- Email: [email protected]
Multidetector CT angiography versus arterial duplex USG in diagnosis of mild lower extremity peripheral arterial disease: Is multidetector CT a valuable screening tool?
European Journal of Radiology 81 (2012) 542–546
Contents lists available at ScienceDirect
European Journal of Radiology journal homepage: www.elsevier.com/locate/ejrad
Multidetector CT angiography versus arterial duplex USG in diagnosis of mild lower extremity peripheral arterial disease: Is multidetector CT a valuable screening tool? Arda Kayhan a,∗ , Figen Palabıyık b , Serdar Serinsöz b , Adem Kırıs¸ b , Sibel Bayramo˘glu b , Joshua T.B. Williams c , Tan Cimilli b a
Department of Radiology, Faculty of Medicine, Namık Kemal University, 100. yıl mahallesi, Tunca caddesi, No: 32, Tekirda˘g Turkey Department of Radiology, Dr. Sadi Konuk Education and Research Hospital, Turkey c University of Chicago, School of Medicine, Chicago, IL, United States b
a r t i c l e
i n f o
Article history: Received 3 September 2010 Received in revised form 19 January 2011 Accepted 28 January 2011 Keywords: Peripheral arterial occlusive disease Duplex ultrasonography MDCT angiography
a b s t r a c t Objective: To prospectively compare the efficacy of 40-row multidetector computed tomography angiography (MDCTA) and duplex ultrasonography (DUS) to diagnose mild peripheral arterial occlusive disease (PAOD) in lower leg and to search whether MDCTA can be used as a screening tool. Methods: Forty-three patients with intermittent claudication and leg pain, diagnosed as mild PAOD, had undergone DUS and MDCTA of lower limb. The arteries of lower leg were initially scanned by DUS, followed by MDCTA. Both modalities were compared for detecting the obstructed and stenotic segments. Results: A total of 774 vessel segments were imaged by both modalities. When all arteries were considered, MDCTA detected obstructed or stenotic lesions in 16.8% of arteries, versus 11.1% compared to DUS. When suprapopliteal arteries alone were considered, MDCTA detected lesions in 15.0% of arteries, versus 11.0% with DUS. When infrapopliteal arteries only were considered, MDCTA detected lesions in 19.6% of arteries, versus 11.3% with DUS. MDCTA showed 5.7% (95% CI: [3.5%, 7.9%]) more lesions than DUS when all arteries were considered together, 8.3% (95% CI: [4.6%, 12.0%]) more lesions when only the infrapopliteal arteries were compared, and 4.0% (95% CI: [1.3%, 6.8%]) more lesions when only suprapopliteal arteries were compared (p < 0.01 for all comparisons). Conclusion: 40-row MDCTA may be used as a screening tool in patients with mild lower extremity PAOD as it is a non-invasive and more accurate modality when compared to DUS. © 2011 Elsevier Ireland Ltd. All rights reserved.
1. Introduction Peripheral arterial occlusive disease (PAOD) is the atheromatous narrowing or occlusion of an artery or arteries of the leg. It is a common vascular disorder with high incidence rates in the industrialized world [1,2]. The main presentation is stable claudication in 75% of patients and progressive disease leading to clinical deterioration (severe claudication or skin lesions) in the remainder [3]. Conventional digital subtraction angiography (DSA) is considered the gold-standard technique in PAOD diagnosis because it enables a better overall visualization of the arterial system and allows simultaneous application of any required therapies [4]. The drawbacks are those associated with its invasiveness by means of arterial puncture, the need for hospitalization, its high radiation
∗ Corresponding author. Tel.: +90 0282 262 01 30; fax: +90 0282 262 03 10. E-mail address: arda [email protected] (A. Kayhan). 0720-048X/$ – see front matter © 2011 Elsevier Ireland Ltd. All rights reserved. doi:10.1016/j.ejrad.2011.01.100
dose, and its potential nephrotoxicity secondary to iodinated contrast agents. There are several alternative imaging modalities to DSA, including Duplex ultrasonography (DUS), computed tomography angiography (CTA) and magnetic resonance angiography (MRA) [5–7]. Duplex ultrasonography (DUS) has been used as the initial imaging modality in mild symptomatic PAOD. Despite its wide use in patients with PAOD [8], DUS has a lower sensitivity than MRA and CT angiography [9]. It does not directly provide a ‘roadmap’ of the vascular system and it is technically difficult to assess the aortoiliac vessels due to interference by bowel gas and the depth of the vessels; this has caused a debate over performing it as the sole diagnostic imaging technique before proceeding to surgery. Fortunately, with advances in CT angiography, especially in the multidetector row technique, larger body volumes can be scanned within shorter time periods at high enough resolution to provide good delineation of arterial inflow and outflow [10]. This has enabled multidetector row CT (MDCT) to become a promising modality in lower extremity arterial imaging [11,12]. Recently,
A. Kayhan et al. / European Journal of Radiology 81 (2012) 542–546
543
Fig. 1. Sixty-eight-year old man with intermittent claudication and pain in right leg. (A) MDCTA image (maximum-intensity-projection reconstruction) shows long segment stenosis (>50%) in the anterior tibial artery. (B) Corresponding DUS spectrum demonstrates low velocity monophasic flow pattern consistent with high grade stenosis.
MDCT angiography (MDCTA) has been shown to be a reliable non invasive tool in quantifying length, number, and grade of stenosis in PAOD patients [13–15]. It has also been shown to be an accurate diagnostic test in patients with stenosis more than 50% [16], and it has even been stated to replace DSA in selected cases [16,17]. The aim of this study is to prospectively compare the efficacy of 40-row MDCTA and DUS as diagnostic and screening tools in patients with mild lower extremity PAOD. 2. Materials and methods Forty-three patients (32 males and 11 females) with a mean age of 61.47(±12.37) were enrolled in the study; all patients were admitted to the cardiovascular surgery department from November 2007 to July 2008 for suspected mild lower limb arterial disease with symptoms of intermittent claudication and leg pain. All patients underwent assessment of PAOD by ankle-brachial index (ABI) measurement. Blood pressures were measured in the supine position with a 8.3-MHz continuous wave Doppler probe over each patient’s ankle from both dorsalis pedis and posterior tibial arteries. Blood pressures were also recorded in the brachial artery of each arm. The greater of ankle systolic to the greater of brachial systolic pressures was used to calculate the ABI. An ABI between 0.8 and 0.9 was considered mild PAOD [18]. All patients underwent arterial DUS followed by MDCT angiography. The study protocol was approved by our institutional review board and a written informed consent was obtained from all patients. 3. DUS All DUS examinations were performed using Applio 80 (Toshiba, Japan) equipment. All scans were performed by a blinded radiologist with 5 years of experience in DUS. The common iliac artery (CIA), external iliac artery (EIA), internal iliac artery (IIA), common femoral artery (CFA), superficial femoral artery (SFA), deep femoral artery (DFA), popliteal artery (PA), anterior tibial artery (ATA), peroneal artery (PEA) and posterior tibial artery (PTA) were examined in each leg. The arteries were scanned with a linear,
phased-array (7.5 mHz) transducer while the patient was in supine position, except for the PA, ATA, PEA and PTA, which were examined in prone position. 3.1. Image analysis of DUS In assessing the vessel of interest, the vessel was initially found in B-mode in the axial plane in order to visualize the lumen and the wall of the vessel. Then, the whole vessel was scanned in axial and longitudinal planes by color-coded duplex followed by spectral tracing of the flow at any suspicious region. A segment was considered as normal when the normal triphasic velocity profile with late diastolic reversal was detected. Suspicious areas with a reduced diameter were detected via higher blood velocities, seen as a shift in the color representing the blood flow on the computer screen. Stenosis was noted when a prestenotic, low velocity, monophasic flow pattern was detected in the proximal vessel segment (Fig. 1). A segment with no flow signal was noted as occluded. 3.2. MDCT angiography 3.2.1. CT protocol MDCT angiography was performed within 1 or 2 days following DUS examination. The examination was performed using a 40-slice multidetector row CT scanner (Siemens Somatom Sensation 40). The CT protocol was identical for each patient as follows: gantry, 0.5 s; pitch, 0.85; detector configuration, 40 × 0.6, table speed: 32 mm/s, scan time, 45 s and slice thickness: 1.25 mm. The tube voltage was 120 KV and mAs was 180. The radiation dose was 9.3 mSv. The patients were scanned in supine position from feet to head, from the level of T2 – at the renal artery bifurcation of the descending aorta – to the heel. A 20-gauge or 22-gauge intravenous catheter was placed in an antecubital vein and tested by rapid manual injection of 10 ml saline. The delay time between the start of contrast material administration and the start of scanning was obtained for each patient individually by using a bolustracking technique (CARE-Bolus software;Siemens) for optimal intraluminal contrast enhancement. First, a precontrast image was obtained
544
A. Kayhan et al. / European Journal of Radiology 81 (2012) 542–546
Fig. 2. Fifty-five-year old woman with intermittent claudication in right leg. (A) MDCTA image (maximum-intensity-projection reconstruction) shows long segment stenosis (>50%) in superficial femoral artery. (B) Corresponding DUS spectrum demonstrates low velocity monophasic flow pattern consistent with high grade stenosis.
at the level of the distal infrarenal abdominal aorta. On the basis of this transverse image, a region of interest (ROI) was set with an area of 10–15 mm2 in the lumen of the distal infrarenal abdominal aorta. This ROI was used as a reference for the following dynamic measurements of contrast enhancement. A total of 150 ml nonionic contrast agent (Iohexol 300) and 20 cc 0.9% NaCl was infused with a flow rate of 4 ml/s using a dual-head pressure injector (Medrad, USA).
3.4. Statistical analysis The statistical analysis was performed with SPSS software package (Chicago, IL). Simple summative statistics were used to calculate the number and proportion of arteries identified as stenotic or occluded. The McNemar’s test, was then used to compare the proportions of segments identified as obstructed or stenotic by DUS versus MDCTA. A significant test result, defined as p < 0.05, rejects the null hypothesis that DUS and MDCTA identify the same proportions of arteries as occluded or stenotic.
3.3. Image reconstruction Using a commercially available workstation (Siemens Avanto, Germany), 900–2500 thin-section axial images were obtained. Three-dimensional reconstructions, including maximum-intensity projection, multiplanar reformatted images, and volume-rendering images, were created by two technicians. These additional data were used in the evaluation of lower extremity arterial anatomy.
3.3.1. Image analysis MDCT angiography The axial and reconstructed CT angiographic images were analysed by a blinded radiologist with an experience of 7 years in CT. The vessels of the lower extremities were divided into 9 segments for each side: CIA, EIA, IIA, CFA, SFA, DFA, PA, ATA, PEA and PTA. Each segment was evaluated for diagnostic sufficiency such that good differentiation of arteries from background tissue could provide an image quality adequate for confident data collection. The steno-occlusive lesions were examined primarily by visual inspection as ‘diameter stenoses’. The readers also detected the degree of stenosis using electronic calipers. Irregular vessel walls with >50% stenosis of vessel diameter were noted. The data for each arterial segment were evaluated and classified as normal, >50% stenosis± or occlusion±. The dorsalis pedis artery was not included in the evaluation as it was not usually visualized on CTA.
4. Results A total of 774 vessel segments were imaged by both DUS and MDCTA in 43 patients. All arterial segments were successfully analyzed by both modalities. The number of segments with greater than 50% stenosis were 27 (3.49%) and 35 (4.52%) on DUS and MDCTA, respectively. The number of segments with occlusion were 59 (7.62%) and 95 (12.27%) by DUS and MDCTA, respectively. The total number of diseased segments found with DUS was 86 (11.1%) versus 130 (16.8%) identified by MDCTA. When DUS and MDCTA are compared in identifying stenotic or occlusive lesions, MDCTA identifies 5.7% (95% CI: [3.5%, 7.9%]) more lesions than DUS when all arteries are considered together, 8.3% (95% CI: [4.6%, 12.0%]) more lesions when only the infrapopliteal arteries are compared (Fig. 1), and 4.0% (95% CI: [1.3%, 6.8%]) more lesions when only suprapopliteal arteries are compared (Fig. 2). P value is < 0.01 for all of the comparisons. The measurement comparisons between DUS and MDCTA modalities in all arteries, infrapopliteal arteries only, and suprapopliteal arteries only are shown on Table 1. Table 2 summarizes the McNemar test results. Fig. 3 shows the percentage of lesions detected by MDCTA versus DUS as a function of arterial group. When all arteries are considered, MDCTA detects obstructed or stenotic lesions in 16.8% of arteries, versus 11.1% when DUS is used. When suprapopliteal arteries alone
A. Kayhan et al. / European Journal of Radiology 81 (2012) 542–546 Table 1 McNemar Test Tables comparing DUS and MDCT findings of stenosis or obstruction (+: positive, −: negative) in all arteries together, suprapopliteal arteries only, and infrapopliteal arteries only. DUS occlusion or stenosis All arteries DUS + DUS − Total Suprapopliteal aa DUS + DUS − Total Infrapopliteal aa DUS + DUS − Total
MDCT occlusion or stenosis MDCT − MDCT +
Total
68 62 130
18 626 644
86 688 774
39 32 71
13 389 402
52 421 473
29 30 59
5 237 242
34 267 301
Table 2 Summary of McNemar Test values computed from the data in Table 1.
Test group
McNemar’s P value DUS % value
All arteries 23.1 Suprapopliteal aa. 7.2 Infrapopliteal aa. 16.5
<0.001 <0.01 <0.001
11.1 11.0 11.3
MDCT %
% Diff
95% CI
16.8 15.0 19.6
5.7 4.0 8.3
[3.5,7.9] [1.3,6.8] [4.6,12.0]
Corresponding p values, DUS and MDCT detection percentages, and 95% confidence intervals are also reported. Significance is indicated by p < 0.05.
are considered, MDCTA detects lesions in 15.0% of arteries, versus 11.0% with DUS. When infrapopliteal arteries only are considered, MDCTA detects lesions in 19.6% of arteries, versus 11.3% with DUS. 5. Discussion Although DUS is considered as the first choice modality and screening method in assessing mild PAOD, it has several limitations. Obesity impairs examining aortailiac and femoral regions, abdominal distention increases the difficulty of examining iliac vascular structures, and it is an operator dependent imaging modality. Furthermore, DUS struggles to assess sequential multisegmental stenosis. The sensitivity of DUS in detection of one segment stenosis
545
is high, but it is decreased when diagnosing multisegmental disease because stenosis in proximal arterial segments decreases peak systolic velocities and reduces poststenotic and postocclusive flows [19]. In recent studies, it has been shown that the median sensitivity and specificity of DUS for the detection of > 50% stenosis for the whole leg are 88% and 96%, respectively. For the detection of occlusion in whole leg, DUS had a median sensitivity of 90% and median specificity of 99% [19,20–22]. In another series, sensitivity, specificity, positive and negative predictive value for correctly detecting a > 50% stenosis by DUS were 0.81, 0.93, 0.84 and 0.9, respectively [23]. MDCTA is increasingly being used as a promising minimallyinvasive tool for the evaluation of patients with PAOD. Previous studies have been performed with 4 and 16-row MDCTA in which the diagnostic accuracy of MDCTA for detection of >50% stenosis and occlusion in whole leg has been searched. The median sensitivity and specificity values have been found to be 91% and 91% for >50% stenosis and 97% and 99.6% for occlusion, respectively [13,24–29]. Laswed et al, in their series performed with 16-row MDCTA, found an overall sensitivity and specificity of 100% in detection of significant stenosis greater than 50%. In segmental analysis a sensitivity and specificity ranging from 91 to 100% and from 81 to 100%, respectively was reported including distal pedal arteries [30]. In our study, in which 40-row MDCTA was performed, sensitivity and specificity values could not be calculated because DSA was not performed as well. It has been shown that, in a patient with the symptoms of intermittent claudication and leg pain, there is a potential possibility to detect an infrapopliteal pathology even when no pathology is detected in a suprapopliteal tract [17]. Certain studies have provided different results concerning the diagnostic accuracies of different modalities for arterial segments above and below the knee. In their series, Favaretto et al. reported a good diagnostic agreement (kappa = 0.70; 95% CI 0.588–0.825) in whole leg and aorto-iliac district with a sensitivity and specificity of 63% and 96%, respectively. In infrapopliteal arteries, kappa showed a poor agreement [31]. In other series, with DUS, the median sensitivity and specificity for detection of >50% stenosis were 88% and 95% above the knee and 84% and 93% below the knee, respectively [19,20]. The diagnostic performance of MDCTA in subdivisions of the lower extremity has been tested, and studies reported a lower sensitivity and specificity for the infrapopliteal tract than for the aortoiliac and
Fig. 3. Percentage of occluded or stenotic arterial segments detected by MDCTA (dark columns) and DUS (white columns). Differences between groups are statistically significant as reported in Table 2.
546
A. Kayhan et al. / European Journal of Radiology 81 (2012) 542–546
the femoropopliteal tracts, although these differences were not statistically significant [14,26,32]. In the study with a lower accuracy rate, the complete infrapopliteal tract was not depicted because a 2-section CT scanner was used [32]. The most encouraging results were reported by Willmann et al. who used a 16-section CT scanner [14]. In a meta-analysis, a sensitivity of 92% and specificity of 93% were reported for lower extremity arterial disease with >50% stenosis. The researchers also stated that the diagnostic performance of MDCTA was almost as good as that of DSA [17]. Overall, analysis of our results showed that when DUS and MDCTA are compared, MDCTA detects more stenotic or occluded arteries in suprapopliteal, infrapopliteal, and whole leg comparisons. Our infrapopliteal data differ from the results for MDCTA in infrapopliteal regions reported above, in which DUS is as good or better than MDCTA. However, these data represent indirect comparisons between different patient groups looking independently at DUS or MDCTA to determine sensitivity and specificity of testing. Our study, conversely, performs a direct comparison between the two imaging modalities on the same patient population. The current study population included the patients with mild PAOD who did not have an indication for DSA. In vascular clinical practice, the ABI, which is the ratio of systolic pressure at the ankle to that in the arm, has been used for many years to confirm the diagnosis and assess the severity of peripheral artery disease in the legs as it is a quick and easy method [33,34]. In this study, our main limitation was that DUS and MDCTA findings were not compared with DSA, which is considered to be the gold standard technique in detecting lower extremity PAOD. Therefore, our results may underestimate the percentages of arteries with lesions that are actually detectable in patients with mild PAOD. However, results of several studies report MDCTA as a noninvasive alternative to conventional DSA [14,17,26]. In conclusion, 40-row MDCTA is a non-invasive, fast, and accurate alternative to DUS, and we believe MDCTA better detects stenotic or obstructed arteries than DUS in patients with clinical symptoms of mild PAOD. References [1] Fowkes FG, Housley E, Cawood EH, Macintyre CC, Ruckley CV, Prescott RJ. Edinburgh Artery Study: prevalence of asymptomatic and symptomatic peripheral arterial disease in the general population. Int J Epidemiol 1991;20:384–92. [2] Hiatt WR. Medical treatment of peripheral arterial disease and claudication. N Engl J Med 2001;344:1608–21. [3] Kannel WB, Shurtleff D. The natural history of arteriosclerosis obliterans. Cardiovasc Clin 1971;3:37–52. [4] Cossman DV, Ellison JE, Wagner WH, et al. Comparison of contrast arteriography to arterial mapping with color flow duplex imaging in the lower extremities. J Vasc Surg 1989;10:522–8. [5] Waugh JR, Sacharias N. Arteriographic complications in the DSA era. Radiology 1992;182:243–6. [6] Pemberton M, London NJM. Colour flow duplex imaging of occlusive arterial of the lower limb. Br J Surg 1997;84:912–9. [7] Egglin TK, O’Moore PV, Feinstein AR, Waltman AC. Complications of peripheral arteriography: a new system to identify patients at increase risk. J Vasc Surg 1995;22:787–94. [8] Androulakis AE, Giannoukas AD, Labropoulos N, Katsamouris A, Nicolaides AN. The impact of duplex scanning on vascular practice. Int Angiol 1996;15:283–90. [9] Visser K, Hunink MGM. Peripheral arterial disease: gadolinium-enhanced MR angiography versus color-guided duplex US: a metaanalysis. Radiology 2000;216:67–77. [10] Rubin GD, Schmidt AJ, Logan LJ, Sofilos MC. Multidetector row CT angiography of lower extremity arterial inflow and runoff: initial experience. Radiology 2001;221:146–58.
[11] Fuchs T, Kachelriess M, Kalender WA. Technical advances in multislice spiral CT. Eur J Radiol 2000;36:69–73. [12] Fleischmann D. Present and future trends in multiple detector-row CT applications: CT angiography. Eur Radiol 2002;12:11–6. [13] Catalano C, Fraioli F, Laghi A, et al. Infrarenal aortic and lower-extremity arterial disease: diagnostic performance of multi-detector row CT angiography. Radiology 2004;231:555–63. [14] Willmann JK, Baumert B, Schertler T, et al. Aortoiliac and lower extremity arteries assessed with 16-detector row CT angiography: prospective comparison with digital subtraction angiography. Radiology 2005;236:1083–93. [15] Schernthaner R, Stadler A, Lomoschitz F, Weber M, Fleischmann D, Lammer Jet al. Multidetector CT angiography in the assessment of peripheral arterial occlusive disease: accuracy in detecting the severity, number, and length of stenoses. Eur Radiol 2008;18:665–71. [16] Adriaensen ME, Kock MC, Stijnen T, et al. Peripheral arterial disease: therapeutic confidence of CT versus digital subtraction angiography and effects on additional imaging recommendations. Radiology 2004;233:385–91. [17] Heijenbrok-Kal M, Kock AC, Hunink MGM. Lower extremity arterial disease: multidetector CT angiography-Meta analysis. Radiology 2007;245: 433–9. [18] McKenna M, Wolfson S, Kuller L. The ratio of ankle and arm arterial pressure as an independent predictor of mortality. Atherosclerosis 1991;87:119–28. [19] Bergamini TM, Tatum Jr CM, Marshall C, Hall-Disselkamp B, Richardson JD. Effect of multilevel sequential stenosis on lower extremity arterial duplex scanning. Am J Surg 1995;169:564–6. [20] Hatsukami TS, Primozich JF, Zierler RE, Harley JD, Strandness DE. Jr. Color Doppler imaging of infrainguinal arterial occlusive disease. J Vasc Surg 1992;16:527–33. [21] Sensier Y, Hartshorne T, Thrush A, Handford H, Nydahl S, London NJ. The effect of adjacent segment disease on the accuracy of colour duplex scanning for the diagnosis of lower limb arterial disease. Eur J Vasc Endovasc Surg 1996;12:238–42. [22] Linke RJ, Davies RP, Giles AJ, Walsh JA, Thompson BW. Colour duplex ultrasound: a screening modality for femoropopliteal disease in patients with intermittent claudication. Australas Radiol 1994;38:320–3. [23] Schlager O, Francesconi M, Haumer M, et al. Duplex sonography versus angiography for assessment of femoropopliteal arterial disease in a“realworld”setting. J Endovasc Ther 2007;14:452–9. [24] Heuschmid M, Krieger A, Beierlein W. Assesment of peripheral arterial occlusive disease: comparison of multislice-CT angiography (MS-CTA) and intraarterial digital subtraction angiography (IA-DSA). Eur J Med Res 2003;8:389–96. [25] Martin ML, Tay KH, Flak B, et al. Multidetector CT angiography of the aortoiliac system and lower extremities: a prospective comparison with digital subtraction angiography. Am J Roentgen 2003;180:1085–91. [26] Portugaller HR, Schoellnast H, Hausegger KA, Tiesenhausen K, Amann W, Berghold A. Multislice spiral CT angiography in peripheral arterial occlusive disease: a valuable tool in detecting significant arterial lumen narrowing. Eur Radiol 2004;14:1681–7. [27] Puls R, Knollmann F, Werk M, et al. Multi-slice spiral CT: 3D CT angiography for evaluating therapeutically relevant stenosis in peripheral arterial occlusive disease. Rontgenpraxis 2002;54:141–7. [28] Rieker O, Düber C, Schmiedt W, von Zitzewitz H, Schweden F, Thelen M. Prospective comparison of CT angiography of the legs with intraarterial digital subtraction angiography. Am J Roentgen 1996;166:269–76. [29] Mishra A, Bhaktarahalli JN, Ehtuish EF. Imaging of peripheral arteries by 16row multidetector computed tomography angiography: A feasible tool? Eur J Radiol 2007;61:528–33. [30] Laswed T, Rizoo E, Guntern D, et al. Assessment of occlusive arterial disease of abdominal aorta and lower extremities arteries: value of multidetector CT angiography using an adaptive acquisition method. Eur Radiol 2008;18:263–72. [31] Favaretto E, Pili C, Amato A, et al. Analysis of agreement between Duplex ultrasound scanning and arteriography in patients with lower limb artery disease. J Cardiovasc Med (Hagerstown) 2007;8:337–41. [32] Mesurolle B, Qanadli SD, El Hajjam M, Goeau-Brissonniere OA, Mignon F, Lacombe P. Occlusive arterial disease of abdominal aorta and lower extremities: comparison of helical CT angiography with transcatheter angiography. Clin Imaging 2004;28:252–60. [33] Hirsch AT, Criqui MH, Treat-Jacobson D, et al. Peripheral arterial disease detection, awareness, and treatment in primary care. JAMA 2001;286: 1317–24. [34] Hiatt WR. Medical treatment of peripheral arterial disease and claudication. New Engl J Med 2001;344:1608–21.
Contents lists available at ScienceDirect
European Journal of Radiology journal homepage: www.elsevier.com/locate/ejrad
Multidetector CT angiography versus arterial duplex USG in diagnosis of mild lower extremity peripheral arterial disease: Is multidetector CT a valuable screening tool? Arda Kayhan a,∗ , Figen Palabıyık b , Serdar Serinsöz b , Adem Kırıs¸ b , Sibel Bayramo˘glu b , Joshua T.B. Williams c , Tan Cimilli b a
Department of Radiology, Faculty of Medicine, Namık Kemal University, 100. yıl mahallesi, Tunca caddesi, No: 32, Tekirda˘g Turkey Department of Radiology, Dr. Sadi Konuk Education and Research Hospital, Turkey c University of Chicago, School of Medicine, Chicago, IL, United States b
a r t i c l e
i n f o
Article history: Received 3 September 2010 Received in revised form 19 January 2011 Accepted 28 January 2011 Keywords: Peripheral arterial occlusive disease Duplex ultrasonography MDCT angiography
a b s t r a c t Objective: To prospectively compare the efficacy of 40-row multidetector computed tomography angiography (MDCTA) and duplex ultrasonography (DUS) to diagnose mild peripheral arterial occlusive disease (PAOD) in lower leg and to search whether MDCTA can be used as a screening tool. Methods: Forty-three patients with intermittent claudication and leg pain, diagnosed as mild PAOD, had undergone DUS and MDCTA of lower limb. The arteries of lower leg were initially scanned by DUS, followed by MDCTA. Both modalities were compared for detecting the obstructed and stenotic segments. Results: A total of 774 vessel segments were imaged by both modalities. When all arteries were considered, MDCTA detected obstructed or stenotic lesions in 16.8% of arteries, versus 11.1% compared to DUS. When suprapopliteal arteries alone were considered, MDCTA detected lesions in 15.0% of arteries, versus 11.0% with DUS. When infrapopliteal arteries only were considered, MDCTA detected lesions in 19.6% of arteries, versus 11.3% with DUS. MDCTA showed 5.7% (95% CI: [3.5%, 7.9%]) more lesions than DUS when all arteries were considered together, 8.3% (95% CI: [4.6%, 12.0%]) more lesions when only the infrapopliteal arteries were compared, and 4.0% (95% CI: [1.3%, 6.8%]) more lesions when only suprapopliteal arteries were compared (p < 0.01 for all comparisons). Conclusion: 40-row MDCTA may be used as a screening tool in patients with mild lower extremity PAOD as it is a non-invasive and more accurate modality when compared to DUS. © 2011 Elsevier Ireland Ltd. All rights reserved.
1. Introduction Peripheral arterial occlusive disease (PAOD) is the atheromatous narrowing or occlusion of an artery or arteries of the leg. It is a common vascular disorder with high incidence rates in the industrialized world [1,2]. The main presentation is stable claudication in 75% of patients and progressive disease leading to clinical deterioration (severe claudication or skin lesions) in the remainder [3]. Conventional digital subtraction angiography (DSA) is considered the gold-standard technique in PAOD diagnosis because it enables a better overall visualization of the arterial system and allows simultaneous application of any required therapies [4]. The drawbacks are those associated with its invasiveness by means of arterial puncture, the need for hospitalization, its high radiation
∗ Corresponding author. Tel.: +90 0282 262 01 30; fax: +90 0282 262 03 10. E-mail address: arda [email protected] (A. Kayhan). 0720-048X/$ – see front matter © 2011 Elsevier Ireland Ltd. All rights reserved. doi:10.1016/j.ejrad.2011.01.100
dose, and its potential nephrotoxicity secondary to iodinated contrast agents. There are several alternative imaging modalities to DSA, including Duplex ultrasonography (DUS), computed tomography angiography (CTA) and magnetic resonance angiography (MRA) [5–7]. Duplex ultrasonography (DUS) has been used as the initial imaging modality in mild symptomatic PAOD. Despite its wide use in patients with PAOD [8], DUS has a lower sensitivity than MRA and CT angiography [9]. It does not directly provide a ‘roadmap’ of the vascular system and it is technically difficult to assess the aortoiliac vessels due to interference by bowel gas and the depth of the vessels; this has caused a debate over performing it as the sole diagnostic imaging technique before proceeding to surgery. Fortunately, with advances in CT angiography, especially in the multidetector row technique, larger body volumes can be scanned within shorter time periods at high enough resolution to provide good delineation of arterial inflow and outflow [10]. This has enabled multidetector row CT (MDCT) to become a promising modality in lower extremity arterial imaging [11,12]. Recently,
A. Kayhan et al. / European Journal of Radiology 81 (2012) 542–546
543
Fig. 1. Sixty-eight-year old man with intermittent claudication and pain in right leg. (A) MDCTA image (maximum-intensity-projection reconstruction) shows long segment stenosis (>50%) in the anterior tibial artery. (B) Corresponding DUS spectrum demonstrates low velocity monophasic flow pattern consistent with high grade stenosis.
MDCT angiography (MDCTA) has been shown to be a reliable non invasive tool in quantifying length, number, and grade of stenosis in PAOD patients [13–15]. It has also been shown to be an accurate diagnostic test in patients with stenosis more than 50% [16], and it has even been stated to replace DSA in selected cases [16,17]. The aim of this study is to prospectively compare the efficacy of 40-row MDCTA and DUS as diagnostic and screening tools in patients with mild lower extremity PAOD. 2. Materials and methods Forty-three patients (32 males and 11 females) with a mean age of 61.47(±12.37) were enrolled in the study; all patients were admitted to the cardiovascular surgery department from November 2007 to July 2008 for suspected mild lower limb arterial disease with symptoms of intermittent claudication and leg pain. All patients underwent assessment of PAOD by ankle-brachial index (ABI) measurement. Blood pressures were measured in the supine position with a 8.3-MHz continuous wave Doppler probe over each patient’s ankle from both dorsalis pedis and posterior tibial arteries. Blood pressures were also recorded in the brachial artery of each arm. The greater of ankle systolic to the greater of brachial systolic pressures was used to calculate the ABI. An ABI between 0.8 and 0.9 was considered mild PAOD [18]. All patients underwent arterial DUS followed by MDCT angiography. The study protocol was approved by our institutional review board and a written informed consent was obtained from all patients. 3. DUS All DUS examinations were performed using Applio 80 (Toshiba, Japan) equipment. All scans were performed by a blinded radiologist with 5 years of experience in DUS. The common iliac artery (CIA), external iliac artery (EIA), internal iliac artery (IIA), common femoral artery (CFA), superficial femoral artery (SFA), deep femoral artery (DFA), popliteal artery (PA), anterior tibial artery (ATA), peroneal artery (PEA) and posterior tibial artery (PTA) were examined in each leg. The arteries were scanned with a linear,
phased-array (7.5 mHz) transducer while the patient was in supine position, except for the PA, ATA, PEA and PTA, which were examined in prone position. 3.1. Image analysis of DUS In assessing the vessel of interest, the vessel was initially found in B-mode in the axial plane in order to visualize the lumen and the wall of the vessel. Then, the whole vessel was scanned in axial and longitudinal planes by color-coded duplex followed by spectral tracing of the flow at any suspicious region. A segment was considered as normal when the normal triphasic velocity profile with late diastolic reversal was detected. Suspicious areas with a reduced diameter were detected via higher blood velocities, seen as a shift in the color representing the blood flow on the computer screen. Stenosis was noted when a prestenotic, low velocity, monophasic flow pattern was detected in the proximal vessel segment (Fig. 1). A segment with no flow signal was noted as occluded. 3.2. MDCT angiography 3.2.1. CT protocol MDCT angiography was performed within 1 or 2 days following DUS examination. The examination was performed using a 40-slice multidetector row CT scanner (Siemens Somatom Sensation 40). The CT protocol was identical for each patient as follows: gantry, 0.5 s; pitch, 0.85; detector configuration, 40 × 0.6, table speed: 32 mm/s, scan time, 45 s and slice thickness: 1.25 mm. The tube voltage was 120 KV and mAs was 180. The radiation dose was 9.3 mSv. The patients were scanned in supine position from feet to head, from the level of T2 – at the renal artery bifurcation of the descending aorta – to the heel. A 20-gauge or 22-gauge intravenous catheter was placed in an antecubital vein and tested by rapid manual injection of 10 ml saline. The delay time between the start of contrast material administration and the start of scanning was obtained for each patient individually by using a bolustracking technique (CARE-Bolus software;Siemens) for optimal intraluminal contrast enhancement. First, a precontrast image was obtained
544
A. Kayhan et al. / European Journal of Radiology 81 (2012) 542–546
Fig. 2. Fifty-five-year old woman with intermittent claudication in right leg. (A) MDCTA image (maximum-intensity-projection reconstruction) shows long segment stenosis (>50%) in superficial femoral artery. (B) Corresponding DUS spectrum demonstrates low velocity monophasic flow pattern consistent with high grade stenosis.
at the level of the distal infrarenal abdominal aorta. On the basis of this transverse image, a region of interest (ROI) was set with an area of 10–15 mm2 in the lumen of the distal infrarenal abdominal aorta. This ROI was used as a reference for the following dynamic measurements of contrast enhancement. A total of 150 ml nonionic contrast agent (Iohexol 300) and 20 cc 0.9% NaCl was infused with a flow rate of 4 ml/s using a dual-head pressure injector (Medrad, USA).
3.4. Statistical analysis The statistical analysis was performed with SPSS software package (Chicago, IL). Simple summative statistics were used to calculate the number and proportion of arteries identified as stenotic or occluded. The McNemar’s test, was then used to compare the proportions of segments identified as obstructed or stenotic by DUS versus MDCTA. A significant test result, defined as p < 0.05, rejects the null hypothesis that DUS and MDCTA identify the same proportions of arteries as occluded or stenotic.
3.3. Image reconstruction Using a commercially available workstation (Siemens Avanto, Germany), 900–2500 thin-section axial images were obtained. Three-dimensional reconstructions, including maximum-intensity projection, multiplanar reformatted images, and volume-rendering images, were created by two technicians. These additional data were used in the evaluation of lower extremity arterial anatomy.
3.3.1. Image analysis MDCT angiography The axial and reconstructed CT angiographic images were analysed by a blinded radiologist with an experience of 7 years in CT. The vessels of the lower extremities were divided into 9 segments for each side: CIA, EIA, IIA, CFA, SFA, DFA, PA, ATA, PEA and PTA. Each segment was evaluated for diagnostic sufficiency such that good differentiation of arteries from background tissue could provide an image quality adequate for confident data collection. The steno-occlusive lesions were examined primarily by visual inspection as ‘diameter stenoses’. The readers also detected the degree of stenosis using electronic calipers. Irregular vessel walls with >50% stenosis of vessel diameter were noted. The data for each arterial segment were evaluated and classified as normal, >50% stenosis± or occlusion±. The dorsalis pedis artery was not included in the evaluation as it was not usually visualized on CTA.
4. Results A total of 774 vessel segments were imaged by both DUS and MDCTA in 43 patients. All arterial segments were successfully analyzed by both modalities. The number of segments with greater than 50% stenosis were 27 (3.49%) and 35 (4.52%) on DUS and MDCTA, respectively. The number of segments with occlusion were 59 (7.62%) and 95 (12.27%) by DUS and MDCTA, respectively. The total number of diseased segments found with DUS was 86 (11.1%) versus 130 (16.8%) identified by MDCTA. When DUS and MDCTA are compared in identifying stenotic or occlusive lesions, MDCTA identifies 5.7% (95% CI: [3.5%, 7.9%]) more lesions than DUS when all arteries are considered together, 8.3% (95% CI: [4.6%, 12.0%]) more lesions when only the infrapopliteal arteries are compared (Fig. 1), and 4.0% (95% CI: [1.3%, 6.8%]) more lesions when only suprapopliteal arteries are compared (Fig. 2). P value is < 0.01 for all of the comparisons. The measurement comparisons between DUS and MDCTA modalities in all arteries, infrapopliteal arteries only, and suprapopliteal arteries only are shown on Table 1. Table 2 summarizes the McNemar test results. Fig. 3 shows the percentage of lesions detected by MDCTA versus DUS as a function of arterial group. When all arteries are considered, MDCTA detects obstructed or stenotic lesions in 16.8% of arteries, versus 11.1% when DUS is used. When suprapopliteal arteries alone
A. Kayhan et al. / European Journal of Radiology 81 (2012) 542–546 Table 1 McNemar Test Tables comparing DUS and MDCT findings of stenosis or obstruction (+: positive, −: negative) in all arteries together, suprapopliteal arteries only, and infrapopliteal arteries only. DUS occlusion or stenosis All arteries DUS + DUS − Total Suprapopliteal aa DUS + DUS − Total Infrapopliteal aa DUS + DUS − Total
MDCT occlusion or stenosis MDCT − MDCT +
Total
68 62 130
18 626 644
86 688 774
39 32 71
13 389 402
52 421 473
29 30 59
5 237 242
34 267 301
Table 2 Summary of McNemar Test values computed from the data in Table 1.
Test group
McNemar’s P value DUS % value
All arteries 23.1 Suprapopliteal aa. 7.2 Infrapopliteal aa. 16.5
<0.001 <0.01 <0.001
11.1 11.0 11.3
MDCT %
% Diff
95% CI
16.8 15.0 19.6
5.7 4.0 8.3
[3.5,7.9] [1.3,6.8] [4.6,12.0]
Corresponding p values, DUS and MDCT detection percentages, and 95% confidence intervals are also reported. Significance is indicated by p < 0.05.
are considered, MDCTA detects lesions in 15.0% of arteries, versus 11.0% with DUS. When infrapopliteal arteries only are considered, MDCTA detects lesions in 19.6% of arteries, versus 11.3% with DUS. 5. Discussion Although DUS is considered as the first choice modality and screening method in assessing mild PAOD, it has several limitations. Obesity impairs examining aortailiac and femoral regions, abdominal distention increases the difficulty of examining iliac vascular structures, and it is an operator dependent imaging modality. Furthermore, DUS struggles to assess sequential multisegmental stenosis. The sensitivity of DUS in detection of one segment stenosis
545
is high, but it is decreased when diagnosing multisegmental disease because stenosis in proximal arterial segments decreases peak systolic velocities and reduces poststenotic and postocclusive flows [19]. In recent studies, it has been shown that the median sensitivity and specificity of DUS for the detection of > 50% stenosis for the whole leg are 88% and 96%, respectively. For the detection of occlusion in whole leg, DUS had a median sensitivity of 90% and median specificity of 99% [19,20–22]. In another series, sensitivity, specificity, positive and negative predictive value for correctly detecting a > 50% stenosis by DUS were 0.81, 0.93, 0.84 and 0.9, respectively [23]. MDCTA is increasingly being used as a promising minimallyinvasive tool for the evaluation of patients with PAOD. Previous studies have been performed with 4 and 16-row MDCTA in which the diagnostic accuracy of MDCTA for detection of >50% stenosis and occlusion in whole leg has been searched. The median sensitivity and specificity values have been found to be 91% and 91% for >50% stenosis and 97% and 99.6% for occlusion, respectively [13,24–29]. Laswed et al, in their series performed with 16-row MDCTA, found an overall sensitivity and specificity of 100% in detection of significant stenosis greater than 50%. In segmental analysis a sensitivity and specificity ranging from 91 to 100% and from 81 to 100%, respectively was reported including distal pedal arteries [30]. In our study, in which 40-row MDCTA was performed, sensitivity and specificity values could not be calculated because DSA was not performed as well. It has been shown that, in a patient with the symptoms of intermittent claudication and leg pain, there is a potential possibility to detect an infrapopliteal pathology even when no pathology is detected in a suprapopliteal tract [17]. Certain studies have provided different results concerning the diagnostic accuracies of different modalities for arterial segments above and below the knee. In their series, Favaretto et al. reported a good diagnostic agreement (kappa = 0.70; 95% CI 0.588–0.825) in whole leg and aorto-iliac district with a sensitivity and specificity of 63% and 96%, respectively. In infrapopliteal arteries, kappa showed a poor agreement [31]. In other series, with DUS, the median sensitivity and specificity for detection of >50% stenosis were 88% and 95% above the knee and 84% and 93% below the knee, respectively [19,20]. The diagnostic performance of MDCTA in subdivisions of the lower extremity has been tested, and studies reported a lower sensitivity and specificity for the infrapopliteal tract than for the aortoiliac and
Fig. 3. Percentage of occluded or stenotic arterial segments detected by MDCTA (dark columns) and DUS (white columns). Differences between groups are statistically significant as reported in Table 2.
546
A. Kayhan et al. / European Journal of Radiology 81 (2012) 542–546
the femoropopliteal tracts, although these differences were not statistically significant [14,26,32]. In the study with a lower accuracy rate, the complete infrapopliteal tract was not depicted because a 2-section CT scanner was used [32]. The most encouraging results were reported by Willmann et al. who used a 16-section CT scanner [14]. In a meta-analysis, a sensitivity of 92% and specificity of 93% were reported for lower extremity arterial disease with >50% stenosis. The researchers also stated that the diagnostic performance of MDCTA was almost as good as that of DSA [17]. Overall, analysis of our results showed that when DUS and MDCTA are compared, MDCTA detects more stenotic or occluded arteries in suprapopliteal, infrapopliteal, and whole leg comparisons. Our infrapopliteal data differ from the results for MDCTA in infrapopliteal regions reported above, in which DUS is as good or better than MDCTA. However, these data represent indirect comparisons between different patient groups looking independently at DUS or MDCTA to determine sensitivity and specificity of testing. Our study, conversely, performs a direct comparison between the two imaging modalities on the same patient population. The current study population included the patients with mild PAOD who did not have an indication for DSA. In vascular clinical practice, the ABI, which is the ratio of systolic pressure at the ankle to that in the arm, has been used for many years to confirm the diagnosis and assess the severity of peripheral artery disease in the legs as it is a quick and easy method [33,34]. In this study, our main limitation was that DUS and MDCTA findings were not compared with DSA, which is considered to be the gold standard technique in detecting lower extremity PAOD. Therefore, our results may underestimate the percentages of arteries with lesions that are actually detectable in patients with mild PAOD. However, results of several studies report MDCTA as a noninvasive alternative to conventional DSA [14,17,26]. In conclusion, 40-row MDCTA is a non-invasive, fast, and accurate alternative to DUS, and we believe MDCTA better detects stenotic or obstructed arteries than DUS in patients with clinical symptoms of mild PAOD. References [1] Fowkes FG, Housley E, Cawood EH, Macintyre CC, Ruckley CV, Prescott RJ. Edinburgh Artery Study: prevalence of asymptomatic and symptomatic peripheral arterial disease in the general population. Int J Epidemiol 1991;20:384–92. [2] Hiatt WR. Medical treatment of peripheral arterial disease and claudication. N Engl J Med 2001;344:1608–21. [3] Kannel WB, Shurtleff D. The natural history of arteriosclerosis obliterans. Cardiovasc Clin 1971;3:37–52. [4] Cossman DV, Ellison JE, Wagner WH, et al. Comparison of contrast arteriography to arterial mapping with color flow duplex imaging in the lower extremities. J Vasc Surg 1989;10:522–8. [5] Waugh JR, Sacharias N. Arteriographic complications in the DSA era. Radiology 1992;182:243–6. [6] Pemberton M, London NJM. Colour flow duplex imaging of occlusive arterial of the lower limb. Br J Surg 1997;84:912–9. [7] Egglin TK, O’Moore PV, Feinstein AR, Waltman AC. Complications of peripheral arteriography: a new system to identify patients at increase risk. J Vasc Surg 1995;22:787–94. [8] Androulakis AE, Giannoukas AD, Labropoulos N, Katsamouris A, Nicolaides AN. The impact of duplex scanning on vascular practice. Int Angiol 1996;15:283–90. [9] Visser K, Hunink MGM. Peripheral arterial disease: gadolinium-enhanced MR angiography versus color-guided duplex US: a metaanalysis. Radiology 2000;216:67–77. [10] Rubin GD, Schmidt AJ, Logan LJ, Sofilos MC. Multidetector row CT angiography of lower extremity arterial inflow and runoff: initial experience. Radiology 2001;221:146–58.
[11] Fuchs T, Kachelriess M, Kalender WA. Technical advances in multislice spiral CT. Eur J Radiol 2000;36:69–73. [12] Fleischmann D. Present and future trends in multiple detector-row CT applications: CT angiography. Eur Radiol 2002;12:11–6. [13] Catalano C, Fraioli F, Laghi A, et al. Infrarenal aortic and lower-extremity arterial disease: diagnostic performance of multi-detector row CT angiography. Radiology 2004;231:555–63. [14] Willmann JK, Baumert B, Schertler T, et al. Aortoiliac and lower extremity arteries assessed with 16-detector row CT angiography: prospective comparison with digital subtraction angiography. Radiology 2005;236:1083–93. [15] Schernthaner R, Stadler A, Lomoschitz F, Weber M, Fleischmann D, Lammer Jet al. Multidetector CT angiography in the assessment of peripheral arterial occlusive disease: accuracy in detecting the severity, number, and length of stenoses. Eur Radiol 2008;18:665–71. [16] Adriaensen ME, Kock MC, Stijnen T, et al. Peripheral arterial disease: therapeutic confidence of CT versus digital subtraction angiography and effects on additional imaging recommendations. Radiology 2004;233:385–91. [17] Heijenbrok-Kal M, Kock AC, Hunink MGM. Lower extremity arterial disease: multidetector CT angiography-Meta analysis. Radiology 2007;245: 433–9. [18] McKenna M, Wolfson S, Kuller L. The ratio of ankle and arm arterial pressure as an independent predictor of mortality. Atherosclerosis 1991;87:119–28. [19] Bergamini TM, Tatum Jr CM, Marshall C, Hall-Disselkamp B, Richardson JD. Effect of multilevel sequential stenosis on lower extremity arterial duplex scanning. Am J Surg 1995;169:564–6. [20] Hatsukami TS, Primozich JF, Zierler RE, Harley JD, Strandness DE. Jr. Color Doppler imaging of infrainguinal arterial occlusive disease. J Vasc Surg 1992;16:527–33. [21] Sensier Y, Hartshorne T, Thrush A, Handford H, Nydahl S, London NJ. The effect of adjacent segment disease on the accuracy of colour duplex scanning for the diagnosis of lower limb arterial disease. Eur J Vasc Endovasc Surg 1996;12:238–42. [22] Linke RJ, Davies RP, Giles AJ, Walsh JA, Thompson BW. Colour duplex ultrasound: a screening modality for femoropopliteal disease in patients with intermittent claudication. Australas Radiol 1994;38:320–3. [23] Schlager O, Francesconi M, Haumer M, et al. Duplex sonography versus angiography for assessment of femoropopliteal arterial disease in a“realworld”setting. J Endovasc Ther 2007;14:452–9. [24] Heuschmid M, Krieger A, Beierlein W. Assesment of peripheral arterial occlusive disease: comparison of multislice-CT angiography (MS-CTA) and intraarterial digital subtraction angiography (IA-DSA). Eur J Med Res 2003;8:389–96. [25] Martin ML, Tay KH, Flak B, et al. Multidetector CT angiography of the aortoiliac system and lower extremities: a prospective comparison with digital subtraction angiography. Am J Roentgen 2003;180:1085–91. [26] Portugaller HR, Schoellnast H, Hausegger KA, Tiesenhausen K, Amann W, Berghold A. Multislice spiral CT angiography in peripheral arterial occlusive disease: a valuable tool in detecting significant arterial lumen narrowing. Eur Radiol 2004;14:1681–7. [27] Puls R, Knollmann F, Werk M, et al. Multi-slice spiral CT: 3D CT angiography for evaluating therapeutically relevant stenosis in peripheral arterial occlusive disease. Rontgenpraxis 2002;54:141–7. [28] Rieker O, Düber C, Schmiedt W, von Zitzewitz H, Schweden F, Thelen M. Prospective comparison of CT angiography of the legs with intraarterial digital subtraction angiography. Am J Roentgen 1996;166:269–76. [29] Mishra A, Bhaktarahalli JN, Ehtuish EF. Imaging of peripheral arteries by 16row multidetector computed tomography angiography: A feasible tool? Eur J Radiol 2007;61:528–33. [30] Laswed T, Rizoo E, Guntern D, et al. Assessment of occlusive arterial disease of abdominal aorta and lower extremities arteries: value of multidetector CT angiography using an adaptive acquisition method. Eur Radiol 2008;18:263–72. [31] Favaretto E, Pili C, Amato A, et al. Analysis of agreement between Duplex ultrasound scanning and arteriography in patients with lower limb artery disease. J Cardiovasc Med (Hagerstown) 2007;8:337–41. [32] Mesurolle B, Qanadli SD, El Hajjam M, Goeau-Brissonniere OA, Mignon F, Lacombe P. Occlusive arterial disease of abdominal aorta and lower extremities: comparison of helical CT angiography with transcatheter angiography. Clin Imaging 2004;28:252–60. [33] Hirsch AT, Criqui MH, Treat-Jacobson D, et al. Peripheral arterial disease detection, awareness, and treatment in primary care. JAMA 2001;286: 1317–24. [34] Hiatt WR. Medical treatment of peripheral arterial disease and claudication. New Engl J Med 2001;344:1608–21.