PDF DIR 359 Carotid CTA

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Turkish Society of Radiology 2011

195

Computed tomographic angiography (CTA) is an excellent meth-od, with low morbidity and great availability, for the evaluationof stroke patients. High-quality images are essential for a correct

diagnosis. To obtain sufficient images, techniques are used to eliminateartifacts and ensure proper image post-processing (13).

Greater density in the neck veins may lead to streak artifacts and mayultimately be the cause of incorrect diagnoses, such as thrombosis or dis-section within the adjacent arteries. Increased densities may also preventhigh-quality reconstructions. Contrast material reflux into the veinsleads to a higher density in the veins and may be seen in daily practicefor no apparent reason. A few studies have suggested that when inject-ing contrast material into the right arm, there is a significant reductionin jugular vein reflux and perivenous artifacts. It has been reported thatbrachiocephalic vein compression and left jugular vein stasis might berelated to decreased retrosternal distance and may be prevented with leftarm injection(36).

We evaluated all of the parameters that have been considered in previ-ous studies related to the injection side and those issues in CTA perform-

ance that may lead to misdiagnoses with nondiagnostic images.In this study, artifacts that may be related to right or left arm injec-

tions, as well as artifacts that may reduce image quality of CTA, wereinvestigated in a systematic fashion.

Materials and methods

Patient population

CTAs of 90 patients with clinically suspected cervical or intracra-nial vascular disease were retrospectively reviewed. CTAs performedon patients with heart failure, vascular anomalies, or occlusions werenot included. All patients were informed of the study before the CTAexamination.

The first group of 44 patients, which consisted of 21 men and 23 wom-en, with a mean age of 6413.2 years and an age range of 31 to 85 years,received contrast material in their right arms. The second group, consist-ing of 18 men and 28 women, with ages ranging from 31 to 87 years anda mean age of 60.7613.23 years, received contrast material injectionsin their left arms.

CT protocol

All CTA scans were obtained using a four-detector row CT scanner(HiSpeed; GE Medical Systems, Milwaukee, Wisconsin, USA). The pa-tients assumed a supine position with their arms at their sides. Priorto the procedure, the patients were instructed to remove any movabledental implants, to breathe quietly without swallowing, and to remainstill during the scan. A lateral scout view including the thorax, neck,

NEURORADIOLOGY

ORIGINAL ARTICLE

Carotid CT angiography: comparison of image quality for leftversus right arm injections

Glen Demirpolat, Mrvet Yksel, Glgn Kavuku, Deniz Tuncel

From the Department of Radiology (G.D. gulendemirpolat@

hotmail.com), Balkesir University School of Medicine, Balkesir,

Turkey; the Departments of Radiology (M.Y.), and Neurology

(D.T.), Kahramanmara St mam University School ofMedicine, Kahramanmara, Turkey; and the Department ofRadiology (G.K.), Ege University School of Medicine, zmir,Turkey.

Received 18 January 2010; revision requested 6 April 2010; revisionreceived 26 May 2010; accepted 29 May 2010.

Published online 9 August 2010DOI 10.4261/1305-3825.DIR.3290-10.1

PURPOSETo evaluate the differences in image quality of carotid com-puted tomographic angiography (CTA) of patients injectedwith contrast material in their right arms versus patients in-jected with contrast material in their left arms.

MATERIALS AND METHODSPatients who had cerebrovascular accidents and subsequentlyunderwent CTA were included in the study. Contrast materialwas injected into the right arms of 44 patients and into the leftarms of 46 patients. Source images of a total of 90 CTAs wereretrospectively evaluated for perivenous streak artifacts andcontrast material reflux into the veins of the neck and upperthorax. After adjusting for differences in gender, the relation-ship between the injection site and the intensity of perivenousstreak artifacts and venous reflux was determined.

RESULTSPerivenous streak artifacts and venous reflux were demon-strated in patients who underwent either right or left arm in-jections. However, the intensity of perivenous streak artifactswas stronger in patients who were injected with contrast ma-terial in the left arm. Venous reflux into the neck and upperthorax veins was also more severe and more frequent withleft arm injections. A decreased retrosternal distance facilitated

reversed flow into the veins when the left arm injection wasused.

CONCLUSIONPerivenous beam hardening streak artifacts and venous re-flux could not be prevented with right or left arm injections.However, patients who were injected with contrast materialin their right arms showed fewer artifacts, thus allowing forbetter quality images on CTA.

Key words: tomography, X-ray computed angiography artifacts veins

Diagn Interv Radiol 2011; 17:195198


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Demirpolat et al.196September 2011Diagnostic and Interventional Radiology

and (c) reflux into all three branchveins. The relationships between thesethree groups and the intensity of theperivenous streak artifacts and injec-tion site were evaluated.

Perivenous artifacts were evaluatedon axial images and were scored as fol-lows: 0, no artifact, clear visualizationof the perivenous tissues; 1, artifacts

that may lead to false positive steno-sis or dissection in the arteries near theveins; and 2, profuse artifacts that makethe image unusable for assessment. Therelationship between artifact scoresand right and left arm injections andvenous reflux was evaluated.

Statistical analysis

Software (SPSS 10.0 for Windows;SPSS Inc., Chicago, USA) was usedfor the statistical analysis. The dif-ferences between right and left arminjection in regards to age, gender,and length of IJV reflux were evalu-ated using a 2 test. Fishers exact testwas used to evaluate the relationshipbetween IJV reflux frequency andright and left arm injections. The dif-ference in the retrosternal distance inpatients with and without IJV refluxwas determined with the Mann-Whit-ney U test. The relationship betweenperivenous artifact scores and gender,injection site, presence of branch veinreflux, and the presence and lengthof IJV reflux was evaluated using a 2

test. A value ofP < 0.05 was consid-ered significant.

Results

The mean age and gender differencesbetween right and left arm injectionswere not statistically significant (Table1) (P > 0.05). IJV reflux was observedin 54.4% (49/90) of the patients. Thefrequency and length were statisticallyhigher in left arm injections as com-pared to right arm injections (Tables 1

and 2). IJV reflux was not affected bygender.

The mean shortest retrosternal dis-tance was 9.35.4 mm for IJV-reflux-negative left arm injections. This valuewas smaller in the patients with IJV re-flux (6.873.98) (Fig. 1a, b).

Branch vein reflux (Fig. 2) was ob-served in 25 patients. It was more fre-quent with left arm injections thanwith the right arm. It was detected in50% of patients in whom a left arminjection was performed and 4.5% ofpatients in whom a right arm injectionwas performed. Severe branch vein re-flux, defined as having reflux into twoor three branch veins, was associatedwith left arm injections, and it was notdetected with right arm injections. Theartifact score was not correlated withthe severity of the branch vein reflux.

Streak artifacts were more frequentwhen the left arm was used for con-trast material injection. The severity ofperivenous streak artifacts (Fig. 3) wasindependent of the injection site, thepresence of branch vein reflux, and the

presence and extension of IJV reflux(Table 3) (P> 0.05).

and skull was acquired. The CTA scanrange reached from the aortic arch tothe vertex. The scan parameters wereas follows: the section thickness was2.5 mm, the table feed for rotationwas 2.5 mm, the pitch was at unity,the voltage was set at 120 kV, and thecurrent was 250 mA. The scanningrange was planned in a caudocranial

direction. Nonionic contrast material,with an iodine concentration of 300mg I/mL (iohexol [Omnipaque 300];Amersham Health, Cork, Ireland),was injected with a power injectorthrough an 18- to 20-gauge IV cannu-la (depending on the size of the vein)in an antecubital vein. All patientsreceived 120 mL of contrast mate-rial, at an injection rate of 3.5 mL/s.Saline was not injected following theadministration of the contrast mate-rial. Synchronization between thepassage of contrast material and dataacquisition was achieved with a bo-lus tracking technique. The CTA scanwas triggered automatically by meansof a threshold, measured in a regionof interest (ROI) set in the commoncarotid artery. The threshold was setat 100 HU.

Slice thicknesses and intervals of 1.25mm were used during post-processingand reconstruction.

Data collection and image analysis

The age and gender of each patient

were noted. Subsequently, the patientswere grouped according to the con-trast material injection site. For eachpatient, axial and reformatted imageswere analyzed for perivenous streakartifacts and reflux. The shortest retro-sternal distance between the sternumor sternoclavicular joint and the aorticarch or its branches was measured inaxial images in patients with left arminjections.

To evaluate the relationship betweenthe injection side and the internaljugular vein (IJV) reflux severity, thelength of the IJV reflux was measuredin millimeters on sagittal or coronalmaximum-intensity-projection imag-es. The length was compared betweenright and left arm injections.

Reflux in the branches of the subclavi-an vein (SCV) and brachiocephalic vein(BCV), involving veins other than theIJV, was grouped as follows: (a) refluxinto one of the branch veins (externaljugular, paravertebral or mediastinalveins), (b) reflux into two branch veins,

Table 1. The relationship of age, gender, internal jugular vein reflux and contrast materialinjection arm

ParameterRight arm

(n=44)Left arm(n=46) P

Age 62.361.95 62.121.95 0.25

Male/female 21/23 18/28 0.411

IJV reflux length (cm) 6.511.73 32.936.57 0.00

Table 2. The relationship between IJV reflux frequency and right and left arm injections

Injection site

IJV reflux

PReflux (-)

n %Reflux (+)

n %

Left arm 16 34.8 30 65.2 0.03

Right arm 25 56.8 19 43.2

IJV, internal jugular vein


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Carotid CT angiography image quality for left versus right arm injections 197Volume 17Issue 3

Figure 1.a, b. Axial CT image (a) demonstrating brachiocephalic vein compression (arrow). Sagittal reformatted image (b) showing reflux ofcontrast medium into the left IJV(arrows) due to constitutional retrosternal narrowing.

ba

Figure 2. Reflux into the branching veins (paravertebral, externaljugular veins) (white arrows) and the IJV(black arrow) are clearlyshown on an axial source image.

Figure 3. Transverse CT image showing prominent perivenous streakartifacts (arrow) due to a higher density in the brachiocephalic vein.The artifacts obscure the supraaortic branches.

Table 3. Relationship of perivenous artifacts and injection site,IJV reflux, length of IJV reflux, gender, and branching vein reflux

Parameter

Artifact score

P

0 1 2

n % n % n %

Injection site

Left arm 3 6.5 12 26.1 31 67.40.22

Right arm 3 6.8 19 43.2 22 50.4

IJV reflux

(+) 1 2.0 16 32.7 32 65.30.12

(-) 5 12.2 15 36.6 21 51.2

IJV reflux length

010 mm 5 8.5 23 39.0 31 52.50.22

>10 mm 1 3.2 8 25.8 22 71.0

Branching vein reflux

(+) 1 1.1 6 6.6 18 200.29

(-) 5 5.5 25 27.7 35 38.8

Age74.1610.6

(n=6)

66.3910.36

(n=31)

58.6413.7

(n=53)

Gender

Female 2 3.9 18 35.3 31 60.80.49

Male 4 10.3 13 33.3 22 56.4

IJV, internal jugular vein


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Demirpolat et al.198September 2011Diagnostic and Interventional Radiology

Discussion

Adequate homogenous luminal con-trast is required for optimal visualiza-tion of an artery with CTA. The attenu-ation of the surrounding structuresshould be less than the arteries to ob-tain good quality reconstructions andto avoid streak artifacts. Venous con-tamination and venous stasis lead to

higher attenuation in veins and distortimages of adjacent arteries. Commonreasons for venous stasis and venoushyperdensity include venous reflux,severe heart failure, expiration, medi-astinal masses, aortic aneurysms, bra-chiocephalic vein stenosis and superiorvena cava syndrome (710).

Barmeir et al. (6) described a technicalartifact that resulted in nondiagnosticexaminations in 3 of 54 carotid CTAs.They changed the technical parametersand the volume of contrast materialused, but could not improve the imagequality. They reported that they did notsee IJV reflux in 1812 carotid CTAs ob-tained after changing the injection sidefrom the left to right arm (6). In ourstudy, reflux into the IJV was found in49 patients (54.4%). This finding signif-icantly increased when the left antecu-bital vein was used for injection. In 30 ofthe 49 patients with reflux (61.2%), thecontrast material was injected into theleft side. We also found that a decreasein the retrosternal distance predisposedpatients to reflux when the left arm was

used for injection. The length of the re-flux was also significantly higher in leftarm injections. The results of our studyare consistent with the study performedby Tseng et al. (4), who measured theretrosternal distance in nine patientsin whom CTAs had been repeated withcontrast material injections to the rightand left arms. Their work showed thatthe retrosternal distance was 6.50.17mm for four patients who had obvi-ous reflux after left arm injection and13.20.22 mm for five patients whohad no reflux (4).

Branching vein reflux, involvingveins other than the IJV, is anotherartifact source and prevents the ac-quisition of high-quality carotid CTAreconstructions. This was found in 25of 90 patients (27.7%) and was signifi-cantly less frequent than IJV reflux.

It was more frequent with left arminjections. Our results are concord-ant with the study of You et al. (5),who evaluated image quality differ-ences between right and left arm in-jections. They administered the con-trast material to the right (n=30) orthe left (n=30) antecubital vein whileobtaining head and neck CT and com-

pared venous reflux into the branch-ing veins and perivenous artifacts be-tween the two groups. They reportedthat the scores of the perivenous ar-tifacts for the right arm injectionswere lower than the scores for theleft arm injections. They suggestedthat the venous system is longer inthe left arm and that this might havea role in the severity of artifacts (5).The authors did not investigate a pos-sible relationship between branchingvein reflux and perivenous artifacts.Our results show that the severity ofthe perivenous streak artifacts is inde-pendent of branching vein reflux.

The factors that predispose certainpatients to IJV reflux may lead to re-flux in the branching veins. However,a small diameter and different angleswith the brachiocephalic and subcla-vian veins with respect to the IJV mayreduce reflux.

Various methods were evaluated foreliminating the perivenous streak arti-facts. Dilution of the contrast materialis one of these methods. However, it

is not suitable for CTA because highlyconcentrated (greater amount of io-dine) contrast medium is preferablein CTA (11). The addition of a chaserbolus is another possible method thatmay be used to reduce streak artifactsin CTA. This method requires a dual-barrel power injector, and it is not use-ful for carotid CTA because the scandelay is shorter in carotid CTA andscanning should be started before theinjection of contrast material is com-plete (12, 13).

In conclusion, the injection site ofthe contrast medium is important tothe image quality of carotid CTA. Injec-tion into the right arm decreases refluxinto the IJV, BCV and SCV branches.Use of the right arm does not preventperivenous streak artifacts but does re-duce their frequency.

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PDF DIR 359 Carotid CTA