[Prediction of ischaemic lesions of the brain in reconstructive operations on internal carotid arteries]

The present study was undertaken to examine the relationship between the level of the intensity of the ultrasonic signal reflected from atherosclerotic plaques (ATP) of carotid arteries and the risk for formation of an ischaemic lesion in the brain matter, detected during diffusion-weighted magnetic resonance imaging (DW-MRI) performed 24 hours after carotid endarterectomy (CEA) or carotid angioplasty and stenting (CAS). Our prospective study included a total of 78 patients presenting with stenosis of the sinus of the interior carotid artery. Of these, 42 patients were subjected to CEA and 36 subjects endured CAS. All patients in the preoperative period underwent ultrasonographic examination with determination of the degree of heterogeneity of ATPs and registration of the values of the intensity of acoustic characteristics of the signal. The condition of the brain matter before and 24 hours after the intervention was assesses by the findings of DW-MRI. None of the patients after the reconstructive intervention during the postoperative period demonstrated any evidence of acute cerebral circulation disorders. DW-MRI carried out 24 hours after the operation revealed acute ischaemia foci (AIF) in 9 (21.4%) patients after CEA and in 18 (50%) patients after CAS (p=0.05). It was revealed that the postoperative occurrence of AIF was related to the intensity of the ultrasonographic signal prior to the operation: in the CEA group patients the postoperative ischaemic foci were associated with high-intensity ultrasonographic signals (more than 25 dB), whereas in the CAS group patients, vice versa - with low-intensity signals (less than 25dB). For CEA, sensitivity and specificity of the preoperative ultrasonographic method of predicting postoperative embolic lesions of the brain appeared to be similar, amounting to 100% each (with the cut-off point of high- and low-intensity signals equaling 25 dB), and for CAS, sensitivity of the method turned out to be 75% and specificity - 100% (with the same cut-off point of 25 dB). A conclusion was drawn that quantitative characteristics of the intensity of an ultrasonographic signal from fragments of atherosclerotic plaques of the sinus of the internal carotid artery made it possible with high probability to predict the risk for the development of AIF in the brain matter after both CEA and CAS and may therefore serve as a reliable criterion for appropriate therapeutic decision-making with the lowest risk of inflicting lesions in a particular case. The threshold cut-off points of high- and low-intensity ultrasonographic signals, as well as their clinical significance are yet to be specified and verified with the growing number of cases.