Brachytherapy seed migration to the lung is a known complication of radioactive seed therapy. These seeds are used for localized treatment of malignancies, most commonly prostate cancer.
Regarding staging, nearly 79% of the cases are localized, 12% are regional and 5% present with distant disea...
Branchio-oculo-facial syndrome (BOFS) is a very rare autosomal dominant genetic disorder that is characterized clinically by abnormalities affecting the eyes, craniofacial structures, and branchial sinuses.
More than 80 cases have been reported in the global literature since its f...
Branchio-oto-renal (BOR) dysplasia is a rare syndromic disorder characterized by:
can involve the outer, middle, and inner ear associated with conductive, sensorineural, or mixed hearing impairment
branchial fistulae and branchial cleft cysts
The bulbospongiosus muscle is found in the superficial perineal pouch which covers the bulb of the penis in males and the bulb of the vestibule in females.
origin: median raphe and perineal body
insertion: dorsum of penis/clitoris, perineal membrane
innervation: pudendal nerve
The bulbourethral glands or Cowper glands are paired small pea-sized glands of the male reproductive tract, homologous to the female Bartholin glands.
The bulbourethral glands are located in the deep perineal pouch posterolateral to the membranous portion of the male urethra and ...
The bulbs of the vestibule (also known as the vestibular, vestibulovaginal or clitoral bulbs) are conglomerations of erectile soft tissue, collectively homologous to the bulb of the penis. However unlike in the male, the developing bulb is bisected by the vaginal opening to form two halves.
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...
Burned-out testis tumors may be present if there is metastatic retroperitoneal lymphadenopathy, but the primary testicular tumor is a relatively occult, scarred intratesticular focus. Approximately 50% of the "burned-out" tumors continue to harbor malignant cells.
Calciphylaxis, or calcific ureamic arteriolopathy, is a rare condition which manifests as subcutaneous vascular calcification and cutaneous necrosis (small blood vessels of the fat tissue and the skin). Some authors describe as a syndrome of vascular calcification, thrombosis and skin necrosis.
The calyceal crescent sign (Dunbar crescents) refers to the early intravenous pyelogram (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 associate...
Calyceal diverticula, also known as pyelocalyceal diverticula are congenital outpouchings from the renal calyx or pelvis into the renal cortex. These diverticula are lined with transitional cell epithelium.
Relatively uncommon, seen in 0.21% to 0.60% of intravenous urograms (IVU)....
Calyceal microlithiasis or more specifically renal calyceal microlithiasis is defined as <3 mm hyperechoic foci noted within the renal calyces on gray scale ultrasonography 1. It has been considered as a precursor for renal stone formation.
The patient may be asymptomati...
Canal of Nuck hernias are rare and occur in female children. They are caused by a failure of complete obliteration of the canal of Nuck with a connection to the peritoneal cavity and transmitted intra-abdominal contents (e.g. bowel, omentum, fluid, ovary, Fallopian tube and/or urinary bladder).
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 appearance are classically...
Carcinogens are substances known to cause cancer. They include:
Nasopharynx / nasal passage
ionizing radiation (not technically a substance)
polyaromatic hydrocarbons (PAH)
Cardiorenal syndrome refers to an association between cardiac failure and renal failure. It can manifest as a new-onset of renal failure, or the aggravation of a pre-existing one within the ambit of an acute or chronic heart failure exacerbation. sometimes it can occur the other way around.
Staging of cervical cancer can either be based on the TNM or FIGO system.
Revised FIGO staging of cervical carcinoma 2018 8
FIGO no longer includes Stage 0 (Tis)
I: confined to cervix uteri (extension to the corpus should be disregarded)
IA: invasive carcinoma only diagnosed by microscopy
Cervical intraepithelial neoplasia (CIN) (also known as cervical dysplasia) is the potentailly premalignant stage in the dysplastic changes in the squamous epithelium of the cervix.
Grading of CIN is based on the degree of dysplasia seen in a sample of cervical tissue:
similar to condy...
There are many signs in radiology that are related to Christmas:
snowcap sign in avascular necrosis
in total anomalous pulmonary venous return
in pituitary macroadenomas
snowstorm appearance in complete hydatidiform and testicular microlithiasis
holly leaf sign in calcified pl...
Chromaffin cells are neuroendocrine cells found predominantly in the medulla of the adrenal gland. They are also found in other ganglia of the sympathetic nervous system and are derived from the embryonic neural crest.
They arise in the fifth week of fetal development when neuroblas...
Chronic kidney disease (CKD), also known as chronic renal failure, is a progressive loss of glomerular function caused by a long-standing renal parenchymal disease. It is present when the glomerular filtration rate (GFR) is less than 60 ml/min/1.73 m2 for three consecutive months or greater than...
Chronic periaortitis is an inflammatory condition which typically involves the infrarenal portion of the abdominal aorta. It is a rare disease usually occurring in middle-aged men.
It has various clinical presentations:
idiopathic retroperitoneal fibrosis (IRF)
perianeurysmal retroperitoneal ...
Chronic primary adrenal insufficiency has a number of causes. Primary adrenal insufficiency is termed Addison disease.
idiopathic atrophy: autoimmune adrenalitis 1
tuberculosis 1: 25% calcify
fungal disease 1
Chronic prostatitis is a heterogeneous condition characterized by chronic inflammation of the prostate gland.
Under the National Institutes of Health (NIH) classification system this may encompass
chronic bacterial prostatitis
chronic prostatitis and chronic pelvic pain syndrome (CPPS)
Chronic pyelonephritis is a form of pyelonephritis where there are longstanding sequelae of renal infection. At the time of writing there is still no definitive consensus as to whether the condition represents an active chronic infection, arises from multiple recurrent infections, or represents ...
Chronic renal transplant rejection is a form of renal transplant rejection. It usually later following transplantation.
Chronic rejection is defined as a gradual deterioration in graft function beginning at least 3 months after transplantation 3.
The creatinine levels may rise but ...
Chyluria is the finding of chyle in the urine, and is due to a pathological communication between the lymphatic system and the renal tract. It is most commonly found in South-Eastern Asia, where it is due to lymphatic filariasis, but in the non-tropical world it is most commonly encountered afte...
Circumaortic left renal vein, also known as circumaortic renal collar is an anomaly of left renal vein when a supernumerary or accessory left renal vein passes posterior to the aorta, apart from the normal renal vein passing anterior to the aorta. This anomaly is potentially hazardous, if unreco...
Circumcaval ureter, also known as retrocaval ureter, is a term used to describe an abnormal course of a ureter that encircles the inferior vena cava. Both of these terms are somewhat misleading, as this configuration is considered a developmental anomaly of the inferior vena cava (IVC). There ar...
Citrate is a compound examined in MR spectroscopy in the setting of possible prostate carcinoma. Citrate resonates at 2.6 ppm and is decreased in prostate cancer.
For more information go to: MR spectroscopy in prostate cancer
The claw sign is useful in determining that a mass arises from a solid structure rather than 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. ...
Clear cell renal cell carcinoma is the most common type of renal cell carcinoma.
The average age of onset of sporadic clear cell renal carcinoma is 61 years-old. In cases associated with Von Hippel-Lindau disease the average age of onset is 37 years 1.
Clear cell sarcomas of the kidney (CCSK) are a rare mesenchymal renal tumor that account for ~5% of primary renal neoplasms in the pediatric population 1.
Clear cell sarcoma of the kidney is the second most common primary malignant pediatric renal neoplasm after Wilms tumor, with...
Cloacal exstrophy (CE) is an extensive congenital abdominal wall defect which encompasses:
exstrophy of the bladder
lower abdominal wall defect
The estimated prevalence is at around 1 in 50,000 to 200,000 live births. There is a recognized male predilection with a M...
The cloaca is the terminal portion of the hindgut. It is an embryonic structure (weeks 4-7) in which the distal ends of the gastrointestinal tract and urogenital system share a common channel. The most distal aspect of the cloaca is termed the cloacal membrane.
The cloaca, or portions of it, ca...
Cobb's collar (also known as a Moormann's ring or congenital narrowing of the bulbar uerthra) is a membranous stricture of the bulbar urethra just downstream of the external urethral sphincter. It is sometimes referred to as a type III posterior urethral valve, and does not maintain a connection...
The cobra head sign, also known as the 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.
During an excretory phase of an int...
COL4A1-related disorders are a group of autosomal dominant disorders caused by a mutation in the COL4A1 gene.
The exact prevalence is unknown, but the group of disorders is considered to be under-recognized, especially asymptomatic variants 1.
The clinical ...
Colovesical fistulas are communications between the lumen of the colon and that of the bladder, either directly or via an intervening abscess cavity (foyer intermediaire). When the communication is between the rectum and urinary bladder, the term rectovesical fistula is used.
Congenital adrenal hyperplasia (CAH) (also known as adrenogenital syndrome) is a form of adrenal hyperplasia related to a variety of autosomal recessive disorders in adrenal steroidogenesis; characterized by low cortisol, low aldosterone, and androgen excess.
Congenital anomalies of the male urethra include various anomalies due to complex development of urethra. These anomalies can be isolated or in association with other coexisting anomalies. They can be categorized as following:
posterior urethral valve
anterior urethral valv...
Congenital megacalyces is an incidental finding which mimics hydronephrosis. It is a result of underdevelopment of the renal medullary pyramids with resultant enlargement of the calyces. It is more frequently seen in males.
The enlarged calyces predispose to stasis, infection and calculus forma...
A congenital (primary) megaureter encompasses causes of an enlarged ureter which are intrinsic to the ureter, rather than as a result of a more distal abnormality; e.g. bladder, urethra (see secondary megaureter). It includes:
obstructed primary megaureter
refluxing primary megaureter
Congenital renal anomalies comprise of vast spectrum of pathologies and include:
congenital renal hypoplasia
congenital cystic renal disease
infantile polycystic renal disease: autosomal recessive polycystic kidney disease (ARPKD):...
Congenital urachal anomalies are a spectrum of potential anomalies that can occur due to incomplete involution of the urachus.
A urachal remnant occurs in approximately 1 in 5000 patients.
The urachus connects the dome of the bladder to the umbilical cord during fetal ...
The conjoint tendon forms when the medial fibers of the internal oblique aponeurosis unite with the deeper fibers of the transversus abdominis aponeurosis. The conjoint tendon then turns inferiorly and attaches onto the pubic crest and pecten pubis 1. It forms part of the posterior wall of the i...
Conn syndrome, also known as primary hyperaldosteronism, is a condition of excess of aldosterone production and occurs secondary to adrenal cortical adenoma, bilateral adrenal hyperplasia, or rarely, adrenal carcinoma. Differentiation between the causes is required to avoid unnecessary surgery. ...
Contrast-enhanced ultrasound (CEUS) involves the administration of intravenous contrast agents consisting of microbubbles/nanobubbles of gas.
First-generation ultrasound contrast agents contained microbubbles of air that were dissolved in blood when exposed to acoustic pressure in the ultrasoun...
Contrast-induced nephropathy (CIN) describes an association between intravenous or intra-arterial contrast administration and renal impairment, but increasingly the evidence shows that contrast is not the cause of the renal impairment and that confounding factors such as sepsis are likely to be ...
Renal cortical nephrocalcinosis is ~20 times less common than medullary nephrocalcinosis.
renal cortical necrosis: common 2
toxemia of pregnancy
extracorporeal shock wave lithotripsy (ESWL)
A mnemonic for common causes of cortical nephrocalcinosis is:
C: cortical necrosis
A: Alport syndrome
G: (chronic) glomerulonephritis
medullary nephrocalcinosis mnemonic
The cortical rim sign describes the thin, viable rim of subcapsular cortex seen on contrast-enhanced CT or MRI in major renal vascular compromise including:
renal artery obstruction from embolism, thrombosis or dissection
renal vein thrombosis
acute tubular necrosis
acute cortical necrosis
Cowper duct syringocele refers to cystic dilatation of the main duct of the bulbourethral (Cowper) glands.
Affected patients may present with postvoid dribbling, urinary frequency, weak stream, or hematuria.
Four groups of syringoceles have been described 2:
The cremasteric artery is a small branch of the inferior epigastric artery that enters the deep inguinal ring of the inguinal canal and supplies the layers of the spermatic cord and also the skin of the scrotum, including the cremaster muscle.
History and etymology
The word "cremaster" derives...
The cremaster muscle is the thin fascial muscle of the spermatic cord made of skeletal muscle. It is also referred to as cremaster fascia or simply the cremaster. Its action is to retract the testes, important in thermoregulation and spermatogenesis.
It is derived from the inter...
Crossed fused renal ectopia refers to an anomaly where the kidneys are fused and located on the same side of the midline.
The estimated incidence is around 1 out of 1000 births 1. There is a recognized male predilection with a 2:1 male to female ratio. More than 90% of crossed ren...
Crossed renal ectopia is said to be present when the kidney is seen in the opposite retroperitoneal space. It is more common for the left kidney to be ectopically located on the right side. More than 85% of these get fused resulting in crossed fused renal ectopia. Less than 15% cases are non-fus...
A crus (plural: crura) is an anatomical term used for a structure which resembles a leg.
crus (internal capsule)
crus (semicircular duct)
Cryptorchidism refers to an absence of a testis (or testes) in the scrotal sac. It may refer to an undescended testis, ectopic testis, or an atrophic or absent testis. Correct localization of the testes is essential because surgical management varies on location.
The testes develop i...
This is a basic article for medical students and other non-radiologists
CT abdomen is an increasingly common investigation that is used to help make diagnoses of a broad range of pathologies. A CT abdomen in its simplest form is a CT from diaphragm to symphysis pubis performed 60 seconds after ...
CT cystography is a variation of the traditional fluoroscopic cystogram. Instead of anterograde opacification of the urinary collecting system (as with CT urography), contrast is instilled retrograde into the patient's bladder, and then the pelvis is imaged with CT.
CT guided adrenal biopsy is usually performed for the diagnosis of indeterminate adrenal nodules or tumors. This procedure has declined in recent years due to improvements in, and validation of, non-invasive CT and MR techniques that can now diagnose benign adrenal lesions with a high degree of ...
Computed tomography of kidneys, ureters and bladder (CT KUB) is a quick non-invasive technique for diagnosis of urolithiasis. It is usually considered the initial imaging modality for suspected urolithiasis in an emergency setting 1.
NB: This article is intended to outline some general principl...
CT polytrauma/multitrauma, also called trauma CT, whole body CT (WBCT) or panscan, is an increasingly used investigation in patients with multiple injuries sustained after significant trauma.
Clinical assessment and mechanism of injury may underestimate injury severity by 30% 8. There is some e...
CT urography (CTU or CT-IVU) has now largely replaced traditional IVU in imaging the genitourinary tract. It gives both anatomical and functional information, albeit with a relatively higher dose of radiation.
The aim is to illustrate the collecting systems, ureters and bladder with intravenous...
The curlicue ureter sign1 was described on intravenous pyelogram studies in cases of ureteral herniation into a sciatic hernia, causing a curled appearance of the herniated ureter. Although very rare, this sign is pathognomonic of sciatic hernia. It can also be seen on CT urogram studies.
Cushing syndrome is due to the effects of excessive glucocorticoids which may be exogenous or endogenous.
Cushing disease refers to glucocorticoid excess solely due to an adrenocorticotropic hormone-secreting pituitary adenoma, while Cushing syndrome encompasses all etiologies of g...
A cyst is an abnormal fluid-filled structure which is lined by epithelium; with one exception: lung cysts may contain gas or fluid. By contradistinction, a pseudocyst lacks an epithelial lining and instead has a vascular and fibrotic capsule.
Cysts are extremely common and found in most organs....
Cystadenocarcinoma of the rete testis is the malignant version of cystadenoma of the rete testis.
Primarily a disease of older men (>60 years old), but has been noted in a wide age range (8-91 years).
Histologic evaluation requires exclusion of malignant mesothelioma...
Cystadenoma of the rete testis is a rare cystic testicular tumor. It does not have specific imaging features, but may be suggested in the differential of a large multiloculated cystic tumor involving the testicle. It cannot be radiologically differentiated from cystadenocarcinoma.
Cystic adrenal neoplasms are uncommon and only account for a minority of cystic adrenal lesions 3. They may be represented several histological types:
adrenal adenoma 1
adrenal cortical carcinoma 1,2
adrenal epithelioid angiosarcoma 2
teratoma (pediatric population) 4
Cystic degeneration of benign prostatic hyperplasia (BPH) is for one of the forms that BPH nodule may present as. They are often located in the transitional zone. They may have irregular shapes, can be of variable size and may contain hemorrhage or calculi. Patients usually have symptoms of urin...
There several cystic lesions around the vagina and female urethra; some of the imaging differential considerations would include:
Gartner duct cyst: at or above the level of the pubic symphysis anterior to the vaginal wall
Bartholin gland cyst: posterolateral to distal v...
Testicular cystic lesions are a relatively common occurrence on testicular ultrasound. They result from widely variable pathological entities ranging from benign to malignant. These entities include:
simple testicular cyst
tunica albuginea cyst (mesothelial cyst)
cystic transformation of rete...
Cystic nephromas, previously known as multilocular cystic nephromas, are rare benign renal neoplasms classically occurring in adult females in the 4th and 5th decades. As of the 2016 WHO classification, they are considered distinct from pediatric cystic nephromas which have associated DICER1 gen...
Cystic renal disease can be confusing. There are many conditions, many of which have similar names or are eponymous, and with a few exceptions, are relatively rare. It is easiest to think of them into two separate demographic:
pediatric cystic renal diseases
adult cystic renal disease
Cystic renal dysplasia refers to a subgroup of congenital anomalies of the kidney and urinary tract characterized by the dysplastic renal parenchyma and formation of cysts. The most severe form is multicystic dysplastic kidney, in which functional renal parenchyma is absent and only undifferenti...
Cystic retroperitoneal lesions can carry a relatively broad differential, which includes:
retroperitoneal mucinous cystadenoma
retroperitoneal cystic teratoma
retroperitoenal cystic mesothelioma
pseudomyxoma retroperitonei with cystic change
perianal mucinous c...
Cystinosis, also known as Abderhalden Kaufmann Lignac syndrome, is the most common hereditary cause of renal Fanconi syndrome. Cystinosis is one of the lysosomal storage disorders.
It has a reported incidence of 1:192,000 1. Cystinosis is typically diagnosed in infancy.
Cystinuria is an inherited condition in which there is an excess of cystine in the urine. This excess predisposes to the formation of cysteine stones.
"Cysteine" refers to the amino acid. "Cystine" is the oxidized dimer of the amino acid.
It is thought to occur in 1:...
Cystitis cystica is the same condition as ureteritis cystica and closely related to cystitis glandularis. It is a relatively common chronic reactive inflammatory disorders that occur in the setting of chronic irritation of the bladder mucosa.
Cystitis cystica is seen in a variety ...
Cystitis glandularis is a proliferative disorder of the urinary bladder in which there is glandular metaplasia of the transitional cells lining the urinary bladder. This entity is closely related to cystitis cystica, with which it commonly co-exists. It is a relatively common chronic reactive in...
A cystocele, also known as a prolapsed bladder, is a form of pelvic organ prolapse where the bladder descends inferiorly and posteriorly into the vagina and perineum. It may be accompanied by prolapse of other pelvic organs.
CT / MRI
Sagittal images are particularly use...
Cystography is a fluoroscopic study that images the bladder. It is similar to a voiding cystourethrogram (VCUG), and the difference between the studies is primarily one of emphasis; a cystogram focuses on the bladder and a VCUG focuses on the posterior urethra. The study has been adapted to CT a...
Cystolithotomy is a urologic procedure to remove one or more bladder stones.
It is typically performed for a patient with large or numerous bladder stones or if an endoscopic approach has not been successful.
The traditional approach described below is an open cystolithotomy. Other approaches...
Dancing megasperm is the ultrasound finding of continuously oscillating/mobile tiny echogenic foci within dilated tubules of the epididymis. This is seen in post-vasectomy patients and is thought to represent clumps/clusters of trapped spermatozoa.
filarial dance sign
The dartos muscle is the thin rugated fascial muscle of the scrotum made of smooth muscle. Hence it is also referred to as dartos fascia or simply the dartos. It forms from the subcutaneous tissue of the scrotum and base of the penis and attaches to the scrotal skin and fibrous midline septum be...
The deep inguinal lymph nodes (often shortened to the deep inguinal nodes) form a subgroup of the inguinal lymph node group, and are located within the femoral sheath, medial to the femoral vein. They receive afferent lymphatic drainage from the deep lymphatics of the distal lower extremity and ...
The deep perineal pouch is an anatomic space superior (deep) to the perineal membrane in the urogenital triangle of the perineum, anterior to the transverse line between the ischial tuberosities.
The deep perineal pouch is above (deep to) the perineal membrane in the urogenital t...
A delayed nephrogram, commonly described on plain film urography, but also visible on CT urography, is when there is absence or reduction of the normal renal parenchymal enhancement on nephrographic phase images.
A delayed nephrogram is characteristically unilateral and is usually distinguished...
The detrusor muscle (or detrusor urinae muscle)is the smooth muscle component of the urinary bladder and facilitates contraction of the bladder wall during micturition.
Forms the smooth muscle component of the bladder wall. The urothelial lining overlies it within the bladder cav...
Developmental anomalies of the kidneys and ureters are numerous and not only potentially render image interpretation confusing but also, in many instances, make the kidneys more prone to pathology:
horseshoe kidney: most common
cross fused ...
Diabetes insipidus (DI) is the deficiency or resistance to the hormone vasopressin (antidiuretic hormone), which results in polyuria and polydipsia.
DI occurs in 3 per 100,000 people 2.
DI may be described as 1-3:
central/neurogenic/hypothalamic: vasopressin deficie...