The Clinical Application Of Acoustic Densitometry In Evaluation Of Carotid Plaques In Patients With Coronary Artery Diseases

ObjectiveTo determine the clinical value of acoustic densitometry (AD) in evaluation of carotid plaque in patients with coronary artery diseases．MethodsThe subjects included 93 patients with coronary artery diseases and 28 healthy volunteers divided into four groups. Thirty patients with first-onset acute myocardial infarction (AMI) within one week were assigned to AMI group (male 24 and female 6 with a mean age of 56.25±12.65 years), according to the AMI diagnostic standard by WHO in 1979. Thirty-two patients with unstable angina pectoris (UAP) were assigned to UAP group(male 27 and female 5 with a mean age of 52.92±10.83 years), according to ischemic cardiomyopathy diagnostic standard by WHO in 1979. Thirty-one with stable angina pectoris (SAP) were assigned to SAP group (male 26 and female 5 with a mean age of 54.36±11.13 years),according with ischemia cardiomyopathy diagnostic standard by WHO in 1979. Twenty-eight age- and gender-matched healthy adults were assigned to control group. A color Doppler ultrasonic system (HP Sonos-5500) with acoustic densitometry (AD)analysis software was used. Two-dimensional examination was taken and the following parameters of common carotid and internal carotid were obtained: luminal diameter, intima-media thickness (IMT),flow velocity at systole and diastole (Vs, Vd),pulse index (PI),resistance index (RI). The measurement of IMT was obtained on posterior wall of vessel. The parameters of common carotid were mean of left and right common carotid. The parameters of internal carotid were mean of left and right internal carotid. Plaques were classified as soft (homogeneous echoes with a lower density than adventitia ) or hard ( bright echoes having a higher density than adventitia and with or without acoustic shadowing). When a plaque was composed of both lower and higher echo, the majority echo was taken as the type of the plaque. The machine was shifted to AD-IBS condition. The dynamic images of the plaques lasting for 2.70s were recorded and saved to CD. Region of interest (ROI) was placed at three different sites within the plaque. The average of integrated backscatter (AII) was measured and corrected as follows: IBS%= AII of plaque/ AII of adventitia of the same site. If patient has more plaques, the IBS% of patient carotid plaques were mean of all plaques. Results (1) The detective rate of carotid plaques were more frequent in AMI and UAP groups than in SAP and control groups. There was no significant difference between AMI and UAP groups and between SAP and control groups(see table 1). (2) The soft carotid plaques were more frequent in AMI and UAP groups than in SAP group while there was no significant difference between AMI and UAP groups and between SAP and control groups (see table 2) . (3) The hard plaques were more frequent in SAP group than AMI group and UAP groups, and there was no significant difference between SAP and control groups, between AMI and UAP groups (see table 2). (4) The IBS% of carotid plaques were significantly lower in AMI and UAP groups than SAP group(p<0.001),and there was no significant difference between AMI and UAP groups, between SAP and control groups (see table 3). (5) Compared with the control group, IMT was significantly increased in patients with coronary artery disease (see table 4). (6) The parameters of common carotid and internal carotid (including luminal diameter, flow velocity,PI,RI)were not significantly different in all groups (see table 5,6 ).　 ConclusionsThe IBS% of carotid plaques was significantly decreased in patients with acute coronary syndromes, indicating that the evaluation of carotid plaques by AD may be clinically useful in risk stratification and estimations of preventive strategies in patients with coronary artery diseases.