Imaging of Skull Base Tumors Henry Ford Health System Systematic Approach to a Complex Problem (eDeE-67) Ciprian Gradinaru MD, Mark Kelly MD Brent Griffith MD, Suresh Patel MD Division of Neuroradiology Henry Ford Health System

Disclosures None of the authors have any disclosures HOME

Introduction The skull base anatomy can be divided into the anterior, middle and posterior compartments Tumors can arise from skull base structures or extend into the skull base region from intra or extra cranial lesions Skull base tumors offer a number of unique challenges: Deep location Complex anatomy (neurovascular foramina, adjacent structures) Close proximity to eloquent structures (brain, orbit, CN’s, vessels) Diverse pathology (benign/malignant tumors, infectious, congenital) The osseous skull base and pachymeninges (dura mater) are effective barriers, but tumor can spread through skull base foramina HOME

Introduction Anatomic location Behavior  Benign or Aggressive? Extension (direct vs. indirect) Integrity of Eloquent Structures Evaluation of skull based tumors require a systematic approach to narrow the differential diagnosis. HOME

Role of Imaging Lesion evaluation Prognostic information Anatomic localization Extent of disease Pattern of growth (benign vs. aggressive) Imaging characteristics Prognostic information Disease staging Morbidity and mortality Treatment planning Biopsy/surgical approach Need for adjuvant therapy Treatment Follow-up Treatment response and effects Recurrence and progression of disease HOME

CT and MR play a complimentary role. Skull Base Imaging CT and MR play a complimentary role. CT Can be performed quickly Excellent anatomic detail of osseous structures Information regarding lesion aggressiveness (smooth remodeling vs. erosion of adjacent bone) Multi-planar reconstructions in any imaging plane from single acquisition Requires ionizing radiation MR Longer scan times. Excellent evaluation of soft tissues Involvement of neurovascular structures. Need multiple imaging pulse sequences for characterization of lesions Prone to artifact (especially at skull base) No radiation HOME

Skull Base Tumor Classification Anatomic Location The skull base is generally grouped into anterior, middle, and the posterior cranial fossae Location-based classification is helpful because: Regional specificity of certain tumor types Similar clinical findings http://www.mayfieldclinic.com HOME

Skull Base Tumor Classification Anterior Cranial Fossa Cancers of the paranasal sinuses or nasal cavity are the most common malignant tumors Tumor examples: Meningioma Esthesioneuroblastoma Sino-nasal (SN) malignancies Giant cell tumor (GCT) Hemangiopericytoma Multiple myeloma (MM)/plasmacytoma Sarcomas (Osteo. and Rhabdo.) Lymphoma Melanoma http://www.mayfieldclinic.com HOME

Skull Base Tumor Classification Middle Cranial Fossa Central region: Pituitary adenoma, meningioma, pseudotumor, craniopharyngioma, sphenoid sinus carcinoma Clival region: Chordoma, meningioma, paraganglioma, naso- pharyngeal (NP) carcinoma, schwannoma, chondrosarcoma, MM/plasmacytoma, pseudotumor Para-central/Cavernous Sinus region: Meningioma, schwannoma, adenoid cystic carcinoma (ACC), NP carcinoma, GCT, pseudotumor Petro-Clival/Lateral region: Meningioma, schwannoma, NP angiofibroma, ACC, sarcoma, acquired/congenital cholesteatoma, cholesterol granuloma, pseudotumor http://www.mayfieldclinic.com HOME

Skull Base Tumor Classification Posterior Cranial Fossa Cerebellopontine (CP) angle: Schwannoma, meningioma, epidermoid, arachnoid cyst, cholesterol granuloma, endo- lymphatic sac tumor, metastasis, leptomeningeal and granulomatous process Jugular foramen: Paraganglioma, schwannoma, meningioma, metastasis Foramen magnum: Meningioma, schwannoma, chordoma, intra- medullary cord tumor, neurenteric cyst http://www.mayfieldclinic.com HOME

Systematic Approach Behavior – Benign or Aggressive? Osseous changes CT  smooth remodeling vs. permeative/destructive pattern MR  bone marrow involvement (T1 signal abnormality) Smooth Remodeling (Pituitary Macro-adenoma) Permeative/Destructive (Sarcoma) T1 Marrow Replacement (NP Carcinoma) HOME

Systematic Approach Behavior – Benign or Aggressive? Osseous changes Tumor cellularity (high) T2WI  hypo to iso-intense signal compared to gray matter DWI/ADC  restricted diffusion Iso-intense T2 signal (Esthesioneuroblastoma) Restricted Diffusion (Meningioma) HOME

Behavior – Benign or Aggressive? Systematic Approach Behavior – Benign or Aggressive? Osseous changes Tumor cellularity Intra-lesion contents (hemorrhagic or necrotic components) T1WI pre  hyper-intense signal (hemorrhage) T1WI post  non-enhancing necrotic tissue T1 Pre T1 Post Hemorrhage (Chondroblastoma) Central Necrosis (Chondrosarcoma) HOME

Behavior – Benign vs. Aggressive? Systematic Approach Behavior – Benign vs. Aggressive? Osseous changes Tumor cellularity Intra-lesion contents Tumor margins MRI  best on T2wi and post T1wi Well-defined/smooth  Benign Ill-defined/infiltrative  Aggressive Well-defined (Meningioma) Ill-defined (AdenoCa) HOME

Extracranial  Intracranial Extracranial  Intracranial Systematic Approach Extension Extra-cranial vs. Intra-cranial Extracranial  Intracranial Extracranial  Intracranial SN Neuroendocrine Carcinoma (SNEC) Meningioma HOME

Systematic Approach Extension Extra-cranial vs. Intra-cranial Direct vs. Indirect (perineural) Skull base bone and pachymeninges (dura mater) act as barrier Neurovascular foramina and cranial nerves provide conduit http://www.imaios.com/Media/Images/e-anatomy/Cranial-nerves-anatomy-diagrams/skull-cranial-base-foramen-cranial-nerves-anatomy-en HOME

Systematic Approach Extension Perineural involvement includes perineural invasion and spread Perineural invasion  microscopic feature of malignancy is often confined to the main tumor mass Perineural spread  clinico-radiologic observation of distant spread of tumor via perineural spaces or within the nerve sheath/nerve itself Most often seen with extra-cranial squamous cell carcinoma Most commonly seen with salivary gland tumors (mainly ACC and Muco-epidermoid carcinoma) HOME

Imaging of Peri-neural Involvement Systematic Approach Extension Imaging of Peri-neural Involvement Focal/segmental/diffuse enhancement and enlargement of the cranial nerve Skull base foramen enlargement and replacement of the normal fat within the foramen Look for denervation atrophy of the muscles supplied by the involved cranial nerve Heterogeneously enhancing mass of the left parotid gland (Mucoepidermoid Carcinoma) with enlargement and enhancement of the left facial nerve as it enters the stylomastoid foramen (normal right facial nerve) HOME

Integrity of Eloquent Structures Systematic Approach Integrity of Eloquent Structures Dural, leptomeningeal and parenchymal invasion T1WI (post-contrast) and T2WI/FLAIR are best Leptomeningeal or dural enhancement (nodular or linear > 5 mm) Enhancement or edema of brain adjacent to tumor SN Poorly Differentiated Adenocarcinoma HOME

Integrity of Eloquent Structures Systematic Approach Integrity of Eloquent Structures Dural, leptomeningeal and parenchymal invasion Skull base foramina and contents Foraminal anatomy is key MRI  Loss of normal fat and enhancement within neuroforamina CT  Helpful for evaluation of osseous walls of neuroforamina Left cavernous sinus meningioma spreading into the left masticator space via the left foramen ovale and into the left pterygopalatine fossa via the left foramen rotundum HOME

Systematic Approach Integrity of Eloquent Structures Dural, leptomeningeal and parenchymal invasion Skull base foramina and contents Orbit and optic nerve Orbital fissures and apex are most commonly involved Periorbital and CN-II dural sheath closely related at orbital apex Lymphoma encasing left optic nerve Meningioma invading the left orbital apex Enhancing soft tissue replacing fat within a widened right superior orbital fissure (Meningioma) HOME

Systematic Approach Integrity of Eloquent Structures Dural/Parenchymal invasion Skull base foramina and contents Orbit and optic nerve Cavernous sinus (CS) involvement Loss of normal CS enhancement Convex bulging of the lateral wall of the CS (normally concave) Nasopharyngeal SCC Invasive Pituitary Macroadenoma HOME

Case 1: Meningioma HOME Location Behavior Extension Floor of the anterior cranial fossa Behavior Hyperostosis of adjacent skull base (non-aggressive) Hyperdense mass (indicates high cellularity, but not behavior) Extension Intact skull base without evidence of extra-cranial extension Eloquent Structures Compression of the bilateral frontal lobes with vasogenic edema Effacement of the frontal horn of the right lateral ventricle HOME

Case 1: Meningioma HOME Location Behavior Extension Floor of the anterior cranial fossa Behavior Homogeneous enhancement Restricted diffusion (indicates high cellularity, but not behavior) Extension Intact skull base without evidence of extra-cranial extension Eloquent Structures Compression of the bilateral frontal lobes Displacement of vessels HOME

Case 2: Esthesioneuroblastoma Location Tumor is centered in the superior olfactory recess region Behavior Homogeneous solid enhancement Destroys the cribriform plate, bilateral ethmoid air cells, nasal septum as well as the bilateral superior and middle nasal conchae Extension Tumor extends into the floor of the anterior cranial fossa Post obstructive changes in the left frontal sinus Eloquent Structures Slight mass effect on the bilateral infero-medial frontal lobes Preserved medial orbital walls HOME

Case 3: Sinonasal Neuroendocrine Carcinoma (SNEC) Location Large mass centered in sinonasal cavity Behavior Poorly defined tumor margins Destruction of the cribriform plate, bilateral medial orbital walls, nasal cavity, ethmoid air cells and maxillary sinuses Extension Tumor extends into the infero-medial anterior cranial fossa, bilateral medial orbits and bilateral maxillary sinuses Eloquent Structures Compression of the bilateral infero-medial frontal lobes with vasogenic edema Mass effect on the bilateral medial rectus muscles HOME

Case 3: Sinonasal Neuroendocrine Carcinoma (SNEC) T1 Pre Location Large mass centered in sinonasal cavity Behavior Heterogeneous enhancement Irregular tumor margin Extension Superior extension into the anterior cranial fossa Extends into bilateral medial orbits and maxillary sinuses Eloquent Structures Compression of bilateral frontal lobes with vasogenic edema Mass effect on medial rectus muscles Mass effect on optic chiasm T1 Post T2 FS HOME

Case 4: Invasive Pituitary Macroadenoma Location Large mass (> 10mm) centered in the central/para-central middle cranial fossa Behavior Homogeneous avid enhancement Smooth well defined margins Extension Left cavernous sinus with convex lateral bulge Supra-sellar region Eloquent Structures Encasement of the left internal carotid artery Mass effect on the optic chiasm Mass effect on anteromedial left temporal lobe Slight flattening of the left anterior pons HOME

Case 5: Chordoma HOME Location Behavior Extension Eloquent Structures Midline mass originating from the clivus Behavior Infiltrative mass with irregular margins Bony destruction Extension Anteriorly into sphenoid sinuses, ethmoid air cells, and nasal cavity Posteriorly into pre-pontine cistern Superorly into sellar/supra-sellar region Inferiorly into nasopharynx Left lateral into medial middle cranial fossa and left maxillary sinus Eloquent Structures Mass effect on antero-medial left temporal lobe Slight flattening of anterior pons Mass effect on pituitary gland HOME

Case 5: Chordoma HOME Location Behavior Extension Eloquent Structures Midline mass originating from the clivus Behavior Infiltrative mass with irregular margins (aggressive) Extension Anteriorly into sphenoid sinuses, ethmoid air cells, and nasal cavity Posteriorly into pre-pontine cistern Superorly into sellar/suprasellar region Inferiorly into nasopharynx Left lateral into middle cranial fossa Eloquent Structures Mass effect on medial left temporal lobe Slight flattening of the anterior pons Mass effect on the pituitary gland HOME

Case 6: Cavernous Sinus Meningioma Location Mass located in the right para-central middle cranial fossa Behavior Homogeneously enhancing mass Smooth widening of the right superior and inferior orbital fissures (non-aggressive) Hyperostosis of the greater wing of the right sphenoid bone (non-aggressive) Extension Right orbital apex Right superior and inferior orbital fissures Right pterygopalatine fossa Eloquent Structures Neurovascular structures involving right cavernous sinus, superior orbital fissure and pterygopalatine fossa Compression of optic nerve at orbital apex HOME

Case 6: Cavernous Sinus Meningioma Location Mass located in the right para-central middle cranial fossa Behavior Homogeneously enhancing mass with smooth margins (non-aggressive) Widening of right pterygomaxillary fissure Extension Right pterygopalatine fossa (replacement of fat on precontrast T1) Eloquent Structures Encasement and narrowing of the right internal carotid artery Slight compression of the medial right temporal lobe Other neurovascular structures within the cavernous sinus and pterygopalatine fossa HOME

Case 7: Nasopharyngeal SCC Location Soft tissue density involving the left pterygopalatine fossa Behavior Intense FDG uptake on PET Widening of the left sphenopalatine foramen and left pterygomaxillary fissure Bony erosion (aggressive) of posterior left maxillary sinus wall and left pterygoid plate Extension Left inferior orbital fissure Left pterygopalatine fossa (replacement of fat on CT) Eloquent Structures Neurovascular structures within the left pterygopalatine fossa and inferior orbital fissure HOME

Case 8: Chondrosarcoma HOME Location Behavior Extension Lesion centered at the left petro-occipital fissure Behavior Permeative osseous destruction of the clivus and left petrous apex (aggressive) Extension Erosion of the wall of the left carotid canal Anterior aspect of the left jugular foramen Eloquent Structures Potential involvement of left internal carotid artery Neurovascular structures within the left jugular foramen HOME

Case 8: Chondrosarcoma HOME Location Behavior Extension Mass centered at the left petro-occipital fissure Behavior Heterogeneous enhancement with areas of central necrosis Extension Involvement of the clivus and left petrous apex Extension into the left pre-pontine and cerebello-pontine cisterns Eloquent Structures Compression of the pons Close proximity to the basilar artery Focal encasement of the left internal carotid artery HOME

Case 9: Glomus Jugulotympanicum Location Mass centered within the region of the left jugular foramen Behavior Moth-eaten bony destruction (aggressive) of the left jugular foramen walls and posteromedial aspect of the left middle ear cavity Extension Posteromedial aspect of the left middle ear cavity Eloquent Structures Neurovascular structures coursing within the left jugular foramen (pars nervosa and pars vascularis) Left middle ear structures HOME

Case 9: Glomus Jugulotympanicum Location Mass centered within the region of the left jugular foramen Behavior Heterogeneous enhancement Extension Left jugular foramen (pars nervosa and pars vascularis) Left sigmoid sinus Eloquent Structures Neurovascular structures within the left jugular foramen (pars nervosa and pars vascularis) Left middle ear structures HOME

Case 10: Endolymphatic Sac Tumor Location Mass in the posterolateral aspect of the left petrous temporal bone Behavior Partially cystic mass with enhancement of the non-cystic component No restriction diffusion Erosive changes of the posterior left petrous temporal bone (aggressive) Extension Left cerebello-pontine cistern Left vestibular aqueduct is not identified Eloquent Structures Slight mass effect on the left cerebellum HOME

Take-Home Points Large variety of pathology  histological diagnosis by imaging is not possible. Imaging plays important role in evaluation: Anatomic localization and extent of disease Biologic behavior (benign vs. aggressive) Involvement of adjacent eloquent structures Treatment planning (3-D surgical navigation) Post-treatment morbidity and mortality Follow-up post-treatment Complex anatomy and diverse pathology Systematic approach for evaluating skull base tumors is important Location and behavior can help shorten the differential diagnosis HOME

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