Clinical Applications for Radiotracer Imaging of Lower Extremity Peripheral Arterial Disease and Critical Limb Ischemia

Abstract

Peripheral arterial disease (PAD) is an atherosclerotic occlusive disease of the non-coronary vessels that is characterized by lower extremity tissue ischemia, claudication, increased prevalence of lower extremity wounds and amputations, and impaired quality of life. Critical limb ischemia (CLI) represents the severe stage of PAD and is associated with additional risk for wound formation, amputation, and premature death. Standard clinical tools utilized for assessing PAD and CLI primarily focus on anatomical evaluation of peripheral vascular lesions or hemodynamic assessment of the peripheral circulation. Evaluation of underlying pathophysiology has traditionally been achieved by radiotracer-based imaging, with many clinical investigations focusing on imaging of skeletal muscle perfusion and cases of foot infection/inflammation such as osteomyelitis and Charcot neuropathic osteoarthropathy. As advancements in hybrid imaging systems and radiotracers continue to evolve, opportunities for molecular imaging of PAD and CLI are also emerging that may offer novel insight into associated complications such as peripheral atherosclerosis, alterations in skeletal muscle metabolism, and peripheral neuropathy. This review summarizes the pros and cons of radiotracer-based techniques that have been utilized in the clinical environment for evaluating lower extremity ischemia and common pathologies associated with PAD and CLI.

Keywords: Critical limb ischemia; Peripheral arterial disease; Positron emission tomography; Radiotracer imaging; Single-photon emission computed tomography.

Conflict of interest statement

DECLARATIONS OF INTEREST

None.

Figures

Figure 1.

[99mTc]-tetrofosmin SPECT/CT perfusion imaging in a CLI patient before and after lower extremity revascularization. A) Transaxial, (B) sagittal, and (C) coronal views of SPECT/CT images demonstrate improvements in foot perfusion that occur from pre-revascularization (left) to post-revascularization (right). These images represent previously unpublished data.

Figure 2.

[18F]-FDG PET/CT imaging of soft tissue infection in the foot of a diabetic CLI patient. A) Transaxial view of [18F]-FDG PET/CT images demonstrate increased radiotracer uptake that is localized to (B) the site of the diabetic wound infected with methicillin-resistant Staphylococcus auereus (MRSA) bacterium. These images represent previously unpublished data.

Figure 3.

[18F]-FDG PET/CT imaging of a patient with Charcot foot. Sagittal and axial views of (A) CT images, (B) [18F]-FDG PET images, and (C) fused [18F]-FDG PET/CT images of a patient with Charcot joint disease. Although diffuse [18F]-FDG uptake was present, no Charcot-related bony abnormalities are revealed by CT imaging, thus revealing a potential underlying inflammatory origin of Charcot disease prior to the presence of structural alterations. This research was originally published in Clinical Nuclear Medicine [88], © 2011 Wolters Kluwer Health, Inc.