Imaging
Angiography for Diagnosing Peripheral Arterial Occlusive Disease – A Technical, Clinical and Cost Comparison of Contrast-enhanced Magnetic Resonance Angiography and Unenhanced Magnetic Resonance Imaging Techniques with a Focus on Fresh Blood Imaging
Carsten Schwenke,1 Monica Boos,2 Rainer Hentrich,3 Michael Blankenburg2 and Martin Rohrer2 1. Schwenke Consulting: Strategies and Solutions in Statistics (SCO:SSiS); 2. Bayer Schering Pharma AG; 3. Radiological Centre, Rottweil
Abstract
This study compares the clinical and technical utility of non-contrast-enhanced magnetic resonance angiography (nce-MRA) and contrast- enhanced MRA (ce-MRA) in a mini-review of patients with suspected peripheral arterial occlusive disease (PAOD) in whom both MRA approaches were indicated. It also looks at the costs of angiography for diagnosing peripheral arterial occlusive disease using either ce-MRA or nce-MRA in comparison with the example of fresh blood imaging (FBI). The costs for MRA were taken from a previous cost study and those for nce-MRA/FBI from published data and appropriate calculations. The average total investigation costs for ce-MRA were found to be €205, including €59 for consumables, mainly originating from the contrast agent costs (according to German list prices for 2009). On the other hand, for nce-MRA, average total costs ranged from €190 to €239, depending on the acquisition time (12–32 minutes), and a larger number of additional diagnostic investigations were found. Irrespective of costs, several clinical and technical benefits such as image quality, higher robustness and the absence of limitations with complex vessel courses favoured ce-MRA. The consequences of using ce-MRA were fewer technical failures and, therefore, a higher throughput of patients indicated for contrast agent use in the radiology department; this led to more procedures per day and, therefore, more efficient use of diagnostic imaging resources.
Keywords
Magnetic resonance angiography (MRA), costs, angiography, peripheral arterial occlusive disease (PAOD), non-contrast-enhanced MRA (nce-MRA), fresh blood imaging (FBI)
Disclosure: This study was funded by unrestricted grants from Bayer Schering Pharma AG. Carsten Schwenke and Rainer Hentrich are consultants to Bayer Schering Pharma AG. Monica Boos, Michael Blankenburg and Martin Rohrer are employees of Bayer Schering Pharma AG. Acknowledgements: This study was funded by Bayer Schering Pharma AG. We thank Karsten Bergmann, Bayer Schering Pharma AG, for his support. Received: 27 April 2010 Accepted: 1 June 2010 Citation: European Cardiology, 2010;6(2):54–60 Correspondence: Carsten Schwenke, SCO:SSiS, Zeltinger Str 58g, 13465 Berlin, Germany. E:
carsten.schwenke@
scossis.de
Since its introduction in 1993,1
contrast-enhanced magnetic
resonance angiography (ce-MRA) has been considered the technique of choice for angiographic examination of most regions of the body. This is because of several technical and clinical advantages in comparison with non-contrast-enhanced MRA (nce-MRA) imaging. In this article, we focus on patients with suspected peripheral arterial occlusive disease (PAOD) who were indicated for both MRA approaches; therefore, the clinical, technical and cost evaluation is restricted to this patient group. Specific nce techniques known as time-of-flight (TOF) methods have been investigated for peripheral MRA, despite their general and well-known limitations in clinical routine. These limitations are related to two main concerns. First, additional acquisition time is needed to obtain adequate images, thus leading to a reduced patient throughput, and second, more artefacts occur. Compared with ce-MRA, TOF MRA is more time-consuming and hence often less appropriate for imaging body regions with larger fields of view (FoV). Among other reasons, time consumption is extended by the necessity of saturation pulses orientating the imaging slice perpendicular to the blood flow. As a result, TOF MRA is particularly sensitive to patient motion. Additionally, signal losses are encountered when flows are complex or turbulent, e.g. in stenotic
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areas, leading to overestimation of the degree and length of stenoses. Furthermore, saturation effects and ghosting artefacts due to vessel pulsatility may be disadvantageous.2–4
These limitations in
terms of motion sensitivity and long acquisition times for larger FoV are less critical for intracranial MRA. In addition, compared with other body regions, a short time window between arterial and venous phase in ce-MRA is obtained, making ce-MRA correspondingly more demanding. Consequently, nce-MRA can be routinely used for many intracranial indications; however, the situation is different for peripheral MRA for diagnosing PAOD.
Recently, technical progress has been achieved in terms of more sophisticated nce-MRA sequences that may reduce artefacts and thus allow the imaging of peripheral vessels with acceptable resolution. These technical aspects, as well as the recently observed possible link between occurrence of nephrogenic systemic fibrosis (NSF) and the use of gadolinium-based MR contrast agents, have motivated equipment manufacturers to develop more advanced nce techniques. For example, novel
nce-MRA techniques based on T2 effects using ultrafast spin-echo sequences (fresh blood imaging [FBI], nce-MRA/FBI) have been
© TOUCH BRIEFINGS 2010
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