Feasibility of Using Fusion Techniques in the Follow Up of Complex Aneurysm Repair

Introduction - Fusion imaging is becoming standard for the endovascular treatment of complex aortic aneurysms, but its role in follow up has not been explored. A critical issue in post operative surveillance is renal functional deterioration over time. Renal volume, stent angulation and stenosis have all been used as a marker of renal impairment (1)(2), however combined assessment of these variables is not always reproducible and remains a complex and resource-intensive procedure. The aim of this study is to determine the accuracy of a fusion-based software to automatically calculate the renal volume changes during follow-up (FU) and standardise its use. Methods - CT scans of 16 patients who underwent complex aortic endovascular repair were analysed. Preoperative, 1-month and 1-year FU CT scans have been analysed using a conventional approach of semiautomatic segmentation in conventional software(3), and using a second approach exploring new software with automatic segmentation. For each kidney and at each time point the percentage of change in renal volume was calculated using both techniques and compared using fusion. Results - Renal volume assessment was feasible for all CT scans included in the study. For the left kidney, the Interclass Correlation Coefficient (ICC) was 0.794 and 0.877 at 1-month and 1-year of follow up, respectively. For the right side, at 1-month the ICC was 0.817 and 0.966 at 1 year. For each kidney and time point, the Pearson correlation was 0.770, 0.811, 0.710 and 0.942 respectively. The figure shows the correlation for the right kidney at 1-year FU. For a small number of kidneys (∼5%) differences greater than 30% between automated and semiautomatic methods were observed. Methods are being tested to improve robustness and automatically detect these outliers. For the vast majority of cases the automated technique was able to reliably detect a decrease in renal volume for patients with occluded renal arteries when preoperative imaging is compared with 1-year follow up. Conclusion - This is the first report of a fusion-based algorithm to detect changes in renal volume during post operative surveillance using an automated process. Using this technique, the standardised assessment of renal volume could be implemented with greater ease and reproducibility in the current FU of endovascular procedures and serve as a warning of potential renal impairment. References1.Ou J, Chan Y-C, Chan CY-T, Cheng SWK. Geometric Alteration of Renal Arteries After Fenestrated Grafting and the Impact on Renal Function. Ann Vasc Surg. 2017 Feb 24;2.Heneghan RE, Starnes BW, Nathan DP, Zierler RE. Renal duplex ultrasound findings in fenestrated endovascular aortic repair for juxtarenal aortic aneurysms. J Vasc Surg. 2016 Apr;63(4):915–21.3.Martin-Gonzalez T, Pinçon C, Hertault A, Maurel B, Labbé D, Spear R, et al. Renal outcomes analysis after endovascular and open aortic aneurysm repair. J Vasc Surg. 2015 Sep;62(3):569–77.