These findings suggest a higher sensitivity of MRI in identification of endoleak compared with CTA, although the authors caution that the increased endoleaks identified could represent false-positive findings or endoleaks that are not clinically important [84]. MRA with IV contrast also allows superior evaluation of flow dynamics compared with CTA. Time resolved and 4-D flow MRA can be used to improve detection and classification of endoleaks [76,87,88]. Use of multiple phases of contrast can be used in 4-D flow MRA to ascertain not only the presence of endoleak but also the endoleak type [88]. MRA with IV contrast has also shown value in predicting the persistence of type II endoleak. A retrospective review of MRAs with type II endoleak performed by Katahashi et al determined that the use of flow quantification could be used to accurately predict persistence or resolution of type II endoleak after EVAR, although this algorithm has not been applied prospectively [20]. MRA Chest, Abdomen, and Pelvis Without IV Contrast Literature supporting the use of MRA without IV contrast for evaluation after endovascular thoracoabdominal aortic repair is limited compared with evidence of MRA with IV contrast. A 2019 study evaluating 8 patients used a noncontrast MRI protocol to assess for endoleak after EVAR [89]. This study compared noncontrast MRA with contrast-enhanced CTA and angiogram and found the MRAs had comparable ability to detect endoleaks and assess aneurysm size [89]. The applicability of these findings to imaging post-thoracoabdominal endovascular intervention is unknown, although applicability may be incomplete because of multiple stents within the aorta and branch vessels. Additionally, the ability of this sequence to obtain widespread use is unclear. As such, noncontrast MRA would generally be expected to have a lower sensitivity for endoleak, false lumen thrombosis, or branch vessel patency, although evidence is lacking.
Thoracoabdominal Aneurysm or Dissection Treatment Planning and Follow Up. These findings suggest a higher sensitivity of MRI in identification of endoleak compared with CTA, although the authors caution that the increased endoleaks identified could represent false-positive findings or endoleaks that are not clinically important [84]. MRA with IV contrast also allows superior evaluation of flow dynamics compared with CTA. Time resolved and 4-D flow MRA can be used to improve detection and classification of endoleaks [76,87,88]. Use of multiple phases of contrast can be used in 4-D flow MRA to ascertain not only the presence of endoleak but also the endoleak type [88]. MRA with IV contrast has also shown value in predicting the persistence of type II endoleak. A retrospective review of MRAs with type II endoleak performed by Katahashi et al determined that the use of flow quantification could be used to accurately predict persistence or resolution of type II endoleak after EVAR, although this algorithm has not been applied prospectively [20]. MRA Chest, Abdomen, and Pelvis Without IV Contrast Literature supporting the use of MRA without IV contrast for evaluation after endovascular thoracoabdominal aortic repair is limited compared with evidence of MRA with IV contrast. A 2019 study evaluating 8 patients used a noncontrast MRI protocol to assess for endoleak after EVAR [89]. This study compared noncontrast MRA with contrast-enhanced CTA and angiogram and found the MRAs had comparable ability to detect endoleaks and assess aneurysm size [89]. The applicability of these findings to imaging post-thoracoabdominal endovascular intervention is unknown, although applicability may be incomplete because of multiple stents within the aorta and branch vessels. Additionally, the ability of this sequence to obtain widespread use is unclear. As such, noncontrast MRA would generally be expected to have a lower sensitivity for endoleak, false lumen thrombosis, or branch vessel patency, although evidence is lacking.