Inflammatory myofibroblastic tumours (IMT), also known as plasma cell granulomas, are rare neoplasms that have a diverse spectrum of biological behaviour.
It can occur at any age and there is currently no recognised gender predilection.
Composed of spindle cells (key ...
The inguinal canal is a passage in the anterior abdominal wall that transmits structures from the pelvis to the perineum formed by the fetal migration of the gonad from the abdomen into the labioscrotal folds.
The inguinal canal has an oblique course, is 4 cm in length and has tw...
The international prostate symptom score (IPSS) is an 8 question (7 symptom questions + 1 quality of life question) screening tool used in screening, diagnosis, symptom tracking and aiding management of the symptoms associated with bladder emptying and is useful in those with benign prostatic hy...
Intra-abdominal calcification in a neonate can be caused by a number of pathologies that cause calcification within the peritoneal space or within organs.
The commonest cause is meconium peritonitis which is the result of aseptic peritonitis secondary...
Intrarenal reflux (IRR) involves intrarenal extension of vesicoureteral reflux (VUR) into the tubular system of the kidney.
IRR occurs in 3-10% of cases and can lead to renal injury, which may eventually result in renal scarring. The condition can be diagnosed by micturating cystourethrography ...
Intratesticular haematomas typically result from testicular trauma.
isoechoic/hyperechoic region in the traumatised testicle, becoming more hypoechoic as it resolves
lack of colour Doppler flow
segmental testicular infarct
Intratesticular varicocele is a rare entity, occurring in ~2% of symptomatic population.
It is defined as dilated intratesticular veins seen in relation to the mediastinum testis and extending peripherally. It is usually seen in the presence of ipsilateral extratesticular varicocele....
An intrathoracic kidney is a very rare form of ectopic kidney. There has been no reported increased incidence of stones or infections as with other forms of ectopic kidneys. The adrenal glands are usually normal in location.
Intrathoracic kidneys are usually asymptomatic ...
Intravenous urography (IVU), also referred as intravenous pyelography (IVP) or excretory urography (EU), is a radiographic study of the renal parenchyma, pelvicalyceal system, ureters and the urinary bladder. This exam has been largely replaced by CT urography.
Some prefer the ter...
Iron deficiency anaemia is a common cause of anaemia and a common precipitant to radiological investigation.
Amongst men and postmenopausal women, the incidence in the developed world is around 2%. Among premenopausal women, the incidence is greater and in most cases, investigatio...
The ischiocavernosus muscles are one of the three main muscles found in the superficial perineal pouch along with the bulbospongiosus and superficial transverse perineal muscle.
origin: ischial tuberosity and ramus
males: corpus cavernosum
Jackstone calculus is the name assigned to the appearance of a subset of urinary calculi.
Jackstone calculi are almost always composed of calcium oxalate dihydrate. They are nearly always created, and thus, located, in the bladder rather than the upper urinary tract.
They are compos...
Junctional parenchymal defects in renal imaging are a normal variant.
It results from the incomplete embryonic fusion of renunculi.
It can be seen as a triangular echogenic cortical defect, frequently seen in upper lobe parenchyma. The defect is th...
Juxtaglomerular cell tumour (JGCT) is an infrequent renal tumour of the juxtaglomerular cells. These cells secrete renin and often cause severe hypertension and hypokalaemia.
JGCT affects all age groups, but is most common in adolescents and young adults, with peak prevalence in t...
Kerr kink a sign of renal tuberculosis. Scarring leads to a sharp kink at the pelvi-ureteric junction.
History and etymology
William "Bill" K Kerr, a Canadian urologist, described his eponymous sign in 1967 3.
The keyhole sign is an ultrasonographic sign seen in boys with posterior urethral valves. It refers to the appearance of the proximal urethra (which is dilated) and an associated thick-walled distended bladder which on ultrasound may resemble a keyhole.
The kidneys are paired retroperitoneal organs that lie at the level of the T12 to L3 vertebral bodies.
The kidneys are located on the posterior abdominal wall, with one on either side of the vertebral column, in the perirenal space. The long axis of the kidney is parall...
The kidney sweat sign refers to the presence of thin, hypoechoic, extracapsular fluid collections around kidneys in renal failure patients. This fluid is thought to represent perirenal oedema. It can be appreciated on ultrasound, CT and MRI.
Lacuna magna (a.k.a. sinus of Guérin) is a congenital blind-ended pouch located dorsal to navicular fossa of penis separated by fold and both share an external common opening to external urethral meatus. This diverticulum is located above and parallel to the urethra.
Although it ...
The lateral fossae are concave depressions of peritoneum in the paravesical space that lie between the lateral umbilical folds and the lateral parietal peritoneum. The lateral fossae are the smallest of the anterior paravesical fossae, and typically partially contain the cecum and/or sigmoid col...
The lateral umbilical folds are raised ridges of parietal peritoneum in the deep aspect of the anterior abdominal wall overlying the inferior epigastric vessels. The paired folds originate medial to the deep inguinal ring and end at the arcuate line on the posterior aspect of the anterior abdomi...
A handy mnemonic to recall the layers of the scrotum is:
Some Damn Englishman Called It The Testes
D: dartos fascia and muscle
E: external spermatic fascia
C: cremasteric fascia
I: internal spermatic fascia
T: tunica vaginalis
T: tunica albuginea
Leiomyoma of the urinary bladder is a rare benign tumour predominantly found in women, although men can also be affected. The most common presenting complaints are urinary voiding symptoms such as obstruction and irritation.
It exhibits characteristics similar to those of uterine leiomyomas on...
The lentiform fork sign has been described on MRI and is seen as bilateral symmetrical hyperintensities in the basal ganglia surrounded by a hyperintense rim delineating the lentiform nucleus.
It has been postulated to result from metabolic acidosis due to any cause 1, e.g. end stage renal dise...
Leptospirosis results from infection of the zoonoses Leptospira sp. The condition can have multi-organ manifestations. Commonly affected organs include:
lung: pulmonary leptospirosis
liver: hepatic leptospirosis
central nervous system: CNS leptospirosis
skeletal muscle: muscular leptospirosi...
Leukoplakia of the urinary tract is a squamous metaplasia of the urothelium (keratinisation).
Clinically the condition presents with haematuria in one-third of cases, dysuria, frequency and nocturia, and thus it can mimic cystitis. Passage of the desquamated keratinised ...
The levator ani, also known as the muscular pelvic diaphragm, is the musculotendinous sheet that forms the majority of the pelvic floor, supports the pelvic viscera, and aids in urinary and faecal evacuation as well as maintaining continence.
The levator ani has three main compon...
A Leydig cell tumour of the testis is an uncommon testicular neoplasm. Its imaging appearance on ultrasound and MRI is nonspecific, but clinically it is associated with serum hormonal imbalance.
1-3% of all testicular tumours, but the most common sex-cord stromal tumour. Tend to b...
Liddle's syndrome is an autosomal dominant condition which inhibits the normal degradation of the ENaC sodium channel, resulting in findings that mimic Conn's syndrome (hyperaldosteronism); hypernatraemia, hypokalaemia and elevated serum bicarbonate. Typically patients are asymptomatic other tha...
Lipomatosis is a condition where there is diffuse excessive fat deposition within the body. This can especially affect certain regions.
neck and upper region of trunk
lipomatous hypertrophy of the interatrial septum
lipomatous metaplasia of th...
Lithium-induced renal disease is characterised by a progressive decline in renal function, evidenced by increasing serum creatinine and decreased creatinine clearance. The lithium salt causes direct injury to the renal tubules. The duration of lithium therapy increases the risk of progression to...
Lobar nephronia refers to an intermediate stage between acute pyelonephritis and renal abscess, and is a focal region of interstitial nephritis.
It appears as a wedge of poorly perfused renal parenchyma, without a cortical rim sign.
The condition is discussed further as part of the article on...
Lobster claw sign refers to a urographic pattern of papillary excavation that may be seen with renal papillary necrosis.
The lobster claw sign occurs when there is excavation around the edge of the papilla and the contrast material that extends into this excavated region looks like the "claws" ...
Localised cystic renal disease (LCRD) or localised cystic kidney disease is an uncommon, non-familial, non-progressive disease characterised by clusters of cysts within normal renal parenchyma. It can be confused with unilateral autosomal dominant polycystic kidney disease (ADPKD), multilocular ...
A loopogram is a fluoroscopic study of an ileal conduit, which is a type of urinary diversion.
This procedure is also known is an ileal conduitogram, ileal loopography or ileostoureterography.
It is a retrograde study in which contrast is injected via the anterior abdo...
The loop-to-loop colon describes an abnormal colonic course associated with the absence of the left kidney from the renal fossa.
The transverse colon extends to the lateral margin of the abdominal wall and the descending colon courses medially to fill the renal fossa, resulting in a "looped" c...
Lower urinary tract symptoms (LUTS) are a constellation of symptoms including 1:
poor stream despite straining
hesitancy, frequency and incomplete emptying of the bladder
Although they are most frequently encountered in men with benign prostatic hypertrophy (BPH) they are also found...
There are relatively few of causes of low signal intensity renal parenchyma. Causes include:
paroxysmal nocturnal haemoglobinurea.
mechanical: malfunctioning prosthetic cardiac valve
sickle cell disease
hemorrhagic fever with renal syndrome (HFRS)
Lymphangioleiomyomatosis (LAM) is a rare multi-system disorder that can occur either sporadically or in association with the tuberous sclerosis complex (TSC) and is often considered a forme fruste of TSC.
It almost exclusively affects women of child-bearing age 7. The estimated in...
Macronodular adrenal hyperplasia refers to a morphological type of adrenal hyperplasia in which there is adrenal enlargement in the form of large distinct nodules. It can be congenital or acquired.
A specific subtype under this entity is adrenocorticotropin independent macronodular adrenocortic...
Maiden waist deformity is the appearance of the deviation of bilateral ureters. This typically occurs in retroperitoneal fibrosis. In this condition, there is medial indrawing of the ureters due to deposition of fibrous tissue in the lumbosacral junction. Due to involvement of both ureters, the ...
Malacoplakia of the urinary tract is an uncommon chronic granulomatous inflammatory disease of the bladder wall. Malakoplakia (meaning "soft plaque") can affect any organ, but the urinary bladder is the commonest location.
Malacoplakia has a peak incidence in middle age and has a ...
Male pseudohermaphroditism (MPH) is a variation of gender development.
Patients with male pseudohermaphroditism have 46 XY karyotype and may manifest as a female phenotype with various degrees of undervirilization secondary to partial androgen insensitivity.
The male reproductive system (or tract) includes:
It can be imaged using almost the entire range of imaging modalities but ultrasound and MRI are most often used (in part because these modalities are n...
The male urethra is a fibromuscular tube that drains urine from the bladder. It has a longer, more complicated, course than the female urethra and is also more prone to pathology.
The male urethra measures, on average, 18-20 cm in length. It commences at the internal urethral ori...
A helpful mnemonic to remember the 4 segments of the male urethra from proximal to distal.
Pet My Big Penis
Posterior urethra equates to the prostatic and membranous urethras. Anterior urethra equates to the bulbous and penile urethras.
In 2017, the Adrenal Subcommittee of the Incidental Findings Committee of the American College of Radiology published a revised algorithm for the management of incidental adrenal masses in patients who are:
adults (i.e. 18-year-old or over)
asymptomatic for adrenal pathology
referred for imag...
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.
On a plain radiograph consider:
open book pelvic injuries: the smooth arc of th...
A mature metastasising teratoma is an uncommon complication of mature testicular teratomas, whereby distant metastatic deposits of histologically mature cells are encountered.
McCune-Albright syndrome (MAS) is a genetic disorder characterised by the association of:
endocrinopathy: precocious puberty
polyostotic fibrous dysplasia: more severe than in sporadic cases
cutaneous pigmentation: coast of Maine 'cafe au lait' spots
Presentation is va...
The medial fossae are concave depressions of peritoneum in the paravesical space bounded by the medial umbilical folds and the lateral umbilical folds. The fossae are contained within the inguinal (Hesselbach’s) triangle. The right medial fossa typically partially contains the cecum and/or ileum...
The medial umbilical folds are raised ridges of parietal peritoneum in the deep aspect of the anterior abdominal wall formed by the underlying medial umbilical ligaments. The paired folds run from pelvis to umbilicus. The medial umbilical ligaments are anatomical remnants of foetal umbilical art...
The median umbilical fold is a raised ridge of parietal peritoneum in the deep aspect of the anterior abdominal wall overlying the median umbilical ligament. It runs from the apex of the bladder to the umbilicus. The median umbilical ligament is the anatomical remnant of the foetal urachus. The ...
Medical devices in the abdomen and pelvis are important to be recognised, just like medical devices of the chest. Often we ignore these devices, considering them to be incidental and non-pathological, however it is essential to be aware of potential complications.
Medullary cystic disease complex belongs to group of paediatric cystic renal diseases charaterised by progressive tubular atrophy with glomerulosclerosis (chronic tubulointerstitial nephritis) and multiple small medullary cysts.
There is no recognised gender predilection
Renal medullary nephrocalcinosis is the commonest form of nephrocalcinosis and refers to the deposition of calcium salts in the medulla of the kidney. Due to the concentrating effects of the loops of Henle, and the biochemical milieu of the medulla, compared to the cortex, it is 20 times more co...
A common mnemonic used to remember the aetiology of medullary nephrocalcinosis is:
A: (renal tubular) acidosis
M: medullary sponge kidney
H: hypercalcemia / hypercalciuria
P: papillary necrosis
renal papillary necrosis mnemon...
Medullary sponge kidney is a sporadic condition where the medullary and papillary portions of the collecting ducts are dysplastic and dilated and in most cases develop medullary nephrocalcinosis.
The incidence of medullary sponge kidney is estimated at ≈1:5000.
Megacystis megaureter syndrome describes the radiologic appearance of a large capacity thin-walled bladder and massive primary vesicoureteral reflux.
The pathophysiology of these massively dilated ureters and the large capacity bladder is the constant recycling of large volumes of r...
Megapolycalycosis is a rare congenital anomaly of the kidney which is characterized by dilatation and increase in number of the renal calyces without any distal obstruction.
It is thought to develop due to an abnormal development of the renal medulla.
Due to the calyceal dilatation...
Mesoblastic nephroma, also sometimes known as a congenital mesoblastic nephroma (CMN) or fetal renal hamartoma, is, in general, a benign renal tumour that typically occurs in utero or in infancy.
It is the commonest neonatal renal tumour. Diagnosis is usually made in the antenatal...
Patients with malignant ureteric obstruction and poor life expectancy usually require placement of ureteral stents to relieve the urinary obstruction and as a palliative measure to reduce pain and avoid major operation.
Metallic ureteric stents have recently been developed to try and offer bett...
Metanephric adenoma (MA) of the kidney is a type of benign renal neoplasm.
While it can present at any age 6, the peak age of occurrence is thought to be around the 5th to 6th decades 2. There may be a 2:1 female preponderance 2.
Metanephric adenoma is as...
Metanephric blastema (or metanephrogenic blastema) is one of the two embryological structure that give rise to the kidney, the other one being the ureteric bud.
Persistent metanephric blastema after 36 weeks of gestational age are called nephrogenic rests. They are associate...
Metastases to testis are a rare cause of a testicular mass and may be bilateral in up to 15% of patients.
Metastases to the testes are apparent in ~0.04% of autopsy studies in patients with known malignancy. The average age is 57 years, much older than the primary age for primary...
Microlithiasis merely means very small stones and may refer to:
The middle adrenal (suprarenal) artery is one of the three adrenal arteries that supply the adrenal gland.
The middle suprarenal arteries arise from the aorta on each side between the inferior phrenic artery and the renal artery. They run laterally across the diaphragmati...
Milk-alkali syndrome is the combination of:
It is due to the large amounts of calcium and alkali being ingested (e.g. milk and antacids for peptic ulcer disease treatment or calcium carbonate for osteoporosis). It is a cause of medullary nephr...
Milk of calcium (MOC) is a term given to dependent, sedimented calcification within a cystic structure or hollow organ. This sort of colloidal calcium suspension layering can occur in various regions:
renal cysts: milk of calcium in renal cyst (most common)
breast cysts: milk of calcium in bre...
Mixed gonadal dysgenesis (MGD) is a type of gonadal dysgenesis characterised by gonadal asymmetry, and/or sex chromosomal mosaicism, as well as retained Müllerian ducts.
Depending on the chromosomal composition, patients may have testes and/or streak gonads.
Mixed epithelial and stromal tumour (MEST) of the kidney is an uncommon and recently recognised distinct neoplasm that should be distinguished from other renal neoplasms.
There is a female preponderance 10:1 1 with tumours occurring predominantly in middle-aged peri-menopausal wo...
Abdominal molar tooth sign refers to the appearance of contrast media spilled 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 to...
Moth eaten calyx refers to the ragged, feathery calyceal outline due to irregular erosions of the calyx. It is one of the earliest excretory urographic appearance of genitourinary tuberculosis.
This appearance is due to necrotizing papillitis, which may further progress to form medu...
MR defecography is a dynamic study for evaluation of the pelvic floor and pelvic organ prolapse.
There are four phases of evaluation:
Method of evaluation
Many variations in the techniques described below exist.
MR spectroscopy is a promising development in the radiological evaluation of possible prostate malignancy.
The MR spectroscopic evaluation is mainly based on the choline peak elevation and choline-creatinine ratios.
Choline/creatine to citrate ratios:
> 0.5: suspicious
> 0.8: very suspiciou...
A mulberry stone is one of the types of urinary tract stones. It is formed of calcium oxalate dihydrate. It can be considered as a subset of a jackstone calculus which has a spiked appearance. When the stone has less well-developed spikes, it may appear to have a mamillated appearance, hence it ...
A Müllerian duct cyst is a cyst that arises from remnants of the Müllerian duct and is one of the midline cystic masses in the male pelvis.
Müllerian duct cysts usually occur in the 3rd and 4th decades of life (whereas utricle cysts are most often detected in the 1st and 2nd decad...
Multicystic dysplastic kidney (MCDK) is a type of non-heritable paediatric cystic renal disease. It results in multiple cysts being formed in utero in the affected kidney.
Unilateral incidence is estimated at 1:2500-4000. There may be a predisposition for the left kidney, a slight...
A multicystic mesothelioma is a rare benign sub type of mesothelioma.
They tend to occur in young females.
Typically comprises of multiple grape-like clusters of cysts which are lined with mesothelium and separated by fibrous tissue components.
Multilocular cystic renal tumours (MCRT) are rare benign renal neoplasms occurring in a bimodal age distribution, involving young children and adults in the 4th and 5th decades.
For logical reasons, this article will discuss together the two ends of the spectrum of this disease, cystic partiall...
Multiple endocrine neoplasia (MEN) syndromes are a collection of syndromes characterised by the presence of, as the name would suggest, multiple endocrine tumours. They are autosomal dominant in inheritance.
MEN1 (Wermer syndrome)
MEN2 (multiple endocrine adenomatosis)
MEN2a (Sipple syndrome)...
Multiple endocrine neoplasia type II (MEN2) is also known as mucosal neuroma syndrome or multiple endocrine adenomatosis. It is a collection of syndromes characterised by the presence of multiple endocrine tumours.
They are autosomal dominant in inheritance, and share medullary thyroid carcino...
Multiple endocrine neoplasia (MEN) type IIb, also known as MEN type 3 (MEN3) 3 or mucosal neuroma syndrome 2, accounts for only 5% cases of MEN2 and is characterised by:
pheochromocytoma(s): in 50% of patients, often bilateral, and can be extra-adrenal
medullary thyroid cancer: 100% of patient...
Multiple filling defects within a ureter, as seen on conventional IVU or CT IVU, have a relatively small differential including:
spreading or multifocal transitional cell carcinoma (TCC)
multiple ureteral stones (steinstrasse)
N-acetylcysteine (NAC) if often used as a prophylaxis against contrast-induced nephropathy. Protocols for administration vary widely from institution to institution and the true efficacy is still controversial.
A typical protocol is [1-2]:
600 mg acetylcysteine twice daily on the day of the ex...
Neonatal hydronephrosis is most commonly diagnosed antenatally as fetal pylectasis, and in the majority of cases is due to pelvi-ureteric junction (PUJ) obstruction.
pelvi-ureteric junction (PUJ) obstruction (50% of cases 1,6)
vesicoureteric reflux (~20% of cases 5)
Nephroblastomatosis refers to diffuse or multifocal involvement of the kidneys with nephrogenic rests (persistent metanephric blastema).
Nephrogenic rest are found incidentally in 1% of infants.
Nephrogenic rests are foci of metanephric blastema that persist beyond 36 ...
Nephrocalcinosis, previous known as Anderson-Carr kidney or Albright's calcinosis, refers to the deposition of calcium salts in the parenchyma of the kidney. It is divided into several types, with differing aetiologies, based on the distribution:
medullary nephrocalcinosis: 95%
Nephroptosis, also known as floating or wandering kidney and ren mobilis, refers to the descent of the kidney more than 5 cm or two vertebral bodies when the patient moves from a supine to upright position during IVU 1-2.
Displacement can also occur medially across the midline, so-called medial...
Nephrostomy is a common urologic or interventional radiology procedure in which a tube/catheter is introduced into the renal collecting system (usually the renal pelvis).
Nephrostomies can either be
"open" nephrostomy: after a urological surgical procedure, such as a UPJ stone removal
Nephrotic syndrome (NS) results from loss of plasma proteins in the urine and characterised by hypoalbuminemia, hyperalbuminuria, hyperlipidemia, and oedema. It may be caused by primary (idiopathic) renal disease or by a variety of secondary causes.
Patients present with ...
Neuroblastomas are tumours of neuroblastic origin. Although they may occur anywhere along the sympathetic chain, the vast majority arise from the adrenal gland.
They represent the most common extracranial solid childhood malignancy and are the third commonest childhood tumour after leukaemia an...
There are two methods of neuroblastoma staging, one that is based on post-operative patients (INSS) and one developed for pre-treatment patients (INRGSS).
International Neuroblastoma Staging System (INSS)
This staging system is for post-operative patients and mainly for prognosis 1: