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.

796 results found
Article

Renal pelvis

The renal pelvis (or, more rarely, the renal infundibulum) forms part of the pelvicalyceal system of the kidney and is the connection between the calyces and the ureter. Gross anatomy The renal pelvis is triangular in shape, lies posteriorly in the renal hilum surrounded by fat and vessels and...
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Renal pseudotumour

A renal pseudotumour is a mass that will simulate a tumour on imaging but is composed of non-neoplastic tissue. There are many examples 1: Developmental prominent column of Bertin persistent fetal lobulation dromedary hump splenorenal fusion cross-fused renal ectopia renal hilar lip Infe...
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Renal replacement lipomatosis

Renal replacement lipomatosis is a rare condition characterised by fatty tissue proliferation in the renal sinus and perinephric space with marked destruction/atrophy of renal parenchyma (due to chronic inflammation). Clinical presentation Patients usually present with non-specific complaints ...
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Renal replacement therapy

Renal replacement therapy (RRT) (also called renal dialysis or just dialysis) is used to supplement renal function in patients with either end-stage chronic kidney disease or medically-refractory acute renal impairment. Theory Haemodialysis refers to the diffusion of solutes in solution across...
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Renal sinus

The renal sinus is a fat-filled compartment of the kidney. Gross anatomy The renal sinus is a fatty compartment located within the medial aspect of the kidney. It communicates with the perinephric space. It contains the renal hilum and is bordered by renal parenchyma laterally.  Contents ren...
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Renal sinus cyst

Renal sinus cysts are simple renal cysts that lie within the renal sinus. Terminology It is worth noting that some authors 5,6 use the term renal lymphangiectasia interchangeably. It is likely that true renal lymphangiectasia is a separate and rare disorder, and is thus discussed separately. ...
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Renal sinus lipomatosis

Renal sinus lipomatosis refers to a condition where there is excessive renal sinus fat replacement. Pathology It results from renal parenchymal atrophy, inflammation, calculous disease, ageing or exogenous or endogenous steroids. There is usually no or rarely little mass effect on collecting ...
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Renal sympathetic denervation

Renal sympathetic denervation (RSDN), also known as renal denervation, is an interventional procedure that uses radiofrequency ablation to destroy the nerve endings in the wall of the renal arteries. Endovascular (trans-catheter) techniques are an alternative to surgical sympathectomy.  Indicat...
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Renal tract calculi (summary)

This is a basic article for medical students and other non-radiologists Renal tract calculi, also known as urolithiasis, refer to renal stone formation at any point along the renal tract (from kidneys to bladder and urethra). Reference article This is a summary article; read more in our artic...
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Renal transplant

Renal transplantation is one, if not the most, common transplant procedures undertaken worldwide. Consequently, purposeful and incidental imaging of renal transplants and renal transplant-related complications are increasingly common. These include acute renal transplant rejection and chronic re...
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Renal transplant rejection

Renal transplant rejection is one of the feared complications of renal transplantation. In terms of onset, this can be broadly divided into two groups acute renal transplant rejection chronic renal transplant rejection: usually after one year post transplantation (at least after 3 months) Ra...
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Renal transplant related complications

The recipients of renal transplants are susceptible to a number of complications. Incidence of each is variable and partially subject to specific surgical transplantation techniques and management patterns 3. Pathology Renal transplant complications These can be broadly categorised as periren...
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Renal transplant ultrasound

The central approach of renal transplant ultrasound is to evaluate for possibly treatable surgical or medical complications arising in the transplanted kidney. Institutions vary in the exact schedule of renal transplant ultrasound assessment, but it is common to obtain an initial ultrasound 24-...
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Renal trauma

Renal trauma can result from direct, blunt, penetrating and iatrogenic injury. Epidemiology Renal injuries account for ~10% of abdominal trauma, and thus the demographic of affected individuals reflects that population. The incidence of renal injuries increases in pre-existing congenital or ac...
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Renal tuberculosis

Renal tuberculosis, a subset of genitourinary tuberculosis, accounts for 15-20% of extra-pulmonary tuberculosis and can result in varied and striking radiographic appearances.  Tuberculosis can involve both the renal parenchyma and the collecting system (calyces, renal pelvis, ureter, bladder a...
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Renal tubular acidosis

Renal tubular acidosis (RTA) refers to defects in the renal tubular transport of hydrogen ions, bicarbonate ions, or both, in the kidneys resulting in a normal anion gap metabolic acidosis.  Epidemiology The exact prevalence of renal tubular acidosis is unknown but the entity is probably u...
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Renal tubular ectasia

Renal tubular ectasia is an incidental finding that is seen more commonly on intravenous pyelography (IVP), but which can also occasionally be seen on CT urography (CTU). Terminology Renal tubular ectasia is also known as benign renal tubular ectasia. The term "benign" was used to differentiat...
Article

Renal tumours

Renal tumours (for the purposes of this article taken to broadly mean neoplastic lesions) should be distinguished from renal pseudotumours. Whilst renal tumours can be broadly divided into primary and secondary (metastatic), benign and malignant or adult and paediatric tumours, they are more fo...
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Renal vascular pedicle injury

Renal vascular pedicle injury  is a severe form of renal trauma, which if not recognised and treated expediently with lead to the loss of the kidney.  Radiographic features CT Contrast enhanced CT is the Imaging modality of choice. On CT it is recognised as a non-enhaning kidney. Perirenal ha...
Article

Renal vein

The renal veins are asymmetric paired veins that drain the kidneys.  Gross anatomy Course The renal vein is formed by the union of two-to-three renal parenchymal veins in the renal sinus. It emerges from the renal hilum anterior to the renal artery and drains into the inferior vena cava at th...
Article

Renal vein anomalies

There are several variations in renal venous anatomy. Some of these are specific to the left renal vein. Left renal vein anomalies are generally classified into four types 2: type I  the ventral pre-aortic limb of the left renal vein is obliterated, but the dorsal retro-aortic limb persists a...
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Renal vein thrombosis

Renal vein thrombosis can be either from "bland" thrombus or tumour thrombus (extension of tumor into the vein). There are numerous aetiologies for bland thrombus, but it most commonly occurs in the hypercoagulable nephrotic syndrome. Renal vein thrombus is commoner on the left side, presumably ...
Article

Renal vein varices

Renal vein varices develop for various reasons and are usually asymptomatic. Clinical presentation Renal vein varices are usually asymptomatic. Some patients may present with flank pain and/or haematuria. Pathology Aetiology chronic renal vein thrombosis nutcracker syndrome retroaortic ...
Article

Renovascular hypertension

Renovascular hypertension (RVH) is a type of secondary hypertension, where high blood pressure develops secondary to renal artery disease.  Epidemiology Approximately 2.5% (range 0.5-5%) of hypertensive patients will have RVH as a cause 2,3.  Pathology Aetiology There are a number of condit...
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Retroaortic left renal vein

Retroaortic left renal vein (RLRV) is a normal anatomical variant where the left renal vein is located between the aorta and the vertebra, and drains into the inferior vena cava. Its recognition is important in order to avoid complications during retroperitoneal surgery or interventional proced...
Article

Retrograde pyelography

Retrograde pyelography (also known as retrograde pyeloureterography) is a method of imaging the upper urinary collecting system. After IVU and CTU were developed, it has been rarely performed as a primary study, but it still has a few potential indications as a secondary study. Indications non...
Article

Retroperitoneal fibrosis

Retroperitoneal fibrosis (RPF), is a condition that has previously been described as chronic periaortitis. It is an uncommon fibrotic reaction in the retroperitoneum that typically presents with ureteric obstruction. The disease is part of a spectrum of entities that have a common pathogenic pr...
Article

Retroperitoneal haemorrhage

Retroperitoneal haemorrhage can be a source of significant yet occult blood loss. Clinical presentation The clinical features are varied depending on the amount of hemorrhage present, rate of onset and ability of the surrounding structures to contain the hemostatic system. The classical featur...
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Retropubic space

The retropubic space (also known as the prevesical space or cave of Retzius) is an extraperitoneal space located posterior to the pubic symphysis and anterior to the urinary bladder. It is separated from the anterior abdominal wall by the transversalis fascia and extends to the level of the umbi...
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Rhabdoid tumour of the kidney

Rhabdoid tumour of the kidney is a rare, highly aggressive malignancy of early childhood, closely related to atypical teratoid/rhabdoid tumours (AT/RT) of the brain (see rhabdoid tumours) Epidemiology Rhabdoid tumours occur exclusively in children, with 60% occurring before the age of 1 year o...
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Rhabdomyosarcoma (genitourinary tract)

Rhabdomyosarcomas of the genitourinary tract are uncommon tumours occurring in pelvic organs.  It is a disease nearly exclusive to the paediatric population.  For a general discussion of this type of tumour, please refer to the article on rhabdomyosarcomas. Epidemiology The peak incidence of ...
Article

Right iliac fossa mass (differential)

Right iliac fossa mass is a common clinical presentation and has a range of differentials that need to be excluded. Radiology plays an important role in this differentiation. Differential diagnosis appendicular mass appendicular abscess appendicular mucocele appendicular neoplasms ileocaec...
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Rim sign in chronic hydronephrosis

The rim sign can be seen in association with chronic hydronephrosis.  In patients 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 calyces 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 MRI, a thin (1-3 mm) rim of su...
Article

Risk factors for testicular germ cell tumours

Risk factors for testicular germ cell tumours (GCT) include: Caucasians at higher risk than African Americans (9:1) undescended testis 10-40x increased risk  around 10% of all tumours are associated with undescended testis higher risk if intra-abdominal testis compared with intra-inguinal ...
Article

Robson staging system of renal cell carcinoma

Robson staging of renal cell carcinoma (RCC) is simple but has largely been replaced by the TNM system (see renal cell cancer staging article). Robson staging revolves around the relationship to Gerota's fascia, involvement of renal vein and regional nodes. stage I: limited to kidney stage II:...
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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

Sarcoidosis (abdominal manifestations)

Sarcoidosis is a systemic inflammatory disease of unknown origin characterized by the formation of non-caseating granulomas. Virtually any organ system may be involved.  Although the involvement of abdominal viscera is less frequent than pulmonary and mediastinal disease when it occurs, it may m...
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Sarcomatoid renal cell carcinoma

Sarcomatoid renal cell carcinomas (sRCC) may develop when one of the more common subtypes of renal cell carcinoma degenerates into a sarcoma. On imaging, they are generally large masses, with irregular contours, and malignant-appearing, but do not have specific imaging features. Epidemiology ...
Article

Schiller-Duval body (histology)

Schiller-Duval body is a perivascular structure that can be found in 50% of testicular yolk sac tumours also known as endodermal sinus tumours. If present it is considered pathognomonic.  Pathology A central vessel is surrounded by tumour cells, and the cell-vessel complex is contained in a cy...
Article

Schistosomiasis

Schistosomiasis (also referred to as bilharzia or snail fever) is the result of infection by blood fluke (trematode worm) of the Schistosoma species. Epidemiology Schistosomiasis is very common, affecting over 200 million people, with the vast majority (85%) in Africa. It is prevalent in tropi...
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Schistosomiasis (urinary tract manifestations)

Bladder schistosomiasis, also known as bilharzia of the bladder, is a major health problem in developing parts of the world predisposing individuals to squamous cell carcinoma. Epidemiology Schistosomiasis is very common, affecting over 200 million people, with the vast majority (85%) in Afric...
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Sciatic hernia

Sciatic hernia is a rare type of pelvic floor hernia, which occurs through either the greater or lesser sciatic foramina. See also curlicue ureter sign
Article

Scleroderma

Scleroderma, also known as systemic sclerosis, is an autoimmune connective tissue disorder characterised by multisystem fibrosis and soft tissue calcification. As such, it affects many separate organ systems, which are discussed separately: musculoskeletal manifestations of scleroderma pulmona...
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Scleroderma (renal manifestations)

Renal manifestations of scleroderma are common, affecting up to 25% of patients. Some patients (5-10%) can present with a scleroderma renal crisis (SRC). These patients have abrupt onset of hypertension, acute renal failure 4.  For a general discussion of scleroderma, please refer to the parent...
Article

Scrotal cystocoele

Scrotal cystocoeles are a type of urinary bladder hernia, where the bladder herniates into the scrotum. Clinical presentation asymptomatic voiding problems scrotal swelling Radiogaphic features Ultrasound Scrotal sac will contain fluid. Emptying of a scrotal cystocoele with voiding is an ...
Article

Scrotal filariasis

Scrotal filariasis is a manifestation of filariasis and refers to scrotal involvement from parasitic nematodes of the superfamily filarioidea. Epidemiology Known disease of the tropics and sub-tropics and a cause of morbidity in Asia, Africa and the Western Pacific regions 2. Clinical present...
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Scrotal haematocele

Scrotal haematocoeles are collections of blood within the scrotal sac, but outside of the testis. Pathology A haematocoele normally occurs following trauma to the scrotum, or on occasion following surgery. Some think that a varicocoele is a risk factor for developing a haematocoele 4. Radiogr...
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Scrotal infections

The scrotum and its content are subject to a number of infective processes including:  scrotal cellulitis scrotal abscess Fournier gangrene epididymitis epididymo-orchitis orchitis testicular abscess
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Scrotal pyocele

Scrotal pyoceles are purulent fluid collections in the scrotal sac, that generally occur in conjunction with epididymo-orchitis. Pathology Scrotal pyoceles are typically a complication of epididymo-orchitis or testicular abscess but can also occur following trauma or surgery. The purulent flui...
Article

Scrotal scintigraphy

Scrotal scintigraphy is a radio-isotope examination of the scrotal contents, primarily in patients presenting with scrotal pain. Indications Although, ultrasound remains the mainstay of scrotal imaging, scintigraphy can be used where the diagnosis is unclear, since ultrasound appearances for s...
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Scrotal tunica cyst

Scrotal tunica cysts are paratesticular cystic lesions. They include: tunica vaginalis cysts tunica albuginea cysts Radiographic features Ultrasound  Typically seen as a simple appearing paratesticular cystic lesion not in the region of the epididymis. See also paratesticular lesions
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Scrotolith

Scrotoliths, also known as scrotal pearls, are benign incidental extra testicular macro-calcifications within the scrotum. They frequently occupy the potential space of the tunica vaginalis or sinus of the epididymis. They are usually of no clinical significance 1,2. Clinical presentation Most...
Article

Scrotum

The scrotum (plural: scrota or scrotums) is a dual-chambered protuberance of skin and muscle that contains the testes, epididymides, and spermatic cord. It consists of two chambers separated by a septum. It is an extension of the perineum, and is located between the penis and anus. Gross anatom...
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Segmental renal hypoplasia

Segmental renal hypoplasia, also known as the Ask-Upmark kidney, is a type of renal hypoplasia. It is often found in young females with severe hypertension. The aetiology is unknown but has been postulated to be congenital or a sequelae of pyelonephritis. It is associated with severe juvenile hy...
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Segmental testicular infarction

Segmental testicular infarctions are uncommon testicular lesions that usually result from arterial embolisation or thrombosis (as opposed to testicular infarction from torsion, which may originate from venous occlusion). Pathology The causes of a segmental testicular infarct include: orchitis...
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Seminal vesicle

The seminal vesicles are paired accessory sex glands of the male reproductive system. The seminal vesicle produces over two-thirds of the ejaculate and is very high in fructose.  Gross anatomy The seminal vesicle is actually a 10-15 cm long tubular structure but is coiled tightly so it only me...
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Seminal vesicle cyst

Seminal vesicle cysts can be congenital or acquired. Congenital It is the presence of cysts within the seminal vesicles since birth. It is seen rarely and occurs probably due to an obstruction at the junction of the seminal vesicle and ejaculatory duct. It is associated with many other urogeni...
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Seminal vesiculitis

Seminal vesiculitis is an uncommon entity characterised by inflammation of the seminal vesicles. It is most commonly infective in aetiology, and often associated with concurrent infection elsewhere in the male genital tract, forming part of the spectrum of male accessory gland inflammation 4. It...
Article

Sertoli cell tumour of the testis

Sertoli cell tumours of the testis are uncommon sex cord stromal tumours. They are less common than Leydig cell tumours of the testis.  Epidemiology May present in both paediatric and adult males, depending on the histologic subtype. Clinical presentation Testicular mass or firmness. May occ...
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Sex cord stromal tumours of the testis

Sex cord stromal tumours of the testis are uncommon testicular neoplasms. Although ~90% of these tumours are benign, they cannot be differentiated from testicular malignancies on imaging, and are therefore usually discovered after orchiectomy. Leydig cell tumour of the testis (most common, ~30%...
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Sexual differentiation

Sexual differentiation refers to the embryological development of male and female phenotypes. Unlike sexual genotype which is determined at the time of fertilisation, the male and female phenotypes do not begin to differentiate substantially until the seventh week of gestation.  Males  Y chrom...
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Sickle cell disease

Sickle cell disease (SCD) is a hereditary (autosomal recessive) condition resulting in the formation of abnormal haemoglobin (a haemoglobinopathy), which manifests as multisystem ischaemia and infarction, as well as haemolytic anaemia.  Epidemiology There is no recognised gender predilection. ...
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Sickle cell disease (abdominal manifestations)

Abdominal manifestations of sickle cell disease (SCD) are wide and can involve many organs. For a general discussion, please refer to sickle cell disease. Splenic splenomegaly may occur transiently with the sequestration syndrome, where rapid pooling of blood occurs in the spleen, resulting ...
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

Sildenafil citrate-induced penile Doppler

In the past 15 years sildenafil citrate-induced penile Doppler has emerged as a technique for evaluating erectile dysfunction. It has greater patient acceptability than the usual papaverine-induced colour Doppler and is safer. Sildenafil citrate is a popular vasodilator drug used in treatment o...
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Small cell carcinoma of the bladder

Small cell carcinomas of the bladder are rare bladder cancers with a poor prognosis. Its appearance overlaps other bladder cancers, in particular, urothelial/transitional cell carcinoma. Epidemiology A very rare tumor, it has been estimated at <0.0001% of bladder cancers. It is thought to have...
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...
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Solitary filling defect of the ureter (differential)

Solitary filling defect with a ureter, as seen on conventional IVU or CT IVU has some differentials, including: within the lumen calculus sloughed papilla blood clot benign polyp within the wall transitional cell carcinoma (TCC) tuberculosis  metastasis endometriosis When multiple fi...
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SpaceOAR

SpaceOAR is a technique in which a physical space is created between the prostate gland and rectum for electron beam radiotherapy targeted to the prostate gland in cases of prostate cancer.  OAR stands for "organ at risk", and in cases of prostate cancer radiotherapy treatment the rectum is the...
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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

Spermatic cord

The spermatic cord is the tubular structure that suspends the testes and epididymis.  Gross anatomy Course The spermatic cord starts at the deep inguinal ring, passes through the inguinal canal and exits at the superficial inguinal ring into the scrotum 3. In the scrotum, the spermatic cord t...
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Spermatic cord contents (mnemonic)

Handy mnemonics to recall the contents of the spermatic cord are: Papers Don't Contribute To A Good Specialist Level 3 arteries, 3 nerves, 3 other things Mnemonic Papers Don't Contribute To A Good Specialist Level P: pampiniform plexus D: ductus deferens C: cremasteric artery T: testicul...
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Spermatic cord hydrocele

Spermatic cord hydrocele (SCH) refers to a loculated fluid collection along the spermatic cord. It is separated from, and located above, the testis and the epididymis. Pathology It results from aberrant closure of the processus vaginalis. There are two recognised subtypes encysted hydrocele ...
Article

Spermatic cord leiomyosarcoma

Spermatic cord leiomyosarcomas are uncommon malignant paratesticular masses. Epidemiology Accounts for ~10% of spermatic cord sarcomas. The average of a patient at presentation is 58 years old (although has been seen as young as 15 years old). Clinical features Patients may have left inguina...
Article

Spermatic cord liposarcoma

Spermatic cord liposarcomas are the most common malignant tumour of the spermatic cord. Most present as painless, slow-growing masses and can be mistaken for inguinal hernias. They are usually well-differentiated and spread by local extension.  Epidemiology In a large population-based registry...
Article

Spermatocele

Spermatoceles are a common type of extra-testicular cyst, and represents cystic dilatation of tubules of the efferent ductules in the head of the epididymis. Clinical presentation Usually a painless, incidental finding but can present as a mass lesion if large 3. Pathology Spermatoceles are ...
Article

Sperm cell granuloma

Sperm cell granuloma, also termed epididymitis nodosa, is a benign lesion that can occur in the scrotum. They can particularly occur in those with a prior vasectomy (occurs after vasectomy in up to 40% of patients 2). Pathology It is considered a form of chronic epididymitis which occurs secon...
Article

Spigelian-cryptorchidism syndrome

Spigelian-cryptorchidism syndrome is the association of Spigelian hernias and cryptorchidism in children.  Pathology It is reported that ~50% (range 28-75%) range of paediatric patients with Spigelian hernias will have ipsilateral cryptorchidism 1,2.  Along with Spigelian hernia and cryptorch...
Article

Spinning top urethra

Spinning top urethra is non-obstructive posterior urethral dilatation seen on voiding cystourethrography, mainly in females. It was initially considered as an indicator of distal urethral narrowing/stenosis. However, it is now believed to be due to functional discoordinate voiding or bladder ins...
Article

Splenogonadal fusion

Splenogonadal fusion is a rare anomaly that occurs when there is congenital fusion between a portion of the spleen and a gonad or other mesonephric derivative. Epidemiology Much more common in male patients (~95%), occurs most commonly on the left (98%) and usually involve the testis (95%). Ha...
Article

Split bolus technique

The split bolus technique is a CT imaging investigation used in patients with haematuria aiming to put together, in a single image acquisition, both the nephrographic and renal excretory phases and thus reducing the radiation dose of the study. It is a CT protocol adopted for some institutions f...
Article

Spoke wheel pattern in kidney

A spoke wheel pattern in renal imaging refers to a vascular appearance seen with certain renal tumours, typically seen in oncocytomas but can also be seen in renal cell carcinomas.  This appearance refers to a peripheral rim of vessels from which centripetal vessels converge centrally giving th...
Article

Spontaneous retroperitoneal haemorrhage

Spontaneous retroperitoneal haemorrhage (SRH) is a distinctive clinical pathology of retroperitoneal bleeding without a preceding history of trauma. Clinical presentation Clinical presentation may be vague and varied: no inciting history no evidence of cutaneous bruising back, lower abdomin...
Article

Spontaneous rupture of the renal pelvis

Spontaneous rupture of the renal pelvis, also known as pyelosinus backflow, is a rare complication that can occasionally occur with obstructive urolithiasis (usually in the distal third of the ureter) or occasionally infection 1. Leakage of urine can result in a urinoma, and there is an increase...
Article

Spotted nephrogram

A spotted nephrogram is a descriptive term indicating an appearance of patchy, segmental and subsegmental renal parenchymal enhancement. Pathology The pattern is indicative of focal areas of cortical ischaemia or necrosis, as a result of small vessel occlusion. This abnormal perfusion pattern ...
Article

Squamous cell carcinoma of the penis (staging)

Squamous cell carcinoma of the penis arises most commonly at the distal end of the penile urethra with local invasion of the glans. In addition to TNM classification, the following staging is used: Staging stage I: confined to the glans or foreskin stage II: invasion of penile shaft stage I...
Article

Squamous cell carcinoma (urinary bladder)

Squamous cell carcinoma of the urinary bladder is rare and accounts for only ~3-8% 1,2 of all bladder cancers (90% are transitional/urothelial cell carcinomas) but nevertheless, SCC is the most common type of nontransitional cell carcinoma involving the bladder 2. SCC of the bladder is observed ...
Article

Staghorn calculus (kidney)

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

Steinstrasse

Steinstrasse [stīn′shtra-se] is the German word for "stone street", describing a possible complication of extracorporeal shock wave lithotripsy (ESWL) for urinary tract calculi, wherein a column of stone fragments forms that blocks the ureter. Incidence Steinstrasse usually develops 1 day to 3...
Article

Stipple sign (transitional cell carcinoma)

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 is a descriptive term indicating an appearance of alternating linear bands of high and low attenuation in a radial pattern extending through the corticomedullary layers of the kidney on iodine-based intravenous contrast enhanced imaging. It is important to know that a simila...
Article

String of beads sign (renal artery)

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 ...

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