Investigating the Role of Intravoxel Incoherent Motion Diffusion-Weighted Imaging in Evaluating Multiple Sclerosis Lesions

<b>Background</b>: Multiple sclerosis (MS) is a chronic and heterogeneous disease characterized by demyelination and axonal loss and damage. Magnetic resonance imaging (MRI) has been employed to distinguish these changes in various types of MS lesions. <b>Objectives:</b> We aimed to evaluate intravoxel incoherent motion (IVIM) diffusion and perfusion MRI metrics across different brain regions in healthy individuals and various types of MS lesions, including enhanced, non-enhanced, and black hole lesions. <b>Methods:</b> A prospective study included 237 patients with MS (65 males and 172 females) and 29 healthy control participants (25 males and 4 females). The field strength was 1.5 Tesla. The imaging sequences included three-dimensional (3D) T₁, 3D fluid-attenuated inversion recovery, two-dimensional (2D) T₁, T₂-weighted imaging, and 2D diffusion-weighted imaging (DWI) sequences. IVIM-derived parameters-apparent diffusion coefficient (ADC), pure molecular diffusion (<i>D</i>), pseudo-diffusion (<i>D</i>*), and perfusion fraction (<i>f</i>)-were quantified for commonly observed lesion types (2506 lesions from 224 patients with MS, excluding 13 patients due to MRI artifacts or not meeting the diagnostic criteria for RR-MS) and for corresponding brain regions in 29 healthy control participants. A one-way analysis of variance, followed by post-hoc analysis (Tukey's test), was performed to compare mean values between the healthy and MS groups. Receiver operating characteristic curve analyses, including area under the curve, sensitivity, and specificity, were conducted to determine the cutoff values of IVIM parameters for distinguishing between the groups. A <i>p</i>-value of ≤0.05 and 95% confidence intervals were used to report statistical significance and precision, respectively. <b>Results:</b> All IVIM parametric maps in this study discriminated among most MS lesion types. ADC, <i>D</i>, and <i>D</i>* values for MS black hole lesions were significantly higher (<i>p</i> < 0.0001) than those for other MS lesions and healthy controls. ADC, <i>D</i>, and <i>D</i>* maps demonstrated high sensitivity and specificity, whereas <i>f</i> maps exhibited low sensitivity but high specificity. <b>Conclusions:</b> IVIM parameters provide valuable diagnostic and clinical insights by demonstrating high sensitivity and specificity in evaluating different categories of MS lesions.