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.

41 results found
Article

Andersson lesion

Andersson lesions refer to an inflammatory involvement of the intervertebral discs by spondyloarthritis. Epidemiology Rheumatic spondylodiscitis is a non-infectious condition that has been shown to occur in about 8% of patients with ankylosing spondylitis, as detected at radiography. Patholog...
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Baastrup syndrome

Baastrup syndrome (also referred to as kissing spines) results from adjacent spinous processes in the lumbar spine rubbing against each other and resulting in hypertrophy and sclerosis with focal midline pain and tenderness relieved by flexion and aggravated by extension.  Epidemiology It tend...
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Bamboo spine

Bamboo spine is a radiographic feature seen in ankylosing spondylitis that occurs as a result of vertebral body fusion by marginal syndesmophytes. It is often accompanied by fusion of the posterior vertebral elements as well.  A bamboo spine typically involves the thoracolumbar and/or lumbosacr...
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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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Bullet-shaped vertebra

Bullet-shaped 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  See also weapons and munitions inspired signs
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Butterfly vertebra

Butterfly vertebra is a type of vertebral anomaly that results from the failure of fusion of the lateral halves of the vertebral body because of persistent notochordal tissue between them. Pathology Associations an anterior spina bifida, with or without an anterior meningocele can be part of...
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Corduroy sign (vertebral haemangioma)

The corduroy sign refers to vertically-oriented, thickened trabeculae seen in intraosseous haemangiomas of the spine. It is the sagittal/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 trabecula...
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Curtain sign

The curtain sign (or draped curtain sign) in neuroimaging refers to the appearance of a vertebral body mass that extends to the anterior epidural space. The posterior longitudinal ligament is strongly attached to the posterior vertebral body cortex in the midline and is more loosely attached la...
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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.
Article

Disc herniation

Disc herniation refers to the displacement of intervertebral disc material beyond the normal confines of the disc but involving less than 25% of the circumference (to distinguish it from a disc bulge. A herniation may contain nucleus pulposus, vertebral endplate cartilage, apophyseal bone/osteop...
Article

Dumbbell appearance of spinal tumours

The dumbbell appearance of spinal tumours refers to a tumour which has both a component within the canal and a component in the paravertebral space contiguous with each other via a thinner tumour component traversing the neural exit foramen. The appearance can be seen in: spinal nerve sheath t...
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Empty thecal sac sign

The empty thecal sac sign or empty sac sign is when the thecal sac appears empty on MRI of the lumbar spine, best seen on T2-weighted images. If the empty thecal sac sign is present, a diagnosis of adhesive arachnoiditis can be made.​ Radiographic features MRI There is usually no gadolinium c...
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Fluid sign (vertebral collapse)

The fluid sign is one of the radiological features of osteoporotic fractures, and can be helpful in distinguishing them from metastatic vertebral fractures, as it is seen more often in osteoporotic fractures and is rarely seen in metastatic fractures 1. It is not as helpful as identifying a para...
Article

Ghost vertebra

Ghost vertebra is a sign, that is generally used synonymously with bone-within-a-bone vertebra, and as such, the causes form a subset of those causing bone within a bone appearance 2: Thorotrast administration: bone within a bone appearance due to temporary growth arrest 1 stress line rickets...
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Haemosiderin cap sign

The haemosiderin cap sign refers to an MR imaging feature in some spinal tumours where a cap of T2 hypointense haemosiderin is above and/or below the tumour due to previous haemorrhage.  It is most often associated with spinal cord ependymomas, being seen in 20-33% of these cases 1. The sign, h...
Article

Honda sign (sacrum)

The Honda sign (H sign / H pattern) is a term used to describe the appearances of bilateral sacral insufficiency fractures on a radioisotope bone scan. Radiographic features Sacral insufficiency fractures are usually vertically through the sacral alae, paralleling the sacroiliac joint, often w...
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 anaemia, and results from microvascular endplate infarction (figure 1)3. It may occasionally...
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

Ivory vertebra sign

The ivory vertebra sign refers to diffuse and homogeneous increase in opacity of a vertebral body that otherwise retains its size and contours, and with no change in the opacity and size of adjacent intervertebral discs. Pathology Aetiology The cause for an ivory vertebra depends on the age o...
Article

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

Matterhorn sign

The Matterhorn sign is a descriptive sign for a calcified disc herniation that impales the dural sac and sometimes the cord, typically located in the thoracic spine. History and etymology The Matterhorn sign is named after one of the most iconic mountains in the Alps: the Matterhorn.
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Naked facet sign (vertebral column)

The naked facet sign (also known as the hamburger sign or reverse hamburger bun sign) refers to the CT appearance of an uncovered vertebral articular facet when the facet joint is dislocated, most often in cases of locked facet.  This CT sign is characteristic of a flexion-distraction injury an...
Article

Owl's eye sign

The owl's eye sign represents bilaterally symmetric circular to ovoid foci of high T2-weighted signals in the anterior horn cells of the spinal cord and is seen on axial MR imaging. The sagittal corollary is a "pencil-like" vertical linear high T2-weighted signal extending usually over a number ...
Article

Picture frame vertebral body

Picture frame vertebral body is a radiologic appearance in which the cortex of the vertebral body is thickened. This sign is seen in a patient with Paget disease.  This is a result of disorganised new cortical bone formation after excessive osteoclastic activity causes the resorption of normal ...
Article

Pine cone bladder

A pine cone bladder or christmas tree bladder is a cystogram appearance in which the bladder is elongated and pointed with thickened trabeculated wall. It is typically seen in severe neurogenic bladder with increased sphincter tone (detrusor sphincter dyssynergia) due to suprasacral lesions (abo...
Article

Polka-dot sign (vertebral haemangioma)

The polka-dot sign is the result of the replacement of the normal cancellous bone by thickened vertical trabeculae surrounded by fat marrow or vascular lacunae in vertebral intraosseous haemangiomas 2. It is the axial equivalent of the corduroy sign seen on sagittal and coronal images. On CT the...
Article

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...
Article

Romanus lesion

The Romanus lesion represents an early finding in inflammatory spondyloarthropathies, such as ankylosing spondylitis and enteropathic arthritis, and appears as irregularity and erosion involving the anterior and posterior edges of the vertebral endplates 1. Healing response to these inflammatory...
Article

Rugger-jersey spine

Rugger-jersey spine describes the prominent subendplate densities at multiple contiguous levels to produce an alternating sclerotic-lucent-sclerotic appearance. This simulates the transverse bands of a rugby jersey. This term and pattern are distinctive for hyperparathyroidism. Pathology In r...
Article

Sandwich vertebral body

Sandwich vertebral body is a radiologic appearance in which the endplates are densely sclerotic, giving the appearance of a sandwich. This term and pattern are distinctive for osteopetrosis. Differential diagnosis the sandwich vertebrae appearance resembles Rugger-jersey spine but can be diff...
Article

Scottie dog sign (spine)

The Scottie dog sign refers to the normal appearance of the lumbar spine when seen on oblique radiographic projection. On oblique views, the posterior elements of the vertebra form the figure of a Scottie dog with: the transverse process being the nose the pedicle forming the eye the inferior...
Article

Shiny corner sign (ankylosing spondylitis)

The shiny corner sign is a spinal finding in ankylosing spondylitis, representing reactive sclerosis secondary to inflammatory erosions at the superior and inferior endplates (corners on lateral radiograph) of the vertebral bodies which are known as Romanus lesions. Eventually, the vertebral bod...
Article

Snake-eye appearance (spinal cord)

Snake-eye appearance refers to symmetric bilateral T1 hypointensity/T2 hyperintensity of the anterior horn of the grey matter on axial cervical MRI, evocative of a pair of snake's eyes. It can be seen in late phase CT myelography, an all but forsaken technique, where it is also known as fried e...
Article

Sugar coating

The so-called "sugar coating" or zuckerguss (German for sugar icing) is seen in post-contrast images of the brain and spinal cord in patients with leptomeningeal drop metastases or leptomeningeal carcinomatosis. It is seen both as a result of CNS involvement from distant primaries as well as dir...
Article

Swischuk line

The Swischuk line is helpful in differentiating pathological anterior displacement of the cervical spine from physiological displacement, termed pseudosubluxation. Measurement the line is drawn from anterior aspect of posterior arch of C1 to anterior aspect of posterior arch of C3 the anterio...
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. It is seen in a variety of conditions including:  Differential diagnosis Ankylosing spondylitis Ankylosing spondylitis is the most common cause of vertebral body squaring. It usually involves multiple level...
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

Vertebra plana

Vertebra plana (a.k.a. pancake / silver dollar / coin-on-edge vertebra) is the term given when a vertebral body has lost almost its entire height anteriorly and posteriorly, representing a very advanced compression fracture. Plural is vertebrae planae. It can occur in a variety of settings, incl...
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 ...
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". 

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