High‐resolution 3D arteriography of chronic total peripheral occlusions using a T₁‐W turbo spin‐echo sequence with inner‐volume imaging

Abstract

Percutaneous revascularization of peripheral artery chronic total occlusion (CTO) is challenging under X-ray guidance without direct image feedback, due to poor visualization of the obstructed segment and underappreciation of vessel tortuosity. Operators are required to steer interventional devices relatively "blindly," and therefore procedural failure or perforation may occur. Alternatively, MRI may allow complete visualization of both patent and occluded arterial segments. We designed and implemented a 3D high-resolution, Atherosclerotic peripheral artery disease (PAD) is a widely prevalent disorder that affects millions worldwide and is associated with significant morbidity and mortality (1,2). Patients with lower-extremity PAD may suffer intermittent claudication or critical limb ischemia due to stenotic or occlusive arterial plaques. Minimally invasive X-ray-guided, catheter-based revascularization procedures, such as percutaneous intravascular angioplasty and stent implantation, can relieve arterial obstruction and improve muscle perfusion in selected patients (3,4). A detailed understanding of the geometry of the patent, stenotic, and occluded arterial segments is crucial to ensure procedural success and freedom from complications such as vascular perforation. Here we present a high-resolution 3D magnetic resonance imaging (MRI) method that provides detailed visualization of the entire artery in a range of anatomic and atherosclerotic configurations within 5Ϫ10 min.Traditional arteriography (radiocontrast X-ray, contrast-enhanced (CE)-MRA, and time-of-flight (TOF)-MRA) requires luminal patency and blood flow. In patients with chronic total occlusions (CTOs), the absence of a lumen to hold the contrast agents makes these vessels completely invisible from the point of total occlusion to the point where the collateral-mediated circulation begins to feed the vessel. Figure 1 shows an example of an X-ray angiogram in a patient with a peripheral CTO. Note the missing segment (nearly 6 cm long) in the left common iliac artery at its origin at the aortic bifurcation. The absence of image guidance, which typically is coupled with long lesion lengths, increased vessel tortuosity, and vessel shrinkage due to negative remodeling, can make it challenging to maneuver through the occluded vessels without rupturing or dissecting the vessel walls. A minority of the atherosclerotic occlusions have sufficient diffuse calcification to allow X-ray visualization in at least part of the occluded vascular trajectory. In the absence of such clues, clinicians need other techniques to plan a recanalization trajectory. In this study we present a high-resolution 3D MRI technique with contrast properties that enable differentiation between the arterial walls, adjacent structures, intraluminal blood, and the CTO lesion, thus providing good visualization of the vascular borders, vessel tortuosity, and the location and length of the lesion within the lumen.The implementation of MRI for high-resolution imaging of arterial vessel walls and...

Multimodality image fusion to guide peripheral artery chronic total arterial occlusion recanalization in a swine carotid artery occlusion model: Unblinding the interventionalist

“…XRF is the clinical standard for endovascular CTO recanalization procedures; however, the course of the CTO segment is poorly visible to the interventionalist due to poor soft tissue contrast and poor penetrance of X‐ray contrast. MRI provides excellent depiction of the CTO segment in this swine CTO model [7] and in humans [15, 16]. Additionally, the high‐resolution 2D T 1 ‐weighted fast spin‐echo MR images that were used to generate the carotid artery surface models do not require gadolinium contrast, which is associated with nephrogenic systemic fibrosis in those with renal impairment.…”

“…Magnetic resonance imaging (MRI) has been shown to provide high‐resolution visualization of both patent and occluded artery segments [6, 7]. We previously demonstrated the feasibility of real‐time MRI‐guided CTO recanalization; however, the lack of commercially available MRI‐compatible catheters and guidewires has prevented adoption of this technology into clinical practice [7].…”

Diagnostic pitfalls in postinterventional intraarterial magnetic resonance angiography after recanalization of femoropopliteal arterial occlusions

“…With the hr-TSE-T1w sequence, a clear delineation of the vessel wall before, during, and after PTA could be achieved. The TSE sequence is an ideal choice for this application because of the low sensitivity to offresonance and susceptibility artifacts, and inherent black-blood suppression (20,22).…”

Technology preview: X‐ray fused with magnetic resonance during invasive cardiovascular procedures

“…Arterial adventitial and luminal contours were derived from 3D contrast-enhanced MRA (typical parameters: TR/TE, 2.3/0.9 ms; flip angle, 25°; FOV, 512 × 314 × 122 mm matrix, 256 × 156 × 54; bandwidth 815 Hz/pixel), from 3D breath-held T1-weighted MRI (typical parameters: TR/TE, 6.2/2.3; flip angle, 12°; FOV 400 × 325 × 220 mm matrix 256 × 156 × 64; bandwidth, 200 Hz/pixel), and/or a high resolution reduced field of view (FOV) technique [13].…”