Isolated occlusion of the right common femoral artery in a 32-year-old woman

Clinical History

A patient with erythema nodosum and migratory arthritis was admitted to our hospital after several episodes of intermittent claudication of the right lower limb. A CD ultrasound showed right external iliac artery stenosis and occlusion of the common femoral and superficial femoral artery. The patient underwent a CE-MRA examination.

Imaging Findings

First-pass MRA after injection of gadobenate dimeglumine (MultiHance; Bracco Imaging, Milan, Italy) with 0.1 mmol/kg, detected a long isolated occlusion of the common femoral artery with a filiform appearance of the vessel downstream, without signs of diffuse atherosclerotic disease (Fig. 1 a, b).
The additional coronal and axial oblique images acquired during the “steady-state” phase, showed a concentric thickened vessel walls enhancement of the third distal of the right common femoral artery with an occlusive thrombosis upstream and a normal calibre downstream (Fig. 2).
The final diagnosis was vasculitis considering the data of the clinical history and examination, the absence of diffuse atherosclerotic disease and the circumferential walls thickening enhancement.

Discussion

Vasculitis are acute and chronic inflammatory changes of the small, medium and large vessels. In large-vessel vasculitis, imaging studies showed homogeneous, circumferential wall swelling and smoothly tapered luminal narrowing [1, 2].
The colour Doppler ultrasound is the first step technique in the study of the peripheral arteries, since it is low-cost and radiation-free. It allows the evaluation of the morphology of the vessel walls and lumen, and gives fundamental information about blood flow [3]. However, the uniform circumferential thickening of the vessels affected by vasculitis can sometimes be indistinguishable from that of an atherosclerotic plaque.
In the last decade contrast-enhanced magnetic resonance angiography (CE-MRA) has gained wide acceptance as a valuable tool in the diagnostic work-up of patients with arterial disease, since it is able to detect and quantify stenoses, provide sub-millimeter resolution with full arterial coverage, and show true vessel delineation without artefacts.
In order to achieve high quality MR angiograms, a number of factors need to be considered. These include magnetic field strength of the MRI system, receiver coil configuration, parallel imaging technique, k-space filling strategies, acquisition protocol (hybrid scan protocols, time-resolved imaging, and steady-state MRA), contrast bolus timing technique and high relaxivity contrast medium [4].
The use of high relaxivity contrast medium significantly produce greater intravascular signal enhancement than conventional gadolinium agents at equivalent dose. [5, 6] Furthermore , due to low protein binding that increases its retention time in the vascular system, it can be used for extended phase imaging ('steady-state'), starting immediately afterward (approximately 1-2 min post injection) . The steady-state phase , with a broad time window enabling high-resolution MR angiography, allows improved evaluation of stenoses and vessel wall morphology [ 7].
In our case, the first pass MRA of the arteries at standard spatial resolution was highly accurate in the assessment of grade of the stenosis showing the absence of other signs of vascular disease. In addition to first-pass MR angiography, the steady state phase provided a good visualisation of the vessel lumen and also showed specific features like vessel wall thickening and enhancement. These findings allowed diagnosing the inflammatory nature of the stenosis.
In conclusion, this case shows the importance of the CE-MRA with emphasis on MRI technique and high relaxivity contrast agents as second and final step technique in the diagnose of unusual vessel diseases.

Differential Diagnosis List

Final Diagnosis

Vasculitis of the right common femoral artery

URL:	https://www.eurorad.org/case/10932
DOI:	10.1594/EURORAD/CASE.10932
ISSN:	1563-4086