Perfusion imaging techniques in lower extremity peripheral arterial disease

Abstract

Lower limb peripheral arterial disease (PAD) characterizes the impairment of blood flow to extremities caused by arterial stenoses or occlusions. Evaluation of PAD is based on clinical examination, calculation of ankle-brachial index and imaging studies such as ultrasound, CT, MRI and digital subtraction angiography. These modalities provide significant information about location, extension and severity of macrovasular lesions in lower extremity arterial system. However, they can be also used to evaluate limb perfusion, using appropriate techniques and protocols. This information may be valuable for assessment of the severity of ischemia and detection of hypoperfused areas. Moreover, they can be used for planning of revascularization strategy in patients with severe PAD and evaluation of therapeutic outcome. These techniques may also determine prognosis and amputation risk in patients with PAD. This review gives a basic overview of the perfusion techniques for lower limbs provided by imaging modalities such as ultrasound, CT, MRI, digital subtraction angiography and scintigraphy and their clinical applications for evaluation of PAD and revascularization outcome.

Figure 1.

Axial CT perfusion maps for hemodynamic parameters such as blood volume (a) and blood flow (b).

Figure 2.

Co-registration of sagittal T ₁W sequence with K^trans perfusion parametric map (a). Sagittal intravoxel incoherent motion microperfusion map for pseudodiffusion coefficient (D*) representing the microcirculation of blood in the capillary network (b).

Figure 3.

Two-dimensional perfusion angiography maps of lower extremity for parameters such as time to peak (a), wash-in rate (b), area under curve (c) and mean transit time (d).