The absent bow tie sign represents the loss of the normal appearance of the menisci on parasagittal MRI images and is suggestive of meniscal injury.
Normally the medial and lateral menisci appear as low signal bow-tie-shaped structures between the femoral condyles and tibial plateaux. As the no...
An Andersson lesion, also known as rheumatic spondylodiskitis, refer to an inflammatory involvement of the intervertebral discs by spondyloarthritis.
Rheumatic spondylodiskitis is a non-infectious condition that has been shown to occur in about 8% of patients with ankylosing spond...
Anomalous insertion of the medial meniscus (AIMM) is an anatomical variation of the insertion of the anterior root of the medial meniscus.
Defined as a congenital variation in the insertion of the anterior root of the medial meniscus onto the anterior cruciate ligament (ACL). The...
The anteater nose sign refers to an anterior tubular elongation of the superior calcaneus which approaches or overlaps the navicular on a lateral radiograph of the foot. This fancifully resembles the nose of an anteater and is indicative of calcaneonavicular coalition 1,2.
History and etymolog...
The anterior tibial translocation sign or anterior drawer sign (a.k.a. anterior translation of tibia) is seen in cases of complete rupture of the anterior cruciate ligament and refers to anterior translocation (anterior tibial subluxation) of the tibia relative to the femur of >7 mm 1. It measur...
The apple core sign has been described in two different pathologies:
apple core sign (colon)
apple core sign (femur)
The apple core sign has been used to describe the circumferential erosion of the femoral neck seen in synovial chondromatosis. Although this is the most common process that may lead to an apple core erosion of the femoral neck, this has also been observed with:
pigmented villonodular synovitis
The arcuate sign is often a subtle but important finding on knee x-rays and represents an avulsion fracture of the proximal fibula at the site of insertion of the arcuate ligament complex, and is usually associated with cruciate ligament injury (~90% of cases) 2. The fracture fragment is attache...
Many signs in radiology have been inspired by astronomical phenomena:
comet tail (disambiguation)
comet tail artifact (ultrasound)
color comet tail artifact
comet tail sign (chest)
comet tail sign (phleboliths)
galaxy sign (chest)
loss of half-moon overlap sign
Baastrup disease/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.
It tends to b...
Bamboo spine is a pathognomonic 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 an...
Bayonet deformity is a term used to describe the shape of the wrist in certain conditions:
hereditary multiple exostosis with pseudo-Madelung deformity
retarded bone growth of the distal ulna with outward bowing of the radius with distal radioulnar joint subluxation
The black line sign refers to a linear finding of the articular cartilage on magnetic resonance imaging initially seen the trochlear groove 1-3.
These lesions have been found also in all other regions of articular cartilage in the knee and not only on T2 weighted images but also in other sequen...
The blade of grass sign, also called the candle flame sign, refers to the lucent leading edge in a long bone seen during the lytic phase of Paget disease of bone.
The blade of grass sign is characteristic of Paget disease of bone. This is akin to osteoporosis circumscripta cranii seen in the s...
Bone marrow edema is the term given to abnormal fluid signal seen within the bone marrow on MRI. It is a non-specific, yet important finding usually indicating the presence of underlying pathology.
There is a long (long) list of possible causes of this finding:
Bone within a bone is a descriptive term applied to bones that appear to have another bone within them. There are numerous causes including:
thoracic and lumbar vertebrae (neonates and infants)
growth recovery lines (after infancy)
cortical splitting and new periostitis
sickle cell d...
Boomerang sign may refer to:
boomerang sign (peroneus brevis tear)
boomerang sign (medial meniscal tear)
boomerang sign (splenium)
History and etymology
Boomerang is of course a curved projectile used originally by the Australian Aborigines, one of its various uses was as a hunting weapon 1.
The boomerang sign is defined as a small displaced flap from a longitudinal horizontal type medial meniscal tear which is displaced inferiorly into the medial meniscotibial recess. The imaging diagnosis of this type of tear is crucial because it is normally hidden from the surgeon during routine...
Bouchard nodes are a clinical sign relating to bony nodules of the proximal interphalangeal joints and are much less common than Heberden nodes. They generally (but not always) correspond to palpable osteophytes.
They are sometimes painful, and are typically associated wi...
Boutonnière deformity is the eponymous name of a musculoskeletal manifestation of rheumatoid arthritis presenting in a digit, with the combination of:
flexion contracture of a proximal interphalangeal (PIP) joint
extension of a distal interphalangeal (DIP) joint
The bowl of grapes sign has been described in synovial sarcoma. It refers to the characteristic multilobulated lesion subdivided by multiple septa, forming large cystic foci with regions of hemorrhage.
The Brahma bull sign (or Brahman) describes the appearance of the femoral neck when an osteochondroma is present, as Brahma bulls have an odd, camel-like hump along the dorsum of their neck resembling a femoral neck osteochondroma. Osteochondromas of the femoral neck, particularly when sessile, ...
The bright rim sign in anterior talofibular ligament injury refers to a sign seen on MRI. A cortical defect with a bright dot-like or curvilinear high-signal-intensity, usually at the fibular attachment site, is seen on MRI. It has been described as an indicator of ATFL injury 1.
Bullet-shaped or ovoid vertebra refers to the anterior beaking of the vertebral body.
It is seen in the following conditions:
mucopolysaccharidosis (Morquio disease, Hurler disease)
weapons and munitions inspired signs
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.
anterior spina bifida +/- anterior meningocele
can be part of the Alagille syndr...
A button sequestrum is a small sequestrum of devascularised bone surrounded by lucency. Although classically described in osteomyelitis and eosinophilic granuloma it is also occasionally seen in fibrosarcoma and lymphoma.
Cartilage interface sign, also referred to as double cortex sign, refers to the sonographic presence of a thin markedly hyperechoic line at the interface between the normally hypoechoic hyaline articular cartilage of the humeral head and an abnormally hypoechoic supraspinatus tendon. This arises...
The Caton-Deschamps index is used to measure patellar height and identify patella alta and patella baja. The Caton-Deschamps index relies upon the length of the patellar articular surface and its distance from the tibia, reducing erroneous measurements in those with long patella bodies, as measu...
Celery stalk appearance can refer to the following:
celery stalk anterior cruciate ligament
celery stalk metaphysis
Celery stalk metaphysis refers to a plain film appearance of the metaphyses in a number of conditions characterized by longitudinally aligned linear bands of sclerosis. They are seen in:
congenital cytomegalovirus (CMV)
The celery stalk sign is a term given to the appearance of the anterior cruciate ligament which has undergone mucoid degeneration and has been likened to that of a celery stalk. Its low signal longitudinal fibers are separated from each other by higher signal mucinous material, best appreciated ...
The champagne glass pelvis is a helpful sign in achondroplasia in which the iliac blades are flattened, giving rise to a pelvic inlet that resembles a champagne glass. The acetabular angles are flattened (horizontal) and the sacrosciatic notch is small.
The Cheerio sign has been described in two different scenarios:
Cheerio sign (pulmonary nodule)
Cheerio sign (shoulder)
The Cheerio sign has been described as a sign seen in a type III superior labral anterior posterior tear (SLAP lesion) of the glenoid labrum. In the Cheerio sign, a rounded core of soft tissue is surrounded by a rim of contrast material and gas.
SLAP type III is the bucket handle tear of the s...
The claw sign on diffusion weighted imaging refers to a pattern of hyperintensity seen in degenerative changes in the spine (Modic type 1): well-defined, paired band-like regions of restricted diffusion affecting two contiguous vertebral bodies, resembling a claw surrounding the disc space on sa...
The cliff sign in hip microinstability is a steep drop-off and loss of normal sphericity of lateral femoral head.
Shenton line distortion
subluxation of the femoral head
sclerosis of the femoral neck
<3 mm anterior lateral capsule
>5 mm anterior...
A cloaca (pl. cloacae/cloacas) can be found in chronic osteomyelitis.
The cloaca is an opening in an involucrum which allows drainage of purulent and necrotic material out of the dead bone. If the tract extends to the skin surface, the portion extending beyond the involucrum to the skin surface...
There are several described cockade signs in radiology:
cockade sign (intraosseous lipoma)
cockade sign (aorto-left ventricular tunnel) 1
cockade sign (appendicitis) 2
cockade sign (hypertrophic pyloric stenosis) 3
cockade sign (GI tumors) 4
The cockade sign describes the classic appearance of a calcaneal intraosseous lipoma seen as a well-defined lytic lesion with a central calcification.
History and etymology
It is named after a cockade, which is a badge, usually in the form of a rosette or knot, generally worn on the hat.
A Codman triangle is a type of periosteal reaction seen with aggressive bone lesions. The periosteum does not have time to ossify with shells of new bone (e.g. as seen in a single layer and multilayered periosteal reaction) in aggressive lesions, so only the edge of the raised periosteum will os...
Congenital hallux valgus is a very rare finding wherein a fetus or newborn shows lateral deviation of the first toe(s). When found on prenatal imaging, bilateral congenital/foetal hallux valgus is highly suggestive of fibrodysplasia ossificans progressiva 1,2.
Cookie bite metastases are characterized by small focal eccentric lytic external cortical destruction in long tubular bones. This type of destruction is typically described for metastases from lung cancer; however, they can also occur with other tumors.
Copper beaten skull, also known as beaten silver skull or beaten brass skull, refers to the prominence of convolutional markings (gyral impressions on the inner table of the skull) seen throughout the skull vault.
The appearance of a copper beaten skull is associated with...
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...
The cotton wool appearance is a plain film sign of Paget disease and results from thickened, disorganized trabeculae which lead to areas of sclerosis in a previously lucent area of bone, typically the skull. These sclerotic patches are poorly defined and fluffy.
Other Paget disease re...
Coxa magna is the asymmetrical, circumferential enlargement and deformation of the femoral head and neck. Definitions in the literature vary but enlargement with asymmetry >10% in size is a reasonable cut-off for diagnosis 1.
Coxa profunda refers to a deep acetabular socket. On pelvis x-rays it is seen as the acetabular fossa being medial to the ilioischial line. It should be differentiated from protrusio acetabuli, where the femoral head is seen additionally medial to the ilioischial (Kohler's) line. Coxa profunda i...
Coxa valga describes a deformity of the hip where there is an increased angle between the femoral neck and femoral shaft.
Coxa valga is often associated with shallow acetabular angles and femoral head subluxation.
neuromuscular disorders, e.g. cerebral palsy
Craniotabes is defined as a softening of the skull bones that may be normally present in newborns.
The crescent sign refers to a linear cleft due to subchondral fracture in the setting of osteonecrosis.
It was originally described as a radiographic finding, however, it can also be seen on cross-sectional imaging.
In the setting of Legg-Calve-Perthes disease, it heralds the beginning of the ...
The crossing sign is seen on true lateral plain radiographs of the knee when the line of the trochlear groove crosses the anterior border of one of the condyle trochlea. It is a predictor of trochlear dysplasia. Trochlear dysplasia has been linked to recurrent patellar dislocation 1,2,4. The cro...
The crossover sign, also known as the 'figure of 8' sign, is a plain film sign that indicates acetabular retroversion 2. Acetabular retroversion is a form of pincer morphology and predisposing factor for femoroacetabular impingement and is thought to promote osteoarthritis of the hip 3.
The C sign is an important radiological sign which may be seen on a lateral radiograph of the ankle in those with the talocalcaneal subtype of tarsal coalition. It can be seen in both osseous and nonosseous coalition.
A continuous C-shaped arc on a lateral ankle radiogr...
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...
The cyclops lesion, also known as localized anterior arthrofibrosis, is a painful anterior knee mass that arises as a complication of anterior cruciate ligament (ACL) reconstruction, although has rarely been reported in patients with ACL injuries that have not been reconstructed.
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.
The deep sulcus sign can refer to two different radiographic signs but is best known in the chest:
deep sulcus sign (chest): of pneumothorax on supine CXR:
deep sulcus sign (knee): better known as the lateral femoral notch sign of ACL injury
The delta sign has been described in several different pathologies:
delta sign (brain)
empty delta sign (brain)
double delta sign (MSK)
A dinner fork deformity, also known as a bayonet deformity, occurs as the result of a malunited distal radial fracture, usually a Colles fracture. The distal fragment is dorsally angulated, displaced and often also impacted. The term is descriptive, as the lateral view of the wrist is similar to...
The disproportionate posterior horn sign is a feature described with a meniscal tear having a posteriorly flipped fragment.
Bucket handle tears of meniscus of the knee joint constitute 10% of meniscal tears. They consist of a vertical or longitudinal tear (which includes vertical-obl...
A positive dorsal fat pad or stripe sign is defined as a convex dorsal displacement of the dorsal fat pad of the wrist. A positive sign may indicate a distal radius fracture. Is it best visualized on the lateral view of the wrist.
The normal dorsal skin subcutaneous fat pad is a thin c...
Dot in a circle sign is an MRI sign for maduromycosis or mycetoma.
It is described as a classic appearance on T2 weighted images which show a small rounded hyperintensity (representing granulation tissue), surrounded by a low signal intensity rim (representing fibrous septa) with a hypointense ...
The double anterior cruciate ligament (ACL) sign describes a curvilinear, low signal intensity bandlike structure paralleling the anterior cruciate ligament 1-3 and is of rare occurrence 1.
It can be seen in bucket handle meniscal tears from either the medial or lateral meniscus 1-3. Dependin...
The double axillary pouch sign is a collection of fluid between a torn anteroinferior glenoid labrum and the glenoid rim, giving the appearance of a second axillary pouch.
The sign is seen best with MR arthrography on the coronal view, and is considered by some, a very specific sign for an ante...
Double contour cartilage line is a sign in ultrasonography of the gout arthropathy which is characterized by an echogenic line on the outer surface of the joint cartilage parallel to the subchondral bone secondary to deposition of monosodium urate crystals on the surface of hyaline articular car...
The double contour sign is a helpful radiologic sign of trochlear dysplasia and is seen on true lateral knee radiographs as a double line at the anterior aspect of condyles that occurs if the medial femoral condyle is hypoplastic.
The double delta sign is a feature that has been described in a bucket handle meniscal tear when the inner meniscal fragment flipped anteriorly adjacent to the anterior horn of the donor site and is referred to as a displaced bucket handle tear. The original location of the posterior horn remain...
The double density sign, also sometimes clumsily referred to as the hotter spot within hot area sign, is a bone scan sign of an osteoid osteoma.
It refers to a central focus of intense uptake (the nidus) within a surrounding lower, but nonetheless increased uptake, rim.
Thickening of the insertion of the lateral pterygoid muscle can mimic an anterior displaced temporomandibular disc. When both thickening of the inferior belly insertion and an anteriorly displaced disc are present, as in temporomandibular joint dysfunction, the two structures parallel each other...
The double line sign is a pathognomonic MRI finding seen at the periphery of a region of osteonecrosis (avascular necrosis, bone infarct), representing the border between the viable and non-viable bone 4. It is best seen on T2 and T2 FS sequences and consists of two serpentine lines: an inner br...
The double Oreo cookie sign refers to the presence of two hyperintense lines in the superior glenoid labrum, one of which represents a superior labral tear and the other a physiological sublabral recess 1, 2.
This pattern is likened to an Oreo cookie with two layers of (white) cream and three l...
The double PCL sign appears on sagittal MRI images of the knee when a bucket-handle meniscal tear (medial meniscus in 80% of cases) flips towards the center of the joint so that it comes to lie anteroinferior to the posterior cruciate ligament (PCL) mimicking a second smaller PCL.
A double PCL ...
The doughnut sign can refer to a variety of different signs:
doughnut sign (bone scan)
doughnut sign (bowel)
crescent in a doughnut sign (bowel)
doughnut sign (chest)
doughnut sign (orbit)
The doughnut sign refers to the bone scan pattern whereby there is increased uptake peripherally with a photopenic center. This appearance may be seen in a number of cystic lesions including:
aneurysmal bone cyst
giant cell tumor
simple bone cyst
The doughnut sign is a non-specific sign, and...
Dripping candle wax sign, also known as flowing candle wax appearance, describes the appearance of sclerotic cortical thickening in melorheostosis. The irregular cortical hyperostosis typically occurs on one side of the involved bone and undulates along much like melted wax down a candle.
The dumbbell appearance of spinal tumors refers to a tumor which has both a component within the canal and a component in the paravertebral space contiguous with each other via a thinner tumor component traversing the neural exit foramen.
The appearance can be seen in:
spinal nerve sheath tumo...
An elbow joint effusion is a key finding to recognize on an elbow radiograph and should be used as a trigger to search for a fracture.
Finding an effusion
Recognizing an elbow joint effusion on lateral radiographs is an essential radiology skill. While the fluid itself is not discretely seen...
Empty notch sign is a direct sign of anterior cruciate ligament (ACL) tear/avulsion at its femoral attachment. It denotes a fluid signal at the expected ACL attachment site at the intercondylar notch (fossa) on axial and coronal fluid-sensitive MR images.
The proximal ACL is the second most com...
The empty vertebral body sign is referred to as a radiolucency on a vertebral body seen on the AP radiograph in patients with a flexion-distraction injury mechanism 1 caused by the absent superposition of the posterior spine elements onto the vertebral body.
In other words, the sign results fr...
Endosteal scalloping refers to the focal resorption of the inner layer of the cortex (i.e. the endosteum) of bones, most typically long bones, due to slow-growing medullary lesions.
It is important to note that although it is evidence of a slow non-infiltrative lesion, it does not equate to ben...
Erlenmeyer flask deformity (EFD), also known as metaphyseal flaring, refers to a radiographic appearance typically on a femoral radiograph demonstrating relatively reduced constriction of the diaphysis and flaring of the metaphysis as a result of undertubulation.
The name refers to the resembl...
The FABER test (abbreviated for Flexion, ABduction and External Rotation test) and also some called the Patrick test) is a clinical test done to assess for pathology in the pathology of the hip joint or the sacroiliac joint
It is done by having the leg flexed and thigh abducted and externally r...
The fallen fragment sign refers to the presence of a bone fracture fragment resting dependently in a cystic bone lesion. This finding is said to be pathognomonic for a simple (unicameral) bone cyst following a pathological fracture. Although it has occasionally been reported with other cystic le...
The fascial tail sign refers to the linear/tapered extension of soft tissue tumors along the fascia.
The sign has been classically described in benign fibrous proliferations 1-4:
However, the same sign has also been described as the tail ...
Fascicular sign is a finding on T2-weighted MRI images that suggests a lesion of neurogenic origin. It is characterized by multiple small ring-like structures with peripheral hyperintensity representing the fascicular bundles within the nerves.
It is found in various neurogenic tumors, includin...
The FBI sign is an acronym referring to the components that form a lipohemarthrosis. It stands for:
Finger clubbing, also called "drumstick fingers", is a common clinical sign in patients with heart or lung disease. The term is used to describe an enlargement of the distal phalanges of the fingers, giving them a drumstick or club-like appearance.
Finger clubbing presen...
The radiographic fleck sign refers to an avulsion fracture in the lower limb at either of two sites:
fleck sign (ankle) due to superior peroneal retinaculum injury
fleck sign (foot) due to Lisfranc injury
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). It is a very subtle, but important finding, since it predisposes to Lisfranc inju...
The so-called flip-flop effect refers to a confusing MRI appearance of the skeletal system and subcutaneous tissues. It is seen in a variety of severe fat depletion conditions responsible for diffuse bone marrow serous atrophy and modification or loss of the subcutaneous fat.
Not to be confused...
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...
Fovea alta is a radiographic sign that refers to as an abnormally superior position of the fovea capitis femoris in relation to the acetabular socket.
Fovea alta is significantly associated with acetabular dysplasia and can be used as an indicator or diagnostic marker for the condition 1...
The fragment-in-notch sign is closely related to, can be thought of as a failed, double PCL sign, in so far as it represents a meniscal fragment lying in the intercondylar notch, but not paralleling the posterior cruciate ligament (PCL).
Although both signs are most frequently seen in the sett...