Head and Neck Imaging E-Book

Mathias Cohnen

• Herausgeber: Thieme
• Kategorie: Fachliteratur
• Sprache: Englisch

Seitenzahl: 266

Veröffentlichungsjahr: 2007

Beschreibung

Dx-Direct is a series of eleven Thieme books covering the main subspecialties in radiology. It includes all the cases you are most likely to see in your typical working day as a radiologist. For each condition or disease you will find the information you need -- with just the right level of detail.

Dx-Direct gets to the point:

• Definitions, Epidemiology, Etiology, and Imaging Signs
• Typical Presentation, Treatment Options, Course and Prognosis
• Differential Diagnosis, Tips and Pitfalls, and Key References

...all combined with high-quality diagnostic images.

Whether you are a resident or a trainee, preparing for board examinations or just looking for a superbly organized reference: Dx-Direct is the high-yield choice for you!

The series covers the full spectrum of radiology subspecialties including: Brain, Gastrointestinal, Cardiac, Breast, Genitourinal, Spinal, Head and Neck, Musculoskeletal, Pediatric, Thoracic, Vascular

Leseprobe

Direct Diagnosis in Radiology

Head and Neck Imaging

Ulrich Moedder, MD

Professor of RadiologyDirector of the Institute of Diagnostic RadiologyUniversity HospitalDüsseldorf, Germany

Mathias Cohnen, MD

Assistant Professor of RadiologyInstitute of Diagnostic RadiologyUniversity HospitalDüsseldorf, Germany

Kjel Andersen, MD

Institute of Diagnostic RadiologyUniversity HospitalDüsseldorf, Germany

Volkher Engelbrecht, MD

ProfessorHead of the Department of RadiologySt.-Marien HospitalAmberg, Germany

Benjamin Fritz, MD, DMD

Department of RadiologyUniversity of Düsseldorf Medical CenterDüsseldorf, Germany

259 Illustrations

Thieme Stuttgart • New York

Library of CongressCataloging-in-Publication Data

Kopf, Hals. English.

Head and neck imaging/Ulrich Moedder…

[etal.]; [translator,Terry Telger].

p.; cm. - (Direct diagnosis in radiology)

Translation of: Kopf, Hals/Ulrich Mödder…

[et al.]. c2006.

Includes bibliographical references and index.

ISBN 978-1-58890-564-2

(TPN, the Americas: alk. paper) -

ISBN 978-3-13-144081-5 (TPS: alk. paper)

1. Head-Radiography 2. Neck-Radiography. I. Mödder, Ulrich, 1945- II. Title. III. Series.

[DNLM: 1. Head-radiography-Handbooks.

2. Diagnosis, Differential-Handbooks.

3. Neck-radiography-Handbooks.

WE 39 K83h 2007a]

RC936.K6413 2007

617.5'107572-dc22

2007026165

This book is an authorized and revised translation of the German edition published and copyrighted 2006 by Georg Thieme Verlag, Stuttgart, Germany. Title of the German edition: Pareto-Reihe Radiologie: Kopf/Hals.

Translator: Terry Telger, Fort Worth,Texas, USA

© 2008 Georg Thieme Verlag KGRüdigerstraße 14,70469 Stuttgart,Germanyhttp://www.thieme.deThieme New York, 333 Seventh Avenue,New York NY 10001, USAhttp://www.thieme.com

Cover design: Thieme PublishersTypesetting by Ziegler + Müller,Kirchentellinsfurt GermanyPrinted by APPL aprinta Druck,Wemding, Germany

ISBN 978-3-13-144081-5(TPS, Rest of World)ISBN 978-1-58890-564-2(TPN, The Americas)            1 2 3 4 5 6

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Contents

1 Skull Base

M. Cohnen, V. Engelbrecht

Hyperostosis frontalis

Arachnoid Cyst

(En)cephalocele

Fibrous Dysplasia

Eosinophilic Granuloma

Meningioma

Clivus Chordoma

Esthesioneuroblastoma

2 Petrous Bone

M. Cohnen

Pneumatization of the Petrous Apex

Otosclerosis, Otospongiosis

Petrous Bone Anomalies

Petrous Bone Fractures

Primary or Idiopathic Facial Palsy

Otitis media

Cholesteatoma

Acoustic Schwannoma

Paraganglioma, Glomus Tumor

Rhabdomyosarcoma

3 Orbit

M. Cohnen, V. Engelbrecht

Endocrine Orbitopathy

Subperiosteal Abscess

Orbital Pseudotumor

Optic Neuritis

Orbital Hemangioma

Optic Glioma

Retinoblastoma

Retinal Melanoma

Optic Nerve Meningioma

Orbital Lymphoma

Apical Orbital Metastasis

4 Paranasal Sinuses

M. Cohnen

Normal Findings

Midfacial Fractures

Sinusitis, Polyposis

Postoperative Status

Choanal Polyp

Mucocele

Fungal Infection

Wegener Granulomatosis

Nasopharyngeal Angiofibroma

Inverted Papilloma

Carcinoma

Non-Hodgkin Lymphoma

5 Pharynx

B. Fritz

Thornwaldt Cyst

Spondylodiskitis

Peritonsillar Abscess

Parapharyngeal Abscess

Pharyngeal Carcinoma

Tonsillar Lymphoma

6 Larynx

K. Andersen

Normal Findings

Laryngocele

Zenker Diverticulum

Laryngeal Edema

Thyroid Cartilage Fracture

Cervical Prevertebral Abscess

Supraglottic Carcinoma

Glottic Carcinoma

7 Oral Cavity

B. Fritz

Nonodontogenic Cyst

Thyroglossal Duct Cyst

Unilateral Muscular Atrophy

Odontogenic Cyst

Intraoral Abscess

Mandibular Osteomyelitis

Ameloblastoma

Carcinoma of the Tongue

Carcinoma of the Floor of the Mouth

8 Salivary Glands

K. Andersen

Normal Findings

Variants of the Salivary Glands

Warthin Tumor

Ranula

Sialolithiasis, Sialadenitis

Sjögren Syndrome

Salivary Gland Abscess

Pleomorphic Adenoma

Lymphoma of the Salivary Glands

Salivary Gland Carcinoma

9 Soft Tissues of the Neck

B. Fritz

Branchial Cleft Cyst

Cervical Hematoma

Jugular Vein Thrombosis

Aneurysm, Dissection of the Internal Carotid Artery

Cervical Abscess, Cellulitis

Cystic Hygroma

Hemangioma

Parathyroid Adenoma

Goiter (Multinodular, Diffuse)

Thyroid Carcinoma

Iatrogenic Changes

10 Lymph Nodes

  K. Andersen

Normal Findings

Cervical Lymphadenitis

Tuberculosis

Lymphoma

Metastasis

Index

Throughout the book, signal intensities in MRI and densities in CT are described in relation to adjacent tissues. In cerebral imaging, hypo- or hyperintense can obviously refer to normal white matter. However, as there are many different tissues and organs in the facial and cervical region, muscle seemed to represent the best comparison. Therefore, hypo- or hyperintense and hypo- or hyperdense usually refers to muscle tissue unless stated otherwise.

Abbreviations

ACE

Angiotensin-converting enzyme

ADC

Apparent diffusion coefficient

AJCC

American Joint Committee on Cancer

AIDS

Acquired immuno-deficiency syndrome

C1

First cervical vertebra

CEA

Carcinoembryonic antigen

CISS

Constructive interference in the steady state

CN

Cranial nerve

CRP

C-reactive protein

CSF

Cerebrospinal fluid

CT

Computed tomography, computed tomogram

CTA

CT angiography

DD

Differential diagnosis

DSA

Digital subtraction angiography

DWI

Diffusion-weighted imaging

ESR

Erythrocyte sedimentation rate

FESS

Functional endoscopic sinus surgery

FLAIR

Fluid-attenuated inversion recovery

FOV

Field of view

GE

Gradient echo

HBO

Hyperbaric oxygenation

HIV

Human immunodeficiency virus

HLA

Human leukocyte antigen

HTLV

Human T-cell leukemia virus

HU

Hounsfield unit

ICA

Internal carotid artery

I.v.

Intravenous

IU

International unit

MALT

Mucosa-associated lymphoid tissue

MEN

Multiple endocrine neoplasia

MIBI

Methoxyisobutylisonitrile

MPR

Multiplanar reformatting

MRA

MR angiography

MRI

Magnetic resonance imaging/image

NHL

Non-Hodgkin lymphoma

PD

Proton density

PET

Positron emission tomography

PRIND

Prolonged reversible ischemic neurologic deficit

SAPHO

Synovitis, acne, palmoplantar pustulosis, hyperostosis, osteitis

SPECT

Single photon emission computed tomography

SPIR

Spectral presaturation inversion recovery

STIR

Short tau inversion recovery

T3

Triiodothyronine

T4

Tetraiodothyronine (thyroxine)

Tc

Technetium

TIA

Transient ischemic attack

TSH

Thyroid-stimulating hormone

USPIO

Ultra-small particles of iron oxide

WHO

World Health Organization

YAG

Yttrium aluminum garnet (laser medium)

1 Skull Base

Hyperostosis frontalis

Definition

Epidemiology

Prevalence of 5–10% Common in women (up to 40%).

Etiology, pathophysiology, pathogenesis

Thickening of the inner table of the calvarium, usually irregular, and mainly affecting the frontal bone Benign variant Uncertain etiology Associated with a number of syndromes and endocrine disorders (e.g., Morgagni syndrome, Stewart–Morel syndrome) Increased prevalence in elderly people with diabetes.

Imaging Signs

Modality of choice

CT.

CT findings

Irregular, sometimes nodular, thickening of the inner table of the calvarium Bone structure is otherwise intact No destruction or matrix changes.

MRI findings

Calvarium thickened and hyperintense because of the fatty content of the diploë.

Pathognomonic findings

Irregular, nodular thickening of the inner table of the calvarium.

Clinical Aspects

Typical presentation

Almost always an incidental finding May occur in various syndromes and endocrine disorders Sometimes accompanied by headache due to a different cause.

Treatment options

None.

Course and prognosis

Benign variant.

What does the clinician want to know?

Exclusion of other differential diagnoses.

Fig. 1.1 a–d A 70-year-old woman presented with left-sided headache. General hyperostosis on axial T2-weighted images (a). Conventional radiography (b) shows irregular thickening of the calvarium. Coronal CT (c) and T1-weighted images (d) present thickened inner table of calcarium.

Differential Diagnosis

Fibrous dysplasia

– Replacement of bone by fibro-osseous tissue, chiefly in the medullary cavity, causing bone expansion

Paget disease

– Usually bilateral

– Mixed osteolytic-osteoplastic new bone formation

Skeletal metastases

– For example, osteosclerotic metastases from breast or prostatic tumors

– History

– Scintigraphy

Hyperparathyroidism

– Hypercalcemia

– Concomitant, symmetrical thickening of other bone structures

“Brush skull” appearance

– Clinical manifestations (thalassemia)

– Medullary hyperplasia with radial densities in the expanded diploë and outer table

Tips and Pitfalls

Hyperostosis frontalis may be difficult to distinguish from a thin subdural hematoma based on its MRI features Resolve doubts by obtaining CT scans.

Selected References

Chaljub G et al. Unusually exuberant hyperostosis frontalis interna: MRI. Neuroradiology 1999; 41(1): 44–45

Dihlmann W. Computerized tomography in typical hyperostosis cranii (THC). Eur J Radiol 1981; 1(1): 2–8

She R, Szakacs J. Hyperostosis frontalis interna. Ann Clin Lab Sci 2004; 34: 206–208

Arachnoid Cyst

Definition

Epidemiology

No age predilection 75% of cases are diagnosed in childhood Cyst is usually located at the cerebellopontine angle in close proximity to the brainstem (middle cranial fossa) 10% of lesions are in the posterior cranial fossa.

Etiology, pathophysiology, pathogenesis

Cystic intracranial or intraspinal mass delineated from the subarachnoid space by the arachnoid membrane.

Imaging Signs

Method of choice

MRI.

CT findings

Cerebellopontine angle mass that is isodense to CSF Does not enhance after contrast administration.

MRI findings

Well-circumscribed mass in proximity to the internal auditory canal with high signal intensity on T2-weighted images and low signal intensity on T1-weighted images Distinguishable from epidermoid by FLAIR (low signal intensity) and DWI (diffusivity not decreased, low signal intensity, high ADC) Does not enhance after gadolinium administration.

Pathognomonic findings

Mass isodense or isointense to CSF Complete signal suppression in FLAIR sequence No decrease in diffusivity on DWI.

Clinical Aspects

Typical presentation

Usually detected incidentally May cause headache, gait disturbance, hearing impairment.

Treatment options

Treatment is unnecessary in most cases Symptomatic cases are treated by surgical drainage (fenestration).

Course and prognosis

No enlargement over time Treatment necessary only in cases with pronounced symptoms Very good prognosis No tendency to recur.

What does the clinician want to know?

Diagnosis or differential diagnosis.

Fig. 1.2a–c Mass isointense to CSF in the right cerebellopontine angle of a 35-year-old man. FLAIR: decreased signal intensity (a). T2-weighted image: high signal intensity (b). DWI: high diffusivity, low signal intensity (c).

Differential Diagnosis

Epidermoid

– Signal intensity resembles a cerebellopontine angle mass on standard MRI sequences.

– Congenital cholesteatoma with intracranial extension

– Nonenhancing

– Decreased diffusivity, high signal intensity on DWI, low ADC

Cystic tumors (e.g., meningioma, schwannoma)

– Not completely isodense or isointense to CSF

– Focal enhancement after contrast or gadolinium administration

Tips and Pitfalls

Misdiagnosing the cyst as a tumor mass.

Selected References

Dutt SN et al. Radiologic differentiation of intracranial epidermoids from arachnoid cysts. Otol Neurotol 2002; 23(1): 84–92

Kollias SS et al. Cystic malformations of the posterior fossa: differential diagnosis clarified through embryologic analysis. Radiographics 1993; 13(6): 1211–1231

Osborn AG, Preece MT. Intracranial cysts: radiologic-pathologic correlation and imaging approach. Radiology 2006; 239: 650–664

(En)cephalocele

Definition

Epidemiology

1–3 in 10 000 births 80% of cephaloceles are occipital, 5–10% parietal and frontal.

Etiology, pathophysiology, pathogenesis

Extracranial protrusion of intracranial structures through a defect in the calvarium Meningoencephaloceles contain CSF, brain tissue, and meninges Meningoceles contain only meninges and CSF.

Causes:

– Skull base and spine: Failure of neural tube closure.

– Calvarium: Faulty growth induction of the bony calvarium.

Imaging Signs

Modality of choice

MRI.

CT findings

Bony defect with protrusion of CSF-filled meninges May contain brain tissue.

MRI findings

Extension of meninges through a calvarial defect with or without brain parenchyma.

Neural tube defects:

– Occipital encephalocele: Myelomeningocele.

– Parietal encephalocele: Midline anomalies such as agenesis of the corpus callosum and holoprosencephaly.

– Frontoethmoid encephalocele: No associated anomalies.

Pathognomonic findings

Prolapse of meningeal and cerebral structures through a bone defect.

Clinical Aspects

Typical presentation

Pulsatile mass in the occipital or midfacial region Possible respiratory difficulties or dysphagia Hypertelorism Neurologic abnormalities in patients with associated anomalies.

Treatment options

Surgical correction.

Course and prognosis

Good prognosis in the absence of associated anomalies Otherwise, prognosis depends on the surgical outcome and other neurologic problems.

What does the clinician want to know?

Diagnosis or differential diagnosis Associated anomalies.

Fig. 1.3a–d Frontobasal meningoencephalocele. The bone defect is visible on CT (a, b), which shows brain tissue protruding into the paranasal facial soft tissues (c). T2-weighted MR image (d) clearly differentiates between brain and meninges.

Differential Diagnosis

Epidermoid

– Fibrous connection with the subarachnoid space without a CSF fistula

– Extension to the expanded foramen cecum

– No extracranial brain tissue

Hemangioma, lymphangioma

– No bone defect, no extracranial brain tissue

Nasal glioma

– Tumor composed of astrocytes and neuroglia, communicates with the subarachnoid space

Tips and Pitfalls

Mistaking the cephalocele for a cystic or solid mass extrinsic to the neurocranium.

Selected References

Denoyelle F et al. Nasal dermoid sinus cysts in children. Laryngoscope 1997; 107(6): 795–800

Rahbar R et al. Nasal glioma and encephalocele: diagnosis and management. Laryngoscope 2003; 113(12): 2069–2077

Willatt JM et al. Calvarial masses of infants and children. A radiological approach. Clin Radiol 2004; 59(6): 474–486

Hedlund G. Congenital frontonasal masses: developmental anatomy, malformations, and MR imaging. Pediatr Radiology 2006; 36: 647–662

Fibrous Dysplasia

Definition

Epidemiology

Most common before 30 years of age (75%) 25% of cases involve the head and neck Monostotic in approximately 75% of cases.

Etiology, pathophysiology, pathogenesis

Replacement of bone marrow by very cellular connective tissue with irregular new bone formation Genetically determined increase in the proliferation of poorly differentiated cells Production of disorganized bone matrix McCune–Albright syndrome: Polyostotic form with hyperpigmentation and precocious puberty.

Imaging Signs

Modality of choice

CT.

CT findings

Ground-glass opacity in expanded bone Osteolytic features in cases with predominantly nonossified matrix (20%) Sclerotic lesions (25%) Normal appearance of the inner and outer tables.

MRI findings

Signal intensity usually low on T1- and T2-weighted images Possible inhomogeneous signal intensity on T1-weighted images Inhomogeneous enhancement after gadolinium administration Possible high signal intensity on T2-weighted images.

Pathognomonic findings

Ground-glass opacity in expanded bone.

Clinical Aspects

Typical presentation

May be detected incidentally Pain Circumscribed swelling Craniofacial asymmetry (especially with polyostotic involvement) Nerve compression syndrome Spontaneous fractures (e.g., of the mandible) Cherubism due to bilateral mandibular involvement (autosomal dominant inheritance).

Treatment options

Surgical removal or correction is indicated only in cases with a pathologic fracture or neurologic symptoms Radiotherapy is contraindicated, as it may promote malignant transformation!

Course and prognosis

Spontaneous regression may occur Lesions tend to stop growing after puberty (especially in the monostotic form).

What does the clinician want to know?

Diagnosis Course.

Fig. 1.4 Fibrous dysplasia of the maxilla, sphenoid, and clivus detected incidentally in a 12-year-old boy. Axial CT (left) and coronal reformation (right) show ground-glass opacity of the expanded bony structures.

Fig. 1.5 MR image from the same patient as in Fig. 1.4. The thickened and sclerosed parts of the bone show a signal void in all sequences (axial T2-weighted, left, and coronal FLAIR, right).

Differential Diagnosis

Paget disease

– Involves the temporal bone and calvarium but not the facial skeleton

– Inhomogeneous bone density

– Combination of osteosclerosis and lytic areas

Osteomyelitis

– Clinical symptoms

– History

Ossifying fibroma

– Thick bony rim

– Low density of medullary cavity

Tumors (e.g., giant cell tumor, eosinophilic granuloma)

– Usually show destructive growth

– May be indistinguishable from monostotic fibrous dysplasia

Tips and Pitfalls

Diagnosing a malignant tumor by MRI without taking CT scans (method of choice).

Selected References

Chong VF et al. Fibrous dysplasia involving the base of the skull. AJR Am J Roentgenol 2002; 178(3): 717–720

Kransdorf MJ et al. Fibrous dysplasia. Radiographics 1990; 10(3): 519–537

Shah ZK et al. Magnetic resonance imaging appearances of fibrous dysplasia. Br J Radiol 2005; 78: 1104–1115

Eosinophilic Granuloma

Definition

Epidemiology

Age range 5–20 years 60–80% of histiocytoses remain localized.

Hand–Schüller–Christian disease: Chronic disseminated form Prevalence of Hand–Schüller–Christian disease in histiocytosis: 14–40% Peak age incidence: third through fifth decades.

Abt–Letterer–Siwe disease: Acute disseminated form Rare Peak age incidence: first through third decades.

Etiology, pathophysiology, pathogenesis

Hereditary, infectious, and/or immunologic etiology Proliferation and infiltration of lipid-laden histiocytes (Langerhans cells) in various organs and tissues Subsequent inflammatory response.

Imaging Signs

Modality of choice

CT, gadolinium-enhanced MRI.

CT findings

Circumscribed osteolytic lesion not surrounded by a sclerotic rim Usually has ill-defined margins CT shows soft-tissue component that enhances after i.v. contrast administration.

MRI findings

Usually shows low signal intensity on T1- and T2-weighted images Possible high signal intensity on T2-weighted images Enhances after gadolinium administration.

Pathognomonic findings

Sharply circumscribed osteolytic lesion with a soft-tissue component.

Clinical Aspects

Typical presentation

Lesions are usually asymptomatic 50% are in the calvarium, 3% in the anterior skull base.

Hand-Schüller-Christian disease: Exophthalmos, diabetes insipidus, lytic calvarial lesion (10%), possible pain, swelling, fever.

Treatment options

Curettage and cancellous bone grafting of unifocal lesions May respond to cortisone, cytostatic agents, or low-dose radiation.

Course and prognosis

Eosinophilic granuloma is a benign tumor with a good prognosis (spontaneous regression) Curettage of spontaneous pathologic fractures Abt–Letterer–Siwe disease: Rapidly progressive course with fatal outcome.

What does the clinician want to know?

Confirmation of diagnosis.

Fig. 1.6 Well-circumscribed osteolytic lesion above the left orbit with an intensely enhancing soft-tissue component (CT).

Fig. 1.7 Intermediate signal intensity (T2-weighted) with an intensely enhancing tissue component after gadolinium administration (MR image of the same patient as in Fig. 1.6).

Differential Diagnosis

Bone tumors (e.g., Ewing sarcoma)

– Permeative osteolytic area with ill-defined margins

– Requires biopsy for histologic confirmation

Osteomyelitis

– History, clinical presentation

– Edematous area on MRI

Dermoid

– Expansile lesion with faint marginal sclerosis

Tips and Pitfalls

Failure to consider Ewing sarcoma in the differential diagnosis.

Meningioma

Epidemiology

Incidence of 2–3 per 100000 peryear 17% of all intracranial tumors 90% are supratentorial Peak age incidence at 40–50 years.

Etiology, pathophysiology, pathogenesis

Benign tumor composed of meningeal cells Genetic causes Association with neurofibromatosis type 2 Progesterone receptor positive.

Histologic classification (WHO):

– Approximately 90% are histologically benign.

– 5–7% atypical.

– 1–2% anaplastic.

Imaging Signs

Modality of choice

Gadolinium-enhanced MRI.

CT findings

Round or patchy mass in an extra-axial meningeal location 70–75% are hyperdense 20–25% contain calcifications Intense enhancement after i. v. contrast administration Possible bony reaction (hyperostosis) or demineralization Potential for extracranial tumor growth.

MRI findings

Isointense to brain on T1-weighted images with intense enhancement after gadolinium administration 60% have a dural “tail” Variable signal intensity on T2-weighted images.

Clinical Aspects

Typical presentation

Neurologic symptoms depend on lesion location Small meningiomas are often detected incidentally Headache Olfactory impairment Ophthalmoplegia.

Treatment options

Surgical resection Stereotactic radiation may be an option, depending on location Preoperative embolization may be considered (to occlude blood supply from middle meningeal artery).

Course and prognosis

Benign 5-year recurrence rate from 5–7% (benign meningiomas) to 75% (anaplastic meningiomas).

What does the clinician want to know?

Diagnosis Extent Relation to neighboring structures (e.g. venous sinuses).

Fig. 1.8 Frontobasal meningioma shows intense enhancement after gadolinium administration. The images show a substantial intracranial mass in the skull base.

Differential Diagnosis

Schwannoma

– No dural tail

– High T2-weighted signal intensity

Metastasis

– Bone destruction

– No dural tail

– High T2-weighted signal intensity

Esthesioneuroblastoma

– Location

– Penetrates the cribriform plate and invades ethmoid cells

Tips and Pitfalls

Misdiagnosing meningioma as metastasis or malignant tumor.

Selected References

Laine FJ et al. CT and MR imaging of the central skull base. Part 2. Pathologic spectrum. Radiographics 1990; 10(5): 797–821

Macdonald AJ et al. Primary jugular foramen meningioma: imaging appearance and differentiating features. AJR Am J Roentgenol 2004; 182(2): 373–377

Turowski B et al. Interventional neuroradiology of the head and neck. Neuroimaging Clin N Am 2003; 13(3): 619–645

Clivus Chordoma

Definition

Epidemiology

Constitutes 3–4% of all primary bone tumors Peak age incidence 50–70 years 35 % located at the skull base.

Etiology, pathophysiology, pathogenesis

Locally destructive midline tumor Originates from cell rests of primitive notochord Myxoid matrix around undifferentiated vacuolated cells.

Imaging Signs

Modality of choice

Gadolinium-enhanced MRI.

CT findings

Areas of low attenuation in bone and surrounding soft tissue Bone destruction (95%) Intratumoral calcifications (50%) and bone fragments Moderate enhancement after contrast administration.

MRI findings

Low signal intensity on T1-weighted images with marked enhancement after gadolinium administration High T2-weighted signal intensity Inhomogeneities due to calcifications and intratumoral hemorrhage.

Pathognomonic findings

Destructive, enhancing midline lesion with an extraosseous component.

Clinical Aspects

Typical presentation

Headache Pain Diplopia Cranial nerve symptoms.

Treatment options

Surgical removal combined with stereotactic radiation.

Course and prognosis

Grows slowly Rarely metastasizes High rate of recurrence after surgical removal alone 5-year recurrence rate of 30–45% after proton beam therapy Recurrent disease has 5-year survival rate of 5%.

What does the clinician want to know?

Diagnosis Extent and relation to neighboring structures (e.g., internal carotid artery and cavernous sinus).

Fig. 1.9 Extensive midline tumor with typical signal characteristics: high T2-weighted signal intensity and intense, homogeneous enhancement after gadolinium administration (T1-weighted).

Differential Diagnosis

Chondrosarcoma

– Located at the petro-occipital fissure

Metastasis

– Similar imaging appearance, but midline occurrence rare

Plasmacytoma

– Possible bone destruction in the clivus

– Low T2-weighted signal intensity

Tips and Pitfalls

Misdiagnosing as a metastasis (note relation of lesion to midline).

Selected References

Erdem E et al. Comprehensive review of intracranial chordoma. Radiographics 2003; 23(4): 995–1009

Soo MY. Chordoma: review of clinicoradiological features and factors affecting survival. Australas Radiol 2001; 45(4): 427–434

St Martin M et al. Chordomas of the skull base: manifestations and management. Curr Opin Otolaryngol Head Neck Surg 2003; 11(5): 324–327

Esthesioneuroblastoma

Definition

Epidemiology

Peak age incidence at 30–50 years 16–33% of all paranasal sinus tumors at this age 2% of all malignant paranasal sinus tumors.

Etiology, pathophysiology, pathogenesis

Neuroendocrine malignancy Arises from the olfactory nerve or olfactory epithelium (olfactory neuroblastoma). Kadish stages:

Type A: Tumor in the nasal cavity.

Type B: Spread to the paranasal sinuses.

Type C: Additional spread.

Imaging Signs

Modality of choice

Gadolinium-enhanced MRI.

CT findings

Homogeneous mass of soft-tissue attenuation Marked enhancement after contrast administration Possible calcifications Bone destruction in the anterior skull base.

MRI findings

Intermediate signal intensity in all sequences Homogeneous enhancement after gadolinium administration T2 weighting clearly discriminates tumor from retained secretions Possible cystic lesions in intracranial portion.

Pathognomonic findings

Bell-shaped tumor extending through the cribriform plate into the ethmoid cells and the nasal cavity.

Clinical Aspects

Typical presentation

Unilateral intranasal mass Possible nasal airway obstruction Epistaxis Pain.

Treatment options

Surgical removal May be supplemented by radiation or chemotherapy.

Course and prognosis

Five-year survival rate is stage dependent: 75–80% for Kadish type A, 68% for type B, 41 % for type C Resection is curative in 90% of cases 20% recurrence rate after 8 years.

What does the clinician want to know?

Diagnosis Tumor extent.

Fig. 1.10a–c Esthesioneuroblastoma: T1-weighted image (a) shows a hypointense midline tumor that enhances intensely after gadolinium administration (b). Inhomogeneous signal intensity on T2-weighted image (c).

Fig. 1.11 Extensive esthesioneuroblastoma with destruction of the bony skull base. CT also shows intense enhancement after contrast administration.

Differential Diagnosis

Paranasal sinus carcinoma

– May be indistinguishable from esthesioneuroblastoma, depending on location

Olfactory meningioma

– Dural tail

– Rarely invades the nasal cavity or sinuses

Tips and Pitfalls

A high midline tumor of the paranasal sinuses should always raise suspicion of esthesioneuroblastoma.

Selected References

Bradley PJ et al. Diagnosis and management of esthesioneuroblastoma. Curr Opin Otolaryngol Head Neck Surg 2003; 11(2): 112–118

Loevner LA et al. Imaging of neoplasms of the paranasal sinuses. Magn Reson Imaging Clin N Am 2002; 10(3): 467–493

Pickuth D et al. Computed tomography and magnetic resonance imaging features of olfactory neuroblastoma: an analysis of 22 cases. Clin Otolaryngol 1999; 24(5): 457–461

2 Petrous Bone

Pneumatization of the Petrous Apex

Definition

Epidemiology

Present in approximately one-third of the population Asymmetrical pneumatization occur in 5 % Fluid retention or aeration disturbance is found in 1 %.

Etiology, pathophysiology, pathogenesis

Pneumatized petrous apex Congenital anatomical variant.

Imaging Signs

Modality of choice

CT, MRI.

CT findings

Asymmetrical pneumatization of the petrous apex (resembles the mastoid) Aeration disturbance, fluid retention, or fatty infiltration will opacify the cells and result in a normal appearance with an intact trabecular structure.

MRI findings

Low signal intensity on T1- and T2-weighted images High T2-weighted signal intensity in cases of fluid retention Increasing T1-weighted signal intensity indicates increasing protein content DD: asymmetrical fatty infiltration.

Pathognomonic findings

Honeycomb structure of pneumatized petrous apex Fatty infiltration causes high T1- and T2-weighted signal intensities on MRI with no associated mass.

Clinical Aspects

Typical presentation

No clinical complaints Incidental finding.

Treatment options

Treatment is unnecessary.

Course and prognosis

Good.

What does the clinician want to know?

Mass or anatomical variant.

Differential Diagnosis

Cholesterol granuloma

– Mass with high T1- and T2-weighted signal intensity

– No enhancement after gadolinium administration

Epidermoid, mucocele

– Elliptical mass

– Low T1-weighted signal intensity

– No enhancement after gadolinium administration

Tumors

– Mass with low T1-weighted signal intensity

– Moderate enhancement after gadolinium administration

Fig. 2.1 Bilateral pneumatization of the petrous apex. CT appearance resembles the aerated trabecular structure of the normal mastoid.

Fig. 2.2a–c Asymmetrical fatty infiltration of the petrous apex. Detected incidentally on MRI based on the high signal intensity in the T1-weighted (a) and T2-weighted (b) images. CT (c) shows normal bony structure with fat-equivalent attenuation values and no mass lesion.

Tips and Pitfalls

Presumptive diagnosis of cholesterol granuloma or tumor in the absence of mass effect Accurate differentiation may require CT scans (intact trabecular structure!) in addition to MRI and/or follow-up.

Selected References

Greess H et al. CT und MRT des Felsenbeins. HNO 2002; 50(10): 906–919

Moore KR et al. ‘Leave me alone’ lesions of the petrous apex. AJNR Am J Neuroradiol 1998; 19(4): 733–738

Yetiser S et al. Abnormal petrous apex aeration. Review of 12 cases. Acta Otorhinolaryngol Belg 2002; 56: 65–71

Otosclerosis, Otospongiosis

Definition

Epidemiology

Present in approximately 1% of the population Autosomal dominant mode of inheritance Female predominance (approximately two thirds) Bilateral occurrence in 80–85% of cases.

Etiology, pathophysiology, pathogenesis

Osteodystrophy of the labyrinth Etiology uncertain Replacement of endochondral bone persisting in the petrous bone by cancellous (spongy) bone, which progressively calcifies to form plaques (“spongiosis”) Fenestral otosclerosis is more common (approximately 85%) than the cochlear or retrofenestral form (approximately 15%) The cochlear form almost always coexists with fenestral sclerosis.

Imaging Signs

Modality of choice

CT (high-resolution).

CT findings

Circumscribed, usually punctate elliptical lucency in the petrous bone, starting at the anterior rim of the oval window Cochlear, circumscribed, curved, or semicircular hypodense area in the bone Later, progressive ossification of the oval window.

MRI findings

May show slightly increased signal intensity on T2-weighted images Active disease (with bone transformation) may show punctate foci of enhancement after gadolinium administration.

Pathognomonic findings

Circumscribed hypodensity of the petrous bone at the anterior rim of the oval window or around the cochlea.

Clinical Aspects

Typical presentation

Conductive hearing loss (fenestral type) Sensorineural hearing loss (cochlear type) Fenestral and cochlear types may coexist Tinnitus.

Treatment options

Stapedioplasty.

Course and prognosis

Usually the progression of hearing loss cannot be halted or reversed.

What does the clinician want to know?

Diagnosis DD: other possible causes of hearing loss or tinnitus.

Fig. 2.3 Otosclerosis with ill-defined spongy area near the cochlea, with increased sclerosis of the oval window.

Differential Diagnosis

Fibrous dysplasia

– Homogeneous “ground-glass” density increased throughout the petrous bone

– Increased density may spare the inner ear

Paget disease

– Diffuse involvement of the skull base in patients with mono- or polyostotic disease

– Combination of bone destruction and repair (foci of increased and decreased density)

Postinflammatory new bone formation

– Not confined to the oval window

Otosyphilis

– Diffuse, permeative osteolytic foci

Tips and Pitfalls

Subtle lesions anterior to the oval window may be missed.

Selected References

Grampp S et al. CT und MRT erworbener Veränderungen des Innenohrs und Kleinhirnbrückenwinkels. Radiologe 2003; 43(3): 213–218

Weissman JL et al. Imaging of tinnitus: a review. Radiology 2000; 216(2): 342–349

Petrous Bone Anomalies

Definition

Epidemiology

Meatal atresia: 1:3300–1:10000 births Usually an isolated anomaly.

Etiology, pathophysiology, pathogenesis

Congenital malformations of the external auditory canal or inner ear Genetically determined Triggered by infection or drug toxicity (e.g., thalidomide) Disruption of normal inner ear development (invagination of the otic pit to form the otocyst in the petrous bone; the otocyst later undergoes medial and ventral elongation and evagination to form the semicircular ducts and cochlea).

Imaging Signs

Modality of choice

CT (high-resolution).

CT findings

Meatal atresia: Area of soft-tissue or bone attenuation occluding the external auditory canal, with normal appearance of the inner ear.

Inner ear malformation: Cochlear aplasia Mondini malformation (incomplete cochlear development with a decreased number of turns, possible associated semicircular canal anomaly) Goldenhar syndrome (posterior superior semicircular canal only, expanded lymphatic duct) Vestibular aqueduct syndrome (enlarged endolymphatic sac) Michel dysplasia (complete failure of inner ear development, rare).

MRI findings

High-resolution steady-state sequences (e.g., CISS) Fluid-filled inner ear structures show an anomalous configuration (e.g., cystic cochlea, absent semicircular canals) Important: Define the internal auditory canal and its structures (vestibulocochlear nerve).

Important structures to evaluate: Superior, posterior, and lateral (horizontal) semicircular canals Cochlea (2.5 turns) Normal position and shape of the ossicular chain Normal external auditory canal.

Pathognomonic findings

Occlusion of the external auditory canal by soft tissue or bone Mondini malformation: Cystic cochlea with missing turns Goldenhar syndrome: Only one semicircular canal.

Clinical Aspects

Typical presentation

Sensorineural hearing loss Secondary delay of speech development Microtia.

Treatment options

Cochlear implant.

What does the clinician want to know?

Diagnosis Meatal atresia: Normal inner ear development (ossicular chain, cochlea)? Normal development of neural structures?

Fig. 2.4 CT scan of the right petrous bone in a 6-year-old child shows severe inner ear dysplasia and a cystic cochlea.

Tips and Pitfalls

High-resolution thin-slice CT scanning should not be omitted.

Selected References

Bamiou DE et al. Temporal bone computed tomography findings in bilateral sensorineural hearing loss. Arch Dis Child 2000; 82(3): 257–260

Benton C et al. Imaging of congenital anomalies of the temporal bone. Neuroimaging Clin N Am 2000; 10(1): 35–53

Graham JM et al. Congenital malformations of the ear and cochlear implantation in children: review and temporal bone report of common cavity. J Laryngol Otol Suppl 2000; 25: 1–14

Fig. 2.5a–d A 13-year-old boy with Goldenhar syndrome. Axial CT scans (a, b)