Objectives

• Learn the of the thoracic inlet (TI) Thoracic Inlet • Review the clinical and radiographic findings of common lesions encountered in this region • Encourage the use of a systematic Deborah L. Reede M.D. approach “ Road Rules” for the evaluation SUNY Downstate Medical Center of pathology in the TI

Thoracic Inlet Boundaries Thoracic Inlet Sagittal View

Posterior - 1st thoracic

Lateral Lateral 1st 1st rib Anterior Posterior

Anterior - Manubrium

ANTERIOR SCALENE

ANTERIOR SCALENE

Sagittal

Coronal Thoracic Inlet Nerves Thoracic Inlet Nerves

• Vagus - recurrent laryngeal • Phrenic • Brachial Plexus • Sympathetic Chain

Brachial Plexus Cervical Sympathetic

Stellate ganglion Sagittal Fusion of the first thoracic and inferior cervical ganglion Found in 80% of the population Will use the term inferior cervical ganglion during this presentation Coronal

Thoracic Inlet – Contents Road Rules The thoracic inlet is a busy anatomic intersection. • Neural structures – , recurrent – Certain disease processes have predictable patterns of disease spread “traffic patterns”. laryngeal nerve, cervical sympathetics, – A knowledge of these patterns aid in imaging interpretation. and brachial plexus – The “Road Rules” outlined in this lecture will help you • Vascular - Subclavian and brachiocephalic remember the location and appearance of common lesions artery and vein , and and their patterns of spread. This knowledge will increase your diagnostic accuracy. internal • Lymphatics - Thoracic and right lymphatic duct • • • Arteries Veins Nerves Normal Anatomy Normal Anatomy

Neck Spaces Crossing the Thoracic Inlet Carotid Space

• Formed by all three layers of the deep cervical (DCF) • Extends from the base to the level of the aortic arch • In the lower contains jugular vein, carotid artery, and vagus nerve • Major pathology is vascular or neural in origin

Thrombosis - Internal Jugular, Brachiocephalic Thrombosis and Subclavian Veins

Extent Etiology

Artery Look up

Vein and down Node

Abscess Venous Thrombosis - Etiologies Carotid Artery Thrombosis

• Trauma Artery • Infection Look Vein • Mass compressing the vein up and Node down • Tumors that cause distant venous Abscess thrombosis (renal cell and pancreatic Ca) • Indwelling catheter • Birth control medications

Aortic Dissection Takayasu’s Arteritis CTA

• Inflammatory disease affecting large elastic arteries • F:M ratio is 8:1, age 15-30 • Commonly affects the aorta and its major branches Look • Radiographs -aortic down calcifications in later stage and up • Findings on CTA: stenoses, occlusions, aneurysms and concentric arterial wall thickening • MR similar findings + enhancement of the vascular wall 32 y/o F with c/o pleuritic chest pain.

Visceral Space Divisions Visceral Space – Pretracheal Component

“Express Lane” Contains: • Thyroid gland Subdivisions • Parathyroid glands • • PRETRACHEAL aka Visceral Space Extends from • Trachea the hyoid to the anterior • Esophagus • RETROPHARYNGEAL • Recurrent laryngeal extends from the base of the nerve skull to anywhere between C6 and T4 where the alar fascia fuses with the visceral fascia (MLDCF) Thyroid Lesions Thyroid Lesions

• Most common lesion crossing the TI • Inferior extent needs to be determined for surgical planning • Lesion extending below the level of the aortic arch may require a combined neck and thoracic approach for removal

Tracheal Lesions Tracheal Stenosis

• Congenital - ring shaped cartilage • Acquired - prior intubation or • Tracheal stenosis tracheostomy • Saber sheath trachea • Edema of the tracheal wall • Tracheal diverticulum intramural granulation tissue fibrosis • Location - Extra-thoracic • Short segment concentric wall thickening (fixed)- hourglass shaped

Tracheal Stenosis Tracheal Stenosis - Stent

40 y/o old male S/P intubation presented with increasing dyspnea

May migrate Saber Sheath Trachea Saber Sheath Trachea

• COPD • Tracheomalacia from chronic coughing or increased intrathoracic pressure • Intrathoracic trachea • Transverse diameter • Transverse diameter • AP diameter • AP diameter • Normal wall thickness • Narrowing expiration

Saber Sheath Trachea Tracheoceles

• Aka right paratracheal air cyst • COPD • Focal herniation of the tracheal mucosa though the tracheal wall between the cartilaginous and mucosal portion of the trachea Point: Always look at the trachea size on the frontal and lateral views • Asymptomatic of the chest • Reservoir for secretions - cough, dyspnea and stridor secondary to chronic infection

Dilated Esophagus Achalasia Look down – Look left and right

• Etiology- unknown • Neuropathy of the • Motility disorder myenteric plexus • Carcinoma Look down incomplete relaxation • Strictures of the lower • Achalasia esophageal sphincter • Scleroderma • 2nd esophageal Ca, • Foreign bodies metastasis,Chagas disease and vagatomy • Stasis – esophagitis

Scleroderma Esophageal Carcinoma Look left

RT Planning CT Ca Hypopharynx and Esophagus Congenital Lesions

• Lymphatic venous malformations • Thymic cysts

• The risk factors for developing head and neck and esophageal carcinoma are the same • Synchronous aerodigestive tract lesions occur in 10 – 40% with H&N Ca

Lymphatic Venous Malformation Thymic Cyst

• Uncommon • Most common lesion involving • 1st decade of life • Lower neck –left the thoracic inlet in children predominance • Locations • 50% mediastinal extension 75% neck • Path- thymic tissue and Hassall's corpuscle 20% axilla • Intermittent occlusion of the 5% mediastinum, retroperitoneum, pelvic and groin 10% extend into the mediastinum

Thymic embryology: • Derived from 3rd pharyngeal pouch • 6th week - descends from along paired thymopharyngeal ducts into the anterior/superior mediastinum • Thymopharyngeal duct eventually atrophies; if portions persist a cyst may develop • Cyst location – deep to thyroid gland, sternocleidomastoid muscle and medial to the carotid sheath Thoracic duct Thymus - Cervical Extensions

Travels posterior to the left common carotid artery and terminates in the posterolateral aspect of the venous angle (junction of the left IJ and ) Newborn with a Brachiocephalic palpable mass in vein the lower neck.

Thymic tissue is found in the neck in 21-42% of infants.

Infection and Spaces Pretracheal (Visceral) Space Abscess

Retropharyngeal Space Abscess

• Extends from the base of the skull to anywhere between C6 and T4 where the alar fascia fuses with the visceral fascia (MLDCF) • Contains: Suprahyoid- nodes & fat Infrahyoid - FAT

• Infection can extend inferiorly into the posterior mediastinum • Look for carotid artery spasm Perivertebral Space

• Anterior, lateral and • Space between the posterior walls formed by the prevertebral fascia (DLDCF) DLDCF (prevertebral fascia) and the , two • Extends from the skull base divisions: to the diaphragm – Prevertebral: posterior to danger • On imaging it is difficult to space differentiate pathology in this – Paraspinal: deep to posterior space from the cervical space retropharyngeal space • Extends from the skull base to unless it extends below T4 the – Pathology in this space can • Contains the prevertebral and extend from the neck to the paraspinal muscles, brachial diaphragm plexus, sympathetic chain, phrenic nerve, and vein Look MEDIALLY for extension of disease along the nerves into the neural foramen and .

Prevertebral Space Abscess Apical Mass

• Neural Tumors • Pancoast (Superior Sulcus) Tumors • Thyroid Lesions • Vascular Lesions

Cases courtesy of Dr.Yoshimi Anzai

Nerves in the Perivertebral Aneurysm Space

Phrenic nerve Cervical nerve root Cervical Sympathetic chain

Remote history of trauma

Courtesy of Dr. Rakesh Shah North Shore Medical Center Brachial Plexus Schwannoma Brachial Plexus and IC Ganglion

Asymptomatic 25 yr. old male with an abnormal CXR.

Vertebral Artery and Sympathetic Ganglion Pancoast Tumor

Vertebral artery Vertebral artery

VERTEBRAL ARTERY ganglion

58-year-old male with weight loss, right brachial plexopathy and Horner’s Syndrome.

Pancoast Tumor Pancoast Tumor B, HS, P,VCP Recurrent Laryngeal Nerve (RLN) RLN Palsy Etiologies

• Tumor • Cardiovascular

• Trauma • Neurologic

• Infection • Idiopathic

RecurrentVagus NervesLaryngeal Nerves

Denervation Atrophy CN X Vagal Schwannoma

Imaging Findings of Vocal Cord Paralysis  Anteromedial positioning of the arytenoid cartilage  Ipsilateral dilatation of * and * laryngeal ventricle  Paramedian position of the vocal cord due to 46 y/o F with a Lt. vocal cord paralysis. paralysis • Heterogenously enhancing mass is splaying the CCA and IJV. • Mass is anterior to the subclavian artery on sagittal image. This is where the vagus nerve is located.

Left Vocal Cord Paralysis Phrenic Nerve Phrenic Nerve What nerve palsies could this patient have ? Esophageal Carcinoma

What nerves could be involved in this patient ? Carcinoma

The vagus and phrenic nerves cross the TI anterior to the subclavian artery.

Metastatic : Mass anterior to the right subclavian artery where the phrenic and vagus nerves cross the TI .

Phrenic Nerve Palsy Cervical Aortic Arch

Most of the lesions that cross the thoracic inlet originate in the neck.

CXR and scout film for CT taken two weeks apart Vascular lesion and Pancoast tumors are the exception Summary Summary

• Anterior scalene muscle • Spaces – carotid, visceral (pretracheal and retropharyngeal), danger and perivertebral • Neural structures (location) • Lesion You must be familiar with the traffic patterns.

Don’t Panic Remain calm and use the ‘Road Rules”

Courtesy of Dr. Salvatore Sclafani Downstate Medical Center Courtesy of Dr. Salvatore Sclafani Downstate Medical Center

Traffic Patterns Traffic Patterns

• Most lesions grow • Look up and look down down not up (neck and chest) especially when evaluating: • Vascular lesions are - Vascular lesions the exception to the - Infection rule - Thyroid lesions • Pancoast tumors can - Thymic lesions in children grow into the base of the neck Traffic Patterns Traffic Patterns

• Dilated esophagus – look down • Lesions in the • Look right and left perivertebral • Look left (paraspinal) region and posterior cervical space • Look up - look medially

Traffic Patterns

• Lung Ca • Neural Tumors • Vascular Lesions • Thyroid Lesions