Authors: YiXiang J Wang Hideto Kuribayashi Maria Wågberg Andrew P Holmes Jean J Tessier John C Waterton
Publish Date: 2006/04/29
Volume: 29, Issue: 4, Pages: 605-612
Abstract
The Watanabe Heritable Hyperlipidemic WHHL rabbit provides an important model of spontaneous atherosclerosis With a strain of WHHL rabbits which do not develop abdominal aorta lumen stenosis even with advanced atherosclerosis we studied the MRI–histology correlation and the natural progression of atherosclerosis in the abdominal aorta In addition intrareader segmentation repeatability and scan–rescan reproducibility were assessedTwo batches of female WHHL rabbits were used The first batch of 6 rabbits was scanned at 20 weeks old A second batch of 17 rabbits was scanned at 50 weeks old and then randomly divided into two subgroups 8 were killed for histologic investigation 9 were kept alive for followup with repeat scanning a week later to assess scan–rescan reproducibility and again at 73 weeks old to assess disease progression MR images were acquired at 47 T using a chemical shift selective fat suppression gradient echo with a saturation band suppressing blood signal within the aortic lumen Five slices per animal were acquired centered around the renal artery region of the abdominal aorta with inplane resolution of 0195 mm and slice thickness of 3 mmThe coefficient of variation for intrareader reproducibility for aortic wall thickness measurements was 25 for repeat segmentations of the same scans on the same day but segmentations of these same scans made 8 months later showed a systematic change suggesting that intrareader bias as well as increased variability could compromise assessments made over time Comparative analyses were therefore performed in one postprocessing session The coefficient of variation for scan–rescan reproducibility for aortic wall thickness was 55 for nine pairs of scans acquired a week apart and segmented on the same day Good MRI–histology correlation was obtained The MRImeasured mean aortic wall thickness of animals at 20 weeks of age was 76 that of animals at 50 weeks of age p 0001 There was a small increase in aortic wall thickness between 50 and 73 weeks of age but this was not significant p 005 The corresponding differences in lumen crosssectional areas at 20 50 and 73 weeks of age were not significant These results were consistent with inhouse historical histology data on this strain of rabbitsWe wish to thank Dr Regina FritscheDanielson and Dr Leif Hultin for initiating the study and the helpful discussions We are grateful to Mr David Checkley for maintaining the performance of the RF coil and animal bed Portions of this paper have been presented at the British Chapter meeting of the International Society for Magnetic Resonance in Medicine London September 2003
Keywords: