Background Over the past decade the rates of successful thrombectomy have risen, with rates of first-pass success of over 50% and reduction in the time to reperfusion. Despite this improvement, less than 50% of patients with a successful first-pass thrombectomy achieve good clinical outcomes. Potential contributors are reperfusion injury and post thrombectomy hyper-perfusion in the affected areas. Intravoxel incoherent motion (IVIM) is a diffusion-weighted (DW) MRI technique that allows the measurement of microvascular perfusion (D*).
Methods Ten dogs were randomly assigned to receive local cooling or no adjunct therapy following a 45-minute occlusion of the middle cerebral artery (MCA) with a retrievable aneurysm coil. Five minutes after the cooling was initiated, the aneurysm coil was removed, simulating a successful thrombectomy. The cooling was continued for a total of 25 minutes. The dog was moved to a 3T Philips MRI. Both standard DW-MRI and IVIM imaging was performed to assess the size of the infarct. DWI was repeated 1 hour later to determine the post reperfusion infarct growth. The entire test protocol was successful in 8 of the 10 canines (n=4 per group). IVIM derived microvascular perfusion (D*) was then compared both between the cooled and control animals within the area of infarct, and between the ipsilateral (infarct) and contralateral side of each animal.
Results The mean D* within the infarct area was significantly lower in the animals that received focal hypothermia compared to the uncooled controls (8.6E-3 vs 2.6E-2, p < 0.001, figure), indicating that local cooling was able to reduce the microvascular perfusion. Furthermore, although D* in the contralateral side of the cooled animals was reduced, this effect was not significant compared to the control animals (1.7E-2 vs 1.94E-2, p = 0.1). Finally, the animals that received local cooling had reduced post reperfusion infarct growth compared to the control animals (13.8% vs 161.3%, p = 0.016).
Conclusion IVIM MRI was able to measure the levels of microvascular perfusion after a 45-minute temporary occlusion. In the animals that underwent focal hypothermia, the level of microvascular perfusion was reduced compared to the uncooled animals. Elevated levels of post thrombectomy perfusion has been shown as an independent predictor of poor outcome. Our observation of controlled reperfusion correlated with reduced infarct growth pursuant to cooling.
Disclosures R. King: None. V. Anagnostakou: None. M. Shazeeb: None. S. Hornibrook: 4; C; FocalCool. 5; C; FocalCool. J. Mitchell: 4; C; FocalCool. 5; C; FocalCool. M. Epshtein: None. C. Raskett: None. T. Merrill: 4; C; FocalCool. 5; C; FocalCool. A. Puri: 2; C; Medtronic, Stryker. N. Henninger: None. M. Gounis: 1; C; Research support from the NIH, the United States – Israel Binational Science Foundation, Anaconda, ApicBio, Arsenal Medical, Axovant, Balt, Cerenovus, Ceretrieve, CereVasc LLC, Cook Medical, Galaxy Th. 2; C; Consultant on a fee-per-hour basis for Alembic LLC, Astrocyte Pharmaceuticals, BendIt Technologies, Cerenovus, Imperative Care, Jacob’s Institute, Medtronic Neurovascular, Mivi Neurosciences, phenox G. 4; C; Imperative Care, InNeuroCo, Galaxy Therapeutics, and Neurogami, and Synchron.
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