Along with other studies demonstrating a mortality benefit in the treatment of subacute to chronic uncomplicated type B dissections, these data suggest that TEVAR is a viable alternative treatment option in the management of these patients compared with optimized medical therapy [12,33,34,78]. Partial false lumen thrombosis is an important predictor of regional luminal growth and reintervention rate. Although incompletely understood, this is postulated to be due to a regional increase in luminal pressure owing to small diameter [79]. Chronic dissections tend to show lesser degrees of remodeling, perhaps because of the frequent presence of multiple intimal tears and development of intercostal collaterals in these patients [14,80]. When there is a question of false lumen thrombosis status, the absence of contrast enhancement on arterial and early delayed-phase CTA does not necessarily indicate complete thrombosis given the possibility of a low-flow state. In such cases, more-delayed imaging demonstrates higher sensitivity for detection of partial thrombosis [81]. Similar to the findings seen in TEVAR for aortic dissection, there is significant vascular remodeling when TEVAR is used for IMH or PAU, with near-complete normalization of aortic diameter at 1 year as measured on CTA [13,82]. CTA is also the preferred imaging modality of choice for evaluation of endograft infection, one of the most serious complications after TEVAR. A recent study demonstrated that in the small number of patients with an infected endograft, CTA suggested the diagnosis in 78% of cases, with the most common findings being periaortic inflammation and erosion into surrounding structures [83]. The principle disadvantages of CTA in the follow-up period are potential nephrotoxicity and cumulative radiation dose, particularly in younger patients.
Thoracic Aortic Aneurysm or Dissection Treatment Planning and Follow Up. Along with other studies demonstrating a mortality benefit in the treatment of subacute to chronic uncomplicated type B dissections, these data suggest that TEVAR is a viable alternative treatment option in the management of these patients compared with optimized medical therapy [12,33,34,78]. Partial false lumen thrombosis is an important predictor of regional luminal growth and reintervention rate. Although incompletely understood, this is postulated to be due to a regional increase in luminal pressure owing to small diameter [79]. Chronic dissections tend to show lesser degrees of remodeling, perhaps because of the frequent presence of multiple intimal tears and development of intercostal collaterals in these patients [14,80]. When there is a question of false lumen thrombosis status, the absence of contrast enhancement on arterial and early delayed-phase CTA does not necessarily indicate complete thrombosis given the possibility of a low-flow state. In such cases, more-delayed imaging demonstrates higher sensitivity for detection of partial thrombosis [81]. Similar to the findings seen in TEVAR for aortic dissection, there is significant vascular remodeling when TEVAR is used for IMH or PAU, with near-complete normalization of aortic diameter at 1 year as measured on CTA [13,82]. CTA is also the preferred imaging modality of choice for evaluation of endograft infection, one of the most serious complications after TEVAR. A recent study demonstrated that in the small number of patients with an infected endograft, CTA suggested the diagnosis in 78% of cases, with the most common findings being periaortic inflammation and erosion into surrounding structures [83]. The principle disadvantages of CTA in the follow-up period are potential nephrotoxicity and cumulative radiation dose, particularly in younger patients.