Articles

Articles are a collaborative effort to provide a single canonical page on all topics relevant to the practice of radiology. As such, articles are written and edited by countless contributing members over a period of time. A global group of dedicated editors oversee accuracy, consulting with expert advisers, and constantly reviewing additions.

58 results found
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Abscess

Abscesses are focal confined collections of suppurative inflammatory material and can be thought of as having three components 1: a central core consisting of necrotic inflammatory cells and local tissue peripheral halo of viable neutrophils surrounded by a 'capsule' with dilated blood vessel...
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Anterior vertebral body beaking

Anterior vertebral body beaking occurs in a number of conditions and may eminate from the central portion or the lower third of the vertebral body. Middle third Morquio syndrome 1 (middle for Morquio) Lower third Hurler syndrome 2 achondroplasia 3 pseudoachondroplasia 4 cretinism 5 Down ...
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Atlantodental interval

The atlantodental interval (ADI), as the name suggests, is the horizontal distance between the anterior arch of the atlas and the dens of the axis, used in the diagnosis of atlanto-occipital dissociation injuries and injuries of the atlas and axis. It is the distance (in mm) between the posteri...
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Basilar invagination

Basilar invagination, also called basilar impression, is a congenital or acquired craniocervical junction abnormality where the tip of the odontoid process projects above the foramen magnum.  Terminology The terms basilar invagination and basilar impression are often used interchangeably becau...
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Basion-axial interval

The basion-axial interval (BAI), as the name suggests, is the horizontal distance between the basion and the posterior cortex of the axis, used in the diagnosis of atlanto-occipital dissociation injuries. It is the distance (in mm) between the basion and the superior extension of the posterior ...
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Basion-dens interval

The basion-dens interval (BDI), as the name suggests, is the distance between the basion and the tip of the dens, used in the diagnosis of atlanto-occipital dissociation injuries. It is the distance from the most inferior portion of the basion to the closest point of the superior aspect of the ...
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Bone within a bone appearance

Bone within a bone is a descriptive term applied to bones that appear to have another bone within them. There are numerous causes including: normal thoracic and lumbar vertebrae (neonates and infants) growth recovery lines (after infancy) cortical splitting and new periostitis sickle cell d...
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Boogards angle

Boogards angle is measured by drawing a line from basion to opisthion and another line along the plane of the clivus to the basion intersecting the first line - the angle between these two lines is measured . The normal angle is 126+/- 6°. If the angle measures more than 136° it is indicative o...
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Cervical spine fractures

Cervical spine fractures can occur secondary to exaggerated flexion or extension, or because of direct trauma or axial loading. Pathology The cervical spine is susceptible to injury because it is highly mobile with relatively small vertebral bodies and supports the head which is both heavy and...
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Chalk stick fracture

Chalk stick or carrot stick fractures are fractures of a fused spine, classically seen in ankylosing spondylitis. Terminology Some authors define the chalk stick fracture as a fracture through a Pagetoid long bone (see Paget disease). Pathology They usually occur through the disco-vertebral ...
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Chamberlain line

Chamberlain line is a line joining the back of hard palate with the opisthion on a lateral view of the craniocervical junction. Significance It helps to recognise basilar invagination which is said to be present if the tip of the dens is >3 mm above this line. McGregor developed a modificatio...
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Chance fracture

Chance fractures, also referred as seatbelt fractures, are flexion-distraction type injuries of the spine that extend to involve all three spinal columns. These are unstable injuries and have a high association with intra-abdominal injuries. Pathology Mechanism They tend to occur from a flexi...
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Coronal vertebral cleft

Coronal vertebral cleft refers to the presence of a radiolucent vertical defect on a lateral radiograph.   Epidemiology It is most often seen in premature male infants 1,3. As they can occur as part of normal variation (especially in the lower thoracic-upper lumbar spine of premature infants) ...
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Craniovertebral junction anomalies

Craniovertebral junction (CVJ) anomalies can be congenital, developmental or due to malformation secondary to any acquired disease process. These anomalies can lead to cranial nerve compression, vertebral artery compression and obstructive hydrocephalus. Pathology  The cranio-vertebral junctio...
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Diffuse T1 bone marrow signal loss

Diffuse T1 vertebral bone marrow signal loss has a number of causes. T1-weighted imaging without fat suppression is one of the most important sequences for distinguishing between normal and abnormal bone marrow. Given the homogeneity, this appearance can often be difficult to spot as abnormal. ​...
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Diffusely increased bone marrow FDG uptake

A diffuse homogeneous bone marrow FDG uptake usually reflects hyperplastic bone marrow which can be seen in the following conditions: therapy-related granulocyte colony stimulating factor (G-CSF) post-chemotherapy erythropoietin pathological process myelodysplastic syndromes beta thalasse...
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Dural ectasia

Dural ectasia refers to ballooning or widening of the dural sac which can result in posterior vertebral scalloping and is associated with herniation of nerve root sleeves. Clinical presentation Patients with dural ectasia may present with low back pain or radicular pain in the buttocks or legs...
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Erosion of the odontoid process (differential)

Erosion of the odontoid peg can result from a number of pathological entities: inflammatory arthropathy rheumatoid arthritis: classic 1-2 systemic lupus erythematosus crystal arthropathy calcium pyrophosphate arthropathy (CPPD): relatively common gout non-inflammatory arthropathy: osteoar...
Article

Extension tear drop fracture

Extension tear drop fracture typically occurs due to forced extension of the neck with resulting avulsion of the anteroinferior corner of the vertebral body. Extension teardrop fractures are stable in flexion, and unstable in extension as the anterior longitudinal ligament is disrupted. Extensio...
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Facet dislocation

Facet dislocation refers to anterior displacement of one vertebral body on another. Without a fracture, the only way anterior displacement can occur is by dislocation of the facets.  Facet dislocation can occur to varying degrees: subluxed facets perched facets locked facets The injury usua...
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Flexion tear drop fracture

Flexion tear drop fractures are the most severe fracture of the cervical spine, often causing anterior cervical cord syndrome and quadriplegia. Pathology Mechanism It typically occurs from severe flexion and compression forces, most commonly at C5-6 (e.g. diving head first, motor vehicle coll...
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Gibbus deformity

Gibbus deformity is a short-segment structural thoracolumbar kyphosis resulting in sharp angulation. Pathology There are a number of causes which can be divided into congenital and acquired. Congenital achondroplasia cretinism (congenital hypothyroidism) Apert syndrome Coffin-Lowry syndro...
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Haematomyelia

Haematomyelia refers to the presence of intramedullary haemorrhage or haematoma within the spinal cord. This is distinct from extramedullary haemorrhage, such as that seen in epidural haematomas. Although this can occur in the setting of trauma, the term is generally used to signify non-traumat...
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Hangman fracture

Hangman fracture, also known as traumatic spondylolisthesis of the axis, is a fracture which involves the pars interarticularis of C2 on both sides, and is a result of hyperextension and distraction. Clinical presentation Post-traumatic neck pain after a high-velocity hyperextension injury is ...
Article

Intervertebral disc calcification

Intervertebral disc calcification is seen with numerous conditions. degenerative: relatively common and may occur in up to 6% in routine abdominal radiographs in adults postoperative/traumatic ochronosis: very dense central (nucleus pulposus) calcification associated with osteopaenia; begins ...
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Intradural extramedullary spinal tumours

Intradural extramedullary neoplasms are located outside the spinal cord but within the dural sheath.  Clinical presentation The most common presenting symptoms include weakness, back pain and radicular pain. Pathology Schwannomas are the most common intradural extramedullary spinal lesions (...
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Intramedullary spinal metastasis

Intramedullary spinal metastases are rare, occurring in ~1% of autopsied cancer patients, and are less common than leptomeningeal metastases. Intramedullary lesions may result from: growth along the Virchow-Robin spaces haematogenous dissemination direct extension from leptomeninges Epidemi...
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Locked facet joint

Locked facet joint is a type of facet joint dislocation that results from jumping of the inferior articular process over the superior articular process of the vertebra below and becomes locked in the position. It can be unilateral or bilateral. Radiographic features Plain radiograph The tip ...
Article

Longitudinally extensive spinal cord lesion

Longitudinally extensive spinal cord lesions (LESCL), also known as longitudinally extensive transverse myelitis (LETM), represent extensive involvement of the spinal cord, with abnormal T2 signal traversing at least three vertebral body segments in length. Differential diagnosis They are typi...
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Loss of intervertebral disc space (differential)

Loss of intervertebral disc space can be due to a variety of causes: degenerative disc disease of the spine: most common cause trauma discitis neuropathic spondyloarthropathy dialysis related spondyloarthropathy ankylosing spondylitis ochronosis crystal deposition diseases sarcoidosis ...
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McRae line

McRae line is a radiographic line drawn on a lateral skull radiograph or midsagittal section of CT or MRI, joining the basion and opisthion. Normal position of the tip of dens is 5mm below this line. If the tip of the dens migrates above this line it indicates the presence of basilar invaginati...
Article

Meningocele

Meningoceles are protrusions of the meninges through a defect or weak point in the skull or spine, usually involving the soft tissues beneath the surface of the skin. They are typically categorized into congenital, iatrogenic (e.g. following a craniotomy, sinus surgery, or as a laminectomy compl...
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Neoplasms of the cauda equina (differential)

The differential diagnosis for masses of the cauda equina region is often considered separately to the remainder of the spinal cord. It is often difficult to determine whether masses in this region are intramedullary or intradural-extramedullary. Most common tumours myxopapillary ependymoma b...
Article

Osteoarthritis of the vertebral column

Osteoarthritis of the vertebral column, also known as spondylosis deformans, is common and usually merely referred to as spinal "degenerative change". Complications such as spinal stenosis are important to recognise.  Radiographic features The hallmark of osteoarthritis in the spine, as is the...
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Parasyndesmophytes

Parasyndesmophytes or floating syndesmophytes are, as the name suggests, paravertebral dystrophic soft tissue calcifications or heterotopic ossifications. Pathology They are known to be seen in psoriatic arthritis and reactive arthritis 4. Radiographic features Initially they begin at a dist...
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Powers ratio

Powers ratio is a measurement of the relationship of the foramen magnum to the atlas, used in the diagnosis of atlanto-occipital dissociation injuries. The ratio, AB/CD, is measured as the ratio of the distance in the median (midsagittal) plane between the: basion (A) and the posterior spinola...
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Primary bone tumours of the spine

The most common tumour of the spine is metastatic deposits. A number of both benign and malignant tumours may arise primarily from the spine. Benign osteoid osteoma osteoblastoma osteochondroma giant cell tumour (GCT) aneurysmal bone cyst (ABC) eosinophilic granuloma (EG) haemangioma Ma...
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Pseudosubluxation of the cervical spine

Pseudosubluxation of the cervical spine is the physiological anterior displacement of C2 on C3 in children. It is common in children <7 years, and less often present in older children. Less often it is seen at C3 on C4. It is more pronounced in flexion and is of clinical significance as it can b...
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Radiation induced MRI signal changes in bone

Radiation induced MRI signal changes in bone are the earliest detectable changes in bone. They increase with increase in the radiation dose. Pathology 1st week: decreased marrow cellularity with oedema and haemorrhage 2nd week: increased marrow cellularity due to influx from unirradiated area...
Article

Retropulsed fragment

A retropulsed fragment is any vertebral fracture fragment that is displaced into the spinal canal, thereby potentially causing spinal cord injury. They usually arise from the vertebral body with or without a portion of the pedicle, and are displaced posteriorly, hence the prefix 'retro'.
Article

Scheuermann disease

Scheuermann disease, also known as juvenile kyphosis, juvenile discogenic disease 11 or vertebral epiphysitis, is a common condition which results in kyphosis of the thoracic or thoracolumbar spine. The diagnosis is usually made on plain film. Epidemiology occurs in ~5% (range 0.4-8%) of the g...
Article

Scoliosis

Scoliosis is defined as an abnormal lateral curvature of the spine. It is quite common in young individuals and is often idiopathic and asymptomatic. In some cases, however, it is the result of underlying structural or neurological abnormalities.  By definition, a scoliosis is any lateral spina...
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Spinal cord compression

Spinal cord compression is a surgical emergency, usually requiring prompt surgical decompression to prevent permanent neurological impairment. Pathology Aetiology There are numerous causes of cord compression. These can be divided according to the location of the compressing mass: interverte...
Article

Spinal dysraphism

Spinal dysraphism is a broad term given to a group of anomalies where there are malformations in the dorsum of the embryo. Neural tube defects come under this group as well.  Pathology There is often abnormal fusion of the midline embryonic neural, vertebral and mesenchymal structures.  Sub t...
Article

Spinal epidural mass

The differential diagnosis for a spinal epidural mass includes: epidural metastasis epidural abscess herniated nucleus pulposus epidural haematoma epidural arteriovenous malformation epidural angiolipoma epidural lipomatosis
Article

Spinal fractures

Spinal fractures are usually the result of significant trauma to a normally formed skeleton, or the result of trauma to a weakened spinal column. Examples include: Jefferson fracture: ring fracture of C1 hangman fracture: bilateral pedicle or pars fracture of C2 dens fracture flexion teardro...
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Spinal metastases

Spinal metastases is a vague term which can be variably taken to refer to metastatic disease to any of the following:  vertebral metastases (94%) may have epidural extension intradural extramedullary metastases (5%) intramedually metastases (1%) Each of these are discussed separately. Below...
Article

Spinal synovial cyst

Synovial cysts of the spine are cystic formations connected to the facet joint and containing synovial fluid lined by a cuboid or pseudostratified columnar epithelium. They may be result in lumbar radiculopathy in a significant number of cases. Clinical presentation They may be asymptomatic an...
Article

Spinal vascular malformations

Spinal vascular malformations (SVM) are rare but knowledge of them is important as if undiagnosed and untreated they can lead to serious complications.  Pathology There are two main types of SVMs 1,2: spinal arteriovenous fistula (AVF): 70% of SVMs pial: small, large, or giant dural AVF (DA...
Article

Subluxed facet joint

Subluxed facet joint is the mildest form of facet dislocation in which the ligamentous injury leads to partial uncovering of facet joint (c.f. complete uncovering in perched facet). This results in mild anterior displacement of one vertebral body on another (anterolisthesis).
Article

Syndesmophyte

Syndesmophytes are calcifications or heterotopic ossifications inside a spinal ligament or of the annulus fibrosus.​ They are seen in only a limited number of conditions including:  ankylosing spondylitis ochronosis fluorosis Radiographic features Appearance on plain radiographs comprises v...
Article

Torticollis

Torticollis (wryneck) is a clinical finding of head tilt with or without rotational spinal malalignment. It is not a diagnosis in itself and there are a wide range of underlying conditions. It is most common in the paediatric age group.  Pathology Torticollis can be acute (<1 week) or chronic ...
Article

Traumatic spinal cord injury

Traumatic spinal cord injury (SCI) can manifest as a wide variety of clinical syndromes resulting from damage to the spinal cord or its surrounding structures. It can result from minor injury if the spine is weakened from disease such as ankylosing spondylitis or if there is pre-existing spinal ...
Article

Unilateral facet dislocation

Unilateral facet dislocation is a relatively stable type of facet dislocation. Pathology Mechanism Flexion/distraction associated with rotation. The inferior articular facet of vertebral above moves over the superior facet of the vertebral below and becomes locked. It usually affects C4-C5 or...
Article

Vertebra plana

Vertebra plana or pancake vertebra is the term given when a vertebral body has lost almost its entire height anteriorly and posteriorly, representing a very advanced crush fracture. It can occur with a variety of settings, including: trauma osteoporosis Langerhans cell histiocytosis (LCH) mo...
Article

Vertebral body mass

The differential diagnosis for a vertebral body mass is broad and may range from a completely benign, sclerotic enostosis (bone island) to a malignant primary bone tumour. Classification Broadly, these lesions can be separated into: non-neoplastic lesions primary bone tumours secondary meta...
Article

Vertebral scalloping

Vertebral scalloping is a concavity to the posterior (or less commonly anterior) aspect of the vertebral body when viewed in a lateral projection. A small amount of concavity is normal, as is concavity of the anterior vertebral body (see vertebral body squaring). Posterior scalloping Causes of...
Article

Winking owl sign (spine)

The (absent) pedicle sign, also called the winking owl sign, occurs on plain film when a pedicle is absent. The term, winking owl sign, where the missing pedicle corresponds to the closed eye, the contralateral pedicle to the other open eye, and the spinous process to the beak of the animal on ...

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