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Measurements before endovascular repair of abdominal aortic aneurysms: MR imaging with MRA vs. angiography and CT
Department of Radiology, Lund University Hospital, Lund, Sweden.
Department of Radiology, Lund University Hospital, Lund, Sweden.
Department of Radiology, Hudiksvall Hospital, Hudiksvall Sweden.ORCID iD: 0000-0002-4111-1693
Department of Vascular Diseases, Lund University, Malmo University Hospital, Malmo, Sweden.
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2003 (English)In: Acta Radiologica, ISSN 0284-1851, E-ISSN 1600-0455, Vol. 44, no 2, 177-184 p.Article in journal (Refereed) Published
Abstract [en]

Purpose: 1) To compare measurements obtained with MR imaging (MRI)/contrast-enhanced MR angiography (CE MRA) with measurements obtained with angiography (DSA) and CT, for stent-graft sizing of abdominal aortic aneurysms (AAA). 2) To compare MRA measurements obtained with the two post processing techniques MIP (maximum intensity projection) and VRT (3D volume rendering technique).

Material and Methods: The prospective study included 20 consecutive patients with AAA identified by DSA and CT as suitable for endovascular repair. For the study, MRI/CE MRA was performed. Five measurement variables for stent-graft sizing were chosen. Comparisons were made between MRI/CE MRA, DSA and CT, and between observers. Comparisons were also made between MIP and VRT.

Results: Significantly shorter lengths were obtained with MRA-MIP than with DSA. Three out of six diameter measurements were significantly smaller on MRI/CE MRA than on DSA and CT. No significant differences were found between the observers. One diameter measurement was significantly smaller on MIP than on VRT, while the other measurements showed no significant differences.

Conclusion: The length measurements obtained with MRA-MIP were probably more correct than those with DSA. For more reliable diameter measurements with CE MRA, improvements of the technique, including VRT reconstructions and a standardized determination of the vessel boundaries, are needed.

Place, publisher, year, edition, pages
2003. Vol. 44, no 2, 177-184 p.
Keyword [en]
Abdominal aortic aneurysm, Angiography, CT, Endograft sizing, MR angiography, Volume rendering technique
National Category
Natural Sciences
URN: urn:nbn:se:liu:diva-46720DOI: 10.1034/j.1600-0455.2003.00029.xOAI: diva2:267616
Available from: 2009-10-11 Created: 2009-10-11 Last updated: 2014-04-23Bibliographically approved
In thesis
1. Volume imaging of the abdomen: three-dimensional visualisation of tubular structures in the body with CT and MRI
Open this publication in new window or tab >>Volume imaging of the abdomen: three-dimensional visualisation of tubular structures in the body with CT and MRI
2005 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The overwhelming amount of image-based information in modem medicine makes it crucial to develop methods to handle and analyze images and make them comprehensible for users. The aim of this thesis was to study the radiological practice of three-dimensional (3D) visualization of tubular structures in the body with CT and MRI. All the studies cancern 3D imaging of tubular structures with camputed tomography (CT) and magnetic resonance imaging (MRI). The first three studies examine the abdominal aorta; the two later ones the, bile ducts.

Study I compared measurements of aorta diameters taken from MR images presented using two visualization methods - maximum intensity projection (MlP) and volume rendering (VRT) - with invasive angiography (DSA) and CT as reference methods. Mean diameters of MR images were smaller than those from DSA and CT when MlP was used, but in general not when VRT was used.

Study II evaluated the dependence on the observer and the choice of method and settings during rendering using the same material as in Study 1. In both MlP and VRT, the choice of settings had significant influence on the results. With DSA as the reference method, VRT gave larger measurement errors than MIP when the rendering parameters were set to fixed values, but not if the user was allowed to select the settings freely.

Study III evaluated three new techniques for standardizing VRT protocols for MRA. Inter-reader variability and agreement with DSA were studied by comparing diameter measurements of the abdominal aorta obtained by the three new techniques, by VRT with freely chosen parameters and by MlP. All three new methods were significantly better than MlP and VRT with freely chosen parameters conceming inter-observer agreement. Agreement with DSA was significantly better for one of the methods. Standardized protocols seem to have a potential to make VRT a clinically useful alternative to MlP for MR angiography measurements.

Study IV evaluated CT imaging of the bile ducts after drip intravenous infusion of the contrast medium iotroxate (CT cholangiography) in terms of adverse effects and visibility. With infusion time adjusted for individual variation in serum bilirubin concentration, a total side-effect frequency of less than 1% was found. A systematic review of previously published studies indicated a frequency of 2.3%. Good contrast excretion and visualization of bile ducts even in patients with elevated bilirubin levels were noted.

Study V evaluated the diagnostic benefits of the same imaging method by comparing it with findings from surgery and endoscopic retrograde cholangiopancreatography (ERCP). The consensus sensitivity and specificity for diagnosing biliary stones was 88% and 94%, respectively. The use of VRT improved diagnostic certainty in 14% of the evaluatians, and the visualization of ductal stones was improved in 38% of the positive cases.

In conclusion, volume rendering technique with standardized parameters may become a clinically useful tool in the clinical MRI environment. DIC-CT with bilirubin-governed infusion time and volume rendering post-processing produces detailed images of the biliary tree, resulting in good sensitivity and specificity. Moreover the safety is acceptable.

Place, publisher, year, edition, pages
Linköping: Linköpings universitet, 2005. 103 p.
Linköping University Medical Dissertations, ISSN 0345-0082 ; 912
National Category
Medical and Health Sciences
urn:nbn:se:liu:diva-29581 (URN)14957 (Local ID)91-85299-25-1 (ISBN)14957 (Archive number)14957 (OAI)
Public defence
2005-10-07, Berzeliussalen, plan 09, Hälsouniversitetet, Campus US, Linköpings universitet, Linköping, 13:00 (Swedish)
Available from: 2009-10-09 Created: 2009-10-09 Last updated: 2013-10-21Bibliographically approved

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Dahlström, NilsPersson, Anders
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Center for Medical Image Science and Visualization (CMIV)Faculty of Health SciencesMedical RadiologyDepartment of Radiology in Linköping
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