CT angiography and Color Doppler ultrasonography features and sensitivity in detection of carotid arteries diseases

© 2013 Kamenjakoviæ et al.; licensee University of Sarajevo Faculty of Health Studies. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. UNIVERSITY OF SARAJEVO FACULTY OF HEALTH STUDIES ABSTRACT


INTRODUCTION
Ultrasonography of neck blood vessels is a noninvasive diagnostic method for evaluating disease in extracranial area of carotid artery.Th e method is not expensive and it can be easily applied (1).Th e reliability of carotid artery ultrasonography has been proved by the use of Doppler ultrasonography.Color Doppler ultrasonography is a technique which is used by the autocorrelation method (2).In the area where the stenosis of blood fl ow speed is increased, Doppler Eff ect registers this change ideally.Estimation of the level of stenosis based only on visual char-acteristics is not reliable (3).Th is is why it is necessary to performe acoustic evaluation as well and this evaluation includes: measuring peak systolic velocity (PSV), end dyastolic velocity, measuring the relation of peak systolic velocity (PSV) in the internal and mutual carotid artery.Staikov and associates (4) specify the optimal duplex ultrasonographic criteria in diagnosing carodid artery stenosis.Th e introduction of "multi -detector CT angiography" (MDCT) method and especially"Post Processing Software" analysis has made an enormous shift in the improvement of vascular test structures as well as carotid arteries.CT angiography is a fast, non-invasive method.Either solely or in combination with other methods it is very good and useful for diagnosing carotid arteries diseases (5).Computed Tomography Angiography (CTA) is a fast developing technology with great potential.Th is is especially true and important for neurovascular diseases.Other diseases including dissection, trauma, intracranial stenosis, trombosis and aneurysms can be easily diagnosed using this method.Although Duplex Ultrasonography can be considered the fi rst method in medical examination of many patients, both Magnetic Resonance Angiogram (MRA) and CTA off er certain advantages with regard to Doppler ultrasonography.CTA and MRA are both highly precise, but CTA has several key advantages which are refl ected by precision, specifi city, accuracy, and data analysis speed related to carotid arteries abnormalities.Th e aim of this research is to compare specifi city and sensitivity of Color Doppler ultrasonography with CT angiography in detection of carotid arteries diseases.

Patients
Prospective consecutive analysis was done; measurements on 200 carotid arteries in 100 patients were analyzed.Patients were referred to an examination due to mild neurological symptoms, dizziness, balance lost and murmurs (registered or subjective).Prior to the scan the following data was noted: age, sex, aortic tension, glucose in blood, smoking, and the state of lipids.After the patients were scanned by Color Doppler ultrasonography, they were also scanned by CT angiography within 15 days from ultrasound examination.All ultrasound tests were published by a radiologist.Eligibility criteria: patients older than 18 with neurological symptoms such as: instability, dizziness, neurological signs of ischemic attacks, patients with murmurs over carotid arteries (registered or subjective).Exclusion criteria: malignant diseases, congenital malformations, trauma, severe neurological diseases, pregnancy, case history of allergies to contrast agents.

Procedure
All patients were examined while they were laying on their back.Bilateral ultrasonography of carotid arteries was performed by the use of standard ultrasound machine (Sonoline G60 Ultrasound Imaging System, Siemens AG Medical Solutions, Erlargen, Germany) and by linear probes (5)(6)(7)(8)(9)(10)(11). CT angiography of carotid arteries was performed by a standard method and by a procedure on a CT scan (Siemens 64 AG Medical Solutions, Erlargen, Germany) which was connected to a computer system and softwer for 3D blood vessels reconstruction and with abnormalities interpretor on blood vessels which were subject to analysis.Th e level of stenosis of carotid artery is estimated based on basic laws of Physics which include interaction, volume, pressure, and their eff ect on blood fl ow in a closed system.Th e relation between fl ow speed and carotid artery level of stenosis is defi ned as a result of more multicentric studies NASCET, ACAS and ESCET (Table 1).

Statistical analysis
Th e statistical test of variation analyses was used in the estimation of statistical signifi cance of diff er-  Pearson correlation test as well as student test were used for examining the existence of correalation between analysed parameters.It was considered that statistically signifi cant diff erence of the mean of analysed parameters did exist if there was p<0.05.

RESULTS
A number of 44 female examinees participated in the study.Th e average age was 61.5 years (age range: from 23 to 85).High blood pressure was registered in 59% of the patients, 33% were diabetic, and 45% had increased lipids (Table 2).
In Figure 1 the structure of participants shows the tendency of mean decreasing in women, with lower mean at ultrasound than at CTA and the tendency of increasing in men who have high arithmetic mean (9 men at ultrasound with mean of 89.5, while there were 6 women with arithmetic mean of 64.5 at ultrasound).It can be seen that there are 26 men and 18 women and that there are 23 men compared to 18 women at CTA which leads to the conclusion that men are dominant as persons with higher arithmetic mean.Arithmetic mean shows that men are more subject to stenosis, while arithmetic mean 100 (occlusion) shows that both men and women are equally represented (Figure 1).
From a total of one 100 examinees, 33 of them were suff ering from diabetes.3 of them had ultrasound arithmetic mean 7.5, and 4 of them had CTA arithmetic mean.Th ereof one patient was positive, and two were negative (at ultrasound), and one patient was positive and three negative (at CTA).Th e fi gure shows the tendency of mean decreasing in patients with diabetes with lower mean at ultrasound in relation to CTA, and the tendency of mean increasing in diabetics with high mean (fi ve positive at ultrasound with mean of 89.5 and seven with mean 100 -in contrast to six with arithmetic mean 89.5 at  CTA, or eight with arithmetic mean 100).It can be concluded that diabetes has a major eff ect on people with high arithmetic mean.Arithmetic mean shows approximately the same number of examinees with and without diabetes (Figure 2).In our study 59 hypertensive patients were registered.Th ereof three of them had ultrasound arithmetic mean 7.5, and four of them had CTA arithmetic mean 7.5.From these seven patients, one was hypertensive, and two were not (at ultrasound), and one was hypertensive and three were not (at CTA).Th e number of patients who had arithmetic mean 32.5 at ultrasound is 28, and this number at CTA is 26.From that, at ultrasound scan 14 of them were hypertensive, and 14 were not.On the other hand, at CTA scan 13 were hypertensive and 13 were not.A number of 44 patients had arithmetic mean at ultrasound 64.5 and at CTA that number is 41.From that, 26 were hypertensive and 18 were not hypertensive at ultrasound, and 25 were hypertensive and 16 were not at CTA.A number of 15 patients had arithmetic mean 89.5 at ultrasound, and 17 had the same mean at CTA. 13 of them were hypertensive and 2 were not, while at CTA 13 were hyperten-sive and 4 were not.A number of 10 patients had arithmetic mean one 100 at ultrasound while that number at CTA was 12 From that, fi ve of them were hypertensive and fi ve were not at ultrasound, while seven of them were hypertensive and fi ve were not at CTA. Th e fi gure shows a tendency of the mean decreasing by hypertension with lower mean at ultrasound in comparison to CTA, and a tendency of the mean increasing by hypertension with higher mean (26 positive at ultrasound with mean 64.5 in comparison to 25 positive at CTA with mean 64.5, 7 with mean one 100, while there are 5 at ultrasound).
It can be concluded that hypertension has greater impact on people with higher arithmetic mean (Figure 3).In our study there were 45 patients registered with higher serum lipids.From that, 3 patients had arithmetic mean 7.5 at ultrasound, and 4 of them had arithmetic mean 7.5 at CTA.From that, 1 patient had increased lipids, and 2 did not (at ultrasound), and 1 patient had increased lipids, and 3 did not (at CTA).Th e number of patients who had arithmetic mean 32.5 at ultrasound is 28, at CTA that number is 26, from that 7 of them had increased lipids, and  Th e fi gure shows a tendency of mean decreasing by hypelipidemia with lower mean at ultrasound in comparison to CTA, and a tendency of mean increasing by hyperlipidemia with higher arithmetic mean (23 positive at ultrasound with mean 64.5 in comparison to 23 with arithmetic mean 64.5 at CTA, 9 with arithmetic mean one 100, while 8 at ultrasound).It can be concluded that hyperlipidemia has greater impact on people who have higher arithmetic mean.(Figure 4) Th e level of stenosis in carotid arteries measured by Doppler ultrasonography and by the use of Computed Tomography Angiography (CTA) is represented in Table 2.

DISCUSSION
Carotid angiography is a Gold standard (test) in determining the degree of carotid arteries stenosis.Th e studies which address diff erences between Doppler ultrasonography and carotid angiography refl ect principal non-precision of both methods (6).Th e study by Nederkoorn and associates (7) shows that Doppler Ultrasonography has a sensitivity from 96% (CI 95%, 94-98), and specifi city from one 100% (CI 95%, 99-100%).For categories in which the degree of carotid arteries stenosis was 50-59%, 60-69%, 70-79%, 80-89%, the mean of sensitivity and specifi city of positive predicted mean and negative predicted mean was over 80%

CONCLUSION
Color Doppler ultrasonography and CT angiography are specifi c and sensitive methods in detection of carotid arteries diseases.Specifi city and sensitivity of CT angiography in detection of carotid arteries diseases is extremely high and it is higher than Color Doppler ultrasonography.

FIGURE 4 .
FIGURE 4. Disrupted lipid profi le in patients subjected to CTA and Color Doppler ultrasonography. .US -Ultrasonography; CTA -Computed Tomography Angiography

TABLE 1 .
Carotid artery stenosis criteria according to NA-SCET, ACAS and ESCET studies ences in measurement of parameters in this research.

TABLE 2 .
Characteristics of patients referred to neck blood vessels examination 1. Sexual structure of patients subjected to CTA and Color Doppler ultrasonography.US -Ultrasonography; CTA -Computed Tomography Angiography.FIGURE 2. Diabetes presence in patients who were subjected to CTA and Color Doppler ultrasonography.US -Ultrasonography; CTA -Computed Tomography Angiography.
(16)gardless of the technique applied, although direct comparison of results had to be avoided considering the fact that test results originate from diff erent population.Anzidei and associates(12)compared in 170 patients Color Doppler Ultrasound (CDU), MRA, CTA of carotid arteries and they established that CTA is a more precise technique for evaluation of carotid stenosis, that it has better performance than MRA (97%:92% for "steady-state" MRA and 92% for "fi rst-pass" MRA) and that it has better precision than CDU (97%:76%).Lovrenčić-Huzjan and associates (13) have examined patients with symptomatic carotid arteries stenoses and correlated Color Doppler ultrasound test with angiography and they proved high correlation between angiography and ultrasound in detection of diff erent levels of carotid stenosis.Berman and associates (14), Lee and associates(15), and Curley and associates(16), have proven that ultrasound is more sensitive in detection of severe stenosis (by occlusions, pseudo-occlusions).