MRI of the Pediatric Mediastinum
Dianna M. E. Bardo, MD Director of Body MR & Co-Director of the 3D Innovation Lab Disclosures
Consultant & Speakers Bureau – honoraria Koninklijke Philips Healthcare N V
Author – royalties Thieme Publishing Springer Publishing Mediastinum - Anatomy Superior Mediastinum thoracic inlet to thoracic plane
thoracic plane to diaphragm Inferior Mediastinum
lateral – pleural surface anterior – sternum posterior – vertebral bodies Mediastinum - Anatomy Anterior
T4 Mediastinum pericardium to sternum Middle Mediastinum pericardial sac Posterior Mediastinum vertebral bodies to pericardium lateral – pleural surface superior – thoracic inlet inferior - diaphragm Mediastinum – MR Challenges Motion Cardiac ECG – gating/triggering Breathing Respiratory navigation
Artifacts Intubation – LMA Surgical / Interventional materials Mediastinum – MR Sequences ECG gated/triggered sequences SSFP – black blood SE – IR – GRE Non- ECG gated/triggered sequences mDIXON (W, F, IP, OP), eTHRIVE, turbo SE, STIR, DWI Respiratory – triggered, radially acquired T2W MultiVane, BLADE, PROPELLER Mediastinum – MR Sequences MRA / MRV REACT – non Gd enhanced
Gd enhanced sequences THRIVE, mDIXON, mDIXON XD Mediastinum – Contents Superior Mediastinum PVT Left BATTLE: Phrenic nerve Vagus nerve Structures at the level of the sternal angle Thoracic duct Left recurrent laryngeal nerve (not the right) CLAPTRAP Brachiocephalic veins Cardiac plexus Aortic arch (and its 3 branches) Ligamentum arteriosum Thymus Aortic arch (inner concavity) Trachea Pulmonary trunk Lymph nodes Tracheal bifurcation Esophagus Right-to-left movement of the thoracic duct Azygos vein drains into SVC Pre-vertebral fascia and pre-tracheal fascia end Mediastinum – Contents Anterior Mediastinum Thymus gland Lymph nodes Middle Mediastinum Fat Pericardium Heart Ascending Aorta Pulmonary artery Posterior Mediastinum Phrenic nerves DATES: Cardiac Plexus Descending aorta Lymph nodes Azygos and hemiazygous veins tracheobronchial Thoracic duct Esophagus Sympathetic trunk/ganglia Mediastinum - Pathology Vascular Infectious / Inflammatory Trauma Autoimmune Metabolic Iatrogenic / Idiopathic Neoplastic Congenital Mediastinum - DDx Superior Mediastinum Inferior • thymus Mediastinum • thyroid & parathyroid glands • lymphoma Anterior • germ cell tumors – teratoma Middle • thoracic aortic aneurysm Posterior Mediastinum - DDx Anterior Middle Posterior Mediastinum Mediastinum Mediastinum • thymus • lymphadenopathy • esophagus/hiatal hernia • thyroid & parathyroid gland • aortic arch aneurysm • foregut duplication cyst • lymphoma • enlarged pulmonary artery • neurogenic tumor • germ cell tumors – teratoma • foregut duplication cyst • neuroblastoma • thoracic aortic aneurysm • pericardial cyst • paraspinal abscess • tracheal lesions • lateral meningocele • extramedullary hematopoiesis Mediastinum – nerves Anatomy right phrenic nerve left phrenic nerve right vagus nerve left vagus nerve left recurrent laryngeal nerve Mediastinum - neoplastic Horner’s Syndrome ptosis myosis anhidrosis Tumor or infection at the superior sulcus of the lung • brachial plexus • cervical sympathetic nerves – stellate ganglion Mediastinum - infection Complications of otitis media which progressed to retropharyngeal abscess Infection spreads from retropharyngeal space along fascial planes from the neck into the superior, anterior, and posterior mediastinum Mediastinum - neoplasm Papillary thyroid cancer
T2* mapping can potentially provide quantitative information to separate PTC from benign thyroid nodules.
Shi et al. J. Magn. Reson. Imaging 2016;43:956–961 Mediastinum – thymus Normal thymus gland
Extension of normal thymus through the thoracic inlet Mediastinum – thymus Cystic & solid mass of the thymus
Signal intensity index & chemical-shift ratio both diagnostically accurate quantitative parameters distinguishing thymic hyperplasia from other mediastinal tumors
Priola et al. Radiology: Volume 274: Number 1—January 2015 Mediastinum – VM Lymphatic malformation
Mediastinal extension can occur from above and below & involve any and all mediastinal spaces cystic masses are very common in the mediastinum Mediastinum – VM Lymphatic malformation
intracystic contents are most often hyperintense on T2 But may have a variable T1 appearance, depending on protein content or prior hemorrhage Mediastinum - VM Lymphatic malformation
Mediastinal extension can occur from above and below Mediastinum – VM Vascular malformation
Extensive mediastinal involvement of apparent upper extremity VM Mediastinum – Gorhams Dz Lymphangiomatosis
Rare lymphatic & vascular malformation of bone extensive upper extremity, chest wall, and mediastinal involvement lymphatic malformation Mediastinum – KTW syndrome Fat & vascular tissue overgrowth
Klipple-Trénaunay-Weber angioosteohypertrophy syndrome and hemangiectatic hypertrophy Mediastinum – esophagus VM Lymphatic malformation
esophageal vascular malformation – risk of GI hemorrhage lymphatic component surrounds CCAs & invades spinal canal Mediastinum – esophageal Foregut duplication cyst
Fluid signal mass in posterior mediastinum Mediastinum – neurenteric cyst congenital remnant of connection between the endoderm and ectoderm
Neurenteric cysts may show mild DWI restriction neurogenic tumors are usually they are benign, but in children, from the autonomic system, tend to be malignant Mediastinum – NF1 Plexiform neurofibroma
10% lifetime risk of developing MPNSTs rapid growth early in life may be when malignant transformation occurs in NF1 – whole body MR
Mautner et al. Neuro-Oncology 10, 593–598, 2008 Mediastinum - neoplasm Ewings sarcoma
Chest wall – primary rib Ewing sarcoma invasive into middle mediastinum – breaches the pericardium Mediastinum – vascular Brachiocephalic vein thrombosis
iatrogenic occlusion due to PICC line Mediastinum – aorta Aortic ectasia
Connective tissue disorder Serial imaging to monitor progressive dilation and ectasia of the aorta Mediastinum – tracheobronchial Bronchogenic foregut malformation
mediastinal cysts = M/F distribution intrapulmonary cysts – male predilection Tips Sequences MRA / MRV Dianna M. E. Bardo, MD Director of Body MR & Co-Director of the 3D Innovation Lab [email protected]