Clinical impact of gradient echo MRI versus CT in detecting hemorrhagic transformation after mechanical thrombectomy.

PURPOSE

Hemorrhagic transformation (HT) following mechanical thrombectomy (MT) is a critical concern in the management of ischemic stroke patients. While both CT and MRI are used to detect HT, the clinical implications of discrepancies between these modalities remain unclear. This study aims to investigate the clinical implications of discordant findings between gradient echo MRI and CT in detecting HT after MT.

METHODS

In this retrospective study, patients who underwent MT for ischemic stroke between 2016 and 2023 were analyzed. Patients were categorized into two groups based on imaging results: CT negative and MRI positive versus CT positive and MRI positive.

RESULTS

A total of 286 patients were included in the study, with 104 in the CT negative and MRI positive group and 182 in the CT positive and MRI positive group. More patients in the CT negative and MRI positive group were started on antithrombotic medications in less than 2 days compared to the patients in the CT positive and MRI positive group (47.3% vs. 34.5%; OR: 1.94, 95% CI: 0.88-4.27, p = 0.09) and still exhibited significantly higher rates of good functional outcomes (mRS 0-2) at discharge (OR: 3.27, 95% CI: 1.03-10.36, p = 0.04). Additionally, the CT negative and MRI positive group had a lower, though not statistically significant, likelihood of readmission for diagnosis of intracranial hemorrhage (ICH) within 30 days (0% vs. 2.7%, p = 0.16).

CONCLUSION

Gradient echo MRI can detect subtle hemorrhages not seen on CT, and both modalities offer complementary insights. In our cohort of MRI-positive patients, those with CT-negative findings had better functional outcomes and earlier antithrombotic resumption without increased risk of ICH readmission. These results suggest that in select scenarios, a negative CT may help inform safe antithrombotic management, though this does not diminish the diagnostic value of MRI. Further prospective studies are warranted to establish thresholds for MRI findings and refine clinical protocols post-MT.