b-flow ultrasonography of peripheral vascular diseases · 2017-01-28 · introduction...

186 J Med Ultrasound 2005 • Vol 13 • No 4 ©Elsevier & CTSUM. All rights reserved.

P I C T O R I A L

E S S A Y

Department of Radiology, Taipei Veterans General Hospital, and National Yang-Ming University School of Medicine,Taipei, Taiwan, R.O.C.

*Address correspondence to: Dr. Yi-Hong Chou, Department of Radiology, Taipei Veterans General Hospital, 201, Section 2,Shih-Pai Road, Taipei 112, Taiwan, R.O.C. E-mail: [email protected]

Introduction

Ultrasonography (US) has been widely utilized as anoninvasive imaging modality for investigation ofvascular diseases. B-mode, color Doppler, and powerDoppler US are currently the most commonly usedUS technology in clinical practice [1–4]. B-mode USacquires echoes from stationary structures but veryweak echoes from red blood cells. Therefore, it pro-vides good information about the vascular wall andsurrounding structures, but blood flow is usuallynot visible. Color Doppler and power Doppler USdisplay flow images as an overlay to the B-modeimages. It is capable of visualizing blood flow butis susceptible to aliasing and overwriting of thevessel wall.

B-flow US is a US technology that has been intro-duced recently. It applies digitally encoded ultra-sound technology to provide direct visualization offlowing blood cells [5,6]. It provides blood flowimages by highlighting the weak flow reflectors (redblood cells) and suppressing the signals from thesurrounding stationary tissue. B-flow US provides a more realistic image of flowing reflectors in theblood spaces. The advantages of B-flow US includesimultaneous visualization of flowing blood and sur-rounding stationary structures, higher frame rate forhemodynamic imaging, and higher spatial resolu-tion for vascular anatomy [5,6].

Two kinds of flow phenomenon can be clearlydemonstrated in B-flow images: jet stream and bloodstream swirl. Jet stream is a region of high grayscale

B-flow Ultrasonography of PeripheralVascular Diseases

Hsin-Kai Wang, Yi-Hong Chou*, Hong-Jen Chiou, See-Ying Chiou, Cheng-Yen Chang

B-flow ultrasonography (US) is a new US technology, which has recently been utilized forthe investigation of vascular diseases. In this pictorial essay, we demonstrate the B-flow USimaging presentations of various peripheral vascular diseases, including diseases of thecarotid artery, peripheral artery, peripheral vein, and hemodialysis fistula. B-flow US is supe-rior in the depiction of complex hemodynamics in the blood spaces of peripheral vasculardiseases. Discrimination between flowing blood and surrounding stationary structures(vessel wall, thrombus, hematoma, intimal flap, venous valve) can be made without difficultyby using B-flow US. Our experiences show that B-flow US is a useful technique in the diag-nosis of peripheral vascular diseases.

KEY WORDS — B-flow, ultrasonography, vascular

■ J Med Ultrasound 2005;13(4):186–195 ■

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B-flow Ultrasonography

187J Med Ultrasound 2005 • Vol 13 • No 4

intensity, which is produced when blood flowsthrough a segment of stenosis [7]. Blood flow swirlrepresents focal turbulence of blood flow. Thismay be observed in regions of ulcerative plaques,vascular tortuosity, and blood spaces with blindends [8].

The clinical application of B-flow US has recentlybeen investigated in several entities, including theliver [9], artery [7,8,10–13], hemodialysis access[14], and superficial vein [15]. In this presentation,we display image findings of B-flow US in variousperipheral vascular diseases. These include carotidstenosis, carotid dissection, stenosis of hemodialysisaccess, arterial pseudoaneurysm, arteriovenous fis-tula, venous aneurysm, and venous insufficiency.The US machines and transducers used for scanning

were: LOGIQ 9 and LOGIQ 700 MR with M12Ltransducer (GE Healthcare, Milwaukee, WI, USA).

Carotid Artery

Carotid artery stenosisThe stenotic vascular lumen shows high intensityechoes in B-flow US as it contains numerous reflec-tors in the flowing blood (Figs. 1 and 2). Jet streammay be found at the site of stenosis or the region justdistal to the stenosis. The vascular lumen, atheromaplaques, and vascular wall can be differentiated inB-flow US. There is no overwriting in B-flow US.The turbulent flow distal to an atheroma plaquepresents as blood flow swirl in B-flow US (Fig. 3).

iFig. 1. Atheroma plaque of the left common carotid artery. (A) B-mode US (longitudinal scan) shows an atheroma plaque(arrows) at the posterior wall of the left common carotid artery. (B) Color Doppler US shows color flow signal flowing pass theatheroma plaque; note the areas of overwriting (arrow) of color signal beyond the vessel lumen. (C) B-flow US with preservation f ofbackground echoes, and (D) suppression of background echoes demonstrates the flowing blood within the vessel lumen.

A B

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Ulcerative plaqueThe flow turbulence at the region of ulcerative plaquecan be depicted in B-flow US as focal blood flow swirl(Fig. 4). In Color Doppler or power Doppler US, it mayoccasionally be difficult to differentiate flowing sig-nal in an ulcerative plaque from overwriting.

Carotid artery dissectionThe true/false lumen, intimal flap, and arterial wallare well-demonstrated in B-flow US (Fig. 5). In somecases, the intimal flaps may be so thin that they areobscured in color Doppler/power Doppler US dueto overwriting.

H.K. Wang, Y.H. Chou, H.J. Chiou, et al

188 J Med Ultrasound 2005 • Vol 13 • No 4

A

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B

iFig. 2. SLeft internal carotid artery stenosis. (A) Color Doppler USl(transverse scan) shows thick atheroma plaques in the left internal

carotid artery where about 70% of luminal narrowing is noted.lThere is some overwriting. The arrows indicate the left internal

carotid artery, the arrowhead indicates the narrowed lumen in thevessel, the star indicates the left external carotid artery, and theheart indicates the left internal jugular vein. (B) B-flow US withppreservation of the background echoes and (C) B-flow US withssuppression of the background echoes show flowing blood in the

rsstenotic lumen (arrows) without significant overwriting as in colorwDoppler US. The flowing blood is further highlighted by B-flow

imaging with background suppression.

BA

iFig. 3.Fig 3 Blood stream swirl distal to an atheroma plaque. (A) Color Doppler US of the left common carotid artery, longitudinal scan,Blood stream s irl distal to an atheroma plaq e (A) Color Doppler US of the left common carotid arter longit dinal scansshows alternation of the direction of blood flow distal to a plaque (arrows). Focal flow reversal is shown (arrowhead). (B) B-f Slow USffdemonstrates blood stream swirl (arrowheads) at the region of flow reversal, providing a more intuitive image than color Doppler US.



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iFig. 4. Atheroma plaque with ulceration. Color Doppler US of the left internal carotid artery: (A) longitudinal scan; (B) transverse scan. Accthin atheroma plaque in the posterior wall of the proximal left internal carotid artery with a small ulcer (arrows). B-flow US: (C) longitudi-nal scan; (D) transverse scan. Bloodstream swirl at the site of the ulcer (arrows) is noted.

BA

iFig. 5. Carotid dissection. (A) B-mode US of the right common carotid artery (longitudinal scan) shows a thick intimal flap (arrow-heads) in the lumen of the right common carotid artery (arrows). (B) Color Doppler US shows flowing blood in the true and falselumen of the dissected artery.



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iFig. 6. lPseudoaneurysm of the femoral artery with partialthrombosis. (A) Color Doppler US shows pseudoaneurysm

S(arrows) with partial thrombosis (arrowheads). (B) B-flow USsshows swirling blood in the vascular space of the pseudoaneurysmwith “yin-yang” sign. (C) Spectral Doppler US in the neck of theppseudoaneurysm demonstrates characteristic to-and-fro flow.

C D

iFig. 5.Fi 5 Carotid dissection.C tid di ti d(C) B-flow US (longitudinal scan) demonstrates good delineation of the flowing blood, intimal flap, and(C) B fl US (l it di l ) d t t d d li ti f th fl i bl d i ti l fl dvessel wall. (D) B-flow US (transverse scan) shows the thick intimal flap (arrowheads).



Peripheral Artery

Arterial pseudoaneurysmB-flow US provides realistic images in cases of arterialpseudoaneurysm. The blood space of an arterial pseu-doaneurysm gives rise to a typical “yin-yang” signin color Doppler US, which is also well-demonstratedby B-flow US in a grayscale format (Fig. 6).

Arteriovenous fistulaThe blood flow through the fistula tract of an arterio-venous fistula flows at a high velocity. In B-flow US,the flowing blood with high velocity results in a jetstream at the fistulous tract (Fig. 7).

Peripheral Vein

Venous aneurysmThe hemodynamics in the blood space of venousaneurysm can be demonstrated in a more realisticfashion using B-flow US (Fig. 8). The turbulent flowin the venous aneurysm presents as blood flowswirl in B-flow US (Fig. 9).

Venous valve insufficiencyThe reverse flow through the incompetent venousvalve results in jet stream in B-flow US (Fig. 10).Turbulent flow around the incompetent venousvalve can be depicted in B-flow US.

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iFig. 7.Fig. 7. Femoral arteriovenous fistula. (A) Color Doppler US (longitudinal scan) shows a tract (arrows) communicating with theFemoral arteriovenous fistula (A) Color Doppler US (longitudinal scan) shows a tract (arrows) communicating with thecommon femoral artery and common femoral vein. (B) Duplex US shows high velocity flow within the tract, causing aliasing in thespectral Doppler image. (C) B-flow US with preservation of background echoes shows a jet stream (arrows) at the common femoralspectral Doppler image. (C) B-flow US with preservation of background echoes shows a jet stream (arrows) at the common femoralvein. (D) B-flow US with suppression of background echoes demonstrates the fistulous tract (arrows).



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iFig. 8.Fi 8 Superficial venous aneurysm of the external jugular vein. (A) B-mode US shows a vascular space (arrows) connecting to theS p fi i l f th t l j l i (A) B d US h l p ( ) ti t thexternal jugular vein through a narrowed neck (arrowheads), suggestive of venous aneurysm. Note partial thrombosis of theaneurysm with hypoechoic patent lumen in the central portion of the aneurysm. (B) Color Doppler US shows filling of the color f wlowffsignals in the aneurysm. (C) B-flow US with preservation of background echoes and (D) B-flow US with suppression of backgroundsignals in the aneurysm. (C) B-flow US with preservation of background echoes and (D) B-flow US with suppression of background

techoes show jet stream (arrowheads), representing the blood flow filling the aneurysm through the neck of the aneurysm. The jetsstream is highlighted after suppression of the background echoes.

A B

C

iFig. 9. rSuperficial venous aneurysm at the calf. (A) ColorDoppler US and (B) power Doppler US show venous aneurysm

S(arrows) with bizarre color signals in the lumen. (C) B-flow USsshows blood stream swirl in the lumen of the venous aneurysm.

Venous thrombosisIn B-flow US, the recanalized venous lumen is com-posed of flowing echoes, which can be differen-tiated from the stationary thrombus in the vein(Fig. 11).

Other

Stenosis of hemodialysis accessStenosis of hemodynamic access can be well-evaluated by B-flow US. B-flow US demonstratesthe stenotic lumen without overwriting (Figs. 12

and 13). The thrill at the region of arteriovenousfistula produces noise in color Doppler and powerDoppler images. This effect is less pronounced inB-flow US [15].

Conclusion

B-flow US provides characteristic imaging featuresin various peripheral vascular diseases. Familiaritywith the unique image presentations of B-flow US(e.g. jet stream, blood stream swirl) aids in imag-ing interpretation of B-flow US.



A B

iFig. 10. Venous valve insufficiency at the saphenofemoral junction. (A) Duplex US shows reverse flow at the greater saphenousvein during the Valsalva maneuver. Note the incompetent valve at the saphenofemoral junction (arrow). (B) B-flow US shows char-acteristic jet stream (arrows) representing the reverse blood flow through the incompetent venous valve.

BA

iFig. 11. tPartial thrombosis of the right basilic vein. (A) Color Doppler US shows color flow signals (arrows) in the partially patentvenous lumen. (B) In B-flow US, the patent lumen with flowing blood (arrows) can be distinguished from the thrombi in the lumen.

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Fig. 12. Stenosis of the arterial limb of an arteriovenous fistula.(A) B-flow US depicts stenosis of the arterial limb of the arterio-venous fistula close to the arteriovenous anastomosis (arrow-heads). (B) Color Doppler US demonstrates the stenosis (arrows)less conspicuously than B-flow US due to artifact caused by promi-nent thrill. (C) Digital subtraction angiography shows stenosis of thearterial limb adjacent to the arteriovenous anastomosis (arrows).

A B

iFig. 13. Stenosis of the venous limb of an arteriovenous fistula. (A) B-flow US shows stenosis of the venous limb of the arteri-ovenous fistula (arrows). (B) Digital subtraction angiography shows the stenotic venous limb (arrow), correlating well with theB-flow image.

comparison with color-coded Doppler and powerDoppler sonography. Eur Radiol 2005;15:342–7.

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15. Lurie F, Kistner RL, Eklof B, et al. Mechanism ofvenous valve closure and role of the valve in circula-tion: a new concept. J Vasc Surg 2003;38:955–61.



b-flow ultrasonography of peripheral vascular diseases · 2017-01-28 · introduction...

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