Diagnosis of systemic arterial diseases with whole-body 3D contrast-enhanced magnetic resonance angiography:

An approach to the diagnosis and management of systemic vasculitis

The systemic vasculitides are a complex and often serious group of disorders which, while uncommon, require careful management in order to ensure optimal outcome. In most cases there is no known cause. Multi-system disease is likely to be fatal without judicious use of immunosuppression. A prompt diagnosis is necessary to preserve organ function. Comprehensive and repeated disease assessment is a necessary basis for planning therapy and modification of treatment protocols according to response. Therapies typically include glucocorticoids and, especially for small and medium vessel vasculitis, an effective immunosuppressive agent. Cyclophosphamide is currently the standard therapy for small vessel multi-system vasculitis, but other agents are now being evaluated in large randomized trials. Comorbidity is common in patients with vasculitis, including the cumulative effects of potentially toxic therapy. Long-term evaluation of patients is important in order to detect and manage relapses.

An image processing algorithm for the in-vivo quantification and visualization of septum motion in type III B - aortic dissections with cine magnetic resonance imaging

Currently, there is no method to predict outcome of endovascular treatment (EVAR) of type III B aortic dissections (TB-AD). A new image processing algorithm is presented for quantifying IS displacement from cine 2D phase contrast magnetic resonance images (2D pcMRI) towards a new classification of TB-AD based on IS mobility. Bulk motion of the true aortic lumen (tAB) center (ALC), maximum, minimum and average displacement of the boundary points composing the IS and tAB excluding the IS were quantified at two locations in one patient. Correlations of the ALC motion and the averaged temporal displacement AD(t) of IS and tAB excluding IS with the aortic flow waveform were calculated. Range of ALC motion was similar in both locations (average 0.56 mm, max 1.37 mm) and correlated with the aortic flow waveform in the abdominal aorta but not the thoracic aorta. Range of displacement of the IS was from 1.27 mm to -1.64 mm (average 0.09 + or - 0.07 mm) in the thoracic aorta, and from 0.38 mm to -3.38 mm (average 0.42 + or - 0.23 mm) in the abdominal aorta. tAB motion excluding the IS was 1.21 mm to 0.84 mm (thoracic, average 0.13 + or - 0.07 mm) and 0.52 mm to -1.88 mm (abdominal, average 0.37 + or - 0.11 mm). AD(t) for IS and tAB excluding the IS both correlated with aortic flow in the abdominal aorta only.

Optimisation of a high-resolution whole-body MR angiography protocol with parallel imaging and biphasic administration of a single bolus of Gd-BOPTA: preliminary experience in the systemic evaluation of atherosclerotic burden in patients referred for endovascular procedures

PURPOSE

This study was performed to validate a high-resolution whole-body magnetic resonance angiography (MRA) protocol with parallel imaging and biphasic administration of a single bolus of contrast agent in the preliminary assessment of systemic atherosclerotic burden in patients referred for endovascular procedures.

MATERIALS AND METHODS

Forty patients referred for endovascular treatment of atherosclerotic disease of the carotid arteries (n=23), peripheral vessels (n=14) or aorta (n=3) on the basis of previous clinical and diagnostic examinations underwent high-resolution whole-body MRA at 1.5 T with 3D spoiled gradient recalled echo (GRE) sequences, featuring parallel imaging acquisition technique with x2 acceleration factor. Sixty-eight surface coil elements and a four-station imaging protocol were employed. Biphasic intravenous administration of a paramagnetic contrast agent [gadolinium benzyloxyproprionic-tetraacetic acid (Gd-BOPTA)] was performed with the following protocol: 10 ml at a speed of 1 ml/s followed by further 10 ml at a speed of 0.5 ml/s. For image analysis, the arterial system was divided into 42 segments for evaluation. The presence or absence of atherosclerotic lesions was evaluated by two observers in consensus; segments were classified as having clinically significant disease (>or=50% stenosis or an aneurysmal dilatation) or no significant disease (<50% stenosis). The presence of stenoocclusive disease, determined at all segments, was compared with findings on digital subtraction angiography (DSA), which were interpreted by a third independent reader. Sensitivity, specificity and concordance of whole-body MRA findings with DSA were calculated, and receiver operating characteristic (ROC) analysis was performed for all vascular territories.

RESULTS

A total of 1,680 arterial segments was evaluated; 138 (8.3%) were affected by atherosclerotic alterations. Carotid lesions were confirmed in 23 patients (34 segments), involvement of peripheral vessels in 14 (57 segments) and abdominal aneurysms in three. Sensitivity and specificity of whole-body MRA were, respectively, 95%-97% for head and neck vessels, 100%-100% for thoracoabdominal vessels, 98%-97% for thigh vessels and 84%-88% for calf vessels; concordance with the DSA findings was significant (p<0.05). Subclinical atherosclerotic lesions were evidenced in 25 patients, involving carotid arteries (12 segments), peripheral vessels (21 segments) and abdominal aorta (one segment). All these lesions were confirmed by a second modality, and ten of these patients required further care.

CONCLUSIONS

High-resolution whole-body MRA with Gd-BOPTA may be considered a reliable modality for imaging systemic atherosclerosis in candidates for endovascular procedures. The subclinical detection of the total atherosclerotic burden has potential implications for secondary care in this population.