CT angiography (CTA) of the lower extremities has evolved into a robust non-invasive angiographic technique with the advent of 160- and 320-multidetector computed tomographic systems and advances in system design. CTA has displaced conventional catheter arteriography in a large range of applications and is predominantly used in the evaluation of atherosclerotic peripheral arterial occlusive disease in symptomatic patients who are candidates for intervention. Other disease entities including atheroembolism, aneurysmal disease, and arteritides including Buerger disease and Takayasu arteritis can be precisely evaluated by CTA [19].
Our study uses a quite different protocol as we used a detector configuration 160 × 1 mm and 0.5-mm-thick section while gantry rotation period is 0.3 s. Also, they started their exams from the abdominal infrarenal aorta while we tried our best to start our exam from the arch of the aorta by butting the sure start at the arch and reducing the wait time. Ozkan et al. [20] examined the segmental distribution of atherosclerosis in 626 symptomatic patients with peripheral arterial disease. Peripheral arterial disease involved one segment in 36% of the patients, two segments in 42% of the patients, and three or more segments in 33.33% of the patients. He concluded that PAD was multisegmental in most of the cases of the study group.
Our result was quite similar as we examined 30 patient, and we found that multisegmental (three or more) peripheral arterial disease definitely takes the upper hand by 73.3% while 20% of patients had two segments and only 6.67% of patients had one segment.
Osama et al. [21] studied the role of multislice CT angiography versus Doppler ultrasonography and conventional angiography in the assessment of aorto-iliac arterial disease and stated that as regards the degree of stenosis, there was an agreement between digital subtraction angiography (DSA) and multidetector row CT angiography in nine lesions (82%), with discrepancy in two lesions (18%). The agreement between DSA and color-coded Doppler occurred in eight lesions (73%), while discrepancy occurred in three lesions (27%). This discrepancy was mainly due to the ability of multidetector CT angiography to detect a small amount of contrast in the stenotic segment and the ability of the color-coded Doppler to detect weak flow within a stenotic artery compared to digital subtraction angiography. He used a low amount of contrast material (120–150 ml) as he had a fast scanner. His gantry rotation period was 0.5 s. His examinations started at the level of the celiac artery. We all agreed with all these studies as we found no significant differences in the sensitivity and specificity between MDCT angiography and CCD in the detection of hemodynamically significant lesions.
With the emergence of new evidence, ACC/AHA 2005 guideline was updated in 2011 with an attempt to establish a harmony with the TASC II guideline. Following this update, Doppler ultrasonography still maintained its diagnostic value by itself or with other tools for the diagnosis of the PAD of the lower extremities [22]. For European countries, the first guideline of PAD was recently published by the European Society of Cardiology [23]. Similar to other guidelines, ESC guidelines recommended non-invasive Doppler ultrasonography among the first diagnostic tests to confirm and localize stenosis lesions (evidence class I, level B). To localize stenosis lesions and consider revascularization options, this latest guideline also indicated the need for either Doppler ultrasonography, CTA, or MRA (evidence class I, level A), without giving superiority to any of them. Finally, the ECS guideline recommended that any patient suggested for surgery based on any of the imaging tools should also be tested hemodynamically, which can be achieved only by Doppler arteriography.
The guideline recommendations on the management of PAD were published by the ACC Foundation in 2013. In this update, Doppler US measurements were demonstrated among the top diagnostic tests to provide an accurate assessment of lower extremity PAD location and severity (evidence class I, level A) and to provide accurate follow-up after revascularization (evidence class I, level A) [24].
Our results made us agreed with all the guidelines as we found that an experienced Doppler radiologist can make the best use of Doppler and avoid consuming time in other modalities especially when there are contraindications and also can help the vascular surgeon to make his decision in choosing intervention or medical treatment.
Bueno et al. [25] examined 1720 segments on 40 patients; the utility of Doppler US and MRA was evaluated by using CA as a reference point. When the detection of stenosis ≥ 50% was taken as the sole criterion, sensitivity and specificity values were calculated respectively to be 81.4% and 99% for Doppler ultrasonography and 91 and 99% for MRA. In the same study, total occlusion sensitivity and specificity values were calculated respectively as 90% and 97% for Doppler US and 95.4% and 98% for MRA. The latter study demonstrated a relatively low sensitivity value for Doppler ultrasonography in the detection of significant stenosis in the lower limb arteries whereas the specificity value was quite acceptable.
We agreed with that as we noted that the sensitivity and specificity of the Doppler US are quite lower than CT angiography, but it is acceptable especially as we already stated that we can make use of Doppler to save time in critical cases and in cases where CT angiography is contraindicated. CT angiography has the advantages of being minimally invasive, requiring only a reasonable amount of the intravenous contrast and imaging surrounding soft tissues, fast, accurate, and safe and has the advantage of using MIP and 3D images for cases of peripheral vascular diseases for diagnosis, for grading, and for preoperative assessment of lower limb arterial disease. US is also a great non-invasive, fast, accurate, safe, and readily available tool for the assessment of lower limb arterial disease. It has an advantage over MDCT angiography that it provides us with hemodynamic data proximal, distal, and at the site of obstruction [26,27,28,29].