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In a preliminary study, 5 healthy volunteers and 6 patients with angiographically documented peripheral vascular disease were examined using Gd-BOPTA at a dose of 0.3 mmol/kg bodyweight. Compared with conventional DSA, two independent blinded readers noted overall sensitivities of 91% (95% CI 0.76-0.98) and 94% (0.8-0.99), and specificities of 93% (0.85-0.97) and 90% (0.820.96), for the detection of substantial vascular disease (luminal narrowing >50%) [15]. Furthermore, inter-observer agreement for the assessment of whole-body MR angiograms was excellent (kap-pa=0.94; 95% CI 0.9-0.98), indicating that the approach was accurate and robust for morphologic vasculature screening.

More recent studies have further defined the value of Gd-BOPTA in whole body 3D CE-MRA (17, 18). In an initial study aimed at establishing the optimum dose to employ, Goyen et al (17) examined 10 healthy volunteers three times each with an ascending dose of Gd-BOPTA (0.1/0.2/0.3 mmol/kg bodyweight) using the AngioSURF rolling table platform system, an integrated torso surface coil, and a 3D FLASH sequence run at five stations from the carotid arteries to the trifurca-tion vessels. SNR and CNR values were calculated for 30 segments per patient and qualitative evaluation was performed using a 4-point visualization scale. Overall, significantly (p<0.05) higher SNR and CNR values were determined for the 0.2 and 0.3 mmol/kg dose groups compared to the 0.1

Healthy Body Systems Torso

Fig. 2. AngioSURF-based whole-body 3D MR angiogram of a 42-year-old male patient with hypertension. The exam consists of five slightly overlapping 3D data sets collected over 72 s. The acquisition time for each 3D data set amounts to 12 s. During a 3s acquisition break, the table is manually repositioned to the center of the subsequent image volume. With five successive acquisitions, cranio caudal coverage was extended over 176 cm, while the total data acquisition time amounted to 72 s. Finding: high-grade stenosis of the right renal artery

Fig. 2. AngioSURF-based whole-body 3D MR angiogram of a 42-year-old male patient with hypertension. The exam consists of five slightly overlapping 3D data sets collected over 72 s. The acquisition time for each 3D data set amounts to 12 s. During a 3s acquisition break, the table is manually repositioned to the center of the subsequent image volume. With five successive acquisitions, cranio caudal coverage was extended over 176 cm, while the total data acquisition time amounted to 72 s. Finding: high-grade stenosis of the right renal artery mmol/kg dose group. Similarly, qualitative evaluation revealed the image quality to be significantly (p<0.05) superior for the 0.2 and 0.3 mmol/kg dose groups compared with the 0.1 mmol/kg dose group. Interestingly, neither qualitative nor quantitative assessment was able to demonstrate a statistically significant difference between the 0.2 and 0.3 mmol/kg dose groups (p>0.05), indicating that Gd-BOPTA at a dose of 0.2 mmol/kg bodyweight is sufficient for satisfactory diagnostic image quality.

Confirmation of the suitability of the 0.2 mmol/kg dose of Gd-BOPTA for whole-body CE-MRA was subsequently demonstrated in 3 volunteers and 10 patients with peripheral vascular disease using the same multi-station 3D imaging approach and rolling table platform system [18]. Similarly high SNR and CNR values were obtained for all subjects. More importantly, sensitivity and specificity values of 95.3% and 95.2%, respectively, were obtained for the detection of significant stenoses (luminal narrowing > 50%) when compared with conventional DSA as reference standard.

A more complete evaluation of both the imaging procedure and contrast agent dose has recently been performed in 102 consecutive patients with peripheral vascular disease [21]. Using an identical whole-body 3D CE-MRA imaging approach, Gd-BOPTA at a dose of 0.2 mmol/kg bodyweight, and similar image assessment criteria based on 30 vascular segments per patient from the carotid arteries to the tibial vessels, two experienced MR radiologists in consensus noted clinically relevant disease in 33 segments in 25 patients that was additional to the known disease in the peripheral vessels. Specifically, the additional disease comprised renal artery narrowing (n=15), carotid arterial stenosis (n=12), subclavian artery stenosis (n=2), and abdominal aortic aneurysms (n=4). The study confirmed the whole body 3D CE-MRA approach with 0.2 mmol/kg Gd-BOPTA to be quick and risk-free and to allow a comprehensive evaluation of the arterial system in patients with atherosclerosis.

The high degree of concomitant arterial disease in patients with peripheral vascular disease is not surprising. It merely underscores the systemic nature of atherosclerosis. Patients with intermittent claudication are at particularly high risk of atherosclerotic disease affecting other parts of the circulation. PVD, due as it is to atherosclerosis, is rarely an isolated disease process.

The extent of coexisting cardiovascular disease needs to be appreciated to ensure that the clinician will treat PVD in a true context. Studies on the prevalence of coronary artery disease (CAD) in patients with PVD show that history, clinical examination, and electrocardiography typically indicate the presence of CAD in 40% to 60% of such patients, although this may often be asymptomatic

Left Femoral Popliteal BypassLeft Femoral Popliteal BypassLeft Femoral Popliteal Bypass

Fig. 3a-c. Invasive catheter angiogram (a) and whole-body MR angiogram (b) in a 54 year old male patient with PVD, history of bypass-graft left leg. The catheter angiogram shows a high-grade stenosis of the proximal anastomosis of the bypass-graft and an occlusion of the superficial femoral artery/popliteal artery on the left. The whole-body MR angiogram reveals these pathologic findings to the same advantage. (c) In addition, due to the extended coverage of the anatomy, a high-grade stenosis of the right internal carotid artery was detected which was clinically not susupected

Fig. 3a-c. Invasive catheter angiogram (a) and whole-body MR angiogram (b) in a 54 year old male patient with PVD, history of bypass-graft left leg. The catheter angiogram shows a high-grade stenosis of the proximal anastomosis of the bypass-graft and an occlusion of the superficial femoral artery/popliteal artery on the left. The whole-body MR angiogram reveals these pathologic findings to the same advantage. (c) In addition, due to the extended coverage of the anatomy, a high-grade stenosis of the right internal carotid artery was detected which was clinically not susupected as it is masked by exercise restrictions in these patients [22]. The link between PVD and cerebrovas-cular disease (CVD) seems to be weaker than that with CAD. Using duplex sonography, carotid disease has been found in 26% to 50% of patients with PVD [23,24]. Most of these patients will have a history of cerebral events or a carotid bruit and seem to be at increased risk of further events [25].

The fact that in this series twelve unsuspected carotid lesions in ten patients were identified highlights the often too symptom-focused means of patient questioning. Since all studied patients presented with symptoms suggestive of peripheral vascular disease, the patients' histories were focused on that region. Only very direct questioning revealed additional symptomatology suggesting carotid disease in three patients.

Approximately one fourth of PVD patients have hypertension, and in these patients consideration should be given to the possibility of renal artery narrowing.

In this cohort 13 patients (13%) showed renal artery disease with a luminal narrowing > 50%.

There is ongoing controversy about the value of screening all patients with PVD, symptomatic or not, for carotid disease and aortic aneurysms [24,26]. There is no doubt that claudicant patients are more likely to have significant asymptomatic disease in these areas than the general population, but the treatment of asymptomatic carotid disease is still controversial, and there is the issue of yield versus cost of such screening tests.

It has to be mentioned that our approach - although referred to as a whole-body MRA-exam -does not cover the intracranial or coronary arteries, which still require a dedicated approach for diagnostic assessment.

However, noninvasiveness, three-dimensionality, extended coverage and high contrast conspicu-ity are the characteristics of whole body MR an-giography that combine to allow a quick, risk-free, and comprehensive evaluation of the arterial system in patients with atherosclerosis.

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