Objective <p>To investigate the utility of intravoxel incoherent motion (IVIM) magnetic resonance imaging (MRI) for early detection of renal injury 24 h after cardiac arrest and cardiopulmonary resuscitation.</p> Materials and methods <p>Twenty-four male Sprague–Dawley rats were randomized into cardiac arrest (<i>n</i> = 15) and sham-operated (<i>n</i> = 9) groups. Five cardiac arrest rats died during the procedure, resulting in 10 cardiac arrest and 9 sham rats for analysis. IVIM-MRI and renal parameters were assessed 24 h after cardiac arrest and cardiopulmonary resuscitation. Diffusion-related parameters, including apparent diffusion coefficient (ADC), true diffusion coefficient (D), pseudo-diffusion coefficient (D*), perfusion fraction (f), and exponential ADC (eADC), were obtained. The primary imaging endpoint was defined as D. Following completion of MRI, renal function, histopathology, and expression of apoptosis markers (Bcl-2, Caspase-3), water channel protein aquaporin-3, and tight junction proteins (zonula occludens-1, occludin) were subsequently evaluated.</p> Results <p>Despite preserved conventional renal function, IVIM MRI detected early renal alterations 24 h after cardiac arrest. Compared with the sham group, eADC, D, ADC, D*, and f values were all significantly reduced. Histopathological analysis revealed pronounced tubular epithelial injury, increased apoptosis (Bcl-2, <i>p</i> &lt; 0.001; Caspase-3, <i>p</i> = 0.010), and reduced expression of aquaporin-3 (<i>p</i> = 0.039), zonula occludens-1 (<i>p</i> &lt; 0.001), and occludin (<i>p</i> &lt; 0.001).</p> Conclusion <p>IVIM MRI enables early, noninvasive detection of renal injury 24 h after cardiac arrest and CPR, reflecting tubular injury, tight junction disruption, and perfusion deficits, potentially facilitating timely intervention and improving prognosis.</p> Relevance statement <p>This approach may facilitate individualized therapy and improve post-cardiac arrest syndrome outcome.</p> Key Points <p><UnorderedList Mark="Bullet"> <ItemContent> <p>The long-term outcomes of cardiac arrest remain poor due to post-cardiac arrest syndrome.</p> </ItemContent> <ItemContent> <p>IVIM MRI enables early, noninvasive detection of renal injury after cardiac arrest and cardiopulmonary resuscitation.</p> </ItemContent> <ItemContent> <p>This approach may facilitate individualized therapy and improve post-cardiac arrest syndrome.</p> </ItemContent> </UnorderedList></p> Graphical Abstract <p></p>