More recently, time-resolved MRA has been used in the characterization of endoleaks and may provide relevant information regarding contrast and flow dynamics within endoleaks [35]. As such, replacing aortography as an effective and noninvasive method for endoleak characterization shows promise [81]. In most cases, MRA of the abdomen and pelvis is appropriate to ensure coverage of the treated aneurysm and stent graft. The MRA should include the chest in patients with TAAA. Blood pool contrast materials such as ferumoxytol [82,83] remain intravascular for a prolonged duration, thereby allowing for generation of high-resolution 3-D multiplanar images [82,83]. Use of these contrast materials may improve detection of slow-flow endoleaks [82,83]. Patients intolerant of GBCM or those at risk for NSF may benefit from the acquisition of noncontrast bSSFP images in post-EVAR surveillance. One small retrospective study found that noncontrast bSSFP images can be used to exclude endoleak after EVAR, with postcontrast imaging reserved for verification and further characterization of a suspected endoleak [84]. US CDUS and CEUS are being increasingly recommended for post-EVAR follow-up. These are convenient, noninvasive, and have a favorable safety profile. In the evaluation of endoleak, CDUS has high specificity but limited sensitivity, reported in two large meta-analyses to be 91% to 93% and 66% to 69%, respectively [85,86]. The major limitations of US are the inability to detect stent-graft kinking, fracture, migration, or component AAA: Interventional Planning & Follow-Up separation [87-89]. For this reason, adjunct four-view radiographs are recommended to be obtained with all post- EVAR US examinations [49,53,84,87,89,90]. For FEVARs that involve the celiac trunk, US is unable to adequately visualize the proximal sealing zone [89]. Not unexpectedly, published results regarding the accuracy of CDUS in post-EVAR follow-up are varied [51,85,91-93].
Abdominal Aortic Aneurysm or Dissection Interventional Planning and Follow up. More recently, time-resolved MRA has been used in the characterization of endoleaks and may provide relevant information regarding contrast and flow dynamics within endoleaks [35]. As such, replacing aortography as an effective and noninvasive method for endoleak characterization shows promise [81]. In most cases, MRA of the abdomen and pelvis is appropriate to ensure coverage of the treated aneurysm and stent graft. The MRA should include the chest in patients with TAAA. Blood pool contrast materials such as ferumoxytol [82,83] remain intravascular for a prolonged duration, thereby allowing for generation of high-resolution 3-D multiplanar images [82,83]. Use of these contrast materials may improve detection of slow-flow endoleaks [82,83]. Patients intolerant of GBCM or those at risk for NSF may benefit from the acquisition of noncontrast bSSFP images in post-EVAR surveillance. One small retrospective study found that noncontrast bSSFP images can be used to exclude endoleak after EVAR, with postcontrast imaging reserved for verification and further characterization of a suspected endoleak [84]. US CDUS and CEUS are being increasingly recommended for post-EVAR follow-up. These are convenient, noninvasive, and have a favorable safety profile. In the evaluation of endoleak, CDUS has high specificity but limited sensitivity, reported in two large meta-analyses to be 91% to 93% and 66% to 69%, respectively [85,86]. The major limitations of US are the inability to detect stent-graft kinking, fracture, migration, or component AAA: Interventional Planning & Follow-Up separation [87-89]. For this reason, adjunct four-view radiographs are recommended to be obtained with all post- EVAR US examinations [49,53,84,87,89,90]. For FEVARs that involve the celiac trunk, US is unable to adequately visualize the proximal sealing zone [89]. Not unexpectedly, published results regarding the accuracy of CDUS in post-EVAR follow-up are varied [51,85,91-93].