Objectives • Learn the anatomy 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 vertebra Lateral Lateral 1st rib 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 – Vagus nerve, 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. phrenic nerve 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 , common carotid artery and and their patterns of spread. This knowledge will increase your diagnostic accuracy. internal jugular vein • Lymphatics - Thoracic and right lymphatic duct • Esophagus • Trachea • Thyroid Arteries Veins Nerves Normal Anatomy Normal Anatomy Neck Spaces Crossing the Thoracic Inlet Carotid Space • Formed by all three layers of the deep cervical fascia (DCF) • Extends from the skull base to the level of the aortic arch • In the lower neck contains jugular vein, carotid artery, and vagus nerve • Major pathology is vascular or neural in origin Thrombosis - Internal Jugular, Brachiocephalic Internal Jugular Vein 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 • Larynx • PRETRACHEAL aka Visceral Space Extends from • Trachea the hyoid bone to the anterior • Esophagus mediastinum • 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, brachiocephalic vein retroperitoneum, pelvic and groin 10% extend into the mediastinum Thymic embryology: • Derived from 3rd pharyngeal pouch • 6th week - descends from pharynx 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 subclavian vein) 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 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- lymph nodes & fat Infrahyoid - FAT • Infection can extend inferiorly into the posterior mediastinum • Look for carotid artery spasm Danger Space Perivertebral Space • Anterior, lateral and • Space between the posterior walls formed by the prevertebral fascia (DLDCF) DLDCF (prevertebral fascia) and the vertebral column, 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 coccyx – Pathology in this space can • Contains the prevertebral and extend from the neck to the paraspinal muscles, brachial diaphragm plexus, sympathetic chain, phrenic nerve, vertebral artery and vein Look MEDIALLY for extension of disease along the nerves into the neural foramen and spinal canal. 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 Subclavian Artery 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 * pyriform sinus 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 ? Lung Carcinoma The vagus and phrenic nerves cross the TI anterior to the subclavian artery. Metastatic Lymph Node: 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