Objective To assess the MR characterization of coronary microembolization (CME)in an animal model as well as the evolution using MR cardiac cine,first-pass perfusion,and delay enhancement imaging.Methods Coronary microembolization models were established through intracoronary infusion of 120 000 microspheres (42 μm)into the left anterior descending artery in 1 1 pigs. Coronary angiography was performed at baseline and immediately after the injection of microspheres.MR imaging was carried out at baseline,6 hours,and 1 week after microembolization.Then,postmortem evaluation was performed using NBT and HE staining.Re-sults Coronary angiography after the injection of microspheres showed normal-appearing epicardial arteries in all animals.Coronary microembolization caused a significant decline in systolic wall thickening of the microembolized myocardial segments on cine MR ima-ges [from (42.6±2.0)% at baseline to (20.3±2.3)% at 6 hours and (31.5±2.1)% at 1 week after CME;P < 0.001 for both]. First-pass perfusion deficit was visualized at 6 hours after microembolization,and was less pronounced at 1 week.Hyperenhanced myocardium was found on delay enhancement MRI at 6 hours after microembolization in microembolized segments,but was not shown at 1 week. The microinfarcts were detectable microscopically through HE staining but invisible for the naked eye on gross NBT specimen.Con-clusion Coronary microembolization may cause a persistent decline in myocardial contraction and its MR characterization may vary with different stages.A combined use of different cardiac MRI techniques and follow-up examinations may be helpful for evaluating myocardial impairment due to coronary microembolization.

OBJECTIVE: To assess magnetic resonance imaging (MRI) features of coronary microembolization in a swine model induced by small-sized microemboli, which may cause microinfarcts invisible to the naked eye. MATERIALS AND METHODS: Eleven pigs underwent intracoronary injection of small-sized microspheres (42 microm) and catheter coronary angiography was obtained before and after microembolization. Cardiac MRI and measurement of cardiac troponin T (cTnT) were performed at baseline, 6 hours, and 1 week after microembolization. Postmortem evaluation was performed after completion of the imaging studies. RESULTS: Coronary angiography pre- and post-microembolization revealed normal epicardial coronary arteries. Systolic wall thickening of the microembolized regions decreased significantly from 42.6 +/- 2.0% at baseline to 20.3 +/- 2.3% at 6 hours and 31.5 +/- 2.1% at 1 week after coronary microembolization (p < 0.001 for both). First-pass perfusion defect was visualized at 6 hours but the extent was largely decreased at 1 week. Delayed contrast enhancement MRI (DE-MRI) demonstrated hyperenhancement within the target area at 6 hours but not at 1 week. The microinfarcts on gross specimen stained with nitrobluetetrazolium chloride were invisible to the naked eye and only detectable microscopically. Increased cTnT was observed at 6 hours and 1 week after microembolization. CONCLUSION: Coronary microembolization induced by a certain load of small-sized microemboli may result in microinfarcts invisible to the naked eye with normal epicardial coronary arteries. MRI features of myocardial impairment secondary to such microembolization include the decline in left ventricular function and myocardial perfusion at cine and first-pass perfusion imaging, and transient hyperenhancement at DE-MRI.
Animals ; Coronary Angiography/*methods ; Coronary Vessels/*pathology ; Disease Models, Animal ; Embolism/*pathology ; Female ; Heart/radiography ; Image Processing, Computer-Assisted ; Magnetic Resonance Imaging/*methods ; Microspheres ; Myocardial Contraction/physiology ; Myocardial Infarction/*pathology ; Myocardium/pathology ; Nitroblue Tetrazolium ; Staining and Labeling ; Swine ; Troponin T/blood ; Ventricular Function, Left

In addition to causing high disability and high fatality rates, ruptured intracranial aneurysms can also cause cognitive impairment. Although preventive surgical treatment can avoid intracranial aneurysm rupture and bleeding, patients may still have a certain degree of cognitive impairment, even in patients with good clinical recovery after surgery. There is no systematic review on the effect of different surgical methods on cognitive function, and the best surgical method is still inconclusive. This article reviews the cognitive impairment in patients with intracranial aneurysm, hoping to provide a basis for clinical treatment decisions.