Acta Radiologica 44 (2003) Copyright # Acta Radiologica 2003 Printed in Denmark. All rights reserved

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2 Act Rdiologic 44 (2003) Copyright # Act Rdiologic 2003 Printed in Denmrk. All rights reserved ACTA RADIOLOGICA ISSN Review Article Downloded y [University of Cliforni, Sn Frncisco] t 15:22 09 Novemer 2015 COLOR DOPPLER US FINDINGS IN THE DIAGNOSIS OF ARTERIAL OCCLUSIVE DISEASE OF THE LOWER LIMB A. TRUSEN, M.BEISSERT nd D. HAHN Deprtment of Dignostic Rdiology, University of Würzurg, Würzurg. Germny. Astrct Peripherl rteril occlusive disese (PAOD) of the lower lim is widely spred disese t the present time. After clinicl exmintion, which includes comprehensive history of the ptient, different imging modlities re competitive in the exct ssessment of PAOD. Besides digitl sutrction ngiogrphy nd MR -ngiogrphy, color Doppler US is n estlished imging modlity in the dignosis of PAOD. This rticle illustrtes the typicl color Doppler US findings in PAOD of the lower lim. Duplex imges of norml nd pthologicl findings re presented, nd the limittions of the method re pointed out. Color Doppler US exmintion strtegies in ptients suffering of PAOD re outlined. Atherosclerosis is the leding cuse of peripherl rteril occlusive disese (PAOD) in ptients over 40 yers of ge. Risk fctors for PAOD re dietes mellitus, nicotine use, hypertension, hyperlipoproteinemi, hypercholesterolemi nd ge. The disese is minly chrcterized y pin, numness nd crmp, which occurs during exercise nd is relieved y rest intermittent cludiction (11). In ptients with severe PAOD, rest pin is persistent. The clinicl mnifesttions re determined y the degree of rteril nrrowing, the rte of development of the ostruction, the extent of collterl circultion, the loction of the rteril ostruction, nd the presence of coexisting disese. There re severl signs of PAOD in the ffected extremities: sent or diminished dorslis pedis pulse, coolness nd/or pleness, ruor of the skin nd trophic lesions. In the end, severe ischemi results in Key words: Peripherl rteril occlusive disese; ultrsound, Doppler studies. Correspondence: Andres Trusen, Institut für Röntgendignostik der Universität Würzurg, Josef- Schneider-Strsse 2, DE Würzurg, Germny. FAX þ E-mil: trusen@roentgen. uni-wuerzurg.de Accepted for puliction 1 April ulcertion. The Fontine clssifiction is n ccepted system for clinicl evlution of PAOD (Tle). Over mny yers invsive ngiogrphy hs een the gold stndrd in dignostic imging of PAOD. The technique hs chnged from conventionl filmscreen ngiogrphy to digitl sutrction ngiogrphy (DSA). Additionl improvements such s pulsed fluoroscopy, rodmpping for interventionl procedures nd the newly developed step trnsltion DSA led to decrese in rdition exposure, mounts of contrst medium used nd reduction of exmintion time (4). After ssessment of physicl findings, n ojective evlution of the severity of the disese should e otined y non-invsive imging techniques, of which color Doppler US plys n importnt role, especilly considering the cost-effectiveness (16). 411

3 A. TRUSEN ET AL. Downloded y [University of Cliforni, Sn Frncisco] t 15:22 09 Novemer 2015 Tle Fontine clssifiction system of peripherl rteril occlusive disese (PAOD) Stge I II II III IV History symptomtic mild cludiction, wlking distnce >200 meters moderte to severe cludiction, wlking distnce <200 meters ischemic rest pin tissue loss or ulcertion Compred to DSA, color Doppler US hs n overll sensitivity in the detection of stenoses nd occlusions of 92%, for the femorl rteries 95% nd femoropoplitel region 100%. Slightly lower sensitivities hve een reported for the ilic region (89%), nd the run-off vessels of the lower lim (82%) (1, 2). Other uthors report similr sensitivities (93.5%) oth for significnt nd nonsignificnt stenoses, with overestimtions in 7% nd underestimtions in 5% of stenoses (13). In recent yers, non-invsive imging of peripherl rteries y MR ngiogrphy (MRA) hs incresed in clinicl prctice nd plys more importnt role thn formerly (9, 20). Contrst-enhnced MRA hs sensitivity of 94% for sustntil stenoses (>50%) nd n overll sensitivity of 91% (18). During the pst few yers the performnce of US imging systems hs improved considerly. Most notly, the dvnces in Doppler technique hve dded the possiility tht this non-invsive imging method could e the primry modlity in exmintion of vsculr diseses in peripherl vessels. The developments include color flow imging (6), which fcilittes rpid ssessment of lood flow in peripherl rteries, nd of duplex US (3), which llows ccurte locliztion nd quntifiction of PAOD. The comintion of these techniques, nmed color duplex US, hs in clinicl prctice gretly rodened scnning y integrting functionl nd ntomicl dt. Color duplex US lredy plys n importnt clinicl role in determining the degree of rteril stenosis (10, 16). As in ll other cross-sectionl modlities, one min prolem of color duplex US in peripherl rteries is to demonstrte the complete vsculr tree (e.g., from the dominl ort distl to the renl vessels to the nkle of oth legs). However, keeping this potentil limittion in mind, color duplex US hs known dvntges, such s widespred vilility, possiility of edside exmintion nd simultneous evlution of morphology nd function. Moreover, the lck of rdition exposure enles repetition s often s required. Due to these dvntges, color duplex US is vlule tool in detection of PAOD nd in plnning further therpy. This rticle illustrtes the current clinicl 412 pplictions nd points out future perspectives for US in the ssessment of PAOD. Doppler techniques Pulse-wve Doppler US/duplex US: The Doppler technique is sed on the frequency shift of insonted ultrsonic echoes. Echoes, which return to the trnsducer from sttionry structures, come ck with the sme frequency, wheres echoes from moving ojects (e.g., lood cells) towrds or wy from the trnsducer, return with higher or lower frequency, i.e., Doppler effect. Thescnnerdetectsnychngein frequency, nd cn clculte the ctul speed of the trget provided the ngle etween the direction of the ultrsonic em nd the direction of the oject movement is known. Pulse Wve Doppler US provides informtion out the depth of the tissue, from where the echo origintes. The comintion of gryscle US nd pulse wve Doppler technique is clled duplex US. Color Doppler US: Color Doppler US uses multiple gtes to produce flow informtion from different depths simultneously. This is then superimposed on the B-mode US imge. Color Doppler US ssigns single representtive numer (usully the men Doppler frequency shift) to ech site, which is then represented s different color sturtions (different colors show flow direction nd mgnitude of lood velocity). The sence of flow is coded lck. Color duplex US/triplex mode: Color duplex US comines duplex nd color Doppler US. Color duplex US should e the current technicl stte-of-the-rt in US devices used for vsculr imging studies. The simultneous color flow imging superimposed on gry-scle B-mode US imge comined with the Doppler frequency velocity wveform profile on the US screen is lso nmed triplex mode. Power Doppler US: The limittions of color Doppler US include ngle dependence nd difficulty in displying low-volume nd low-velocity lood flow. In n ttempt to ddress these limittions, n dditionl color flow imging technique termed power Doppler US hs een developed in which color encodes the integrted energy power of the Doppler signl insted of its men Doppler frequency shift (17). The lood flow is lso visulized in superimposition on the B-mode imge in rel-time. US exmintion technique in PAOD ptients: For vsculr scnning liner-rry proe with 5 10 MHz is recommended. The ilic region nd the ort re exmined using MHz sector proe. The color Doppler US exmintion comprises oth functionl nd morphologicl dt. The exmintion should strt with functionl test, the nkle/rchil index (ABI). The rtio of nkle to

4 COLOR DOPPLER US FINDINGS IN PAOD Downloded y [University of Cliforni, Sn Frncisco] t 15:22 09 Novemer 2015 Fig. 1. Schemtic drwing of the rteries of the lower extremity. Ankle/rchil index (ABI) of systolic lood pressure (mmhg), sites of mesurements (: proximl upper leg, : distl upper leg, c: proximl lower leg, d: distl lower leg; \:knee joint); on the right side norml pressures, on the left pthologic ABI with n occlusion in the superficil femorl rtery, seen in decrese of lood pressure etween proximl nd distl upper leg. the periphery s sign of proximl stenoses or occlusions. Additionl sites for segmentl mesurement re the proximl lower leg followed y distl nd proximl upper leg (Fig. 1). The use of different cuff sizes in order to djust for the vrying dimeter of the extremity is mndtory. Contrindictions for mesuring the lood pressure of the leg re ulcertions of the skin, surgicl ypss or vsculr segments fter percutneous trnsrteril ngioplsty (PTA) or stent implnttion. In dietic ptients with medi sclerosis, clcified vessel wlls led to diminished compressiility nd thus to elevted nkle pressure, so tht the ABI my e misleding. Norml ABI, spectrum nd wveform of the distl posterior nd nterior tiil rtery exclude hemodynmic relevnt stenosis requiring therpy. In the sence of norml findings or in cse of suspected medi sclerosis, further exmintion must e crried out y evluting the vessels from the ort to the vessels of the lower leg. The trnsducer Fig. 2. Norml superficil femorl rtery. ) Color Doppler US shows lminr flow without turulences. ) Triplex mode revels triphsic norml spectrum with systolic pek velocity of 90 cm/s, short distolic reflux followed y n enddistolic forwrd flow. Fig. 3. Norml triphsic spectrum of the nterior tiil rtery, pek velocity 100 cm/s, steep incline of the velocity slope. rchil systolic rteril lood pressure is normlly greter thn 1.0 nd rtios elow 0.9 re considered norml (11). For this test the lood pressure is determined over the rchil rtery nd then over the nkle of the lower leg. In the ltter cse, the US proe is positioned over the nterior nd posterior tiil rteries. The lood pressure t which color signls pper when the cuff is deflted is the systolic lood pressure. The distolic lood pressure is not mesured. At the sme time the wveform of the spectrum gives informtion out the perfusion of Fig. 4. Pthologic, monophsic poststenotic rodened spectrum with less steep systolic rise, no distolic retrogrde flow. 413

5 A. TRUSEN ET AL. Downloded y [University of Cliforni, Sn Frncisco] t 15:22 09 Novemer 2015 Fig. 5. High-grde stenosis of the externl ilic rtery. ) Color Doppler US: color lising in the ilic rtery, turulences nd mixture of colors re seen in high-grde stenosis. ) Triplex mode: the highest pek velocity is detected t the site of mximl lumen nrrowing. tr with pek systolic velocity etween 90 nd 140 cm/s cn e oserved. A monophsic spectrum indictes proximl stenosis or occlusion (Fig. 4). Different clssifiction schemes for evluting peripherl stenosis hve een developed. The criteri include pek systolic velocity (12, 14), description of the wveform of the spectrum s well s reduction of vessel dimeter (7, 8). The spectrl chnges in stenosis with increse of velocity re highest t the point of mximl lumen reduction (Figs 5 7). Increse of the pek systolic velocity s well s turulence indicte hemodynmic relevnt stenosis. A 50% stenosis yields fourfold increse of velocity. Two stenotic lesions in series (tndem stenosis) my e dditive with respect to hemodynmic relevnce. Occlusion: Complete occlusion shows n sence of color signls even with scnning prmeters le to depict low lood flow. The typicl preocclusive spectrum shows high peripherl resistnce with nrrow, smll systolic pek nd sence of distolic flow (Fig. 8). Collterl vessels (Fig. 9) s well s the level of re-entrnce in cse of distl perfusion cn e loclized. The postocclusive spectrum is chrcterized y monophsic wveform with reduced nd is plced on the vessels in the longitudinl plne, which is used routinely to exmine ll peripherl rteries; however, the trnsversl plne is needed in cse of excentric stenosis. Primrily, the exmintion is performed in color Doppler US. In ech vsculr segment s well s in regions with turulence, triplex mode is recommended (Fig. 2). Color duplex US findings in PAOD Stenosis: The norml wve form of the rteril spectrum is i- or triphsic (Fig. 3). Tri- or iphsic spec- Fig. 6. High-grde stenosis of the externl ilic rtery: the spectrum shows pek systolic velocity of 600 cm/s, representing stenosis with 80 90% reduction of the lumen. The distolic reflux is missing. Fig. 7. High-grde stenosis of the superficil femorl rtery. ) Nrrowing of the lumen is seen in color Doppler mode s well s color lising nd turulence. ) An increse of the pek systolic velocity to 350 cm/s representing high-grde stenosis is shown in triplex mode. 414

6 Downloded y [University of Cliforni, Sn Frncisco] t 15:22 09 Novemer 2015 COLOR DOPPLER US FINDINGS IN PAOD Fig. 8. Acute occlusion of the poplitel rtery. ) The occlusion is depicted y missing color signls in the vessel (rrows), ove the occlusion collterl vessel rnches off showing color lising (rrowhed). ) The triplex mode demonstrtes preocclusive spectrum with nrrow pek, low pek systolic velocity nd missing distolic forwrd flow, indicting n norml high peripherl resistnce. lower rising systolic pek velocity. A specil form is the emolic occlusion tht cn e suspected if convex shped flow void is found typiclly ove the vessel ifurction (Fig. 10). Plque morphology: Plque chrcteriztion in peripherl rteries cn help to predict the initil success of PTA. Incresing echodensity of plques shows correltion to restenosis fter PTA (15). Hypoechogenic plques my rise in intiml hyperplsi fter PTA (Fig. 11). Clcified plques my led to difficulty in visulizing the lumen. An exmintion from nother scnning window should e tried in cses of excentric clcified plques. If direct visuliztion is not possile, the poststenotic re cn yield informtion in terms of turulence or incresed velocity (Fig. 12). Evlution of plque morphology cn e improved y using tissue hrmonic imging (THI) which rings out etter delinetion of the vessel wll nd plque morphology (Fig. 13). Aneurysm: The increse in dimeter produces reduction of velocity requiring setting for low lood flow. Thromosed prts of n neurysm cn e esily visulized in color or power Doppler US (Fig. 14). Pseudoneurysms, most often of itrogenic origin, e.g., formed t ngiogrphy, re esily Fig. 9. Occlusion of the superficil femorl rtery. ) Collterl vessels in the color Doppler US cn e trced from the originl superficil rtery to the poplitel rtery. ) Post-occlusive spectrum in the poplitel rtery with low pek systolic velocity, rodened systolic pek nd monophsic wveform of the spectrum nd low distolic forwrd flow. Fig. 10. Emolus in color Doppler US: flow void (rrows) with rounded shpe in the longitudinl () nd in trnsversl () plnes. Typicl loction of n emolus is usully ove ifurction. 415

7 Downloded y [University of Cliforni, Sn Frncisco] t 15:22 09 Novemer 2015 A. TRUSEN ET AL. Fig. 11. Intiml hyperplsi (rrow) with low echogenicity fter stent implnttion in the superficil femorl rtery (power Doppler US). dignosed y color Doppler US. In pseudoneurysms, the communicting neck with flow to nd from the neurysm cn e noted. US provides the option for closing pseudoneurysms y compression therpy (Fig. 15) (19). Posttherpeutic findings in PAOD: Color Doppler US is useful tool in follow-up of ptients with PAOD fter therpy. Occlusions of ypss grft cn e esily detected (Fig. 16). Complictions of interventionl ngiogrphy such s dissection (Fig. 17) or rteriovenous fistuls cn e sensitively dignosed using color Doppler US. In B-mode US dissection memrne my e seen s liner echogenic we. Arteriovenous fistuls present with urst of color nd ndlike spectrum (Fig. 18). Fig. 12. Clcified plque in the superficil femorl rtery. No visuliztion of the lumen ehind the clcified plque re due to coustic shdowing (). Turulence nd increse of pek systolic velocity to 180 cm/s indicte moderte stenosis (). To loclize the origin of the rteriovenous fistul, proximl compression diminishing the turulence y reducing the lood flow is often helpful. Pitflls: An underestimtion of stenosis occurs in tndem stenoses. The second stenosis hs reduced pek velocity nd reduced turulence. Fully developed collterliztion cn hide proximl stenosis or n occlusion y not showing pthologic spectr in the Fig. 13. Echogenic plques in the superficil femorl rtery without () nd with () tissue hrmonic imging (THI)! etter delinetion of plque morphology with THI. 416 Fig. 14. Extended field-of-view in power Doppler US: prtilly thromosed neurysm of the poplitel rtery. The rrow mrks the thromosed prt of the neurysm, extended field-of-view US in power Doppler US enles etter morphologicl overview.

8 COLOR DOPPLER US FINDINGS IN PAOD Downloded y [University of Cliforni, Sn Frncisco] t 15:22 09 Novemer 2015 Fig. 15. Pseudoneurysm of the common femorl rtery. Pre- () nd post () US compression therpy. The pseudoneurysm demonstrtes systolic inflow nd distolic outflow. After successful US compression therpy, no color signls re detected within the pseudoneurysm. Fig. 16. Occlusion of ypss grft (rrows) in extended field-of-view in power Doppler US cn provide the morphologicl informtion for therpy plnning. distl portions. Another pitfll might e to differentite etween stenosis nd occlusion, missing miniml flow if the exmintion is crried out using only prmeters detecting high lood velocity. Further cuse of error is n incorrect Doppler ngle. Exct positioning of the Doppler ngle is needed in order to ccurtely mesure pek systolic velocity. Conclusion Fig. 17. A dissection is detected s liner flow void (rrow) in color Doppler US. Fig. 18. An rteriovenous fistul fter ngiogrphy presents with urst of color in color Doppler US (), ndlike spectrum is depicted in the fistul (). Mny rdiologists hve some concerns regrding the use of color Doppler US, s the results re dependent on the experience of the sonogrpher. As rdiologists we re involved in ll fields of vsculr imging nd interventionl procedures, nd color Doppler US should e prt of them. Color 417

9 A. TRUSEN ET AL. Downloded y [University of Cliforni, Sn Frncisco] t 15:22 09 Novemer 2015 Doppler US is non-invsive imging technique useful for screening for PAOD, s it comines morphologic nd functionl dt in the vsculr system. The widespred vilility enles the use of color Doppler US not only for primry dignosis of PAOD, ut lso for therpeutic guidnce nd follow-up fter therpy. Future perspectives Developments in US such s extended field-of-view US in comintion with power Doppler US nd 3D US might ring improvements in the dignosis of PAOD (17). US contrst gents cn produce n increse in Doppler signl intensity, which my led to etter delinetion of ilic rteries s well s collterl vsculrity or peripherl smll vessels (5, 21). With the development of contrst gents with prolonged enhncement of Doppler signls y extending the stility of microules, vsculr dignosis might even e improved further. Another new technique for detection of lood flow is the B-(rightness)-flow -mode (22), demonstrting etter sptil resolution thn color Doppler US (1). Whether this method, especilly in comintion with superimposed color scle (color-coded B-flow), will e successfully integrted in US strtegies of the peripherl rteries in ptients with PAOD cnnot e estimted t the present time. Despite the dvnces in cross-sectionl imging, ecuse of oth morphology nd functionl evlution, US will still mintin its primry role s the initil dignostic modlity for ptients with PAOD. REFERENCES 1. Aly S, Jenkins MP, Zidi FH, Coleridge Smith PD, Bishop CC. Duplex scnning nd effect of multisegmentl rteril disese on its ccurcy in lower lim rteries. Eur. J. Vsc. Endovsc. Surg. 1998; 16: Aly S, Sommerville K, Adiseshih M, Rphel M, Coleridge Smith PD, Bishop CC. Comprison of duplex imging nd rteriogrphy in the evlution of lower lim rteries. Br. J. Surg. 1998; 85: Brer FE, Bker DW, Ntion AWG, Strndness DE Jr, Reid JM. Ultrsonic duplex echo-doppler scnner. IEEE Trns. Biomed. Eng. 1974; 21: Biederer J, Link J, Stolley C, Heller M. Digitl sutrction ngiogrphy of the extremities using step trnsltion technique. RÖFO. 2000; 172: Corres JM, Boespflug O, Hmid K et l. Doppler ultrsonogrphy of peripherl vsculr disese: the potentil for ultrsound contrst gents. J. Comput. Assist. Tomogr. 1999; 23: S119 S Curry GR, White DN. Color coded ultrsonic differentil velocity rteril scnner (Echoflow). Ultrsound Med. Biol. 1978; 4: Grenier N, Bsseu F, Rey MC, L Gorde-Segot L. Interprettion of Doppler signls. Eur. Rdiol. 2001; 11: Lndwehr P, Schindler R, Heinrich U, Dölken W, Krhe T, Lckner K. Quntifiction of vsculr stenosis with color Doppler flow imging: In vitro investigtions. Rdiology 1991; 178: Lundin P, Svensson A, Henriksen E et l. Imging of ortoilic rteril disese. Duplex ultrsound nd MR ngiogrphy versus digitl sutrction ngiogrphy. Act Rdiol. 2000; 41: Lunt MJ. Review of duplex nd colour Doppler imging of the lower lim rteries nd veins. J. Tissue Viility 1999; 9: Murito JM, Evns JC, Nieto K, Lrson MG, Levy D, Wilson PW. Prevlence nd clinicl correltes of peripherl rteril disese in the Frminghm Offspring Study. Am. Hert J. 2002; 143: Pemerton M, London NJM. Colour flow duplex imging of occlusive rteril disese of the lower lim. Br. J. Surg. 1997; 84: Pinto F, Lencioni R, Npoli V et l. Peripherl ischemic occlusive rteril disese: comprison of color Doppler sonogrphy nd ngiogrphy. J. Ultrsound Med. 1996; 15: Ri C. Color Doppler sonogrphy of lim rteries. Eur. Rdiol. 2001; 11: Rmswmi G, Tegos T, Nicolides AN et l. Ultrsonic plque chrcter nd outcome fter lower lim ngioplsty. J. Vsc. Surg. 1999; 29: Reimer P, Lndwehr P. Non-invsive vsculr imging of peripherl vessels. Eur. Rdiol. 1998; 8: Ruin JM, Bude RO, Crson PL, Bree RL, Adler RS. Power Doppler US: potentilly useful lterntive to men frequency-sed color Doppler US. Rdiology 1994; 190: Ruehm SG, Goyen M, Brkhusen J et l. Rpid mgnetic resonnce ngiogrphy for detection of therosclerosis. Lncet 2001; 357: Tschmmler A, Elsner H, Jenett M, Hhn D. Compression repir of femorl post-ctheristion pseudoneurysms guided y colour Doppler flow imging. Eur. Rdiol. 1995; 5: Visser K, Hunink MGM. Peripherl rteril disese: Gdolinium enhnced MR-ngiogrphy versus colorguided duplex-us met-nlysis. Rdiology 2000; 216: Vogt K, Jensen F, Schroeder TV. Does Doppler signl enhncement with Levovist improve the dignostic confidence of duplex scnning of the ilic rteries? A pilot study with correltion to intrvsculr ultrsound. Eur. J. Ultrsound 1998; 7: Wescott HP. B-flow new method for detecting lood flow. Ultrschll Med. 2000; 21: