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.

46 results found
Article

Aubergine sign

The aubergine sign (also known as egg-plant sign or deformity) is a clinical sign of a fractured penis. Haemorrhage beyond the tunica albuginea produces swelling and bruising of the penis simulating the appearance of an aubergine.  
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Balloon on a string sign - IVU

In renal imaging, the balloon on a string sign refers to the appearance on IVU in ureteropelvic junction obstruction. It is seen due to the high and eccentric point of exit of ureter from a dilated renal pelvis. 
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Bear paw sign

The bear paw sign is seen in xanthogranulomatous pyelonephritis and refers to the cross-sectional appearance of the kidney which is said to resemble the paw of a bear. The renal pelvis is contracted whereas the calyces are dilated, mimicking the toe-pads of the paw.
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Bouquet of flowers appearance

A bouquet of flowers appearance is a description given to the appearances of medullary sponge kidney on a traditional intravenous pyelogram (IVP) study. The ectatic distal collecting ducts contain the microcalcification typical of the disease. This is also known as a 'bunch of grapes' appearance...
Article

Bullet and bodkin sign

Bullet and bodkin sign is the appearance of the ureter when there is an abrupt transition in the ureteral caliber. Bullet in the name is represented by the dilated proximal ureteric segment which appears to be perched on the constricted / non dilated encased ureter which gives an appearance of a...
Article

Calyceal crescent sign

The calyceal crescent sign (Dunbar's crescents) refers to the early IVP appearance of markedly dilated renal calyces. It is formed by early contrast opacification of the dilated collecting ducts and ducts of Bellini with the characteristic shape as a result of the associated enlarged calyces.  ...
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Cannonball metastases

Cannonball metastases refer to large, well circumscribed, round pulmonary metastases that appear, well, like cannonballs. The French term "envolée de ballons" which translates to "balloons release" is also used to describe this same appearance. Metastases with such an appear...
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Claw sign

The claw sign is useful in determining whether a mass arises from a solid structure or is located adjacent to it and distorts the outline.  It refers to the sharp angles on either side of the mass, which the surrounding normal parenchyma forms when the mass has arisen from the parenchyma. As su...
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Cobblestoning

Cobblestoning (having a cobblestone appearance) can occur in a number of hollow organs with mucosa, most commonly the bowel, in the setting of Crohn's disease.  Longitudinal and circumferential fissures and ulcers separate islands of mucosa, giving it an appearance reminiscent of cobblestones. ...
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Cobra head sign

The cobra head sign (or spring onion sign) refers to dilatation of the distal ureter, surrounded by a thin lucent line, which is seen in patients with an adult-type ureterocoele. The cobra head appearance indicates an uncomplicated ureterocele. The lucent "hood" of the cobra represent...
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Cortical rim sign

The cortical rim sign is useful in distinguishing acute pyelonephritis from a segmental renal infarct and is seen on contrast enhanced CT or MRI. The wedges of reduced enhancement seen in the setting of acute pyelonephritis represent oedema and ischaemia which involves the whole wedge or renal ...
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Delayed nephrogram

Delayed nephrogram, commonly described on plain film urography, but also visible on CT urography, is when there is absence or reduction of normal renal parenchymal enhancement on nephrographic phase images. A delayed nephrogram is characteristically unilateral and is usually distinguished from ...
Article

Drooping lily sign

The drooping lily sign is a urographic sign in some patients with a duplicated collecting system. It refers to the inferolateral displacement of the opacified lower pole moiety due to an obstructed (and unopacified) upper pole moeity. The similarity to a lily is further strengthened by the smal...
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Faceless kidney

A faceless kidney refers to one in which the normal appearance of the renal sinus on cross-sectional imaging is absent. It was initially described as a sign of duplication of the collecting system 1 (a slice obtained between the two collecting systems will not demonstrate the normal components o...
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Female prostate sign

Female prostate sign is a characteristic imaging sign seen in patients with a large urethral diverticulum.  A large urethral diverticulum in females surrounds the urethra, and elevates the base of the bladder, mimicking the typical appearance of enlarged prostate in males. 
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Fishhook ureters

Fishhook ureters, also known as "J-shaped ureters" or "hockey stick ureter" describe the course of the distal ureter in patients with significant Benign prostatic hypertrophy. It has also been used to describe the appearance of a retrocaval ureter further up, as the right ure...
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Goblet sign

The goblet sign (or champagne glass sign) refers to the appearance of the ureter when it is focally dilated by an intraluminal mass. It is best seen when the ureter is opacified from below, by a retrograde ureterogram. Presence of this sign indicates the pathology to be chronic, permitting the l...
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Kerr kink

Kerr Kink a sign of renal tuberculosis. Scarring leads to a sharp kink at the pelvi-ureteric junction.
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Keyhole sign

The keyhole sign is an ultrasonographic sign seen in boys with posterior urethral valves. It refers to the appearance of posterior urethra which is dilated, and associated thick walled distended bladder which on ultrasound may resemble a key hole.
Article

Kidney sweat sign

The kidney sweat sign applies to the presence of thin, hypoechoic, extracapsular fluid collections around kidneys in renal failure patients. This fluid is assumed to represent perirenal oedema. It can be appreciated on ultrasound, CT and MR imaging.  Differential diagnosis perirenal haematoma ...
Article

Lentiform fork sign

The lentiform fork sign has been described on MRI seen as bilateral symmetrical hyperintensities in the basal ganglia surrounded by a more/brightly hyperintense rim delineating the lentiform nucleus. It has been postulated to result from metabolic acidosis due to any cause 1, e.g. end stage ren...
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Maiden waist deformity

Maiden waist deformity is the appearance of the deviation of bilateral ureters. This typically occurs in retroperitoneal fibrosis. In this condition, there is medial drawing of the ureter due to deposition of fibrous tissue in the lumbosacral junction. Due to involvement of both ureters, the cou...
Article

Manta ray sign

The manta ray sign is a radiographic appearance in bladder exstrophy. It describes wide midline separation of the pubic bones simulating the appearance of a manta ray swimming towards you 1. Differential diagnosis On a plain radiograph consider: open book pelvic injuries: the smooth arc of th...
Article

Molar tooth sign - abdominal

Abdominal molar tooth sign refers to the appearance of contrast media spillled out of the urinary bladder on CT cystography after extraperitoneal bladder rupture. Contrast flows out of the ruptured bladder, occupying preperitoneal cavum Retzii and surrounds the bladder in the shape of a molar t...
Article

Oncocalyx

An oncocalyx is a dilated tumour filled renal calyx, typically seen in patients with transitional cell carcinomas of the renal pelvis.
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Pear-shaped bladder

Pear-shaped (or tear-drop-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 Aetiology Causes of a pear-shaped bladder i...
Article

Perinephric stranding

Perinephric stranding refers to the appearance of oedema 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 inflammati...
Article

Perirenal cobweb

Perirenal cobwebs is the presence of prominent perinephric septae. 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

Phantom calyx

Phantom calyx is a calyx which fails to fill with contrast admist a well opacified remainder of pyelocalyceal system. It refers to an intrarenal process which has infilterated and caused obliteration of the involved collecting system element. It may be seen in: tumour: especially transitional ...
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

Putty kidney

A putty kidney refers to a pattern of renal calcification associated with renal tuberculosis conventionally described on plain radiography. Calcification characteristically is very homogeneous and ground glass like, representing calcified caseous tissue 3-4. Premkumar et al labelled calcificatio...
Article

Renal arterial cut-off sign

Renal arterial cut-off sign  as the name suggests is an abrupt termination of the vascular contrast opacified renal arterial lumen. It may be associated with or without any contrast extravasation It is seen in a vascular injury like segmental or main renal artery thrombosis or occlusion.
Article

Rim sign in chronic hydronephrosis

The rim sign can be seen in association with chronic hydronephrosis.  In patient's with chronic hydronephrosis, in all forms of contrast-enhanced imaging of the obstructed kidney, enhancement may occur in the residual, but markedly atrophic, renal parenchyma, surrounding the dilated calices and...
Article

Rim sign in renal vascular compromise

Rim sign in renal vascular compromise is seen in major renal vascular compromise. It can be seen in: renal artery obstruction from embolism, thrombosis or dissection renal vein thrombosis acute tubular necrosis Radiographic features At contrast enhanced CT or MR imaging, a thin (1-3 mm) ri...
Article

Salt and pepper sign

The salt and pepper sign is used to refer to a speckled appearance of tissue. It is used in many instances, but most commonly on MRI. Please note that pathologists also use the term. Differential diagnosis Vascular tumours Used to describe some highly vascular tumours which contain foci of ha...
Article

Sigmoid kidney

A sigmoid kidney is an uncommon variant of the horseshoe kidney. Whereas the typical horseshoe kidney is fused only at the lower poles, in a sigmoid kidney both the upper and the lower poles are fused 1.
Article

Soft tissue rim sign

The soft-tissue rim sign is used to distinguish a ureteric calculus from a phlebolith. The former appears as a calcific density with a surrounding rim of soft tissue which represents the oedematous ureteric wall. Phleboliths on the other hand usually have imperceptible walls (although up to 8% m...
Article

Spaghetti sign in the bladder

The spaghetti sign refers to the presence of a linear worm like filling defect within a contrast opacified bladder. This linear filling defect is considered to represent blood clot extruded from the ureter and thereby moulded in the tubular shape. It is seen in patients with gross haematuria. Pr...
Article

Staghorn calculus

Staghorn calculi, also sometimes called coral calculi, are renal calculi that obtain their characteristic shape by forming a cast of the renal pelvis and calyces, thus resembling the horns of a stag. For a general discussion of renal calculi please refer to nephrolithiasis. Epidemiology Stagh...
Article

Stipple sign

The stipple sign refers to the pointillistic end-on appearance on intravenous pyelography or retrograde pyelography of contrast material tracking into the interstices of a papillary lesion. Because the majority of transitional cell carcinomas (TCC) have a papillary configuration, the presence of...
Article

Striated nephrogram

Striated nephrogram, originally described on plain film urography, but just as easily seen on CT urography represents linear bands of contrast extending from the medulla of the kidney towards the cortex. Pathology Striations result from stasis and concentration of contrast material in oedemato...
Article

String of beads sign

The string of beads sign is the description typically given to the appearance of the renal artery in fibromuscular dysplasia (FMD) but may also be used to describe the appearance of splanchnic arteries in segmental arterial mediolysis (SAM). It refers to the appearance arising from the stenoses ...
Article

Threads and streaks sign

The threads and streaks sign refers to an angiographic appearance of a vascularised tumour thrombus extending into the ipsilateral renal vein or the inferior vena cava from a renal cell carcinoma. This gives an appearance of linear, thread like or string like appearance of the involved vessel.  ...
Article

Throckmorton sign

Throckmorton sign, also known as John Thomas sign, refers to when the penis points in the direction of unilateral disease, typically of the pelvis or hip.  Throckmorton sign is a slang term used jokingly by medical students and residents. History and etymology It is named after Tom Bentley Th...
Article

Tubal ring sign

Tubal ring sign is one of the ultrasound signs of a tubal ectopic. It comprises of an echogenic ring which surrounds an unruptured ectopic pregnancy. It is said to have a 95% positive predictive value (PPV) for ectopic pregnancy. Differential diagnosis It can be mimicked by a normal corpus lut...
Article

White pyramid sign

Medullary pyramids of kidney can be seen normally on unenhanced CT scans as high-attenuation structures and this is known as the white pyramid sign: bilateral high-attenuation renal pyramids are an occasional incidental normal finding unilateral appearance of white pyramids is subtle secondary...

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