Role of recent imaging modalities in the evaluationof lower limb vascular diseases in diabetic patients

Abstract

Foot disorders are a significant complication of diabetes mellitus and are leading causes for morbidity. Diabetic angiopathy is often a major contributing factor in the diabetic foot disease that must be recognizedand treated to avoid prolonged hospitalization, spreading of infection, and unnecessary amputation. Doppler US is a first choice instrumental examination for the diagnosis and staging of peripheral arterial occlusive disease in diabetic patients. Doppler US is a noninvasive, reproducible and cost-effective procedure. Grey-scal images identify plaque and thrombus, duplex assessment provides a measurement of blood velocity through a vessel, and color Doppler imaging enables the rapid localization of arterial stenosis and occlusions. Direct morphologic and flowmetric evaluations of stenotic-occlusive alterations, and direct evaluations based on the interprtation of velocimetry findings proximal and distal to the lesions, are feasible. The conventional basic examination can be enhanced with the power module. Disadvantages of the procedure are related to the poor panoramic view, subjectve (operator-dependent) interpretation and limitations related to the physics of ultrasound. Computed tomography angiography with multidetector scanners has increasingly been in favor over traditional angiography with digital subtraction. One consideration with CTA imaging is the use of iodinated contrast material for visualization of the vasculature. There is also the risk of contrast-induced acute kidney injury due to iodinated contrast media. This risk is most pronounced when patients have preexisting renal impairment, especially due to diabetic nephropathy(Andreucci et al., 2014). However, the reliability of CTA does suffer when discerning heavily calcified vessel walls from IV contrast, making interpretation sometimes challenging. Another limitation of CTA relates to the significant artifact caused by any metal prostheses, making the study limited in its usefulness. Another issue is direct evidence from epidemiologic studies that the organ doses corresponding to a common CTA study (two or three scans, resulting in a dose in the range of 30 to 90 mSv) result in an increased risk of cancer) (Brenner and Hall, 2007). Overall, multidetector CTA is an emerging non-invasive modality that enables one to assess vasculature including the coronary artery anatomy. In comparison to conventional angiography or duplexultrasound, multidetector CTA is less expensive, less invasive and faster (Met et al., 2009). Magnetic resonance angiography is another less invasive alternative to traditional angiography. This modality has become more prevalent as the technology and relevant gadolinium contrast protocols have improved(Koelemay et al., 2001).