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 continuously improved upon by countless contributing members. Our dedicated editors oversee each edit for accuracy and style. Find out more about articles.
64 results found
Article
Harris ring
A Harris ring is a ring-like shadow observed at the base of the odontoid process on a lateral radiograph of the cervical spine. It is formed by the superimposition of the lateral masses of the C2 vertebra (axis) on its body.
Disruption of the Harris ring is seen in type III, and less commonly, ...
Article
H-shaped vertebra
H-shaped vertebrae, also known as Lincoln log vertebrae, are a characteristic finding of sharply delimited central endplate depression, classically seen in approximately 10% of patients with sickle cell disease, and results from microvascular endplate infarction (Figure 1) 3.
It may occasionall...
Article
Baastrup disease
Baastrup disease or syndrome (also referred to as kissing spines) is a cause of low back pain characterized by interspinous bursitis and other degenerative changes of the bones and soft tissues where adjacent spinous processes in the lumbar spine rub against each other.
Epidemiology
It tends t...
Article
Collar sign in spondylolysis
The Collar sign in spondylolysis refers to a break in the pars interarticularis of the vertebra on oblique radiographs that can have the appearance of a collar around the Scotty dog's neck.
unilateral or bilateral
90% seen at the L5 level and less than10% noted at the L4 level1,2
65% of patie...
Article
Fleck sign (foot)
The fleck sign in the foot is a small bony fragment seen in the Lisfranc space (between the base of the 1st and 2nd metatarsal) associated with avulsion of the Lisfranc ligament (at the base of the 2nd metatarsal or the medial cuneiform). It is a very subtle, but important finding since it predi...
Article
Powers ratio
The 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 spi...
Article
Dagger sign (spine)
The dagger sign is a radiographic feature seen in ankylosing spondylitis as a single central radiodense line on frontal radiographs related to ossification of the supraspinous and interspinous ligaments secondary to enthesitis 1. It is possible for the radiodense line to extend into the sacrum 2...
Article
Toothpaste sign
The toothpaste sign in spinal imaging represents an extrusion of an intervertebral disc into the epidural space. It is called after the shape of extruded material relatively to the parent disc in a sagittal plane.
Article
Vertebral body squaring (differential)
Vertebral body squaring refers to the loss of normal concavity of the anterior border of the vertebral body. It is seen in a variety of conditions, some of which are listed below.
Differential diagnosis
Ankylosing spondylitis
Ankylosing spondylitis is the most common cause of vertebral body ...
Article
Bullet-shaped vertebra
Bullet-shaped vertebra, also known as ovoid vertebra, refers to the anterior beaking of the vertebral body.
It is seen in the following conditions:
mucopolysaccharidosis (Morquio disease, Hurler disease)
achondroplasia
congenital hypothyroidism
progressive pseudorheumatoid dysplasia 4
Wils...
Article
Corduroy sign (vertebral hemangioma)
The corduroy sign refers to vertically-oriented, thickened trabeculae seen in intraosseous hemangiomas of the spine. It is the sagittal and coronal equivalent of the polka-dot sign seen on axial imaging.
It is caused by the replacement of the normal cancellous bone by thickened vertical trabec...
Article
Rim sign (spinal cord metastasis)
The rim sign has been described as a helpful MRI sign of spinal cord metastases, enabling them to be distinguished from other enhancing spinal cord lesions (e.g. ependymoma and astrocytoma).
Radiographic features
MRI
The rim sign is seen on sagittal post contrast T1 weighted imaging of the s...
Article
Flame sign (spinal cord metastasis)
The flame sign has been described as a helpful MRI sign of spinal cord metastases, enabling them to be distinguished from other enhancing spinal cord lesions (e.g. ependymoma, astrocytoma and hemangioblastoma) 1.
Radiographic features
MRI
The flame sign is seen on sagittal post contrast T1 w...
Article
Y sign (epidural lipomatosis)
The Y sign refers to a common appearance in lumbar epidural lipomatosis where excess fat in the extradural space compresses the dural sac into the shape of the letter "Y".
NB: Y sign also refers to the appearance of incudomalleolar disarticulation on CT, more commonly known to radiologists as t...
Article
Sugar coating
So-called "sugar coating" or zuckerguss (German for sugar icing) refers to the appearance of diffuse linear/sheetlike leptomeningeal contrast enhancement in the brain or spinal cord due to drop metastases or leptomeningeal carcinomatosis. It is seen both as a result of CNS involvement from dista...
Article
Inverted Napoleon hat sign
The inverted Napoleon hat sign is a radiologic sign seen on the frontal pelvic or lumbar radiograph at the level of the 5th lumbar vertebra and the sacrum.
It is seen when there is bilateral spondylolysis with marked anterolisthesis of L5 on S1 or marked exaggeration of the normal lordosis at t...
Article
Scimitar (disambiguation)
The term scimitar, referring to the characteristic shape of the Middle Eastern sword, may refer to the following:
scimitar syndrome (lungs)
scimitar sign (cystic adventitial disease)
scimitar sacrum (bones)
Article
Curtain sign (vertebral body mass)
The curtain sign, also known as the draped curtain sign, in neuroimaging refers to the appearance of a vertebral body mass that extends posteriorly towards the anterior epidural space.
The posterior longitudinal ligament is strongly attached to the posterior vertebral body cortex in the midline...
Article
Meniscus sign (myelography)
The meniscus sign refers to the intradural filling defect which is outlined by the sharp meniscus of intrathecal contrast due to blockage of subarachnoid space by an intradural lesion. The CSF above the blocked segment remains unopacified.
Article
H sign (spinal cord)
The H sign is a radiological sign appreciated on MRI spine that is classically described in patients with myelin oligodendrocyte glycoprotein antibody-associated disease (MOGAD).
The sign describes the involvement of spinal cord grey matter as seen on axial T2 sequences in patients with myelit...
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