Indian Journal of Radiology and Imaging Indian Journal of Radiology and Imaging

VASCULAR IMAGING
Year
: 2005  |  Volume : 15  |  Issue : 1  |  Page : 91--98

Color and duplex doppler imaging evaluation of extracranial carotid artery in patients presenting with transient ischaemic attack and stroke : a clinical and radiological correlation.


SK Sethi, RS Solanki, H Gupta 
 Lady Hardinge Medical College and Associated Hospitals, New Delhi, India

Correspondence Address:
S K Sethi
C P-109, Pitampura, Maurya Enclave, Delhi-110088
India

Abstract

OBJECTIVES -Present study was done to evaluate carotid artery disease by color and duplex imaging in 63 patients (126 vessels) presenting with transient ischaemic attack and stroke. METHODS Vessel wall thickness and plaque characterization were done by gray scale ultrasound and site and severity of stenosis was assessed on color and duplex Doppler. Doppler finding were correlated with clinical presentation, risk factors, CT and echocardiographic findings. RESULTS-Male sex (p<0.01), post menopausal state (p<0.05) Presence of hypertension (p<0.01), systolic blood pressure, smoking (p<0.05), diabetes mellitus (p<0.05), history suggestive of peripheral arterial disease (p<0.01), previous CVA (p<0.01) were determined to be statistically significant risk factors. All the patients with a carotid bruit had abnormal carotid Doppler. Mean cholesterol levels in patients with normal carotid arteries was 186.52 ( 36.88) mg% and mean cholesterol level in patients with carotid lesion was 219.11( 35.13) All patients with >40% stenosis had a cortical infarct, none of patients with >40% stenosis had a subcortical infarct. All 22 patients with sub cortical infarcts had either normal extra-cranial carotids or had <40% stenosis. . Majority of plaques (50%) in the present study were located at the bifurcation. Color Flow imaging showed a definite advantage over B-mode scanning in identification of the hypoechoic plaques and in identification of plaque ulcerations. The overall perfect agreement between Color Doppler Flow Imaging and Conventional Duplex scanning was 96.8%. In patients with complete occlusion findings of color flow imaging and spectral analysis were confirmed on power Doppler imaging. Mean IM thickness of patients with normal echocardiography was 0.9250 ( 0.2863) and IM thickness of patients with echocardiographic evidence of IHD was 1.3455 ( 0.2734). CONCLUSION-As progression of the atherosclerotic disease can be stopped by reducing the risk factors and critical (>70%) stenosis treated surgically present study highlights the importance of doppler imaging in stroke prevention through surveillance for atherosclerosis that predisposes a person to cerebral ischaemia.



How to cite this article:
Sethi S K, Solanki R S, Gupta H. Color and duplex doppler imaging evaluation of extracranial carotid artery in patients presenting with transient ischaemic attack and stroke : a clinical and radiological correlation. Indian J Radiol Imaging 2005;15:91-98


How to cite this URL:
Sethi S K, Solanki R S, Gupta H. Color and duplex doppler imaging evaluation of extracranial carotid artery in patients presenting with transient ischaemic attack and stroke : a clinical and radiological correlation. Indian J Radiol Imaging [serial online] 2005 [cited 2019 Aug 17 ];15:91-98
Available from: http://www.ijri.org/text.asp?2005/15/1/91/28756


Full Text

 INTRODUCTION



Cerebrovascular insufficiency is the leading cause of mortality and morbidity all over the world. Lesions of the extracranial carotid arteries, particularly the internal carotid artery near the bifurcation, are implicated in majority of cases of cerebrovascular disorders [1]. The North American Symptomatic Carotid Endarterectomy Trial (NASCET) and European Carotid Surgery Trialists' Collaborative Group (ECST) showed a benefit of carotid endarterectomy for recently symptomatic patients with internal carotid lumen diameter narrowing of 70% or more [2]. At present Doppler is the main non-invasive imaging technique, widely available, with sensitivity approaching that of angiography [3] Clinical studies have suggested that an accurate evaluation of carotid occlusive disease may be possible non-invasively through a combination of MRA and ultrasound examinations of the carotid arteries [4],[5]. Hence, the present study was done to study the color and duplex imaging features of extracranial carotid artery in patients presenting with clinical features of TIA and stroke.

 MATERIAL AND METHODS



This study was carried out using a real time ultrasound equipment capable of B-mode imaging, pulsed wave duplex scanning, color Doppler flow imaging and power Doppler imaging (HDI 5000 system, ATL ultrasound Inc.). All patients of adult age group presenting with clinical features of stroke or patients presenting with history suggestive of transient ischaemic attacks were taken up for the study. Detailed clinical history was taken from each patient. This included -Age, Sex, Pre/Post menopausal state and Risk Factors including Hypertension,Diabetes Mellitus,H/S/O CAD, Smoking, Alcohol intake,Previous stroke or TIA,Peripheral arterial disease,Hyperlipidemia (S.cholesterol, triglyceride levels). A detailed Cardiovascular and, Neurological examination was done Investigations like postero-anterior radiograph of chest, Computed tomography of head, Echocardiography were carried out.

 DOPPLER TECHNIQUE



 VISUAL INSPECTION OF GRAY SCALE IMAGES



Vessel wall thickness -Thickening of I-M complex greater than 0.8mm was considered abnormal [6],[7] [Figure 1][Figure 2]

Plaque characterization -Plaque texture was classified as being hypoechoic,echogenic or calcified..

The uniform hyperechoic acoustic texture corresponds pathologically to dense, fibrous, connective tissue. Calcified plaque produces posterior acoustic shadowing and is common in asymptomatic individuals. Hypoechoic plaque is characterized pathologically by containing deposits of lipid and cholesterol [6].

Doppler measurements were obtained in the stenotic portion of the carotid lumen.

Parameters measured included [8]: -

1. Peak systolic velocity (PSV)

2. Peak end diastolic velocity (EDV)

3. Systolic and diastolic ratios

Carotid occlusion was diagnosed by-Absence of arterial pulsations, occlusion of lumen by echogenic material, absence of Doppler flow signals, and subnormal vessel size (chronic occlusion).

Statistical analysis was carried out using Z-test, chi-square test (using Yates correction) and student's t-test. Results of Color Doppler Flow Imaging, Duplex scanning were compared and perfect agreement between these was calculated. Data analysis was done with statistical package for social sciences (SPSS) In this study, p40% stenosis and one (10%) had total occlusion (p40% stenosis and one (6.25%) had complete occlusion. (p40% stenosis and one (16.7%) had complete occlusion. None of the patients had normal carotid arteries. (p40% stenosis and 1 had 40% and one (4.34%) had complete occlusion. All 11 of premenopausal women had normal carotid arteries. (p 40% and one (8.33%) had complete occlusion.

Cholesterol levels in the study group ranged from 129 to 296mg%. Mean cholesterol levels in patients with normal carotid arteries was 186.52( 36.88) mg% and mean cholesterol level in patients with carotid lesion was 219.11( 35.13). [Statistically significant (student's t-test)].

All patients with >40% stenosis had a cortical infarct, none of patients with >40% stenosis had a subcortical infarct. All 22 patients with subcortical infarcts had either normal extracranial carotids or had 1mm could be taken as an indicator for presence of IHD.

 ECHOCARDIOGRAPHIC FINDINGS



Echocardiography was normal in 20 patients (31.7%) and showed diastolic dysfunction in 13 patients (20.6%), left ventricular hypertrophy in 10 patients (15.9%), left ventricular hypokinesia in 11 cases (17.5%) and rheumatic heart disease in four cases (6.3%). Thus, a potential cardioembolic source was present in 23.8% of cases.

When carotid Doppler and echocardiographic findings were compared it was observed that of 15 patients with potential cardioembolic source 10 (66.7%) had normal carotid arteries. 2 (13.3%) had 40% stenosis and 1 (6.7%) had complete occlusion. Of patients with > 40% stenosis 2 (50%) had normal echocardiography or diastolic dysfunction and 2 (50%) had left ventricular hypokinesia. Of 2 patients with complete occlusion 1 (50%) had normal echocardiography and 1 (50%) had left ventricular hypokinesia

 DISCUSSION



Prevalence of atherosclerosis increases with age [11]. Wolf et al (1991) reported a mean age of 65. 4years in men and 66.1 years in females[12]

Overall men are more prone to atherosclerosis than women. This might be explained on the basis of protective role of the female hormones. After menopause, when this effect wanes, the rates of diseases become similar. [13] Smoking is a recognized significant risk factor [14],[15] Smoking causes a reduction of HDL levels and fibrinogenemia [11] Hypertension produces a continuous trauma to endothelium and predisposes to the early stage of atherogenesis. In advanced atherosclerosis it might contribute to plaque growth [11] In North Trondelag health survey raised systolic and diastolic blood pressures and anti hypertensive treatment were identified as significant risk factors [15] Wolfe et al (1991) using the Framingham study cohort found Mean systolic blood pressure to be 139.3mm Hg in males and 142.8mm Hg in females. [12] Dhamija et al (1998) also concluded hypertension was the most consistent risk factor and systolic blood pressure being more closely related to ischaemic stroke than diastolic pressure[16] Diabetes mellitus is recognized significant risk factor [14],[15] Incidence of stroke in diabetics has been found to be 2 to 3 times higher than in general population [17] Presence of PVD has been associated with presence of carotid atherosclerotic disease [14] March et al (1996) screened 188 patients with claudication out of which 8% had an internal carotid artery stenosis of 16% to 49%, 21.8% had a stenosis that exceeded 50%, and 2.7% had an occluded internal carotid artery. They recommended routine carotid duplex screening to detect asymptomatic high-grade stenosis in patients with PVD. [18] Asymptomatic bruit is recognized as an indication for carotid Doppler evaluation [19]. In North Trondelag health survey prior stroke was identified as a significant risk factor [15] Higher cholesterol levels are associated with higher incidence of carotid atherosclerotic disease [14] There is evidence that high levels of LDL cholesterol predispose to atherosclerosis, while high levels of HDL cholesterol have protective role [20]

In our study the mean age of patients without any carotid lesion was 48.83 ( 15.27) years and mean age of patients with carotid lesion was 60.03 ( 11.29) years. Out of 29 males 18 (62%) had a carotid lesion and out of 34 females only 8 (23%) had a carotid lesion. (p1mm could be taken as an indicator for presence of IHD. These findings were similar to those by Polak et al (1989) and Jadhav et al (2001) who considered thickening of I-M complex greater than 0.8mm as abnormal and as the earliest changes of atherosclerotic disease.[6],[7]

Echocardiography showed a potential cardioembolic source in 23.8% of cases. These findings are similar to Cerebral embolism task force (1986) results according to which one in six ischaemic strokes is due to cardiogenic embolism. [29] Two-dimensional echocardiography, introduced for clinical use in 1978, has acquired importance in screening patients of cerebrovascular disease [30]. When carotid Doppler and echocardiographic findings were compared it was observed that of 15 patients with potential cardioembolic source two (13.3%) had > 40% stenosis and one (6.7%) had complete occlusion. Of patients with > 40% stenosis two (50%) had left ventricular hypokinesia. Of 2 patients with complete occlusion one (50%) had left ventricular hypokinesia. This observation is similar to De Rook et al (1992) who observed that even in patients with a cerebrovascular or a carotid flow-limiting lesion, a concurrent cardiac lesion may be present and hence such patients should be screened by echocardiography too. [31]

 CONCLUSION



The introduction of Doppler imaging has dramatically changed the diagnostic evaluation of suspected carotid disease. Doppler sonography provides a rapid, non-invasive, relatively inexpensive and accurate means of diagnosing carotid stenosis. Physicians have long sought methods for identifying stroke-prone patients, with the hope that timely intervention might avert stroke and its accompanying disability. The present study highlights the importance of Doppler sonography in this stroke prevention effort through surveillance for atherosclerosis that predisposes a person to cerebral ischaemia.

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