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Vascular Pathology in Loeys-Dietz Syndrome: The Role of 64 row MDCT with 3D Rendering for Vascular Screening and Detection of Vascular Abnormalities

Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins School of Medicine

Loeys-Dietz Syndrome (LDS) is a recently identified genetic syndrome, with phenotypic resemblance to Marfan syndrome (MFS), Marfanoid craniosynostosis syndrome (Shprintzen-Goldberg syndrome) and in some cases, Ehlers-Danlos type IV (EDS-IV).

Characteristic Traits of LDS (common)

Widely spaced eyes
Bifid uvula
Cleft palate
Generalized arterial tortuosity
Ascending aortic aneurysm with/without dissection

Characteristic Traits of LDS (less common)

Craniosynostosis
Mental retardation
Structural brain abnormalities
Blue sclerae
Malar hypoplasia
Congenital heart disease
Aneurysm with dissection throughout the arterial system

Loeys Dietz Syndrome: Clinical Subtypes

LDS type I:

craniofacial and vascular pathology
“craniofacial index” determines severity of syndrome
- cleft palate
- craniosynostosis
- degree of increased intraocular distance
- uvular configuration
earlier need for surgical intervention vs. LDS type II

Loeys Dietz Syndrome: Clinical Subtypes

LDS type II:

bifid uvula
no craniosynostosis, cleft palate or hypertelorism
phenotype resembles Ehlers-Danlos type IV
- surgery difficult in EDS-IV due to fragility of arterial tissues
- reserved for life threatening emergencies
However, LDS type II patients do well after surgical repair of aneurysms

Phenotypic spectrum and pathogenesis of a new aortic aneurysm syndrome caused by mutations in TGFBR1 and TGFBR2

LDS: Thoracic CT Findings

Thoracic aortic aneurysms are one of the hallmark findings of Loeys-Dietz syndrome.
- The cause is a loss in elastin content in the aortic media resulting from defects in elastogenes
Pulmonary arteries may be enlarged
Coronary artery aneurysms, patent ductus arteriosus, congenital cardiac anomalies
Arterial tortuosity

LDS: Aortic Root Aneurysm

These are more aggressive than in MFS and require careful monitoring
Leading cause of death in LDS is dissection of the thoracic aorta
Surgery is performed in adults with LDS when the aortic root measures 4 cm

Aortic Root Aneurysm

For children, because the normal arterial dimensions increase with age, z-scores are calculated based on body surface area, using a database and software developed by Dr. Steven Colan at Boston Children's Hospital.
For a young child who has severe craniofacial features, surgery will be performed if the aortic root z-score is greater than 3, indicating that the aortic root dimension exceeds the 99th percentile
In addition, the annulus must be at least 1.8 cm to allow placement of a graft of sufficient caliber to accommodate growth

Dilated Aortic Root

Dilated aortic root as well ectatic carotid arteries

Carotid Arteries and Intracranial Vessels: CT Findings

Tortuosity of the carotid vessels is not uncommon and may be severe
Vertebral arteries can be tortuous
Intracranial aneurysms can be present

Tortuous Carotid Arteries

Loeys-Dietz Syndrome: Ectatic Carotid Artery

CT angiogram demonstrates markedly ectatic internal carotid arteries with no evidence of aneurysmal dilatation or dissection.
The patient had prior spinal surgery with orthopedic hardware present.

Abdominal Aorta: CT Findings

Aneurysmal dilatation of the aorta and branch vessels do occur, with branches including the celiac artery, the SMA and the IMA.
These aneurysms can be large
Small aneurysms of branch vessels off the SMA and celiac axis have also been seen.

This case is unique with so many aneurysms seen off the abdominal aorta, as well as the origins of the celiac, SMA, IMA and smaller branch vessels.

Small Aneurysms of the SMA

Conclusion

In Loeys-Dietz syndrome, early diagnosis of arterial pathology and rapid surgical intervention are instrumental to delaying fatal events.
As the most significant features of the syndrome involve vascular pathologies, CTA serves as an excellent noninvasive method for detection of findings and stigmata of Loeys-Dietz syndrome.

Acknowledgements:

Elliot K. Fishman, MD
Jennifer K. Chen, BA
Pam T. Johnson, MD
Bart L. Loeys, PhD
Harry C. Dietz, MD