Acute Trauma and Midaortic Syndrome
Acute traumatic aortic injury requires prompt endovascular intervention—stent-graft placement (e.g., with coverage of the a. subclavia sinistra). Follow-up imaging (CT with 3D reconstruction and maximum intensity projection [MIP]) demonstrates complete thrombosis of the excluded segment and its shrinkage.
Rare pathologies include midaortic syndrome (midaortic syndrome), which is characterized by narrowing of the thoracic or abdominal segments. Its causes include:
- Congenital aortic coarctation (congenital aortic coarctation). In some cases, it is associated with fetal alcohol syndrome (co-occurring with intellectual disability).
- Neurofibromatosis (neurofibromatosis). Abdominal ultrasound in such patients (often presenting with arterial hypertension and café-au-lait spots) reveals irregular aortic contours and stenosis at the origins of major branches, such as the superior mesenteric artery.
CT Semiotics of Wall Lesions
Computed tomography reveals specific changes in the wall of the descending thoracic aorta:
- Acute aortitis (acute aortitis): axial slices show circular wall thickening with avid contrast enhancement. On non-enhanced scans, the wall appears hyperdense.
- Intramural hematoma (intramural haematoma): manifests as typical crescentic thickening of the aortic wall.
Granulomatous Vasculitis (Takayasu Disease)
Takayasu disease (Takayasu disease) is a chronic inflammation of the aorta, its branches, and the pulmonary arteries of unknown etiology. The pathology predominantly affects young adults and exhibits marked racial and geographic variability (associated with HLA antigens). It is more common in females, with a female-to-male ratio of 9:1 in Japan and 1.3:1 in India.
Pathomorphology:
- Early stage: inflammation is localized around the vasa vasorum in the tunica media (tunica media) and tunica adventitia (tunica adventitia) of the vessel.
- Late stage: nodular fibrosis develops across all layers; the tunica intima (tunica intima) may completely occlude the lumen.
In late stages, imaging reveals contour irregularities, occlusions, or dilations. It is important to differentiate the disease from atherosclerosis, although secondary atherosclerotic changes may superimpose on vasculitis in older patients.
Features of Involvement and Classification
The distribution of Takayasu arteritis varies by region: the aortic arch is most commonly affected in Japan, while the thoracoabdominal segment is more frequently involved in Korea and India. The infrarenal segment and iliac vessels are usually not involved.
Angiographic classification:
- Type I: involves the aortic arch and its branches.
- Type II: involves the thoracoabdominal aorta and its branches.
- Type III: combined involvement (Type I + Type II).
- Type IV: additional involvement of the pulmonary arteries.
Characteristic features:
- Absence of a prominent network of intercostal collaterals (unlike coarctation). This is because diffuse intimal involvement blocks the ostia (ostia) of the intercostal vessels.
- Saccular (saccular) or fusiform (fusiform) aneurysms occur in 2–26% of cases (often alongside stenoses). Isolated aneurysms are rare (1–2%).
- Intimal calcification may be present.
- Pseudoaneurysms or dissections (dissection) are extremely rare.
CT, ultrasound, and MR angiography have become the primary diagnostic modalities. FDG-PET is used to detect active inflammatory foci, particularly in cases of fever of unknown origin.
Briefly: answers to topical questions
What pathologies lead to the development of midaortic syndrome?
Midaortic syndrome can be caused by congenital aortic coarctation, type 1 neurofibromatosis, and Alagille syndrome.
- Congenital aortic coarctation (Congenital aortic coarctation) is a very rare cause characterized by narrowing of the thoracic or abdominal aorta.
- Type 1 neurofibromatosis (Von Recklinghausen disease) is accompanied by vascular anomalies in which vessels are encased by neurofibromatous or ganglioneuromatous tissue within the adventitia.
- Alagille syndrome (Alagille syndrome) is a multisystem disorder.
What types of Takayasu disease are distinguished by the angiographic classification?
Based on the angiographic classification, four types of Takayasu arteritis are distinguished according to the location of involvement.
- Type I — involvement of the aortic arch and its branches.
- Type II — involvement of the thoracoabdominal aorta and its branches.
- Type III — combined involvement, including features of both Type I and Type II.
- Type IV — involvement of the pulmonary arteries (pulmonary arteries) in addition to any of the above types.
Which imaging modalities are used to detect foci of active inflammation in Takayasu disease?
To detect foci of active inflammation in Takayasu disease, modalities that evaluate vessel wall changes and radiopharmaceutical uptake are utilized.
- FDG-PET (FDG PET) visualizes increased radiopharmaceutical uptake in affected vessels, which is particularly useful in fever of unknown origin.
- Contrast-enhanced MRI and MR angiography (MRA) provide detailed information regarding vessel wall alterations.
- CT and ultrasound are also among the primary modalities for diagnosis and monitoring.
What conditions must Takayasu disease be differentiated from in its late stages?
Takayasu disease must be differentiated primarily from aortic atherosclerosis. These conditions differ in their clinical and morphological features. Differential diagnosis relies on typical angiographic morphology, medical history, and the presence of constitutional symptoms indicative of a systemic disease. The process can be complicated by the fact that older patients with Takayasu arteritis may develop secondary atherosclerotic changes.
Stenosis of which branches of the abdominal aorta is most commonly detected in neurofibromatosis?
In neurofibromatosis, stenosis of the renal and mesenteric arteries is most frequently detected.
- Renal arteries are most commonly affected, which can lead to renovascular hypertension.
- Mesenteric arteries — ultrasound may reveal stenosis at the origin of the superior mesenteric artery (superior mesenteric artery).
Patients with type 1 neurofibromatosis may also exhibit narrowing and contour irregularities of the abdominal aorta itself.
What parameters and potential complications are evaluated on follow-up CT after aortic stent-graft placement?
Follow-up CT after stent-graft placement assesses device integrity, the status of the excluded injury, and the presence of endoleaks.
- Injury thrombosis — visualizes complete thrombosis of the excluded segment with near-total shrinkage.
- Device integrity — requires long-term monitoring to evaluate the condition of the stent-graft.
- Type II endoleak — a complication characterized by retrograde filling of the aneurysmal sac from collateral branches.
- Aneurysmal sac expansion (aneurysmal sac expansion) — its enlargement is an indication for surgical intervention.
Takayasu arteritis classification is easy to remember from top to bottom: Type I — aortic arch (top), Type II — thoracoabdominal aorta (bottom), Type III — both, Type IV — additionally pulmonary arteries.
Class and exam questions
How does acute intramural aortic hematoma appear on CT?
It is visualized as a typical crescentic thickening of the aortic wall on axial slices.
Why do intercostal collaterals rarely form in Takayasu disease?
Diffuse intimal involvement in this vasculitis occludes the ostia (ostia) of the intercostal arteries, which prevents the formation of collateral blood flow.
Which parts of the aorta are usually spared in Takayasu arteritis?
The infrarenal abdominal aorta, as well as the iliac vessels and inferior mesenteric artery, are rarely involved.
What else to study on this topic
- Differential diagnosis of Takayasu arteritis and atherosclerosis
- Evaluation of stent-grafts on CT angiography
- Ultrasonic signs of abdominal aortic neurofibromatosis
- Role of FDG-PET in the diagnosis of systemic vasculitides
Master the entire topic in the "Diagnostic Radiology" course
This is a summary. The course covers everything tested in classes and exams.
- Complete study guide on "Radiodiagnosis of descending aortic lesions" and 2,199 more pages on the subject
- Assignments and quizzes after every topic — just like in a colloquium
- AI tutor answers questions on the topic anytime
- 10 video lessons on the subject
Other topics in the «Chest Radiology» section
Prepared by WhiteCoat Pro faculty in accordance with the medical school curriculum. For educational purposes only.