Early cerebral hypoperfusion with small artery vasospasm and delayed development of cortical T2* hypointense lesions in contrast-induced encephalopathy.

Background: Contrast-induced encephalopathy (CIE) is a rare complication arising from neurotoxicity caused by iodinated contrast agents. Its clinical presentation closely resembles that of acute stroke, which can occur following endovascular procedures. Distinguishing these two conditions is essential for proper patient management but is challenging based on clinical symptoms alone. While characteristic computed tomography findings for CIE and magnetic resonance imaging (MRI) findings for acute stroke are well established, early MRI findings of CIE - particularly in magnetic resonance angiography (MRA) and perfusion imaging (MRP) - remain underrecognized. In addition, delayed cortical hypointensities on T2*-weighted imaging (T2*WI) in chronic-stage cases have not been previously reported. Case Description: A 78-year-old woman developed CIE immediately following endovascular coil embolization for an unruptured cerebral aneurysm. Small artery vasospasms and hypoperfusion were identified on MRA and MRP, respectively, in the affected hemisphere 6 h postprocedure and resolved a day before symptom improvement. Ten months later, asymptomatic, punctate, and short linear cortical hypointensities appeared on T2*WI, suggesting microhemorrhages. Conclusion: Early transient small artery vasospasms and hypoperfusion on neuroimaging are indicative of CIE and likely contribute to the neurological symptoms of this condition. Persistent blood-brain barrier dysfunction may underlie the delayed development of cortical hypointensities on T2*WI, seen in chronic-stage CIE cases.