Quantification and mapping of cerebral hemodynamics before and after carotid endarterectomy, using four-dimensional
Laleh Zarrinkoob1, Anders Wåhlin2, Khalid Ambarki3
1Division of Neuroscience, Department of Clinical Sciences, Umeå University, Umeå, Sweden; Department of Surgical and Perioperative Sciences, Umeå University, Umeå, Sweden.
Insights
Four-dimensional (4D) phase-contrast MRI revealed that carotid endarterectomy (CEA) significantly increased total cerebral blood flow by 15%. Post-surgery, blood flow distribution normalized, resolving pre-existing laterality in major cerebral arteries.
Area of Science:
- Neuroscience
- Medical Imaging
- Cardiovascular Science
Background:
- Carotid stenosis significantly impacts cerebral hemodynamics, which cannot be solely determined by the degree of stenosis.
- Assessing cerebral blood flow dynamics is crucial for understanding the effects of carotid stenosis and its surgical treatment.
Purpose of the Study:
- To quantify and map cerebral blood flow rate (BFR) distribution before and after carotid endarterectomy (CEA) using four-dimensional (4D) phase-contrast MRI.
- To investigate the influence of collateral recruitment on cerebral hemodynamics in patients with carotid stenosis.
Main Methods:
- Nineteen patients with symptomatic carotid stenosis (≥50%) underwent 4D phase-contrast MRI before and after CEA.
- Blood flow rate (BFR) was measured in 17 cerebral and ophthalmic arteries.
- Collateral recruitment and BFR laterality were quantified and analyzed in relation to surgical intervention and patient subgroups.
Main Results:
- Total cerebral blood flow increased by 15% (P < .01) after CEA.
- Pre-operative BFR laterality in the internal carotid artery, anterior cerebral artery, and middle cerebral artery (MCA) was resolved post-surgery.
- MCA laterality was observed in patients with collateral recruitment before CEA but not after, unlike those without collateral recruitment.
Conclusions:
- 4D PC-MRI offers a comprehensive, noninvasive method to evaluate cerebral hemodynamics in carotid stenosis before and after CEA.
- Pre-operative MCA laterality in patients with collateral recruitment indicates hemodynamic disturbances.
- This imaging technique provides valuable insights into the pathophysiology of cerebral hemodynamics affected by carotid stenosis.
Background:
Carotid stenosis can profoundly affect cerebral hemodynamics, which cannot simply be inferred from the degree of stenosis. We quantified and mapped the distribution of the blood flow rate (BFR) in the cerebral arteries before and after carotid endarterectomy using four-dimensional (4D) phase-contrast (PC) magnetic resonance imaging (MRI).
Methods:
Nineteen patients (age, 71 ± 6 years; 2 women) with symptomatic carotid stenosis (≥50%) undergoing carotid endarterectomy (CEA) were investigated using 4D PC-MRI before and after surgery. The BFR was measured in 17 cerebral arteries and the ophthalmic arteries. Collateral recruitment through the anterior and posterior communicating arteries, ophthalmic arteries, and leptomeningeal arteries was quantified. BFR laterality was significantly different between the paired contralateral and ipsilateral arteries. Subgroups were defined according to the presence of collateral recruitment.
Results:
The total cerebral blood flow had increased by 15% (P < .01) after CEA. Before CEA, laterality was seen in the internal carotid artery, anterior cerebral artery, and middle cerebral artery (MCA). On the ipsilateral side, an increased BFR was found after CEA in the internal carotid artery (246 ± 62 mL/min vs 135 ± 80 mL/min; P < .001), anterior cerebral artery (87 ± mL/min vs 38 ± 58 mL/min; P < .01), and MCA (149 ± 43 mL/min vs 119 ± 34 mL/min; P < .01), resulting in a postoperative BFR distribution without signs of laterality. In the nine patients with preoperatively recruited collaterals, BFR laterality was found in the MCA before, but not after, CEA (P < .01). This laterality was not found in the 10 patients without collateral recruitment (P = .2). The degree of stenosis did not differ between the groups with and without collateral recruitment (P = .85).
Conclusions:
Using 4D PC-MRI, we have presented a comprehensive and noninvasive method to evaluate the cerebral hemodynamics due to carotid stenosis before and after CEA. MCA laterality, seen in the patients with collateral recruitment before CEA, pointed toward a hemodynamic disturbance in MCA territory for those patients. This methodologic advancement provides an insight into the pathophysiology of cerebral hemodynamics in patients with carotid stenosis.
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