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Diffusion-weighted MRI: detection of cerebral ischemia before and after carotid thromboendarterectomy
R Tomczak1, A Wunderlich, F Liewald
1Department of Radiology, University of Ulm, Ulm, Germany. reinhard.tomczak@t-online.de
Insights
Diffusion-weighted MRI detects clinically silent ischemic events after carotid endarterectomy. Postoperative MRI revealed new ischemic changes in 11.8% of patients, often without noticeable neurologic deficits.
Area of Science:
- Neurology
- Radiology
- Vascular Surgery
Background:
- Postoperative evaluation after carotid thromboendarterectomy (TEA) typically includes neurological exams, ultrasound, and CT scans.
- Diffusion-weighted MRI (dMRI) shows higher sensitivity than conventional MRI and CT in detecting acute ischemic lesions.
- Understanding perioperative ischemic events is crucial for patient outcomes following TEA.
Purpose of the Study:
- To determine the incidence of clinically asymptomatic perioperative ischemic infarctions detected by MRI.
- To evaluate the utility of diffusion-weighted MRI in identifying subtle ischemic changes post-TEA.
Main Methods:
- Fifty-one patients undergoing carotid TEA were included in the study.
- Cranial MRI with diffusion-weighted sequences was performed 24 hours before and 24 hours after the surgical procedure.
- Pre- and postoperative MRI findings were analyzed for diffusion abnormalities indicative of ischemia.
Main Results:
- No diffusion abnormalities were observed in 56% of patients.
- Preoperative MRI detected fresh ischemic insults in 31% of patients, leading to surgery postponement in some cases.
- Postoperative MRI revealed new ischemic changes in 11.8% of patients, with only 3.9% experiencing transient neurologic deficits.
Conclusions:
- Diffusion-weighted MRI is highly effective in visualizing perioperative ischemic events.
- MRI can detect clinically asymptomatic embolisms occurring during the perioperative period.
- These findings highlight MRI's role in comprehensive postoperative assessment after carotid TEA.
Purpose:
Conventional postoperative evaluation of patients following carotid thromboendarterectomy (TEA) consists of a clinical neurologic examination to assess neurologic deficits, color duplex ultrasound to document the surgically reestablished patency of the carotid artery, and CT for exclusion of postoperative ischemic infarctions. Recent studies prove that diffusion-weighted MRI is more sensitive in the detection of fresh insults than conventional MRI and CT. The objective of the study was to ascertain the incidence of clinically asymptomatic peri-and postoperative ischemic infarctions visualized at MRI.
Method:
We included 52 patients in the study. Fifty-one patients (31 men, 20 women; average age 68 years) underwent cranial MR examination including a diffusion-weighted sequence at 24 h prior to carotid TEA and again 24 h following the procedure. One patient did not agree to participate.
Results:
In 29 of 51 patients (56%), neither the pre-nor the postoperative MR scans showed any diffusion abnormalities. In 16 patients (31%), however, preoperative MRI detected fresh ischemic insults. In nine patients (17.6%), the size of the insult resulted in surgery being postponed for 4 weeks. In six patients (11.8%), postoperative MRI returned findings of fresh disturbances of diffusion suggestive of ischemia that were not visualized on preoperative scans. Discrete neurologic deficits were observed in only two (3.9%) of these patients. Deficits were transient and disappeared within 72 h.
Conclusion:
Our findings underscore MRI's capacity for visualizing perioperative ischemic events. Moreover, MRI provides evidence of clinically asymptomatic embolisms that occur perioperatively.