Advanced Imaging in Limb Salvage

Abstract

The evaluation of patients at risk for limb loss secondary to peripheral arterial disease begins with a complete history and physical exam, and noninvasive studies in the vascular lab, including duplex ultrasonography. However, successful revascularization depends on high-quality, accurate imaging of the lower extremity vasculature. The traditional gold standard for vascular imaging, digital subtraction angiography, has been improved upon as technologic advances have enabled high-quality alternatives for preoperative (i.e., computed tomography [CT] angiography and magnetic resonance angiography [MRA]) and intraoperative imaging (i.e., intravascular ultrasound [IVUS], cone beam CT, and CO 2 angiography). Here we describe these advanced invasive and noninvasive imaging alternatives and their utility in limb salvage procedures.

Multimodality Imaging Approach for Serial Assessment of Regional Changes in Lower Extremity Arteriogenesis and Tissue Perfusion in a Porcine Model of Peripheral Arterial Disease

“…CT angiography, which provides visualization of vessel morphology, is a common technique for assessing the extent of PAD and provides guidance for vascular interventions 15 . Although visual analysis of in vivo contrast angiograms allows for qualitative assessment of vascular remodeling, the quantitative approach used in the present study for the evaluation of arteriogenesis allows for objective assessment of vascular remodeling in specific muscle regions of the lower extremities following intervention.…”

“…Typical clinical methods for detecting the response to therapy have been maximum walking distance (MWD; i.e., the distance at which the pain is severe enough for a patient to stop), the initial claudication distance (ICD; i.e., the distance at which pain first occurs), the ankle-brachial pressure index (ABI), quality of life questionnaires, duplex ultrasonography, and X-ray angiographic parameters 9,10 . However, ABIs can be problematic in the setting of microvascular disease and medial calcification 11,12 , ultrasound only permits evaluation of blood flow in major vessels and is not useful for the estimation of collateral vessel flow 13 , and angiography is traditionally used for only anatomical or visual assessment of vessels in the clinical setting 14,15 . Magnetic resonance (MR) imaging can evaluate lower extremity tissue perfusion and oxygenation in the setting of PAD; however, MR techniques are limited by their insensitivity to measure perfusion at rest and usually require exercise or reactive hyperemia protocols to adequately augment flow 16-18 .…”

Novel Applications of Radionuclide Imaging in Peripheral Vascular Disease

“…However, both CT and MR angiography are limited by the lack of standard quantitative tools to assess the physiologic consequences associated with vessel stenosis and occlusion. 17 Additional MR approaches exist for evaluation of lower extremity tissue perfusion and oxygenation, but commonly require exercise, pharmacological, or reactive hyperemia protocols to produce quantifiable changes in image signal intensity. 18,19 Other techniques that have been utilized in more severe cases of PVD, such as critical limb ischemia (CLI), have included ankle and toe systolic pressures.…”

Intravascular Ultrasound in Aortic Disease

“…Distinct advantages of IVUS include the following: no need for nephrotoxic contrast material, reduction of radiation exposure to the patient and the healthcare providers, as well as a highly accurate assessment of the lumen area, residual stenosis, and completeness of treatment (Duran and Bismuth 2012). However, it is less useful for detecting type I endoleaks, which are the most frequent cause of postoperative rupture (Hoshina et al 2010).…”