Contrast-enhanced MR imaging is significantly superior to 16 slice multidetector CT in the detection of endoleaks after endovascular repair of abdominal aortic aneurisms (EVAR), according to a recent study conducted by researchers at Ospedale San Giovanni in Bellinzona, Switzerland.
Endovascular repair of abdominal aortic aneurysms has become a viable alternative treatment to open surgery for many patients. Endoleak development represents a complication of endovascular aortic aneurysm repair and is characterized by blood flow outside the stent-graft lumen but within the aneurysm sac, said Rolf Wyttenbach, MD, lead author of the study. Patients after EVAR need livelong imaging surveillance to detect endoleaks. CT is most commonly used for imaging follow-up of these patients. , A few prior studies suggested that MRI may be superior to CT for the detection of endoleaks. However, these studies mostly used single or 4-row MDCT and standard gadolinium contrast media for MR imaging, he said.
The study consisted of 43 patients who had undergone EVAR. Each of the patients had both MDCT and MRI within one week of the procedure. According to the study, MRI was performed using a high relaxivity contrast medium and for MDCT, an iodine containing agent was used. Upon the completion of the study, two observers evaluated MRI and MDCT separately.
The study showed that 21 endoleaks were detected in 18 patients. Sensitivity, specificity and accuracy for endoleak detection were 100%, 96% and 98% for reader 1 and 90%, 81% and 85% for reader 2 on MRI and 48%, 96% and 74% for both readers on MDCT.
The results indicate that MR is a good choice for diagnosing endoleaks. In addition, MRI does not expose the patients to radiation and the MR contrast agent is less nephrotoxic in the clinically used dose compared to iodinated contrast agents used for CT. For this reason MRI may become a preferred imaging modality to follow-up patients after endovascular aneurysm repair, said Dr. Wyttenbach.
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