| Abstract: |
Summary & conclusionCT angiography emerges as a powerful minimally invasive alternative to conventional angiography for identifying aorto-iliac and femoro-politeal aneurysms, stenoses, occlusions, and dissections. It has been particularly successful in imaging patients with aorto-iliac and femoro-popliteal aneurysms. The minimally invasive nature of the method, short examination time, and capability of three dimensional depiction of arteries, all make it an attractive alternative.Color Doppler ultrasound determines not only the presence but also the location and most importantly the homodynamic significance of vascular disease. It is a simple, cheap, and completely non-invasive method, it could replace arteriography in some patients, especially if revealed normal findings. In other patients it will determine the affected segments to be subjected to arteriography leading to improving its results, saving time, contrast media and decreasing complications.This work aimed to evaluate the role of CT angiography and color Doppler imaging as two non invasive techniques in the assessment of different femoral artery diseases.The pathological vascular lesions in the femoral artery segments were classified into: normal, irregular, hemodynamically non-significant (less than 50% DR), hemodynamically significant lesions (50-99% DR) and total occlusion (100% DR).Twelve patients with limb threatening ischemia or intermittent claudications were referred from the vascular surgical departments of Zagazig University Hospital and outpatients clinics. Their ages ranged from 40-80 years with a mean age of 60 years. Patients population consisted of 9 males (75%) and 3 females (25%). Ten cases were studied with angiography, color Doppler ultrasound and CT angiography, the other two cases were studied by CT angiography and color Doppler US.With ten femoral stenotic and occluded segments; MIP had overall sensitivity of 97% and specificity of 91%. With color Doppler sensitivity of 94% and specificity 89%.In our study that was conducted on twelve cases of lower limb with different vascular pathological lesions as irregularity, non significant stenosis, significant stenosis and occlusion vascular lesions. They were examined by conventenal angiography, Doppler scanning and CT angiography. There is ten examined cases of 100 arterial segments where the femoral artery divided into three main arterial segments, common femoral artery, profunda femoral artery and superficial femoral artery that was subdivided into three vascular arterial segment, proximal, middle and distal segment.In this study, we had 2 cases, one of them was failed to be examined by conventional angiography because there was no detected femoral pulsation at both sides, when examined by C.T.A revealed bilateral common-iliac, external iliac and bilateral proximal CFA occlusion, also with C.D.S no Doppler signals were detected.So CTA was mere suitable in such cases with absent or weak femoral pulsation as it does not depend upon puncture site. The other case was referred for CTA, it revealed soft tissue mass causing displacement of adjacent distal femoral artery, CTA is more consent in such cases as it well demonstrate the soft tissue, bone and vascular component as well.The results of our study were comparable to the results of others, in detecting and grading the femoral artery stenoses and occlusions, considering catheter arteriography as the ”gold standard” of references.Conventional angiography, though still generally regarded as the definitive examination for vascular diagnosis, has some limitations. It is invasive, expensive, and poorly suited for screening or long-term follow up testing. In addition, it provides a biplanar view for anatomic rather than physiologic information.CT angiography provides a rapid relatively non-invasive method for assessing the ilio-femoral segment with less radiation exposure than with conventional arteriography. It can be performed in a fraction of the time required for either color Doppler or conventional arteriography. It is not as operator dependent as color Doppler. It can provide views of the aorto-iliac and femoral segments that are simply not possible with any other modality. It provides different imaging formats from a single scan acquisition; the standard CT cross-sectional views and MIP. The cross-sectional view can detect associated unsuspected intra abdominal or lower limb pathology.CT angiography limitations are: It requires administration of contrast material. It covers a limited craniocaudal span. It gives no blood flow velocity information. It has a lower resolution than conventional angiography. Although data acquisition time is short, the postprocessing into CTA models is time-consuming.Despite its known advantages, the most significant limitation of Doppler U.S., particularly in the pelvic arteries, is the inability to visualize a vessel well enough to obtain accurate velocity measurements. Visualization may be limited due to obscuration by bowel gases, patient obesity, heavy vascular calcifications, vessel tortuousity and in areas of slow flow distal to total occlusions.On the basis of our initial results, we conclude that:CT angiography can obviate the need for conventional angiography before routine aorto-iliac and femoro-popliteal aneurysm repair. Conventional angiography will remain to be indicated only when coexistent occlusive disease is expected in the run off vessels.Color Doppler ultrasound has the capability of providing anatomic and hemodynamic information from the pelvis and lower extremity arteries. It has been shown to have the anatomic accuracy of arteriography in addition to providing direct hemodynamic information. The information generated is reliable, cost effective and accurate enough in many cases to allow intervention without confirmatory arteriography. Although, CDS will not completely replace arteriogrpahy, it has assumed an important initial role in preangioplasty and pre-operative evaluation. We recommend that CDS should become the standard modality for screening patients with lower extremity ischemia thus eliminating unnecessary invasive studies.CT angiography, because of its very short scanning time ,can asses hemodynamically unstable patients with impending acute aneurysm rupture or risky occlusive ischemic disease critically ill patients.Although operative strategies in cases of atherosclerotic aortoiliac and peripheral occlusive disease are still based on angiographic findings, the role of non-invasive testing is being progressively increasing.We hope that, as our experience increases and technology advances. It is likely that angiography by percutaneously placed arterial catheter, will become a relic of the past.
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