Peripheral arterial disease treatment planning using noninvasive and invasive imaging methods

Abstract

With the growing prevalence and mortality of peripheral arterial disease, preoperative assessment, risk stratification, and determining the correct indication for endovascular and open surgical procedures are essential for therapeutic decision-making. The effectiveness of interventional procedures is significantly influenced by the plaque composition and calcification pattern. Therefore, the identification of patients for whom endovascular treatment is the most appropriate therapeutic solution often remains a challenge. The most commonly used imaging techniques have their own limitations and do not provide findings detailed enough for specific, personalized treatment planning. Using state-of-the-art noninvasive and invasive imaging modalities, it is now possible to obtain a view, not only of the complex vascular anatomy and plaque burden of the lower extremity arterial system, but also of complex plaque structures and various pathologic calcium distribution patterns. In the future, as these latest advancements in diagnostic methods become more widespread, we will be able to obtain more accurate views of the plaque structure and anatomic complexity to guide optimal treatment planning and device selection. We reviewed the implications of the most recent invasive and noninvasive lower extremity imaging techniques and future directions.

Keywords: Diagnostic imaging; Endovascular procedures; Future perspectives; Peripheral arterial disease; Treatment planning.

Fig 1

Comparison of 7T magnetic resonance imaging (MRI) and color duplex ultrasound examination of a middle popliteal artery segment plaque. A,B, Color duplex ultrasound images showing an echogenic, solid, nodular, calcified plaque (yellow arrow) with shadowing artifact (red star). Doppler ultrasound (A) showing significant hemodynamic stenosis (peak systolic velocity, 440 m/s). On color duplex ultrasound, detailed plaque morphology can be determined only to a very limited extent. In contrast, 7T T2 and ultrashort echo time (UTE) images of the same plaque show explicit plaque structure with speckled calcium as a signal void in an isointense dense collagen matrix. MID, Middle segment; POP, popliteal artery; RT, right.

Fig 2

Conventional angiography using iodinated contrast material (A-D) compared with noncontrast quiescent-interval single-shot magnetic resonance angiography (E). The latter promising technique allows the entire lower extremity arterial system to be mapped without the use of contrast material.

Fig 3

7T magnetic resonance imaging histology (MRI-Histo) of anterior tibial artery. Bony landmarks of the tibia and fibula can be used for image registration, as illustrated. Concentric calcium (green outline) is detectable on both 7T MRI-Histo and intravascular ultrasound (IVUS) images showing similar area and diameter measurements of the reference vessel. The area is not measurable on angiographic images, and assessment of the vessel wall is particularly limited. The diameters shown illustrate how each modality can be used to determine the optimal stent and balloon size for endovascular interventions.

Fig 4

Decision-making algorithm for diagnostic imaging modalities in peripheral arterial disease (PAD). ABI, Ankle brachial index; CDS, color duplex ultrasound; CEMRA, contrast-enhanced magnetic resonance angiography; CLTI, chronic limb-threatening ischemia; CO₂, carbon dioxide; CTA, computed tomography angiography; DE-CTA, dual-energy computed tomography angiography; DSA, digital subtraction angiography; DVA, digital variance angiography; EVUS, extravascular ultrasound; IVUS, intravascular ultrasound; MRI, magnetic resonance imaging; NEMRA, nonenhanced magnetic resonance angiography; OCT, optical coherence tomography; PCCT, photon-counting computed tomography; TBI, toe brachial index; US, ultrasound.

Fig 5

Anterior tibial artery plaque morphology on 7T magnetic resonance imaging (MRI) and computed tomography angiography (CTA). The 7T MRI images (ultrashort echo time [UTE], T1, T2) show a detailed structure of a concentric, calcified plaque with calcium as a signal void. Assessment on the CTA image is limited because of extensive calcification and consequential blooming artifact.

Fig 6

Detailed ex vivo plaque morphology of tibioperoneal trunk compared with preoperative computed tomography angiography (CTA) for the same patient in Fig 3. The vessel was affected by extensive, circular calcification. Assessment of the plaque was limited on in vivo CTA. On intravascular ultrasound (IVUS), ex vivo histologic samples (A,B), and micro-computed tomography (CT; C,D), we can see the explicit pattern with a concentric calcium sheet.