Thoracic vascular anatomical variants

Transcription

1 Thoracic vascular anatomical variants Poster No.: C-0944 Congress: ECR 2010 Type: Educational Exhibit Topic: Chest - Vascular Authors: R. dos Santos, Â. Marques, H. M. R. Marques, N. Costa, O. Fernandes, M. Passos Faria, L. Figueiredo, Z. Seabra; Lisbon/PT Keywords: vascular anatomical variants, thorax anatomy, congenital variants Keywords: Lung, Vascular, Respiratory system, Thorax DOI: /ecr2010/C-0944 Any information contained in this pdf file is automatically generated from digital material submitted to EPOS by third parties in the form of scientific presentations. References to any names, marks, products, or services of third parties or hypertext links to thirdparty sites or information are provided solely as a convenience to you and do not in any way constitute or imply ECR's endorsement, sponsorship or recommendation of the third party, information, product or service. ECR is not responsible for the content of these pages and does not make any representations regarding the content or accuracy of material in this file. As per copyright regulations, any unauthorised use of the material or parts thereof as well as commercial reproduction or multiple distribution by any traditional or electronically based reproduction/publication method ist strictly prohibited. You agree to defend, indemnify, and hold ECR harmless from and against any and all claims, damages, costs, and expenses, including attorneys' fees, arising from or related to your use of these pages. Please note: Links to movies, ppt slideshows and any other multimedia files are not available in the pdf version of presentations. Page 1 of 40

2 Learning objectives To make a comprehensive review of the spectrum of imaging findings of common and uncommon thoracic vascular anatomical variants and the impact of their recognition and reporting. Page 2 of 40

3 Background Thoracic vascular anatomical variants are a frequent finding in everyday pratice and are also a well-known cause of diagnostic pitfalls. Although most vascular variants are inconsequential and are discovered incidentally on imaging studies, some may become symptomatic and ultimately require surgical intervention. Also, it is important to report these variants to ensure alternative catheterizations are chosen, thus preventing possible complications. CT and MR, with the possibility of multiplanar reformating, volume rendering and virtual reconstructions, are excellent for characterizing vascular anatomy and have replaced most of the diagnostic angiographic procedures. Besides providing precise anatomical information, cross-sectional imaging allows excluding other pathologies and aids planning eventual interventional procedures. Page 3 of 40

4 Imaging findings OR Procedure details Congenital abnormalities of the aortic arch and great vessels are most often discovered incidentally in radiological practice, and it is important to recognize and distinguish them from serious pathology. NORMAL AORTIC ARCH # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # Fig.: 1- Normal aortic arch and origin of the supra-aortic branches. Drawing and CT reconstruction 3D VRT. References: Radiology, Hospital de Santo António dos Capuchos, CHLC - Lisbon/PT 1 LUSORIA ARTERY # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # Page 4 of 40

5 Incidence: 0.1% of the population. Description: - Retroesophageal vascular structure, which originates from the aortic arch. Clinically: Usually assymptomatic. When symptoms arise, the most common is due to esophageal compression: Dysphagia lusoria. Diagnostic Pittfall: adenopathy; following the course of this structureor filling with endovenous contrast help recognizing this variant. Fig.: 2- Lusoria artery- Drawing and unenhanced axial CT. Awareness of the lusoria artery's paths prevents the false positive diagnosis of an adenopathy, in unenhanced examinations. References: Radiology, Hospital de Santo António dos Capuchos, CHLC - Lisbon/PT Page 5 of 40

6 2 VASCULAR RINGS # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # In 1737, Hommel described the anatomy of the double aortic arch. In 1945, Gross uses for the first time the expresssion "vascular ring" and performs the first surgical division of a double aortic arch. Most of the times, vascular rings are an isolated cardiovascular anomaly. Clinically: They represent less than 1% of all cardiovascular congenital anomalies. In spite of such low incidence, a high clinical suspicion is necessary for its diagnosis and it should be included in the work-up of upper airway obstruction and dysphagia. Symptoms are quite similar in all kinds of vascular rings. When symptomatic, vascular rings usually present between 2,5 months and five years of age. Page 6 of 40

7 Fig.: 3- Clinical manifestations of vascular rings. References: Radiology, Hospital de Santo António dos Capuchos, CHLC - Lisbon/PT # # # # # # # # # # # # # # TYPES OF VASCULAR RINGS# # # # # # # # # # # # # Page 7 of 40

8 Fig.: 4- Types of vascular rings References: Radiology, Hospital de Santo António dos Capuchos, CHLC - Lisbon/PT DOUBLE AORTIC ARCH 1,2 ############################ - Most common vascular ring (40%) - Usually an isolated anomaly Embriology: - The caudal most part of the right dorsal aorta fails to involute and therefore the ascending aorta remains divided into two arches: a right posterior and a left anterior. The right arch is usually dominant and travels posteriorly to the esophagus to join the descending aorta. Right dominant (70%) Page 8 of 40

9 Left dominant (20%) Balanced (10%) Description: - The right common carotid and subclavian arteries originate from the right arch - The left common carotid and subclavian arteries originate from the left arch Clinically: - The double aortic arch is the variant which most frequently becomes symptomatic (nearly 70%). Fig.: 5- Double aortic arch. References: Radiology, Hospital de Santo António dos Capuchos, CHLC - Lisbon/PT RIGHT AORTIC ARCH # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # Page 9 of 40

10 There are 2 main types of right aortic arch: 1. RIGHT AORTIC ARCH WITH LEFT ANOMALOUS SUBCLAVIAN ARTERY 1,2 Right aortic arch with aberrant left subclavian artery - 65% Four branches arise from the aortic arch. The aberrant left subclavian artery (LASA) is the last branch and passes to the left behind the oesophagus. A less frequent variant is a right aortic arch with a left descending aorta and left arterial ligament. The LASA may arise from an aortic diverticulum representing a remnant of the distal primitive left arch-kommerell diverticulum. Fig.: 6- Right aortic arch with left anomalous subclavian artery. Drawing and contrastenhanced CT. References: Radiology, Hospital de Santo António dos Capuchos, CHLC - Lisbon/PT Page 10 of 40

11 2. RIGHT AORTIC ARCH WITH MIRROR IMAGE 1,2 Right aortic arch with mirror image branching - 35% It represents a ''mirror image'' of the normal anatomy. Three branches originate from the aortic arch: left brachiocephalic trunk, right common carotid artery and right subclavian artery. This congenital anomaly is associated to a much higher incidence of severe congenital heart disease, and the most frequent symptoms are related to cyanotic heart disease, usually due to tetralogy of Fallot. Embriology: Persistence of the entire right dorsal arch and involution of a segment of the left arch between the LCCA & the LSCA. The arch lies to the right of the spine before descending on either the right or the left of the spine. Page 11 of 40

12 Fig.: 7- Right aortic arch with mirror image. Drawing and contrast-enhanced CT. References: Radiology, Hospital de Santo António dos Capuchos, CHLC - Lisbon/PT Invasive and non-invasive diagnostic procedures 3,4,5 : CXR (AP and lateral) - Tracheal narrowing or displacement - Aortic arch location - Tracheal Position: abnormal deviation to the left (due to the aorta coursing over the right mainstem bronchus) or mmidline position with double aortic arch. Esophagogram shows good sensibility for the detection, once there is clinical suspicion, %. It usually shows indentations on the outer contour. Once a diagnosis has been made, it is important to study the anatomy of the vascular ring. Page 12 of 40

13 CT and MRI are the techniques that best depict vascular rings, especially with the aid of MPR and excellent soft-tissue contrast and high resolution. Aditionally, they provide good visualization of the relations with adjacent anatomical structures, aid in the detection of aortic coarctation and electing the thoracotomy site. Angiography can accurately delineate the vascular anatomy, however it does not evaluate the relationship of the vessels with surrounding structures, with the major setback of being an invasive technique. In the presence of important symptoms, surgery is indicated. 1 AORTIC COARCTATION # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # Aortic coartation is not included in the normal vascular variants, but it is sometimes an imaging findng previously unknown and therefore, with an educational purpose, we included it in this exhibit too. This occurs when there is partial involution of the left dorsal aortic arch. Pre-ductal coarctation- results from partial involution of the dorsal aorta, cranial to the left sixth arch artery. Post-ductal coarctation- involution is distal to the left sixth arch artery. Inferior rib notching of the third to eighth ribs, due to collateral circulation via intercostal arteries, is bilateral in post-ductal coarctation, right sided in pre-ductal coarctation and left sided in coarctation associated with an aberrant right subclavian artery. Page 13 of 40

14 Fig.: Aortic coartation. Drawing and 3D VRT-CT image. References: Radiology, Hospital de Santo António dos Capuchos, CHLC - Lisbon/PT 6 AORTIC NIPPLE # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # Curvilineous vascular structure running along the outer border of the aortic arch. - Connects the left innominate and hemyazygous veins - Curvilineous vascular structure running along the outer border of the aortic arch. - Connects the left innominate and hemyazygous veins Page 14 of 40

15 Fig.: 9- Aortic Nipple. Drawing and contrast-enhanced CT. References: Radiology, Hospital de Santo António dos Capuchos, CHLC - Lisbon/PT 1 ABSENCE OF THE PULMONARY ARTERY # # # # # # # # # # # # # # # # # # # # - Rare anomaly. - Abnormal involution of the 6th proximal primitive homolateral arch. - The ipsilateral lung's irrigation is provided by bronchial arteries or a patent duct from the arch. - Ipsilateral lung hypoplasia Page 15 of 40

16 Fig.: 10- Absence of the pulmonary artery. Drawing and contrast-enhanced CT. Drawing, contrast-enhanced CT and 3D VRT-CT image. Notice extensive collateral circulation towards the right hemithorax. References: Radiology, Hospital de Santo António dos Capuchos, CHLC - Lisbon/PT 1 PULMONARY SLING # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # Rare anomaly. Probably due to involution of the proximal left sixth arch. Description: An anastomotic vessel linking the primitive pulmonary circulations becomes the anomalous left pulmonary artery which arises from the right pulmonary artery and courses to the left, passing between the trachea and oesophagus. Clinical relevance: Page 16 of 40

17 A vascular sling occurs, which may cause repeated pulmonary infections by tracheal compression. Fig.: 11- Pulmonary sling. Schematic drawing. References: Radiology, Hospital de Santo António dos Capuchos, CHLC - Lisbon/PT 1 PERSISTENCE OF THE LEFT SUPERIOR VENA CAVA # # # # # # # # # # # # Embriology: - right cardinal vein >>>> right superior vena cava - left cardinal vein>> usually involutes There are two variations: Page 17 of 40

18 1. DOUBLE SUPERIOR VENA CAVA # # # # # # # # # # # # # # # # # # # # # # # Persistence of both cardinal veins. The Left SVC drains into the right coronary sinus, which may be dilated. Fig.: 12- Double Superior Vena Cava. Contrast-enhanced CT, cornal and axial MPRs. References: Radiology, Hospital de Santo António dos Capuchos, CHLC - Lisbon/PT 2. PERSISTENCE OF THE LEFT SUPERIOR VENA CAVA # # # # # # # # # # # -Very rare. -Formation of the oblique vascular channel and regression of the right anterior cardinal vein. -The Left SVC drains into the right coronary sinus. Page 18 of 40

19 Fig.: 13- Left sided Superior Vena cava. Contrast-enhanced CT, coronal and axial MPRs. References: Radiology, Hospital de Santo António dos Capuchos, CHLC - Lisbon/PT 6 AZYGOUS VEIN CONTINUATION OF THE INFERIOR VENA CAVA # # # # # - Azygous vein dilatation, due to blood overflow. - This anomaly may be isolated or associated to IVC or abdominal anomalies such as polysplenia, asplenia, dextrocardia, or abdominal organ transposition. 1. Azygous vein continuation: The azygous vein leaves the retrocrural space on the right side of the vertebral column. 2. Hemiazygous vein continuation: The hemiazygous vein passes posteriorly to the aorta. Page 19 of 40

20 Fig.: 14- Azygous continuation of the Inferior Vena Cava. Contrast-enhanced CT, axial section. References: Radiology, Hospital de Santo António dos Capuchos, CHLC - Lisbon/PT 6 ARTERIO-VENOUS MALFORMATION # # # # # # # # # # # # # # # # # # # # # # Definition: Abnormal communication between the pulmonary artery and the pulmonary vein. Usually congenital; other causes iclude schistosomiasis, mitral stenosis, trauma, actinomycosis and metastatic thyroid carcinoma. Description: - The malformation may appear as a large single sac, a plexiform mass of dilated vascular channels, or a dilated, tortuous, direct communication between the pulmonary artery and the pulmonary vein. Page 20 of 40

21 - Approximately 50-70% are located in the lower lobes, 70% of patients have unilateral disease, 36% have multiple lesions and 50% may have bilateral disease. The size of the PAVMs may vary from microscopic to the typical size of 1-5 cm. Contrast-enhanced CT scanning remains the standard for the diagnosis. Fig.: 15- Arterio-venous malformation.contrast-enhanced CT, axual and oblique sagital MPRs. References: Radiology, Hospital de Santo António dos Capuchos, CHLC - Lisbon/PT 6 SCIMITARRA LUNG # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # The primitive pulmonary vein can develop normally, but the pulmonary venous plexus only partially involute, resulting in a partial anomalous pulmonary venous drainage. It may drain into the right atrium, SVC, IVC or azygos veins. Page 21 of 40

22 It is frequently associated with atrial septal defects. Fig.: Scimitarra lung. Drawing and axial and coronal contrast-enhanced CT. References: Radiology, Hospital de Santo António dos Capuchos, CHLC - Lisbon/PT Page 22 of 40

23 Images for this section: Fig. 0: 1- Normal aortic arch and origin of the supra-aortic branches. Drawing and CT reconstruction 3D VRT. Radiology, Hospital de Santo António dos Capuchos, CHLC - Lisbon/PT Page 23 of 40

24 Fig. 0: 2- Lusoria artery- Drawing and unenhanced axial CT. Awareness of the lusoria artery's paths prevents the false positive diagnosis of an adenopathy, in unenhanced examinations. Radiology, Hospital de Santo António dos Capuchos, CHLC - Lisbon/PT Page 24 of 40

25 Fig. 0: 3- Clinical manifestations of vascular rings. Radiology, Hospital de Santo António dos Capuchos, CHLC - Lisbon/PT Page 25 of 40

26 Fig. 0: 4- Types of vascular rings Radiology, Hospital de Santo António dos Capuchos, CHLC - Lisbon/PT Page 26 of 40

27 Fig. 0: 5- Double aortic arch. Radiology, Hospital de Santo António dos Capuchos, CHLC - Lisbon/PT Page 27 of 40

28 Fig. 0: 6- Right aortic arch with left anomalous subclavian artery. Drawing and contrastenhanced CT. Radiology, Hospital de Santo António dos Capuchos, CHLC - Lisbon/PT Page 28 of 40

29 Fig. 0: 7- Right aortic arch with mirror image. Drawing and contrast-enhanced CT. Radiology, Hospital de Santo António dos Capuchos, CHLC - Lisbon/PT Page 29 of 40

30 Fig. 0: Aortic coartation. Drawing and 3D VRT-CT image. Radiology, Hospital de Santo António dos Capuchos, CHLC - Lisbon/PT Page 30 of 40

31 Fig. 0: 9- Aortic Nipple. Drawing and contrast-enhanced CT. Radiology, Hospital de Santo António dos Capuchos, CHLC - Lisbon/PT Page 31 of 40

32 Fig. 0: 10- Absence of the pulmonary artery. Drawing and contrast-enhanced CT. Drawing, contrast-enhanced CT and 3D VRT-CT image. Notice extensive collateral circulation towards the right hemithorax. Radiology, Hospital de Santo António dos Capuchos, CHLC - Lisbon/PT Page 32 of 40

33 Fig. 0: 11- Pulmonary sling. Schematic drawing. Radiology, Hospital de Santo António dos Capuchos, CHLC - Lisbon/PT Page 33 of 40

34 Fig. 0: 12- Double Superior Vena Cava. Contrast-enhanced CT, cornal and axial MPRs. Radiology, Hospital de Santo António dos Capuchos, CHLC - Lisbon/PT Page 34 of 40

35 Fig. 0: 13- Left sided Superior Vena cava. Contrast-enhanced CT, coronal and axial MPRs. Radiology, Hospital de Santo António dos Capuchos, CHLC - Lisbon/PT Page 35 of 40

36 Fig. 0: 14- Azygous continuation of the Inferior Vena Cava. Contrast-enhanced CT, axial section. Radiology, Hospital de Santo António dos Capuchos, CHLC - Lisbon/PT Page 36 of 40

37 Fig. 0: 15- Arterio-venous malformation.contrast-enhanced CT, axual and oblique sagital MPRs. Radiology, Hospital de Santo António dos Capuchos, CHLC - Lisbon/PT Page 37 of 40

38 Conclusion Awareness of the spectrum of thoracic vascular anatomical variants allows prompt identification of these frequent and potential diagnostic pitfalls. Recognizing and reporting these variants may ultimately take an important role in the prevention of unexpected complications in interventional procedures. Page 38 of 40

39 Personal Information Rosana dos Santos; Radiology Resident Lisbon Portugal The authors thank the graphic artist who provided the drawings. Page 39 of 40

40 References 1. Davies M, Guest PJ. Developmental abnormalities of the great vessels of the thorax and their embryological basis. Br J Radiol Jul;76(907): Vera de Pedro E, Martínez Ayúcar M, Marín Gonzalo A et al. Complete vascular rings. An Pediatr (Barc) Jul;69(1): Kastler B, Livolsi A, Germain P et al. Value of MRI in the evaluation of congenital anomalies of the heart and great vessels. J Radiol Oct;85(10 Pt 2): Siegel MJ. Multiplanar and three-dimensional multi-detector row CT of thoracic vessels and airways in the pediatric population. Radiology Dec;229(3): Lee EY, Siegel MJ, Hildebolt CF et al. MDCT evaluation of thoracic aortic anomalies in pediatric patients and young adults: comparison of axial, multiplanar, and 3D images. AJR Am J Roentgenol Mar;182(3): emedicine, "Radiology". Page 40 of 40