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Updated: Mar 11, 2026
Author Spotlight: A Novel Approach to Cerebral Ischemia Modeling – Enhancing Reperfusion and Simplifying Procedure
Published on: May 31, 2024
Variable MR and pathologic patterns of hemorrhage after iodinated contrast infusion in MCA occlusion/reperfusion
Humberto Morales1, Aigang Lu2, Yuko Kurosawa2
1Department of Radiology, University of Cincinnati Medical Center, Cincinnati, Ohio, USA.
Objective:
To examine the hypothesis that IA reperfusion with iso-osmolar iodixanol, low-osmolar iopamidol, or saline causes different effects on MR signal changes and pathologic cut-brain section related to hemorrhagic transformation (HT) or iodinated radiographic contrast media (IRCM) deposition.
Methods:
Infarct was induced in 30 rats by middle cerebral artery suture occlusion. Reperfusion was performed after 5 hours with iso-osmolar iodixanol (n=9), low-osmolar iopamidol (n=12) or saline (n=9). MR images were obtained immediately after reperfusion and rats were sacrificed at 24 hours. Hypointense areas within the infarction on T2-weighted (T2-WI) or gradient echo (GRE) images were recorded and compared with HT on pathology. Fisher's exact test was used for proportions, and receiver operator curve analysis to evaluate MRI discrimination of hemorrhage.
Results:
Two types of HT were noted on pathology: confluent >0.2 mm petechial hemorrhage (PeH, 78%) or well-defined ≤0.2 mm hemorrhagic focus (HF, 22%). PeH was least common in the iodixanol subgroup (p<0.02). HF was more common in the IRCM group. Hypointense areas on T2-WI but not on GRE were significantly more common in the IRCM group (p<0.05). Hypointense areas on T2-WI and GRE discriminated HT (area under the curve: 0.714, p<0.002).
Conclusions:
IRCM and saline induced different MRI signal and pathologic patterns in our sample. We postulate that T2 hypointensity with no GRE hypointensity might be associated with IRCM deposition; and decreased frequency of PeH after iodixanol infusion and the presence of HF almost exclusively in the IRCM group might represent a direct/indirect effect of contrast infusion/deposition in the brain parenchyma after reperfusion. Our results support previous observations in IMS III and are hypothesis generating.
Insights
Different iodinated radiographic contrast media (IRCM) and saline reperfusion strategies impact brain MRI signals and pathology after stroke. Iodixanol reduced petechial hemorrhage, while IRCM deposition may correlate with specific MRI signal changes.
Area of Science:
- Neurology
- Radiology
- Pathology
Background:
- Hemorrhagic transformation (HT) is a complication of ischemic stroke reperfusion.
- Iodinated radiographic contrast media (IRCM) are used during endovascular procedures.
- The impact of different IRCM on post-reperfusion brain injury is not fully understood.
Purpose of the Study:
- To investigate if iso-osmolar iodixanol, low-osmolar iopamidol, or saline reperfusion differentially affects MR signal changes and pathological findings related to HT or IRCM deposition.
- To evaluate the association between specific MRI signal abnormalities and pathological evidence of hemorrhage or contrast media deposition.
Main Methods:
- Middle cerebral artery occlusion was induced in 30 rats, followed by 5-hour reperfusion with iodixanol, iopamidol, or saline.
- MRI was performed immediately post-reperfusion, and rats were sacrificed at 24 hours for pathological examination.
- Hypointense areas on T2-weighted (T2-WI) and gradient echo (GRE) MRI were analyzed and correlated with histological findings of HT and IRCM deposition.
Main Results:
- Two pathological types of HT were observed: petechial hemorrhage (PeH) and hemorrhagic focus (HF).
- Iodixanol reperfusion was associated with a lower incidence of PeH (p<0.02).
- HF was more frequent in the IRCM groups, and T2-WI hypointensity without GRE hypointensity was more common in the IRCM group (p<0.05), potentially indicating IRCM deposition.
Conclusions:
- IRCM and saline reperfusion induce distinct MRI signal and pathological patterns.
- T2 hypointensity without GRE hypointensity may suggest IRCM deposition in the brain parenchyma.
- The observed differences in HT frequency and type suggest a direct or indirect effect of contrast media infusion/deposition during reperfusion.
