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Vascular: Stents Imaging Pearls - Educational Tools | CT Scanning | CT Imaging | CT Scan Protocols - CTisus
Imaging Pearls ❯ Vascular ❯ Stents

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  • Post-stent findings
    Normal
    - Aneurysm sac decreases in size progressively
    Complications
    - Aneurysm size increasing (endoleak)
    - Change in stent positioning (migration, kinking)
    - Branch vessel compromise
    - Infection
    - Limb thrombosis
    - Aneurysm formation elsewhere in aorta
  • Type I Endoleak
    - Proximal or distal stent not in complete contact with aortic wall
    - Diameter of aorta too large at stent landing zone
    - Gap between stent and aortic wall allows blood to flow into aneurysm sac
  • Bird-Beak Configuration
    - Proximal stent not in complete contact with aortic wall
    - Wedge shaped gap between undersurface stent and wall
    - Associated with endoleak risk (Type I)
    - Longer beak higher risk of leak
    - Adverse events: death, need for endoleak repair, graft collapse and infolding.
  • Type II Endoleak
    - Retrograde flow through aortic branch vessels into aneurysm sac
    - Intercostal arteries in chest, lumbar arteries and IMA in abdomen
    - May be difficult to see on arterial phase images
    - Must distinguish from calcification in aneurysm sac
  • Type III Endoleak
    - Device failure
    - Leakage of contrast through a hole in the graft
    - Leakage between segments of a modular graft
  • Type V Endoleak
    - Refractory occult endoleak
    - No identifiable endoleak on imaging
    - Aneurysm continues to expand
  • Aortic Arch Stenting
    Fenestrated grafts with curvature to accommodate the arch
    - Designed to fit the patients’ arch anatomy based on preliminary 3D CT or
    - Fenestrations placed at time of deployment

    Branching grafts have the advantage of a better seal than fenestrated grafts, but can be difficult to position and deploy
  • Left Subclavian Coverage
    - Occlusion of the left subclavian artery may result in left upper extremity ischemia, stroke or paraplegia
    - Branches of the left vertebral artery perfuse the anterior spinal artery
    - Preoperative LSA bypass
    - Varying practice
  • Endoluminal Stent Graft: CT
    - Aneurysm sac decreases in size progressively
    - Lack of regression or increase in size reflects underlying endoleak
    - Evaluate branch vessels for compromise
    - Change in stent positioning
    - Stent fracture
  • Aortic Stent Complications
    - Vascular Occlusion
    - Endoleak
    - Dissection
    - Stent Migration
  • Endoleak Classification
    - Type I: proximal or distal end of stent
    - Type II: retrograde perfusion by patent arterial branch
    - Inferior mesenteric, lumbar
    - Type III: through the stent, overlapping stents
    - Type IV: transient porosity
    - Type V: endotension~ occult endoleak
  • Endoleak Classification
    - Type I: proximal or distal end of stent
    - Type II: retrograde perfusion by patent arterial branch
    - Inferior mesenteric, lumbar
    - Type III: through the stent, overlapping stents
    - Type IV: transient porosity
    - Type V: endotension~ occult endoleak
  • Endoleak Management
    - Type I and III
    - immediate intervention
    - Type II
    - May resolve spontaneously
    - Enlarging aneurysm sac size: risk of rupture
    - Type V
    - Dictates search for endoleak (angio)
    - Enlarging aneurysm sac size: risk of rupture
  • Endoleak: CT Configuration
    - Type II
    - Feeding vessel (not always seen)
    - Tubular configuration
    - Peripheral or peripheral and central
    - Type I and III
    - Often larger
    - Minority tubular
    - Centrally location
    - Type I proximal or distal
  • Type II Endoleak Duration
    - 19% (164/873) type II endoleaks
    - 80% of resolved in 6 months
    - Persistent leak (>6 months) associated with
    - Aneurysm sac growth
    - Need for reintervention
    - Rupture
  • Type II Endoleak: Predictors
    - Maximum diameter of feeding vessel
    - 0.34 cm ± 0.11 cm in nonreintervention
    - 0.40 cm ± 0.11 cm in reintervention
    - Ratio of transverse diameter of the endoleak to aneurysm sac size
    - 0.20 ± 0.14 in the nonreintervention 
    - 0.31 ± 0.17 in the reintervention 
  • Thoracic Aortic Stent Repair
    - Thoracic endovascular aortic repair
    - First reported in 1994 @ Stanford
    - Favorable outcomes and reduced complications compared to open repair
    - Between 1998 and 2007: 60% rise in thoracic aortic repair concomitant with 6-fold increase in TEVAR
  • Post Stent Placement
    1. Aneurysm sac decreases in size progressively
    - Lack of regression or increase in size reflects underlying endoleak
    2. Evaluate branch vessels for compromise
    3. Change in stent positioning
    4. Stent fracture
  • Stent Complications
    - Dissection
    - Vascular Occlusion
    - Endoleak
    - Stent Migration
  • Endoleak Classification
    1. Type I: proximal or distal end of stent
    2. Type II: retrograde perfusion by patent arterial branch
    - Inferior mesenteric, lumbar
    3. Type III: through the stent, overlapping stents
    4. Type IV: transient porosity
    5. Type V: endotension~ occult endoleak
  • Endoleak: CT Configuration
    1. Type II
    - Feeding vessel (not always seen)
    - Tubular configuration
    - Peripheral or peripheral and central
    2. Type I and III
    - Often larger
    - Minority tubular
    - Centrally location
    - Type I proximal or distal
  • Endoleak Management
    1. Type I and III
    - immediate intervention
    2. Type II
    - May resolve spontaneously
    - Enlarging aneurysm sac size: risk of rupture
    3. Type V
    - Dictates search for endoleak (angio)
    - Enlarging aneurysm sac size: risk of rupture
  • Type II Endoleak Duration
    1. 19% (164/873) type II endoleaks
    2. 80% of resolved in 6 months
    3. Persistent leak (>6 months) associated with
    - Aneurysm sac growth
    - Need for reintervention
    - Rupture
  • Type II Endoleak: CT Predictors
    - Transverse diameter of endoleak
    - Mean 1.13 ± 0.83 cm for nonreinterv.
    - Mean 1.85 ± 1.01 for reintervention
    - Transverse diameter > 1.42 cm
    - 74% sensitive, 80% specific
  • Type II Endoleak: CT Predictors
    1. Maximum diameter of feeding vessel
    - 0.34 cm ± 0.11 cm in nonreintervention
    - 0.40 cm ± 0.11 cm in reintervention
    2. Ratio of transverse diameter of the endoleak to aneurysm sac size
    - 0.20 ± 0.14 in the nonreintervention 
    - 0.31 ± 0.17 in the reintervention 
  • Elephant Trunk
    -Protects the diseased descending thoracic aorta until the second segment of the surgery can be performed
    -Used as part of the descending aortic graft at second surgery
    -Enables second surgery to be performed distal to first surgical location, in unaltered tissue planes
  • Extensive Aortic Pathology
    Stage 1:
    -Ascending aortic graft   
    -Elephant trunk prosthesis arch/proximal descending thoracic aorta

    Stage 2:
    -Descending aorta +/- abdominal aorta repair
  • Extensive Aortic Pathology

    Aneurysm, dissection or other surgical pathology that involves
    -ascending aorta
    -aortic arch
    -descending
    -+/- abdominal aorta

    Necessitates staged repair
  • Complications of Stent Placement
    -Incomplete Apposition
    -Endoleak
    -Vascular Occlusion
    -Stent Migration
    -Dissection
  • Post Stent Placement
    -Aneurysm sac decreases in size progressively
    --Lack of regression or increase in size reflects underlying endoleak
    -Evaluate branch vessels for compromise
    -Change in stent positioning
  • Thoracic Endovascular Stents: Endoleaks
    - Type I: these result from incomplete seal of the ends of the stent to the aortic wall
    - Type II: result from retrograde flow of blood into excluded lumen from patent branch vessels of the aorta
    - Type III: result from junctional dehiscence or device degeneration
    - Type IV: result from porosity of the stent
    - Type V: are increase in size of excluded lumen w/o enhancement in excluded lumen
  • Thoracic Endovascular Stents: Endoleaks
    - Occur in up to 29% of cases
    - Five types of endoleaks occur
    - Type I account for 40% of all endoleaks
  • Thoracic Endovascular Stents: Complications
    - Collapse of stent
    - Migration of stent
    - Endoleak
    - Pseudoaneurysm or dissection
    - Pulmonary embolism
  • Thoracic Endovascular Stents:Indications
    - Aortic aneurysms
    - Acute and chronic dissection
    - Penetrating ulcer
    - Intramural hematoma
    - Traumatic aortic rupture
  • Complications of Endovascular Stent Placement
    • Endoleaks
    • Stent migration
    • Pseudoaneurysms
    • Dissection
    • Aortic perforation
    • Kinking
    • Thrombosis
    • Coverage of key arch vessels
  • "Postprocedure multidetector CT is mandatory to assess stent placement, efficacy, and complications. Important factors to document are location of the stent, stent patency, size of the aorta, thrombosis of disease outside the aortic lumen, and any complications."


    Thoracic Aortic Stent-Grafts: Utility of Multidetector CT for Pre- and Postprocedure Evaluation
    Bean MJ, Johnson PT, Roseborough GS, Black JH, Fishman EK
    RadioGraphics2008; 28:1835-1851

  • "In this article, we discuss which patients are potential candidates for thoracic aortic stent graft placement and demonstrate how multidetector computed tomography with two dimensional multiplanar reformation (MPR) and three dimensional rendering (3D) is relevant in preoperative imaging and post operative assessment of thoracic stent grafts."


    Thoracic Aortic Stent-Grafts: Utility of Multidetector CT for Pre- and Postprocedure Evaluation
    Bean MJ, Johnson PT, Roseborough GS, Black JH, Fishman EK
    RadioGraphics2008; 28:1835-1851

  • Thoracic Endovascular Stent Placement: Patient Selection
    • Penetrating ulcers
    • Aortic aneurysm
    • Aortic dissection
    • Acute traumatic aortic injury
    • Aortic coarctation
  • Thoracic Aneurysm Repair in Elderly Patients: Complications
    • Mortality rate is 7-12% in elective cases
    • Mortality is up to 40% in elective cases
  • CTA and Thoracic Stent Grafts
    • Pre-operative planning
    • Post-operative assessment
        - Endoleak Graft movement or fracture
        - Size of native aorta
  • "Potential complications of endovascular stent placement include endoleaks, stent migration, pseudoaneurysms, dissection, aortic perforation, kinking, thrombosis, and coverage of vital branch vessels."

    Thoracic Aortic Stent-Grafts: Utility of Multidetector CT for Pre- and Postprocedure Evaluation
    Bean MJ, Johnson PT, Roseborough GS, Black JH, Fishman EK
    RadioGraphics 2008; 28:1835-1851
  • Endovascular Stent Placement: Applications
    • Penetrating ulcers
    • Aortic dissection
    • Aortic aneurysms
    • Aortic rupture
    • Congenital abnormalities
  • Endovascular Stent Placement: Complications
    • Endoleaks
    • Stent migration
    • Pseudoaneurysms
    • Dissection
    • Aortic perforation
    • Kinking
    • Thrombosis
    • Coverage of vital branch vessels
  • "The combination of arterial enhanced phase and unenhanced imaging performed at 1-month follow-up offers improved specificity and positive predictive values compared with arterial phase images alone. Delayed phase imaging does not significantly increase sensitivity for detection of endoleaks, but it does depict low flow endoleaks not seen on arterial enhanced phase."

    Iezzi R et al. Radiology 2006;241:915-921.

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