Introduction 1 8 9 11 12 25 Technique Preparation 1 Table 1 Prescanning preparation Parameter Description Clothing No metal parts on clothing Oral contrast None I.V. cannula antecubital Minimally 22 G (0.6 mm inner diameter, blue valve) Positioning Supine, stabilized and lightly strapped, feet-first and arms elevated Respiratory phase Inspiration during abdominal-pelvic range Technical parameters 1 Fig. 1 a b c d  Scan duration 2 26 2 2 26 27 12 Table 2 Acquisition parameters for various multi-detector row computed tomography (MDCT) configurations for the angiography of peripheral arteries Type of scanner b Rotation time (s) c Table feed (mm/ rotation) Table speed (mm/s) d Characteristics a 4 × 2.5 0.5 1.5 15 30 40 Slow scan protocol, thick minimal slice width a 16 × 0.75 0.5 1.3 15 30 40 Slow scan protocol, high resolution 16 × 1.5 0.5 0.7 17 34 35 Slow scan protocol, less resolution, better in obese patients 16 × 1.5 0.5 1.0 24 48 25 Fast scan protocol, less resolution, reduction of contrast media a 2 × 32 × 0.6 0.5 0.8 15 30 40 z 2 × 32 × 0.6 0.33 0.8 16 48 25 z 2 × 32 × 0.6 0.33 1.0 19.8 60 20 z a b c d Fig. 2 a b white arrows c d c asterisk d black arrows  2 Collimation 3 10 Fig. 3a, b a b b  2 Contrast injection 12 13 Acquisition timing Due to the interindividual hemodynamic variability in peripheral CT angiography, reliable timing techniques are preferred over using a fixed delay. The test-bolus technique relies on the dynamic monitoring of small contrast boluses to measure the contrast arrival and travel time at the proximal and distal arteries, respectively. The bolus-triggering technique is a commonly used timing technique that is based on repetitive low-dose sequential scans at the level of the abdominal aorta, to monitor the arrival time of the contrast media. The acquisition starts automatically when the preferred threshold is reached, approximately 100 to 150 HU above the baseline value. During a transition delay, which is the time needed for the table to move and start the scan, of approximately 4 s, breathing instructions can be given to the patient. During this delay, the enhancement of the aorta will further increase to an absolute value of more than 200 HU. 28 26 27 Contrast injection 12 9 25 29 36 37 26 37 Patient dose in MDCT z 38 40 9 41 42 z 9 41 42 9 12 24 31 43 44 46 Display and evaluation Image reconstruction 1 9 10 16 20 23 32 47 The field of view (FOV) is selected as small as possible to optimize pixel size. A FOV of 380 mm, 350 mm, and 300 mm for the abdominal, femoral, and crural data sets, results in pixel sizes of approximately 0.74 mm, 0.68 mm, and 0.58 mm, respectively. Also, the FOV can be further decreased to 200 mm by including only one leg, leading to a pixel size of 0.4 mm. Advanced postprocessing and image evaluation Additional two-dimensional (2D) and three-dimensional (3D) postprocessing techniques are required to facilitate interpretation and presentation. Reviewing exclusively the transverse images is inefficient and less accurate than reviewing a combination of reformatted images. 4 1 5 Fig. 4a–d a b b d c d  Fig. 5a–d a b arrows c d arrows  4 6 19 25 6 7 8 5 6 6 19 9 Fig. 6a–d a b c d  Fig. 7a–c a arrows b arrows c arrows  Fig. 8a–c a b c  Fig. 9a, b a upper section lower section asterisk b  Wall calcification problem 2 10 14 19 11 19 48 How can we deal with the vessel wall calcifications depicted with MDCTA? It is important to use a wider window width (WW) and higher window center (WC) level settings from the usual CT angiography level of around 150 WC ± 250 WW to 200 WC ± 1000 WW for a better differentiation of calcifications and stents from the enhanced lumen and to minimize the effect of blooming. A further minimization of blooming is reached by using a sharper reconstruction kernel and higher spatial resolution. 11 24 49 50 Clinical value 3 Table 3 Validity of CT angiography in peripheral arterial disease (PAD) a No. of patients No. of analyzed segments No. of detectors e e Assessed segments h Richter et al. 1994 32 ns 1 84 ns Iliac >50 Lawrence et al. 1995 6 134 1 93 96 Femorocrural >50 Raptopoulos et al. 1996 39 624 1 93 96 Aortoiliac 85–99 Rieker et al. 1996 50 400 1 b b Femorocrural 75–99 Rieker et al. 1997 30 210 1 93 99 Aortoiliac 75–99 Kramer et al. 1998 10 ns 2 94 ns Iliocrural >90–99 Ishikawa et al. 1999 49 ns 1 97 95 Bypass grafts ns Bourlet et al. 2000 22 318 1 95 90 Aortoiliac >50 Puls et al. 2001 31 186 4 89 86 Total tree 50–99 Willman et al. 2003 46 769 4 91 99 Aortoiliac grafts ns Ofer et al. 2003 18 410 4 91 92 Total tree >50 Heuschmid et al. 2003 18 568 4 c c Total tree >50 Martin et al. 2003 41 1,312 4 92 97 Total tree 75–99 Catalano et al. 2004 50 1,148 4 96 93 Total tree >50 Mesurolle et al. 2004 16 168 2 91 93 Total tree >50 Ota et al. 2004 24 470 4 99 99 Total tree >50 d 12 144 4 g ns ns >50 Portugaller et al. 2004 50 740 4 92 83 Total tree area >70 Romano et al. 2004 42 3,402 4 93 95 Total tree ns Romano et al. 2004 22 1,782 4 92 94 Total tree ns Stueckle et al. 2004 52 ns 4 82 100 Total tree ns Edwards et al. 2005 44 1,024 4 79 93 Total tree 50–99 Fraioli et al. 2006 75 1,425 4 h h Total tree 50–99 Schertler et al. 2005 17 170 16 96 90 Popliteocrural >50 Willmann et al. 2005 39 1,365 16 96 96 Total tree >50 Unpooled mean    91 94   a 1 6 8 10 13 24 31 34 35 56 57 b c d e f g h 4 12 21 23 35 5 9 11 9 11 20 22 23 Table 4 Intertest agreement between CT angiography and digital subtraction angiography in PAD a No. of patients No. of assessed segments No. of detectors d Assessed segments Raptopoulos et al. 1996 39 624 1 90% Aortoiliac Beregi et al. 1997 20 52 1 100% Popliteal Tins et al. 2001 35 219 1 84% Aortoiliac Walter et al. 2001 22 456 4 c Total tree Rubin et al. 2001 18 351 4 100% Total tree Heuschmid et al. 2003 23 1,136 4 86% Total tree Ofer et al. 2003 18 444 4 78% Total tree Romano et al. 2004 42 3,402 4 κ = 0.68; 90% Total tree Romano et al. 2004 22 1,782 4 κ = 0.68; 90% Total tree a 3 7 12 14 16 18 35 55 b c d Table 5 Interobserver agreement of CT angiography in PAD a No. of patients No. of analyzed segments No. of detectors b Assessed segments Rieker et al. 1997 30 210 1 ρ=0.95 Aortofemoral Walter et al. 2001 22 456 4 c Total tree Tins et al. 2001 35 219 1 78% Aortofemoral Martin et al. 2003 41 1,312 4 κw = 0.84 Total tree Romano et al. 2004 42 3,402 4 d Total tree Romano et al. 2004 42 1,782 4 e Total tree Catalano et al. 2004 50 1,137 4 κ = 0.80 Total tree Ota et al. 2004 24 470 4 κ = 0.88 Iliac Portugaller et al. 2004 50 740 4 κ = 0.81 Total tree f 73 2,268 4 κw = 0.84 Total tree Ouwendijk et al. 2005 79 2,419 16 κw = 0.85 Total tree Willmann et al. 2005 39 1,365 16 κ = 0.85–1 Total tree a 4 7 9 11 15 17 19 21 23 35 b 15 c d e f 51 52 53 25 54 6 Table 6 Advantages and limitations of multi-detector row CT angiography (MDCTA), contrast enhanced MR angiography (CEMRA), and digital subtraction angiography (DSA)   MDCTA CEMRA DSA Intermittent claudication (Fontaine II) + + + Chronic critical ischemia (Fontaine III or IV) − + + Short examination time + − − Short postprocessing time − + + Outpatient setting + + − Availability + − + b + + − Low diagnostic imaging costs + − − Contrast media tolerance − + − Three-dimensional imaging + + − c + − + Radiation risk d − d Acute clinical setting + − + Hemodynamic assessment − a + Extraluminal pathology visualization + a − a b 58 c 59 d 2 14 11 43 10 11 55 Fig. 10a, b a arrows b arrows  Fig. 11a–d a b c d  Conclusion Multi-detector row CT angiography (MDCTA) is an outstanding non-invasive imaging test in the evaluation of patients with peripheral arterial disease (PAD) and is currently the modality of choice in patients with intermittent claudication. The technique can be used in the evaluation of patency after revascularization procedures and in acute ischemia. MDCTA has been shown to have high diagnostic performance and reproducibility in evaluating peripheral arterial disease (PAD). MDCTA reduces diagnostic costs and provides adequate information for decision making. The most important drawback is the limited lumen evaluation of extensive calcified arteries. MDCTA appears to be clinically less valuable in critical limb ischemia because of extensive crural artery calcifications.