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
ionising 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 2009 8
stage 0: cervical intraepithelial neoplasia (HSIL or CIN III)
stage I: confined to cervix
stage Ia: invasive carcinoma only diagnosed by microscopy.
Ia1: stromal inva...
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 recognised 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.
The lucent "hood" of the cobra repr...
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-recognised, 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) 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.
virilization/genital ambiguity of female fetuses (d...
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, floppy calyces predispose to stasis, infection and calcul...
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 containing microbubbles of perfluorocarbon or nitrogen gas. The bubbles greatly affect ultrasound backscatter and increase vascular contrast in a similar manner to intravenous contrast agents used in C...
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
toxaemia 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 is useful in distinguishing acute pyelonephritis from a segmental renal infarct and is seen on contrast enhanced CT or MRI.
In the setting of acute pyelonephritis, the areas of abnormally reduced enhancement typically involve a complete wedge of renal parenchyma, extending...
Cowper duct syringocele refers to a 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 recognised 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...
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 localisation 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.
identification of calc...
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 is seen intravenous pyelogram in cases of ureteral herniation in sciatic hernia, causing a curled appearance of the herniated ureter. Although very rare, this sign is pathognomonic of sciatic hernia.
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 contain gas, not 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. E...
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
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 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 group congenital renal anomalies characterized by the formation of cysts. Many of the congenital cystic renal diseases fall under this group.
A cystic retroperitoneal lesion can carry a relatively broad differenital which includes:
retroperitoneal cystic lymphangioma
retroperitoneal mucinous cystadenoma
retroperitoneal cystic teratoma
retroperitoenal cystic mesothelioma
pseudomyxoma retroperitonei with cystic change
Cystinosis, also known as Abderhalden Kaufmann Lignac syndrome, is the most common hereditary cause of renal Fanconi syndrome. Cystinosis is a form of lysosomal storage disease.
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 are small focal polypoid bladder mucosal thickenings and irregularities due to metaplasia of the urothelium (to mucin producing goblet cells) which proliferates into buds growing down into the lamina propria; this entity is closely related to cystitis cystica, with which it ...
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 perinuem. It may be accompanied by prolapse of other pelvic organs.
CT / MRI
Sagittal images be particularly usef...
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...
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 nodes 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 perineum (e.g. glans penis / clitoris), and drain proximally into external iliac lymph nodes via channels...
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...
The dialysis disequilibrium syndrome (DDS) is a situation characterized by development of neurological symptoms caused by rapid removal of urea during hemodialysis. It develops primarily from an osmotic gradient that develops between the brain and the plasma as a result of rapid haemodialysis. I...
Diverticula are outpouchings of a hollow viscus and can be either true or false.
Occasionally a diverticulum is used in a more general sense to mean the outpouching of other anatomical structures, e.g. frontal intersinus septal cells are hypothesised to form as diverticula from the frontal sinu...
Dorsal nerve of penis or clitoris is one of the two terminal branches of the pudendal nerve that arises from nerve whilst in the pudendal canal. The other terminal branch is the perineal nerve.
Entering the urogenital triangle of the perineum, the dorsal nerve of penis o...
Double contrast cystography (pneumocystography) is an older technique to evaluate the bladder lumen. It has rarely been used (if ever) after the advent of cross-sectional imaging.
The exam is performed similarly to a conventional cystogram, but gas is also introduced through the Foley catheter....
Double retroaortic left renal vein is a very rare entity that is usually clinically silent and detected incidentally at imaging, surgery or autopsy.
The knowledge of anatomical variations helps the surgeon or interventionist to avoid complications during surgery and interventional procedures 4 ...
Drash syndrome, also known as the Denys-Drash syndrome, is associated with an abnormal WT1 gene (Wilms tumor gene) and consists of:
Dromedary humps are prominent focal bulges on the lateral border of the left kidney. They are normal variants of the renal contour, caused by the splenic impression onto the superolateral left kidney.
Dromedary humps are important because they may mimic a renal mass, and as such is considered a...
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 moiety.
The similarity to a lily is further strengthened by the smal...
Drug-induced renal calculi are a subtype of renal calculi, whereby the stone formation is related to the patient's medication.
Two main types of drug-induced calculi are described:
Overall drug-induced urolithiasis accounts for 1-2% o...
The ductus deferens (plural: ducti deferentia or deferentes) forms part of the male internal genitalia where it transports sperm from the epididymis to the ejaculatory duct. In modern anatomic nomenclature, it is no longer referred to as the vas deferens (plural: vasa deferentia or deferentes).
Calcification of the ductus deferens can result from:
diabetes mellitus - most common
chronic infection - more frequently irregular; unlike diabetic calcification, inflammatory calcification tends to be unilateral and segmental 3
A duplex collecting system, or duplicated collecting system, is one of the most common congenital renal tract abnormalities. It is characterized by an incomplete fusion of upper and lower pole moieties resulting in a variety of complete or incomplete duplications of the collecting system. While ...
Dynamic contrast enhancement (DCE) MRI is emerging as a useful clinical technique as part of a multiparametric approach for evaluating the extent of primary and recurrent prostate cancer.
Protocol and equipment
Typically 3D T1-weighted fast spoiled gradient-echo MRI sequences with an endorect...
Echogenic renal pyramids in children can be due to many different causes.
Iatrogenic (most common cause)
Ectopic kidney, also known as renal ectopia, is a congenital renal anomaly characterized by abnormal location of one or both of the kidneys.
They can occur in several forms:
cross fused renal ectopia
ectopic thoracic kidney
The estimated incidence of an ectopic k...