F. Manstad-Hulaas, G. A. Tangen, S. Demirci, M. Pfister, S. Lydersen, T. A. Nagelhus Hernes Endovascular Image-Guided Navigation - Validation of Two Volume-Volume Registration Algorithms Minimally Invasive Therapy & Allied Technologies 20(5), pp. 282 - 289, 2011 (bib)
	Purpose The limited volume covered by intraoperatively acquired CT scans makes the use of navigation systems difficult. Preoperative images cover a larger volume of interest. Hence, reliable registration of high quality preoperative to intraoperative CT will provide the necessary image information required for navigation. This study evaluates two algorithms (Siemens, CAMP) for volume-volume registration for usage during endovascular navigation. Methods 20 patients treated for abdominal aortic aneurysm were scanned with pre-, intra- and postoperative CT. 6 data sets were excluded due to variations in image acquisition parameters and severe artifacts. 14 intra- and postoperative datasets were registered 10 times with both algorithms, altogether 140 registrations for each program. In all data sets five specified landmarks placed by two radiologists were used to evaluate registration accuracy. The distance between the paired landmarks in the registered intra- and postoperative volumes were measured and the root mean square value calculated. Reference registrations were based on rigid body registration of the 5 landmarks in the intra- and postoperative volumes. Results Registration accuracy (mean ± SD) was for Siemens 5.05 ± 4.74 mm, for CAMP 4.02 ± 1.52 mm and for the Reference registrations 2.72 ± 1.18 mm. The registration algorithms differed significantly, p<0,001.</TD>
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