THE ROLE OF MRI IN DETECTING ACUTE LESIONS OF MULTIPLE SCLEROSIS USING DIFFUSION-WEIGHTED IMAGING AND CONTRAST-ENHANCED T1WI

Sara Shmayyes*, Fawaz Baddour and Issa Layka

ABSTRACT

Introduction: Multiple Sclerosis (MS) or disseminated sclerosis is a chronic inflammatory demyelinating disease, expressed as a degenerative disease in the central nervous system (CNS). MS is a heterogeneous, multifactorial disease mediated by the immune system and caused by complex interactions between genes and the environment. The pathological hallmark of MS is the accumulation of demyelinating lesions primarily in the white matter and partially in the gray matter of the brain and spinal cord. There is no single diagnostic tool for MS, as the diagnosis relies on a combination of clinical history, laboratory tests, and medical imaging examinations. MRI is the most sensitive imaging method for detecting the spatial and temporal dispersion of asymptomatic white matter lesions, which underscores its importance in the early diagnosis of MS patients. Its sensitivity during the first year after an attack is about 94%, with a specificity of approximately 83%. MRI also helps in excluding alternative differential diagnoses such as spinal cord compressions and brain tumors. Early diagnosis is crucial as MS is the most frequent cause of neurological disability of non-traumatic origin, and early diagnosis plays a significant role in the immediate initiation of effective treatment. The contrast enhanced T1 Weighted Imaging (CE T1WI) has been used as the gold standard for distinguishing between active and inactive MS lesions3. However, there are some cases in which the use of gadolinium-based contrast agents (GBCAs) is contraindicated, or costly for patients, in addition to the extra time required for the examination with injection. Therefore, finding an alternative imaging technique with fewer contraindications, no additional cost, and reduced examination time while maintaining good diagnostic value is important. This highlights the significance of Diffusion-Weighted Imaging (DWI), which has emerged over the past decade as a new functional alternative for detecting brain lesions in MS patients. Moreover, distinguishing between active and chronic lesions is somewhat subjective due to several factors that can affect enhancement. Given the drawbacks of conventional MRI, finding an alternative imaging technique could be of significant value. Study Objective: This study aims to evaluate the sensitivity and specificity of Diffusion-Weighted Imaging (DWI) in detecting active lesions in MS patients, in addition to comparing the diagnostic value of DWI and CE-T1 in detecting active lesions. Patients and Methods: The study includes patients diagnosed with multiple sclerosis (MS) who are currently experiencing clinical symptoms indicative of active lesions. These patients underwent 1.5 Tesla MRI scans at Tishreen University Hospital between March 2022 and January 2024. Results: In this study, we followed 66 MS patients who were experiencing clinical symptoms indicative of active lesions. The ages of the patients in the sample ranged from 13 to 53 years, with a mean age of approximately 29.7 ±7.09 years. Conclusion: Our study showed that contrast-enhanced T1-weighted imaging (CE-T1) detected the highest number of MS lesions compared to Diffusion-Weighted Imaging (DWI). Despite the presence of false-positive lesions, the DWI/ADC map demonstrated a good ability to detect active lesions compared to CE-T1, with a sensitivity of 94%, specificity of 82%, positive predictive value (PPV) of 79%, negative predictive value (NPV) of 80%, and diagnostic accuracy of 83.4%. Therefore, DWI can be used during acute attacks alongside CE-T1 in cases where contrast injection is not feasible. Nevertheless, CE-T1 remains the gold standard for detecting active lesions in MS patients.

Keywords: Multiple Sclerosis (MS), Contrast-Enhanced T1-Weighted Imaging (CE-T1WI), Diffusion-Weighted Imaging (DWI), Magnetic Resonance Imaging (MRI).