Diffusion Weighted Imaging versus Contrast-enhanced T1-weighted Imaging Sequences in Inflammatory Demyelinating Diseases of Brain: A Cross-sectional Study

Abstract

Introduction: Based on the literature, Contrast-enhanced T1-Weighted (CE T1WI) imaging sequence is considered as the gold standard radiological marker of active inflammatory demyelinating diseases of brain. However, administration of gadolinium based contrast agents is not always possible due to various comorbidities that the patient may suffer from, such as chronic kidney disease or contrast allergy. Diffusion Weighted Imaging (DWI) may potentially play a role in identifying disease activity in such cases without the need for intravenous administration of contrast. Aim: To compare signal intensity of lesions in inflammatory demyelinating diseases of brain on DWI with the status of enhancement on CE T1WI. Materials and Methods: This was a cross-sectional study conducted for two years from June 2015 to June 2017 among patients in the age group of two to 50 years presenting with clinicoradiological features of inflammatory demyelinating diseases in the Department of Radiodiagnosis in collaboration with Department of Neurology, Vardhman Mahavir Medical College (VMMC) and Safdarjung Hospital, New Delhi, India. Magnetic Resonance Imaging (MRI) of brain was done using different imaging sequences such as T1-Weighted Imaging (T1WI), T2-Weighted Imaging (T2WI), Fluid Attenuated Inversion Recovery (FLAIR), DWI, CE T1WI and were analysed for the lesions of demyelinating diseases. The signal intensity of demyelinating lesions on DWI were assessed against Contrast Enhancement on CE T1W1 imaging. Validity measures were estimated using appropriate formulae. Data was entered into Microsoft Excel software and qualitative variables were assessed for significance using Fisher’s-exact test. Sensitivity, specificity, negative predictive value, positive predictive value and accuracy were assessed. Data analysis was done using Statistical Package for the Social Sciences (SPSS) software version 18.0. Results: There were a total of 73 contrast enhancement lesions. DWI hyperintensity showed 100% sensitivity, 60.9% specificity, positive predictive value of 84.7% and negative predictive value of 100% with accuracy of 87.7% whereas diffusion restriction showed 100% specificity, 12% sensitivity, positive predictive value of 100% and negative predictive value of 34.3% with accuracy of 39.7%. Conclusion: Hence, hyperintense lesions in DWI can be considered as a better screening tool and diffusion restriction can be considered as a diagnostic tool in active phase of inflammatory demyelinating diseases of brain, when compared to CE T1WI sequence.