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    I use IVUS when I place endografts and have found it helpful and reliable. I do not call our vascular techs in, however, and run the system myself with my co-operator, one of our interventional radiologists. I haven't done a huge number, about two dozen cases, but we have generally found it helpful pre- and post-placement. There is some literature on the topic as well:

      Tabbara and coworkers compared IVUS to uniplanar angiography in the aorta, iliac, and femoral arteries and found that IVUS was accurate.  Similarly, Sheikh and coworkers compared IVUS to conventional Duplex color-flow ultrasound, 2-D transcutaneous ultrasound, and digital angiography.  IVUS compared well to the other three modalities in terms of lumen diameter (r=0.91-0.98) and cross-sectional area (r=0.92-0.97).  In addition, both studies comment that IVUS provides additional information about the location and characteristics of plaque, not provided by other modalities.  A number of studies have suggested that plaque characteristics may relate to the success of coronary angioplasty.  A good review of the topic by Korogi et al has been published.

     Verbin and coworkers from Harbor-UCLA Medical Center compared CT scans and IVUS in an experimental canine model before and after endovascular graft placement.  The average difference between the two modalities was 0.17  0.92 mm.  IVUS measurements were slightly larger than CT measurements: 8.84  1.0 compared to 8.65  1.1 mm (p<0.03) but there was good correlation with linear regression (r=0.948, p<0.02).  However, qualitative assessments of the endovascular graft (folding, stent-aorta interfaces, thrombus) were more accurate with IVUS.  The full report is highly recommended.

     Van essen and colleagues compared IVUS to CTA.  IVUS correctly identified 31 of 32 renal arteries and 4 of 5 accessory renal arteries.  IVUS tended to underestimate the length compared to CTA (0.48  0.52 cm; p < .001).  Compared to Verbin's study, however, these authors determined that  IVUS tended to underestimate diameter (0.68  1.76; p = .006).  However, these authors did find that interobserver variances were minimal (r = 1.0).    

      Wilson and coworkers also demonstrated the usefulness of IVUS during endovascular graft deployment in a dog model.  These authors positioned the endovascular graft initially with fluoroscopy and then replaced the guidewire with an IVUS catheter for real-time observation of deployment.  IVUS was useful in determining vessel size, graft position, and proper deployment against the aortic wall.   

    I will send references in a separate post since Flownet has been rejecting my post because of length. 

    

Michael A. Ricci, MD 
Professor of Surgery

University of Vermont College of Medicine
Vice President for Clinical Services

 



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