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December 04, 2023

Despite a slower time to randomization, patients who were selected into the SWIFT PRIME trial based on the results of MRI or CT perfusion imaging had similar outcomes, according to a new analysis of the data.

Both tests are equally suited to identifying patients who are appropriate for mechanical thrombectomy, said Josser E. Delgado Almandoz, MD (Abbott Northwestern Hospital and St. Francis Regional Medical Center, Minneapolis, MN). The upshot of the findings, published in the June 2017 issue of Stroke, is that “either CT or MR perfusion could be used for stroke patient selection for mechanical thrombectomy,” he told Neurovascular Exchange in an email.

Plain CT and CT perfusion are both widely used and typically available 24/7 in most hospitals, said Delgado Almandoz, who was not involved in the subanalysis. MRI, on the other hand, is not always available at all times and thus can take longer to be acquired. But these findings suggest that either can be used for patient selection, he added.

No Difference in Outcomes

For the SWIFT PRIME trial, nearly 200 patients with middle cerebral artery and distal carotid occlusions were randomized to receive tPA alone or tPA in combination with stentriever thrombectomy. Of the 173 patients included in the current subanalysis, MRI selection was performed in 34 and CT perfusion in 139. Led by Nicolas Menjot de Champfleur, MD (Hôpital Gui de Chauliac, Montpellier, France), the investigators looked at outcomes based on whether MRI or CT perfusion was used for patient selection.

Baseline NIHSS score was 17 in both groups. Target mismatch profile was present in 95% of patients who underwent MRI and 83% of those who underwent CT perfusion. A greater proportion of MRI patients was transferred from an outside hospital (P = 0.02), and had a longer time from stroke onset to randomization (P = 0.003). The time from emergency department arrival to randomization was similar for both groups, however.

Reperfusion rates among patients treated with stentrievers were similar for patients who underwent MRI and CT perfusion. In addition, the primary endpoint of 90-day mRS score revealed a statistically significant benefit for both groups of patients. Infarct growth was also reduced in both.

Outcomes by Imaging Type


CT Perfusion

(n = 139)


(n = 34)

P Value

Median 90-Day mRS




Functional Independence




TICI 2b-3




Median Absolute Infarct Growth, mL





The authors conclude that while time to randomization into the SWIFT PRIME trial was longer for patients who underwent MRI compared with CT perfusion, “this time delay did not seem to impact the clinical response to endovascular therapy. The benefits of endovascular therapy in the MRI-selected subgroup were comparable to those seen in the CT perfusion subgroup.”


Menjot de Champfleur N, Saver JL, Goyal M, et al. Efficacy of stent-retriever thrombectomy in magnetic resonance imaging versus computed tomographic perfusion-selected patients in SWIFT PRIME trial (Solitaire FR With the Intention for Thrombectomy as Primary Endovascular Treatment for Acute Ischemic Stroke). Stroke. 2017;48:1560-1566.


  • Delgado Almandoz reports being a consultant for Medtronic Neurovascular and Penumbra.
  • Menjot de Champfleur reports no relevant conflicts of interest.
  • The SWIFT PRIME trial was funded by Covidien.

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