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.
972 results found
Article
Mushroom sign (pyloric stenosis)
The mushroom sign (also called umbrella sign) is a radiological sign described in pyloric stenosis on barium examination.
This sign refers to the impression made by the hypertrophic pylorus on the duodenal cap.
See also
shoulder sign
double track sign
caterpillar sign
string sign
beak sign
Article
Naclerio V sign
The Naclerio V sign is a sign described on the plain film in patients with a pneumomediastinum occurring often secondary to an esophageal rupture.
It is seen as a V-shaped air collection. One limb of the V is produced by mediastinal gas outlining the left lower lateral mediastinal border. The ...
Article
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
Napkin ring sign (disambiguation)
The napkin ring sign may refer to either of the following imaging findings:
napkin ring sign (colon): colonic stenosis such as due to colon cancer
napkin ring sign (coronary): coronary artery vulnerable plaque
A napkin ring is a decorative household item used in some Western societies to hold...
Article
Napkin-ring sign (heart)
The napkin-ring sign is a feature of high-risk coronary artery atherosclerotic plaque on CT coronary angiogram (coronary CTA). It has been shown to possess a high predictive value in predicting future cardiac events and is considered one of the imaging correlates of an unstable plaque.
It is n...
Article
Neuhauser sign (distal ileum)
Neuhauser sign refers to a soap bubble appearance seen in the distal ileum in cases of meconium ileus, related to the air mixed with meconium. It may be seen with barium enema if contrast passes beyond the ileocecal valve or with small-bowel follow-through.
Although classically described with m...
Article
Nodule-in-nodule appearance (liver)
In hepatic imaging, a nodule-in-nodule appearance represents foci of abnormal arterial enhancement within a liver lesion, in cases of a liver regenerative nodule with a focus of hepatocellular carcinoma or high-grade dysplastic nodule. It is so called because of the nodular arterial enhancement ...
Article
Northern exposure sign (sigmoid volvulus)
The northern exposure sign has been described as a high specificity sign in sigmoid volvulus. On a supine abdominal radiograph, the apex of the sigmoid volvulus is seen above (cranial to) the transverse colon.
Article
Notch sign
There are many so-called notch signs. They include:
focal notch in the wall (or tail extending from) a 2nd branchial cleft cyst between the internal and external carotid arteries
peripheral notches in the contour of a solitary pulmonary nodule (SPN) suggests malignancy
thymic notch sign
late...
Article
Nubbin sign
Nubbin sign (also called as cystic duct sign) is an important sign in a HIDA scan (cholescintigraphy using iminodiacetic acid analogs) that may be seen in cases of gallbladder neck obstruction. The "nubbin" refers to a small amount of radiotracer activity in the cystic duct, with absence of trac...
Article
Nutmeg liver
A nutmeg liver appearance is due to a perfusion abnormality of the liver usually as result of hepatic venous congestion. When hepatic veins are congested, contrast is prevented from diffusing through the liver in a normal manner. This results in a mottled pattern of contrast enhancement in the a...
Article
Obliteration of the retrosternal airspace
Obliteration of the retrosternal airspace is seen in any cause of an anterior mediastinal mass.
Article
O'Donoghue unhappy triad
O'Donoghue unhappy triad or terrible triad often occurs in contact and non-contact sports, such as basketball, football, or rugby, when there is a lateral force applied to the knee while the foot is fixated on the ground. This produces an abduction-external rotation mechanism of injury ("pivot s...
Article
Esophageal intubation
Esophageal intubation refers to the incorrect placement of an endotracheal tube in the esophagus. Within minutes its consequences can be catastrophic with the seriousness of its outcome depending largely on the timeliness of its diagnosis.
Epidemiology
Accidental esophageal intubation can happ...
Article
Oncocalyx
An oncocalyx is a dilated tumor filled renal calyx, typically seen in patients with transitional cell carcinomas of the renal pelvis.
Article
Onion bulb formation
Onion bulb formation is a histopathologic finding in hypertrophic neuropathies such as Charcot-Marie-Tooth type 1A (CMT1A) and chronic inflammatory demyelinating polyneuropathy (CIDP).
Pathology
Onion bulb formations are concentric layers of Schwann cell processes and collagen surrounding axon...
Article
Onion peel sign
The onion peel sign (also called the Cumbo sign or double arch sign) is a feature seen with complicated pulmonary hydatid cyst in which the gas lining between the endocyst and pericyst has the appearance of an onion peel. It is pathognomonic for a ruptured hydatid cyst.
History and etymology
I...
Article
Open ring sign
The open ring sign is a relatively specific sign for demyelination, most commonly multiple sclerosis (MS), and is helpful in distinguishing between the causes of ring-enhancing lesions.
Radiographic features
The enhancing component is thought to represent advancing front of demyelination and ...
Article
Orbital emphysema
Orbital emphysema is the presence of gas within the orbital soft tissues. It is usually due to orbital fractures communicating with the paranasal sinuses but can be caused by penetrating trauma and infection. It is a common finding also after orbital or ocular surgery.
Location
preseptal
pos...
Article
Oreo cookie sign (heart)
The Oreo cookie sign refers to the appearance of pericardial effusion on lateral radiographs of the chest. A vertical opaque line (pericardial fluid) separating a vertical lucent line directly behind the sternum (paracardial fat) anteriorly from a similar lucent vertical lucent line (epicardial ...
Article
Osborne-Cotterill lesion
Osborne-Cotterill lesions represent a shear or depression fracture of the posteroinferior aspect of the capitellum and an avulsed fragment in posterolateral elbow most commonly seen in patients with chronic posterolateral rotatory instability.
Pathology
It is thought to be due to posterolater...
Article
Owl-eyes sign (spinal cord)
The owl-eyes sign, also referred to as snake-eyes sign or fried-eggs 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 ...
Article
Paint brush borders sign
The paint brush borders sign may be seen on MRI of a giant cell tumor, at the margin between the lesion and the normal bone. The sign specifically refers to the jagged interface as the tumor penetrates into the bone which mimics the profile of the bristles of a paint brush.
It has recently been...
Article
Palla sign
Palla sign is a sign seen on chest radiographs suggestive of pulmonary embolism, usually seen in the acute setting.
Although uncommon, it can be seen along with several other described signs of pulmonary embolus on chest radiography.
Pathology
Palla sign describes an enlarged right descending...
Article
Pancake brain
Pancake brain is the classical sign of alobar holoprosencephaly. It is due to fusion of the cerebral hemispheres leaving a single ventricle in its center. It is the most severe form of holoprosencephaly. It is associated with multiple facial abnormalities.
See also
pancake vertebra
vegetable ...
Article
Panda sign (disambiguation)
The humble panda has a few signs to its name:
panda sign of the midbrain
double panda sign
panda sign of sarcoidosis
panda eyes (base of skull fracture)
See also
animal and animal produce inspired signs
Article
Panda sign (sarcoidosis)
The panda sign of sarcoidosis is a gallium-67 citrate scan finding. It is due to bilateral involvement of parotid and lacrimal glands in sarcoidosis, superimposed on the normal uptake in the nasopharyngeal mucosa.
The presence of perihilar adenopathy adds the lambda distribution of increased up...
Article
Panzerherz (heart)
Panzerherz (or armoured heart) is a term used to describe the appearance of the heart in calcified constrictive pericarditis.
The pericardium becomes circumferentially thickened with calcification, limiting the ability of the heart to contract. The rim of dense calcification describes how the h...
Article
Papilledema
Papilledema is an ophthalmoscopic diagnosis and refers to swelling of the optic disc. The MRI appearance relates to the dural anatomy of the optic nerve, which is continuous with the subarachnoid space, thereby allowing increased intracranial pressure (ICP) to be transmitted to the optic disc. T...
Article
Parrot beak meniscal tear
Parrot beak meniscal tear is a type of radial meniscal tear with a more oblique course, which on axial images gives the characteristic appearance of a curved V, similar to a parrot's beak. As it is obliquely oriented in relation to the coronal and sagittal plane, it results in a marching cleft s...
Article
Patellotrochlear index
Patellotrochlear index (PTI) is one of the methods to determine patellar height.
Measurement
Patellotrochlear index is measured on a sagittal MR image with the maximal patellar cartilage thickness and the maximal craniocaudal diameter of the patella.
Two measurements are made:
A: the length...
Article
Patent track sign (ultrasound)
Patent track sign is a finding on color Doppler ultrasound, representing blood traveling along the course a biopsy needle track. It can occur after a biopsy of any organ, but is more often seen after liver or kidney biopsies.
Radiographic findings
linear color Doppler flow along the course of ...
Article
Peaking sign (tension pneumocephalus)
The peaking sign is seen in cross-sectional imaging of the brain suggestive of a tension pneumocephalus. It represents the frontal lobes being pushed together forming a peak in the midline giving a heaped up appearance surrounded by air 1. Later, as the frontal lobes are separated they take on t...
Article
Pearl necklace sign
The pearl necklace sign occurs in adenomyomatosis of the gallbladder, on both oral cholecystograms and MRCP. It represents the contrast/fluid-filled intramural mucosal diverticula (Rokitansky-Aschoff sinuses); lined up, these are reminiscent of pearls on a necklace. It is synonymous with the CT ...
Article
Pear-shaped bladder
Pear-shaped (or teardrop-shaped) bladder is one whose normal round or ovoid shape has been extrinsically compressed to resemble a pear. The pear may be inverted or upright, depending on how the excess pelvic tissue compresses the bladder.
Pathology
Etiology
Causes of a pear-shaped bladder inc...
Article
Peg-like tonsil (cerebellum)
Peg-like tonsils refer to the CT or MR appearances of pointed cerebellar tonsils on sagittal scans. The may help distinguish low-lying tonsils from cerebellar tonsillar ectopia due to a Chiari I malformation.
The terminology of caudally displaced tonsils is discussed in the article on cerebell...
Article
Pellegrini-Stieda lesion
Pellegrini-Stieda lesions are ossified post-traumatic lesions at (or near) the medial femoral collateral ligament adjacent to the margin of the medial femoral condyle. One presumed mechanism of injury is a Stieda fracture (avulsion injury of the medial collateral ligament at the medial femoral c...
Article
Pelvic brim sign
The pelvic brim sign is seen in the AP view of the pelvis and refers to a thickening of the pelvic brim outlined by the iliopectineal line. It is due to an osteoblastic reaction seen and first described in Paget disease, which leads to cortical thickening and sclerosis 1.
Article
Pelvic teardrop
The pelvic teardrop, also known as U-figure or Köhler teardrop, is a radiographic feature seen on pelvic x-rays and results from the end-on projection of a bony ridge running along the floor of the acetabular fossa.
This was shown to be the case by demonstrating that sawing away this bony plat...
Article
Penumbra sign (bones)
The penumbra sign represents a rim of vascularized granulation tissue around a bone abscess cavity that has a higher T1 signal intensity than the cavity itself 1.
It should not be confused with the ischemic penumbra of cerebral infarction.
The penumbra is isointense to muscle on T1, enhances...
Article
Peribronchial cuffing
Peribronchial cuffing refers to a radiographic term used to describe haziness or increased density around the walls of a bronchus or large bronchiole seen end-on, both on plain radiographs and on CT. It is sometimes described as a "doughnut sign". When viewed tangentially, it can give the appear...
Article
Pericardial fat tag sign (pneumothorax)
The pericardial fat tag sign is a sign of pneumothorax on supine CXR where the cardiac border has a lumpy contour.
When gas is located in the pleural space between the lung and mediastinum, the pericardial fat is no longer compressed against the mediastinum and therefore can hang or dangle late...
Article
Perilymphatic fistula
A perilymphatic fistula (also known as a labyrinthine fistula) is a pathologic communication between the fluid-filled space of the inner ear and the air-filled space of the middle ear, most commonly occurring at either the round or oval window.
Clinical presentation
Symptoms of perilymphatic ...
Article
Perinephric stranding
Perinephric stranding refers to the appearance of edema within the fat of the perirenal space on CT or MRI. While a degree of symmetric bilateral perinephric stranding is common, particularly in the elderly, asymmetric or unilateral perinephric stranding is an important sign of renal inflammatio...
Article
Periportal free gas sign
The periportal free gas sign has been described as being strongly suggestive for upper gastrointestinal tract perforation.
See also
bowel perforation (summary)
pneumoperitoneum
Article
Periportal halo (CT/US)
Periportal halo or periportal collar sign refers to a zone of low attenuation seen around the intrahepatic portal veins on contrast-enhanced CT or hypoechogenicity on liver ultrasound. It likely represents periportal edema, which is often used as a synonymous term. Periportal haloes may occur ar...
Article
Periportal halo sign (MRI)
The periportal halo sign on liver MRI is a specific sign of primary biliary cholangitis (formerly primary biliary cirrhosis) that is characterized by rounded low signal intensity around portal venous branches, 5-10 mm in size, on T1- and T2-weighted images. These lesions are usually numerous, in...
Article
Perirenal cobweb
Perirenal cobwebs are the presence of prominent perinephric septa. It is best appreciated on CT images.
Pathology
The cobweb is considered to be due to engorged venous collaterals or due to edema and fluid extravasation into the perirenal space 1.
Perirenal cobwebs may be seen in many benign ...
Article
Peritoneal stripe sign (pneumoperitoneum)
The peritoneal stripe sign in abdominal ultrasonography is considered indicative of intraperitoneal free air, present in pneumoperitoneum. Free air in the abdomen will collect in an anti-dependent manner, typically the anterior prehepatic space in the supine patient, settling against the parieta...
Article
Peritoneal to abdominal height ratio (PAR)
Peritoneal to abdominal height ratio (PAR) ≥ 0.52 is a statistically associated sign for raised intra-abdominal pressure > 12 mmHg in the context of abdominal compartment syndrome in critically ill patients in CT.
It can be calculated by dividing the distance from the linea alba to the poster...
Article
Periwinkle sign (supratentorial ependymoma)
The periwinkle sign has been coined to describe what has been claimed to be a characteristic appearance of intraparenchymal supratentorial ependymomas on non-enhanced CT axial images.
The central solid component with centripetal calcification surrounding central necrotic area resembles a flower...
Article
Persistent nephrogram
Persistent nephrograms occur when intravenous contrast media is retained by both kidneys for more than 3 minutes.
Terminology
Persistent nephrograms are characteristically bilateral and are usually distinguished from delayed nephrograms, which occur unilaterally.
Pathology
Etiology
hypoten...
Article
Phantom calyx
A phantom calyx is a solitary calyx which fails to opacify with contrast amidst an otherwise well-opacified pelvicalyceal system. It is due to an intrarenal process which has infiltrated and caused obliteration of the involved collecting system element.
It may be seen in:
tumor: especially tra...
Article
Phantom organ sign
The phantom organ sign is a term used when a large mass arises from a small organ and as a consequence, it is impossible to detect the affected organ.
The identification of this sign and other radiological signs such as the embedded organ sign, beak sign, and prominent feeding artery sign on CT...
Article
Phemister triad (tuberculosis)
The triad of Phemister refers to three radiographic features seen classically with tuberculous arthroplasty 4:
juxta-articular osteopenia/osteoporosis
peripheral osseous erosions
gradual narrowing of joint space
History and etymology
Named after Dallas Burton Phemister (1882-1951), American...
Article
Phrygian cap
Phrygian caps are the most common congenital anatomic variant of the gallbladder. It denotes folding of the fundus back upon the gallbladder body and is asymptomatic with no pathological significance.
Radiographic findings
A Phrygian cap may be identified on ultrasound, multiphase CT/MRI or ch...
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 can be seen in patients with Paget disease.
It is a result of disorganized new cortical bone formation after excessive osteoclastic activity causes the resorption of normal...
Article
Piece of pie sign (wrist)
The piece of pie sign refers to an abnormal triangular appearance of the lunate on a PA image of the wrist representing either lunate dislocation or perilunate dislocation 1,2. A lateral image will help differentiate whether there is lunate or perilunate dislocation, with lunate dislocation demo...
Article
Piglet sign (osmotic demyelination)
The piglet sign is seen in osmotic demyelination syndrome. It refers to the appearance of the upper pons in axial T2 and FLAIR images. The areas of coalescent T2 signal increase are reminiscent of a pig's snout, with other features on axial MR images resembling the rest of the face of a piglet w...
Article
Pine cone bladder
A pine cone bladder or Christmas tree bladder is a cystographic appearance in which the bladder is elongated and pointed with a thickened, trabeculated wall. It is typically seen in severe neurogenic bladder with increased sphincter tone (detrusor sphincter dyssynergia) due to suprasacral lesion...
Article
Pistol grip deformity (hip)
The pistol grip deformity is considered a typical radiographic sign of cam-type femoroacetabular impingement. The shape of the proximal femur is reminiscent of a flintlock pistol known from old pirate movies.
History and etymology
It was first described by American orthopedic surgeon S David S...
Article
Pitt pit
Pitt pit refers to an oval or round lucency in the anterosuperior aspect of the femoral neck, just distal to the articular surface. It represents a herniation of synovium or soft tissues into the bone through a cortical defect, hence the alternate name synovial herniation pit. They are usually a...
Article
Pivot shift test
The pivot shift test forms part of the orthopedic examination of a post-traumatic knee. A positive test shows high specificity for injury of the anterior cruciate ligament.
Procedure
The pivot shift test is performed on a supine patient.
At the start the subject's knee is permitted to droop ...
Article
Plankton sign (ultrasound)
The plankton sign refers to swirling, punctiform internal echoes within an otherwise anechoic pleural effusion which demonstrate slow, whirling dynamics, occasionally buffered by cardiac and respiratory impulses. When present, one may rule out a transudative effusion, and should be highly suspic...
Article
Pleural mouse
A pleural mouse (also known as a fibrin body), is a 1-2 cm mobile rounded clump of fibrin left over after resolution of a pleural effusion.
Article
Pleural pointillism
Pleural pointillism is multiple high signal regions on b=1000 diffusion-weighted imaging but not at lower b-values. It can be a reliable tool allowing differentiation of malignant from benign pleural lesions and can help guide biopsy 1-3. Its sensitivity is reported to be 93-100% and specificit...
Article
Pneumolipohaemarthrosis
Pneumolipohaemarthrosis is the presence of intra-articular gas in a lipohemarthrosis. It indicates an open intra-articular fracture.
Article
Pneumothorax in supine projection
A pneumothorax does not display classical signs when a patient is positioned supine for a chest radiograph as commonly occurs in acute trauma or the critical care setting. Of course, pneumothoraces are common in both these scenarios and even relatively small pneumothoraces may be significant due...
Article
Pneumothorax (ultrasound)
Pneumothorax is a serious potential consequence of blunt thoracic trauma and, if misdiagnosed, it may quickly become life-threatening.
For a discussion on epidemiology, clinical presentation, pathology, and treatment and prognosis please see the main pneumothorax article.
Radiographic feature...
Article
Polka-dot sign (vertebral hemangioma)
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 hemangiomas 2. It is the axial equivalent of the corduroy sign seen on sagittal and coronal images. On CT the ...
Article
Polo mint sign (venous thrombosis)
The polo mint sign is a description given to a venous thrombosis on contrast-enhanced CT imaging. When viewed in the axial plane, a thin rim of contrast persists around a central filling defect due to thrombus. This gives an appearance like that of the popular UK mint sweet, the Polo (figure 1)...
Article
Polycoria
Polycoria is the presence of more than one true pupil in the iris, each possessing their own fully functional sphincter pupillae muscle, which responds appropriately to light and drugs. It is a very rare entity with only a few case reports in the global literature 1,2. Pseudopolycoria occurs whe...
Article
Pool sign (intracranial; metastatic adenocarcinoma)
The pool sign is a recently described brain MRI appearance where an intracranial mass exhibits a T2 hyperintense rim adjacent to a solid mass surrounded by peritumoral edema. This appearance has been recently suggested to be a feature characteristic of metastatic adenocarcinoma (with various pri...
Article
Pooping duck sign
Pooping duck sign indicates the presence of a triquetral fracture in a lateral wrist radiograph, where an avulsed fracture fragment from the dorsal cortex of the triquetrum projects along the dorsal aspect of the osseous structures of the wrist.
In this sign, the fracture fragment represents th...
Article
Popcorn calcification
Popcorn calcification refers to amorphous calcifications often with rings and arcs that resemble popped corn kernels. This type of calcification may be seen in many radiological settings including 1:
chondroid lesions (e.g. enchondroma, chondrosarcoma)
fibrous dysplasia
pulmonary hamartomas
...
Article
Popcorn calcification within the breast
Popcorn calcification in the breast is the classical description for the calcification seen in involuting fibroadenomas which, as the name suggests, has a popcorn-like appearance.
Pathology
A fibroadenoma in the long run may degenerate and calcify. Initially, there are a few punctate peripher...
Article
Popeye sign
Popeye sign is a pronounced bulging muscle in the distal aspect of the biceps region of the arm. It is clinically apparent with a complete long head of biceps tendon tear which causes distal migration of the long head of biceps muscle.
Terminology
Defined by the distal migration of the long ...
Article
Porcelain gallbladder
Porcelain gallbladder refers to extensive calcium encrustation of the gallbladder wall. The term has been used to emphasize the blue discolouration and brittle consistency of the gallbladder wall at surgery but is often an incidental finding on multiple different imaging modalities.
Clinical p...
Article
Porcelain left atrium
Porcelain left atrium, also known as coconut left atrium, is a term used when a large part of or the entire left atrial wall becomes calcified. It can occur as a rare consequence of endocarditis (with underlying rheumatic heart disease). It has also been described in the setting of end-stage ren...
Article
Positive bronchus sign
The positive bronchus sign is seen on CT chest, and refers to the presence of a bronchus leading directly to a peripheral lung lesion 1,2.
In one study, four types of tumor-bronchi relationships were described 3:
patent bronchus leads directly to the tumor mass
bronchus is within the tumor ma...
Article
Positive carpal sign
The positive carpal sign is a useful radiographic sign for the diagnosis of Turner syndrome in association with the other musculoskeletal manifestations.
Radiographic features
Abnormality in the shape of the proximal carpal row in the dorsopalmar radiographs of the wrist and hand (taking in th...
Article
Positive metacarpal sign
In the metacarpal sign, a line drawn along the heads of the 4th and 5th metacarpals will intersect the head of the 3rd metacarpal if shortening is present. The shortened 4th metacarpal is the key to the sign.
The sign is positive in up to 9.6% of normal individuals 3. It is however seen in a va...
Article
Positive PCL line sign
The positive PCL line sign is an indirect sign of anterior cruciate ligament (ACL) tear based on secondary changes of the posterior cruciate ligament (PCL) on MRI images. A line tangent to the upper border of the PCL should normally intersect the medullary cavity of the distal femur, if it does ...
Article
Posterior fat pad sign (elbow)
The posterior fat pad sign is the visualization of a lucent crescent of fat located in the olecranon fossa on a true lateral view of an elbow joint with the elbow flexed at a right angle indicating an elbow joint effusion. Normally, the posterior fat pad will not be seen in this view.
In the s...
Article
Posterior pituitary bright spot
The posterior pituitary bright spot is an MRI feature of the normal pituitary gland wherein the posterior pituitary appears bright on non-contrast T1 weighted images.
Pathology
The posterior pituitary bright spot, having intrinsically high signal on T1 weighted images is believed to be from t...
Article
Posterior wall sign (femoroacetabular impingement)
Posterior wall sign is a radiographic sign used to assess the morphology of posterior acetabular wall. A deficient posterior acetabular wall is often associated with acetabular retroversion or acetabular dysplasia, while a too-prominent posterior acetabular wall is a predisposing factor for post...
Article
Potato nodes
Potato nodes are a classical moniker for the large nodes seen in the lung hila and mediastinum on the chest radiograph in pulmonary sarcoidosis. This name is derived from the characteristic bulky irregular morphology of the nodes which is reminiscent of large lumpy potatoes. Although this appear...
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
Pretzel sign (serpentine aneurysm)
The pretzel sign is seen on DSA and is indicative of a serpentine aneurysm 1.
The sign refers to the sinusoid configuration of the intra-aneurysmal vascular channel seen in serpentine aneurysms, giving it the appearance of a pretzel.
Article
Prévost sign (eyes)
The Prévost sign, also known as the Vulpian sign, refers to conjugate ocular deviation in patients with acute cortical hemiparetic stroke.
The direction is variable, depending on the location of the stroke 3.
In a hemispheric stroke, the eyes usually deviate towards the lesion (away from the h...
Article
Pronator quadratus sign
The pronator quadratus sign can be an indirect sign of distal forearm trauma. It relies on displacement of the fat pad that lies superficial to the pronator quadratus muscle.
Pathology
Displacement, anterior bowing, or obliteration of the fat plane in the setting of trauma may indicate a dista...
Article
Pseudoboutonniere deformity
The pseudoboutonniere deformity is the result of an untreated hyperextension injury of the proximal interphalangeal joint.
It is due to an uncommon avulsion of the volar plate from the proximal phalanx causing a flexion deformity of the PIP joint, while the central slip of the extensor tendon r...
Article
Pseudocalculus sign (common bile duct)
The pseudocalculus sign is a term coined to describe a mimic of a distally impacted common bile duct (CBD) stone on ERCP, MRCP and the various forms of cholangiography, including T-tube, CT, intraoperative, and percutaneous 1.
It results from the forceful contraction of the choledochal sphincte...