Book contents
- Frontmatter
- Dedication
- Contents
- Preface
- Case 1 Dense basilar artery sign
- Case 2 Global anoxic brain injury
- Case 3 Acute infarction
- Case 4 Vertebral artery dissection
- Case 5 Subacute infarct
- Case 6 Subarachnoid hemorrhage
- Case 7 Intracranial aneurysms
- Case 8 Giant aneurysms
- Case 9 Acute intracerebral hematoma
- Case 10 Cerebral amyloid angiopathy
- Case 11 Primary CNS vasculitis
- Case 12 Reversible cerebral vasoconstriction syndrome
- Case 13 Moyamoya disease/syndrome
- Case 14 Cortical venous thrombosis
- Case 15 Developmental venous anomalies
- Case 16 Dural arteriovenous fistula
- Case 17 Cavernous malformation
- Case 18 Tumefactive demyelinating lesion
- Case 19 Acute disseminated encephalomyelitis
- Case 20 Progressive multifocal leukoencephalopathy
- Case 21 Osmotic myelinolysis
- Case 22 Neurosarcoidosis
- Case 23 Posterior fossa masses in children
- Case 24 Low-grade glioma
- Case 25 Diffuse intrinsic pontine glioma
- Case 26 Pseudoprogression of GBM
- Case 27 Pseudoresponse in treatment of GBM
- Case 28 Low-grade oligodendroglioma
- Case 29 Primary CNS lymphoma
- Case 30 Pineal region tumors
- Case 31 Intraventricular masses
- Case 32 Colloid cyst
- Case 33 Primary intraosseous meningioma
- Case 34 Suprasellar meningioma
- Case 35 Pituitary macroadenoma
- Case 36 Brain abscess
- Case 37 Neurocysticercosis
- Case 38 Tuberculosis
- Case 39 Creutzfeldt–Jakob disease
- Case 40 Herpes encephalitis
- Case 41 Wernicke’s encephalopathy
- Case 42 Hypertrophic olivary degeneration
- Case 43 Adrenoleukodystrophy
- Case 44 Mild traumatic brain injury
- Case 45 Isodense subdural hematoma
- Case 46 Posterior reversible encephalopathy syndrome
- Case 47 Late-onset adult hydrocephalus secondary to aqueductal stenosis
- Case 48 Intracranial hypotension
- Case 49 Idiopathic intracranial hypertension
- Case 50 Rathke’s cleft cyst
- Case 51 FLAIR sulcal hyperintensity secondary to general anesthesia
- Case 52 Virchow–Robin spaces
- Case 53 Arachnoid granulations
- Case 54 Benign external hydrocephalus
- Case 55 Pitfalls in CTA
- Case 56 Asymmetric pneumatization of the anterior clinoid process
- Case 57 Fibrous dysplasia of skull base
- Case 58 Sphenoid bone pseudolesion
- Case 59 Clival lesions
- Case 60 Perineural spread
- Case 61 Cochlear dysplasia
- Case 62 Labyrinthitis ossificans
- Case 63 Superior semicircular canal dehiscence
- Case 64 Fluid entrapment in the petrous apex cells
- Case 65 Acquired cholesteatoma
- Case 66 Malignant otitis externa
- Case 67 Temporal bone fractures
- Case 68 Allergic fungal sinusitis
- Case 69 Invasive fungal sinusitis
- Case 70 Spontaneous CSF leaks and sphenoid cephaloceles
- Case 71 Juvenile nasal angiofibroma
- Case 72 Idiopathic orbital pseudotumor
- Case 73 Optic neuritis
- Case 74 Intraparotid lymph nodes
- Case 75 Benign mixed tumor
- Case 76 First branchial cleft cyst
- Case 77 Nasopharyngeal cysts
- Case 78 Cystic nodal metastasis
- Case 79 Low-flow vascular malformations
- Case 80 Parapharyngeal masses
- Case 81 Third branchial apparatus anomaly
- Case 82 Parathyroid adenoma
- Case 83 String sign
- Case 84 Carotid artery dissection
- Case 85 Traumatic arterial injury
- Case 86 Craniovertebral junction injuries
- Case 87 Odontoid fractures
- Case 88 Vertebral compression fractures
- Case 89 Sacral insufficiency fracture
- Case 90 Paget’s disease of the spine
- Case 91 Renal osteodystrophy
- Case 92 Calcific tendinitis of the longus colli
- Case 93 T2 hyperintense disc herniation
- Case 94 Disc herniation and cord compression
- Case 95 Postoperative disc herniation versus postsurgical scarring
- Case 96 Degenerative endplate alterations
- Case 97 Spinal dysraphism
- Case 98 Tethered spinal cord
- Case 99 Chiari I malformation
- Case 100 Spinal vascular malformations
- Case 101 Cord compression
- Case 102 Demyelinating/inflammatory spinal cord lesion
- Case 103 Subacute combined degeneration
- Case 104 Intradural cyst
- Case 105 Spinal CSF leaks
- Case 106 Leptomeningeal drop metastases
- Index
Case 56 - Asymmetric pneumatization of the anterior clinoid process
Published online by Cambridge University Press: 18 December 2013
- Frontmatter
- Dedication
- Contents
- Preface
- Case 1 Dense basilar artery sign
- Case 2 Global anoxic brain injury
- Case 3 Acute infarction
- Case 4 Vertebral artery dissection
- Case 5 Subacute infarct
- Case 6 Subarachnoid hemorrhage
- Case 7 Intracranial aneurysms
- Case 8 Giant aneurysms
- Case 9 Acute intracerebral hematoma
- Case 10 Cerebral amyloid angiopathy
- Case 11 Primary CNS vasculitis
- Case 12 Reversible cerebral vasoconstriction syndrome
- Case 13 Moyamoya disease/syndrome
- Case 14 Cortical venous thrombosis
- Case 15 Developmental venous anomalies
- Case 16 Dural arteriovenous fistula
- Case 17 Cavernous malformation
- Case 18 Tumefactive demyelinating lesion
- Case 19 Acute disseminated encephalomyelitis
- Case 20 Progressive multifocal leukoencephalopathy
- Case 21 Osmotic myelinolysis
- Case 22 Neurosarcoidosis
- Case 23 Posterior fossa masses in children
- Case 24 Low-grade glioma
- Case 25 Diffuse intrinsic pontine glioma
- Case 26 Pseudoprogression of GBM
- Case 27 Pseudoresponse in treatment of GBM
- Case 28 Low-grade oligodendroglioma
- Case 29 Primary CNS lymphoma
- Case 30 Pineal region tumors
- Case 31 Intraventricular masses
- Case 32 Colloid cyst
- Case 33 Primary intraosseous meningioma
- Case 34 Suprasellar meningioma
- Case 35 Pituitary macroadenoma
- Case 36 Brain abscess
- Case 37 Neurocysticercosis
- Case 38 Tuberculosis
- Case 39 Creutzfeldt–Jakob disease
- Case 40 Herpes encephalitis
- Case 41 Wernicke’s encephalopathy
- Case 42 Hypertrophic olivary degeneration
- Case 43 Adrenoleukodystrophy
- Case 44 Mild traumatic brain injury
- Case 45 Isodense subdural hematoma
- Case 46 Posterior reversible encephalopathy syndrome
- Case 47 Late-onset adult hydrocephalus secondary to aqueductal stenosis
- Case 48 Intracranial hypotension
- Case 49 Idiopathic intracranial hypertension
- Case 50 Rathke’s cleft cyst
- Case 51 FLAIR sulcal hyperintensity secondary to general anesthesia
- Case 52 Virchow–Robin spaces
- Case 53 Arachnoid granulations
- Case 54 Benign external hydrocephalus
- Case 55 Pitfalls in CTA
- Case 56 Asymmetric pneumatization of the anterior clinoid process
- Case 57 Fibrous dysplasia of skull base
- Case 58 Sphenoid bone pseudolesion
- Case 59 Clival lesions
- Case 60 Perineural spread
- Case 61 Cochlear dysplasia
- Case 62 Labyrinthitis ossificans
- Case 63 Superior semicircular canal dehiscence
- Case 64 Fluid entrapment in the petrous apex cells
- Case 65 Acquired cholesteatoma
- Case 66 Malignant otitis externa
- Case 67 Temporal bone fractures
- Case 68 Allergic fungal sinusitis
- Case 69 Invasive fungal sinusitis
- Case 70 Spontaneous CSF leaks and sphenoid cephaloceles
- Case 71 Juvenile nasal angiofibroma
- Case 72 Idiopathic orbital pseudotumor
- Case 73 Optic neuritis
- Case 74 Intraparotid lymph nodes
- Case 75 Benign mixed tumor
- Case 76 First branchial cleft cyst
- Case 77 Nasopharyngeal cysts
- Case 78 Cystic nodal metastasis
- Case 79 Low-flow vascular malformations
- Case 80 Parapharyngeal masses
- Case 81 Third branchial apparatus anomaly
- Case 82 Parathyroid adenoma
- Case 83 String sign
- Case 84 Carotid artery dissection
- Case 85 Traumatic arterial injury
- Case 86 Craniovertebral junction injuries
- Case 87 Odontoid fractures
- Case 88 Vertebral compression fractures
- Case 89 Sacral insufficiency fracture
- Case 90 Paget’s disease of the spine
- Case 91 Renal osteodystrophy
- Case 92 Calcific tendinitis of the longus colli
- Case 93 T2 hyperintense disc herniation
- Case 94 Disc herniation and cord compression
- Case 95 Postoperative disc herniation versus postsurgical scarring
- Case 96 Degenerative endplate alterations
- Case 97 Spinal dysraphism
- Case 98 Tethered spinal cord
- Case 99 Chiari I malformation
- Case 100 Spinal vascular malformations
- Case 101 Cord compression
- Case 102 Demyelinating/inflammatory spinal cord lesion
- Case 103 Subacute combined degeneration
- Case 104 Intradural cyst
- Case 105 Spinal CSF leaks
- Case 106 Leptomeningeal drop metastases
- Index
Summary
Imaging description
Radiologists rely on symmetry of the paired anatomic structures when interpreting images of the brain and skull base. Pneumatization of the paranasal sinuses and mastoids is not always symmetric, however. While asymmetrically pneumatized cells are easy to characterize on CT, they may lead to diagnostic errors on MRI due to decreased conspicuity of bony landmarks (Figs. 56.1, 56.2). When a part of the skull base is not pneumatized it usually contains normal marrow (and surrounding cortical bone), which appears on MRI as a T1 hyperintense structure that may mimic an enhancing mass. Completely pneumatized cells are extremely hypointense on all pulse sequences and may mimic the flow void of an aneurysm when in close proximity to the vessels (Figs. 56.1, 56.3). Alternatively, a pneumatized air cell may develop mucosal inflammation that can create diagnostic confusion when asymmetric (Figs. 56.4, 56.5).
Importance
Erroneous calls made on MRI as a result of asymmetrically pneumatized cells are usually reversed by additional work-up. There is usually no harm inflicted other than unnecessary anxiety and cost. The radiologist’s reputation may be damaged irreversibly, however.
Typical clinical scenario
Since asymmetric pneumatization of air cells is merely an anatomic variation, no specific clinical presentation can be ascribed. These are frequently misinterpreted as aneurysms or mass lesions.
Differential diagnosis
The primary role of the radiologist in these cases is to make the diagnosis of a normal anatomic variant and not invoke a diagnostic work-up. The common locations for asymmetric pneumatization include the anterior clinoid and pterygoid processes of the sphenoid bone, and the petrous apices of the temporal bone. Non-pneumatized bone contains fatty marrow, which can be positively characterized by comparing the unenhanced T1-weighted images to the contrast-enhanced ones and making sure that the “lesion” follows the fat signal on all pulse sequences. Fat-suppressed images are not essential but very helpful in confirming the presence of fat. In differentiating an anterior clinoid process air cell from an aneurysm, knowledge of the precise location of this cell is important. When there is a true aneurysmone can also identify the anterior clinoid process next to it whether it is pneumatized or not.
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- Pearls and Pitfalls in Head and Neck and NeuroimagingVariants and Other Difficult Diagnoses, pp. 264 - 266Publisher: Cambridge University PressPrint publication year: 2013
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