Table 3.6.

Comparison of different imaging modalities for patients with chronic limb-threatening ischemia (CLTI)

Techniques	Advantages	Limitations
DUS	• Noninvasive • Inexpensive • Quick, widely available worldwide • Useful to monitor efficacy of therapeutic intervention	• Highly operator dependent • Limitations to the visualization of iliac arteries due to body habitus, bowel gas • Calcification may produce incomplete examination • Most DUS studies were performed in mixed populations; thus, the validity of DUS imaging for CLTI patients alone is uncertain
CTA	• Noninvasive • Excellent patient acceptance Ability to evaluate previously stented arteries • Mostly applicable in patients with contraindications to MRA	• Image interference from calcified arteries • Potentially nephrotoxic contrast agents Radiation exposure • Less reliable for imaging of IP vessels • Patients with CLTI who require a complete assessment of their lower extremity (including foot) arteries for planning of a revascularization are under-represented in the current studies. The clinical value of CTA in the CLTI target population remains uncertain.
MRA	• Noninvasive • Eliminates exposure to ionizing radiation • Unaffected by arterial calcification • Three-dimensional images of the entire arterial tree are presented in a maximum intensity projection format produced on a workstation • Easily produced arterial map aids in planning of revascularization strategies	• Patients with pacemakers and defibrillators and some cerebral clips cannot be scanned safely • Tendency to overestimate stenosis • Metal clips can cause artifacts that mimic vessel occlusions • Venous contamination can obscure arteries below the knee
Catheter angiography (DSA)	• Provides a complete map of the lower limb arteries • Images are easily displayed and interpreted by most physicians in charge of patients with CLTI • Selective catheter placement during lower extremity angiography enhances imaging, reduces contrast material dose, and enhances sensitivity in patients with CLTI	• Exposure to ionizing radiation and contrast media • Alternatively, carbon dioxide and magnetic resonance contrast agents (eg, gadolinium) can be used instead of conventional contrast media • Complications of catheterization despite improvements in catheter and guidewire technology

CTA, Computed tomography angiography; DSA, digital subtraction angiography; DUS, duplex ultrasound; IP, infrapopliteal; MRA, magnetic resonance angiography.