Quiescent-Interval Single-Shot Magnetic Resonance Angiography May Outperform Carbon-Dioxide Digital Subtraction Angiography in Chronic Lower Extremity Peripheral Arterial Disease

Employing magnetic resonance histology for precision chronic limb-threatening ischemia treatment planning

OBJECTIVE

Recent randomized controlled trials have demonstrated a notable prevalence of immediate technical failures in percutaneous vascular interventions (PVIs) for complex arterial lesions associated with chronic limb-threatening ischemia. Current imaging modalities present inherent limitations in identifying these lesions, making it challenging to determine the most suitable candidates for PVI. We present a novel preprocedural magnetic resonance imaging (MRI) histology protocol for identifying lesions that might present a higher rate of immediate and midterm PVI failure.

METHODS

We enrolled 22 patients (13 females, average age 65.8 ± 9.72 years) scheduled for PVI were prospectively and underwent 3T MRI using ultrashort echo time and steady-state free precession contrasts to characterize target lesions before PVI. Lesions were scored as hard if >50% of the lumen was occluded by hard components (calcium/dense collagen) on MRI in the hardest cross-section. Two readers evaluated MRI datasets. Trans-Atlantic Inter-Society Consensus Document on Management of Peripheral Arterial Disease (TASC)/Global Limb Anatomic Staging System (GLASS)/Wound, Ischemia and Foot infection scoring was performed based on intraprocedural angiograms and chart review. The relationship between MRI scoring, TASC/GLASS scoring, and procedural outcomes was investigated using univariate analysis. Midterm follow-up (revascularization and amputation rates) was recorded at 3 and 6 months after the intervention.

RESULTS

Our cohort of 22 patients yielded 40 target lesions. Five lesions were excluded (two for nondiagnostic image quality; three PVIs were ultimately diagnostic only). Six lesions (17%) were scored as hard. MRI-scored hard lesions had a higher proportion of immediate technical failure (hard vs soft 83% [5/6] vs 3% [1/29]; P < .001). Hard vs soft MRI scoring was the only factor significantly associated with immediate PVI technical success (P < .001), as opposed to TASC/GLASS scoring. Both at 3 months and 6 months after PVI, the reintervention rate was significantly higher among those lesions which were scored hard on MRI (3 months hard, 80% vs soft, 16% [P =.011]; 6 months hard, 80% vs soft, 27%; P = .047).

CONCLUSIONS

MRI histology could be a valuable tool for optimizing PVI patient selection and treatment strategies.

Peripheral Arterial Disease: A Narrative Review

Peripheral arterial disease (PAD) describes the partial or complete occlusion of blood flow in the distal arteries of the body. A decreased arterial patency may occur due to a reduction in the elasticity or diameter of the vessel. The goal of interventions is to decrease incidence and reduce complications by identifying and minimizing the primary causes. This paper discusses PAD affecting the aortoiliac, common femoral, and femoropopliteal arteries. In a significant portion of the population, PAD may lack usual symptoms such as limb pain, claudication, and diminished pulses. Imaging techniques become crucial to ensuring timely diagnosis, monitoring treatment effectiveness, and preventing recurrence. Duplex ultrasound (DUS) is a cheap and non-invasive preliminary technique to detect atherosclerotic plaques and grade arterial stenosis. Magnetic resonance angiography (MRA) provides the added advantage of minimizing artifacts. Digital subtraction angiography (DSA) remains the gold standard for grading the degree of stenosis but is only employed second-line to DUS or MRA due to the high dose of nephrotoxic contrast. Computed tomography angiography (CTA) is able to overcome the anatomical limitations of DUS and MRA and proves to be a suitable alternative to DSA in patients with renal disease. Preventative measures involve monitoring blood pressure, cholesterol levels, and tobacco usage. First-line treatment options include endovascular procedures as well as surgical interventions in cases of significant arterial involvement. Endovascular treatments involve the use of balloon angioplasty, drug-coated balloons, and drug-coated stents, to name a few, that serve as minimally invasive techniques to manage PAD. Surgical procedures, although more complex, are considered gold-standard treatment options for long and intricate lesions. Endovascular methods are generally preferred over surgical options as the complication risk is severely reduced and the rates of reintervention are comparable to surgical options.

Non-contrast MR angiography of pelvic arterial vasculature using the Quiescent interval slice selective (QISS) sequence

To evaluate Quiescent Interval Slice Selective (QISS) balanced steady-state free precession (bSSFP) and QISS fast low-angle shot (FLASH) sequences for non-contrast Magnetic Resonance Angiography (MRA) of iliac arteries regarding image quality and diagnostic confidence in order to establish these sequences in daily clinical practice. A prospective study of healthy subjects (n = 10) was performed. All subjects underwent the QISS MRI protocol with bSSFP und FLASH sequences. Vessel contrast-to-background ratio (VCBR) were measured in pre-defined vessel segments. Image quality and diagnostic confidence was assessed using a Likert scale (five-point scale). Inter-reader agreement was determined using Cohen's kappa coefficient (κ). Ten healthy subjects (median age 29 years, IQR: 26.25 to 30 years) were included in this prospective study. Median MR examination time was 2:05 min (IQR 1:58 to 2:16) for QISS bSSFP and 4:11 min (IQR 3:57 to 4:32) for QISS FLASH. Both sequences revealed good VCBR in all examined vessel segments. VCBR (muscle tissue) were marginally higher for FLASH sequences (e.g., 0.82 vs. 0.78 in the right femoral artery, p = 0.035*), while bSSFP sequence showed significantly higher VCBR (fat tissue) in the majority of examined arterials vessels (e.g., 0.78 vs. 0.62 in right femoral artery, p = 0.001*). The image quality and diagnostic confidence of both sequences were rated as good to excellent. Moderate to good inter-reader agreement was found. QISS MRA using bSSFP and FLASH sequences are diagnostic for visualization of iliac arterial vasculature. The QISS bSSFP sequence might offer advantages due to the markedly shorter exam time and superior visualization of smaller vessels. The QISS FLASH sequence seems to be a robust alternative for non-contrast MRA since it is less sensitive to magnetic field inhomogeneities.