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The Role of CTA with 3D Mapping in the Evaluation of Vascular Stents beyond the Abdominal Aorta: Techniques, Interpretation, and Pitfalls

Johns Hopkins Hospital
Department of Radiology

Introduction

Vascular stents can be placed in branch vessels of the aorta including the celiac, superior mesenteric artery (SMA) , hepatic artery, renal arteries and inferior mesenteric artery (IMA)
Common indications include atherosclerotic disease and aneurysms
Additionally, branch vessel stenting may be necessary during repair of aortic pathology
CT is used for preoperative planning and follow up imaging, particularly if complications suspected

Complications of Stent Placement

Malpositioning
Smaller branch vessel occlusion
Embolization
Dissection
Arterial rupture
Thrombosis (immediate or delayed)
Stenosis/Occlusion

Technique: Data Interpretation

Assessment of vascular patency and end-organs (kidneys, bowel) requires review of axial images and use of all post-processing tools.
Multiplanar review essential for vascular patency using interactive 2D and 3D rendering
- Tailor visualization perpendicular to long axis of stent
- Renal arteries optimally visualized w/coronal and axial
- Celiac and SMA origins - sagittal orientation
- Mid to distal celiac and SMA – sagittal and coronal
End organs- axial images, MPRs and volume rendering (display incorporates original voxel density and maintains 3D relationships)

Interactive 2D and 3D Rendering

Axial images and 2D MPRs perpendicular to long axis of stent to evaluate stent lumen

Interactive 2D and 3D Rendering

VR (volume rendering) and MIP (maximum intensity projection) to create vascular map and show distal vessel patency. Volume rendering conveys 3D relationships and is best for evaluation of end organs because tissue density is maintained; MIP is better for small branch visualization.

Indications

Mesenteric arterial disease
- Ischemia: Atherosclerosis and other causes
- Aneurysm
- Dissection
Renal artery pathology
- RAS: atherosclerosis, fibromuscular dysplasia
- Aneurysm
- Dissection
Aortic aneurysms that involve branch arteries may require branch artery stenting
- as part of primary repair or
- following aortic endoluminal stent placement if branch orifice is compromised

Mesenteric Ischemia

Chronic mesenteric ischemia is caused by occlusive disease of mesenteric vessels (celiac artery, SMA, IMA)
Most often due to atheroma
Chronic mesenteric ischemia is more common in women and those who are >60 years
Severe stenosis (often multi-vessel) manifests with abdominal pain as well as other nonspecific symptoms

Mesenteric Ischemia

Stenting is indicated if post-angioplasty result is unsatisfactory
- residual stenosis >30%
- pressure gradient > 15 mmHg
- markedly eccentric lesions
- lesions located at the ostium
- history of dissection after previous angioplasty
- chronic occlusion
Restenosis is common but well tolerated

SMA Stenosis

66 year old woman, long standing smoker with severe atherosclerotic disease s/p aortobifemoral bypass and stenting of SMA for stenosis. Coronal and coronal oblique color coded volume renderings show show stent in the proximal SMA with patency of the distal vessel.

SMA Stenosis

66 year old woman, long standing smoker with severe atherosclerotic disease s/p aortobifemoral bypass and stenting of SMA for stenosis. Sagittal and coronal MPRs show stent in the proximal SMA with patency of the distal vessel.

Mesenteric Ischemia: Stent Occlusion

45 year old woman with history of chronic mesenteric ischemia secondary to multiple vascular occlusions, s/p multiple arterial stents (celiac artery, proximal and distal SMA) shown with coronal and sagittal VR, which provide a nice overview of the anatomy.

Occluded SMA Stent

45 year old woman with history of chronic mesenteric ischemia secondary to multiple vascular occlusions, s/p multiple arterial stents. Sagittal MPR and MIP demonstrate the thrombosed lumen of the inferior SMA stent and absence of enhancement in the artery distal to the stent.

Chronic Mesenteric Ischemia

Other Causes

Takayasu disease
fibromuscular dysplasia
thromboangiitis obliterans
periarteritis nodosum
radiation therapy
median arcuate ligament syndrome

Median Arcuate Ligament Syndrome

Compression of celiac artery by the median arcuate ligment.
20-40 age group
Most patients asymptomatic
CT characteristic hooked configuration and collaterals if hemodynamic stenosis or occlusion
Treatment is directed at cause of compression

Celiac Artery Stent for MALS

46 year old woman with long history of postprandial abdominal pain who underwent division of median arcuate ligament and celiac artery stent placement. Coronal color coded volume rendering shows patent celiac axis. Modification of the rendering parameters and application of a clip plane with a sagittal MIP rendering document patency of the stent lumen.

Celiac Artery Stent for MALS

43 year old man with median arcuate ligament syndrome s/p surgical repair with celiac artery stent. Axial image shows stent, but patency best demonstrated by sagittal MPR through the lumen and sagittal volume rendering to show distal vessel perfusion.

Visceral Arterial Aneurysms

Often diagnosed incidentally
May present with rupture
Treatment options include surgical vs endovascular approaches based on location
- For many cases, ligation or coil embolization is the treatment of choice
- Stents are used primarily in cases of aneurysms of major branches, where preservation of arterial flow is required

Visceral Arterial Aneurysms

splenic artery in 60%–80% of cases
hepatic artery in 20%
SMA in 5.5%
celiac artery in 4%
gastric and gastroepiploic artery in 4%
gastroduodenal artery, pancreatic branches in 6%
jejunal and ileocolic arteries in 3%
IMA in less than 1%

Splenic Artery Aneurysm

62 year old woman with splenic artery aneurysm s/p attempted stent placement complicated by splenic artery dissection. Coronal volume renderings in various obliquities show persistent aneurysm of the splenic artery despite presence of stent.

Mesenteric Artery Dissection

Isolated celiac or superior mesenteric artery dissection (right images) can occur exclusive of aortic dissection
Approximately 10% of patients will have both vessels involved
May present acutely w/ abdominal pain
Often incidentally identified on CT for other indication
Commonly stable without complication
In some cases, intervention required for persistent symptoms, expansion of the false lumen or true lumen malperfusion

SMA Dissection

66 year old man with marfanoid connective tissue disorder presented with acute abdominal pain. Diagnosed with SMA dissection and underwent stent placement in SMA and celiac arteries. Coronal and coronal oblique color coded volume renderings nicely map patent celiac artery and SMA following stent placement.

SMA Dissection

66 year old man with marfanoid connective tissue disorder who presented with acute abdominal pain. Diagnosed with SMA dissection and underwent stent placement in SMA and celiac arteries. Stent patency confirmed by axial image through the lumen and vascular mapping with sagittal MIP, demonstrating perfusion distal to the stents.

Renal Artery Stenosis

Role of revascularization vs medical therapy for atherosclerotic renal artery stenosis remains controversial
Restenosis rate is lower in renal arteries than coronary arteries
Emboli into renal vascular bed and elsewhere remains a major concern

RAS: Benefits of Stenting

improves hypertension
stabilizes renal failure
reduces recurrent cardiac events such as flash pulmonary edema

Renal Artery Stenosis

63 year old man s/p infrarenal abdominal aortic repair and bilateral renal artery stents for renovascular hypertension. Axial CT and coronal MPR show perfused stent lumen. Coronal MIP and volume rendering depict aortoiliac graft, patent renal arteries and symmetric renal enhancement in a single image.

Renal Artery Aneurysms

Complications include rupture, RA thrombosis, infarction by distal embolization, AV fistula, hypertension
Treatment can decrease blood pressure and improve renal function
Intervention (surgery, stent) indications
- aneurysms > 1 cm in in women of childbearing age, patients with hypertension or renal artery stenosis
- most aneurysms 1.5 to 2 cm
- all > 2 cm

Renal Artery Aneurysm

59-year-old woman with left renal artery aneurysm, treated by endoluminal stent placement. Coronal volume renderings shows aneurysm (left) and stent patency after intervention (right) by applying a clip plane to visualize the lumen.

©2010 by American Roentgen Ray Society, Johnson P T et al. AJR 2010;194:1001-1012

Aortic Aneurysm

Treatment is with open surgical or endovascular graft placement
Repair may primarily necessitate branch vessel revascularization
Complications include branch vessel occlusion by aortic endoluminal stent, which may necessitate stenting

Aortic Aneurysm

77 year old man with 6.5 cm infrarenal abdominal aortic aneurysm involving branch vessels. Repair included individual stent placement in celiac, SMA and renal arteries. Color coded volume rendering provides overview and shows patent distal vessels. Stent lumen patency demonstrated with axial images.

Endoluminal Aortic Repair and Renal Artery Compromise

Left kidney perfusion compromised by aortic endoluminal stent crossing renal artery orifice. Diminished renal enhancement shown on axial image (ring).

Endoluminal Aortic Repair and Renal Artery Compromise

Left renal artery compromise (ring) treated with left renal artery stent (arrow), which restored perfusion to the left kidney.

Conclusion

CT is the imaging modality of choice for diagnosis, treatment planning and follow up renal and mesenteric artery pathology
Optimization of data acquisition essential to generate high quality 2D and 3D renderings
Interactive rendering is optimal, but necessitates an understanding of how 2D MPRs, volume rendering and MIP are used to demonstrate stent patency and create vascular maps

References

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Acknowledgements: S Deshmukh, MD
P T Johnson, MD
K M Horton, MD
E K Fishman, MD