions in CE Flair was superior than CE-T1. We found excellent agreement between the two observers, Kappa value (0.4). lesion to background ratio was found to be significantly higher (p<0.05) in post contrast FLAIR than in post contrast T1. The CE FLAIR sequence was found to be superior than CE-T1 in the detection of cerebral metastasis ,follow up of brain tumors after therapy, hypo-vascularized brain tumors, in superficial parenchymal lesions , inflammatory brain conditions and in detection of meningeal enhancement and other extra-axial lesions . Conclusion: Compared to CE-T1 and pre-contrast FLAIR, CE-FLAIR was found to have better lesion detection, higher contrast enhanced index and lesion to background ratio, especially in peripherally located lesions in many intracranial pathologies.