Abnormal renal rotation (renal malrotation) refers to an anatomical variation in the position of the kidneys, in particular to anomalous orientation of the renal hilum. It may occur unilaterally or bilaterally. It is almost always an asymptomatic incidental finding.
The diaphragm is the dome-shaped muscle that separates the thoracic cavity from the abdominal cavity, enclosing the inferior thoracic aperture.
The muscular fibres of the diaphragm originate around the circumference of the inferior thorax and converge to a common insertion point ...
Paradoxical embolism is a clinical scenario in which an embolism arising in the venous system crosses into the arterial circulation where it causes tissue infarction. The most common clinically important site of embolisation is the cerebral circulation.
The prevalence of paradoxic...
The ventriculus terminalis or terminal ventricle of Krause, also known as the 5th ventricle, is an ependymal-lined fusiform dilatation of the terminal central canal of the spinal cord, positioned at the transition from the tip of the conus medullaris to the origin of the filum terminale.
The Macklin effect describes one of the pathophysiological processes of pneumomediastinum in blunt chest trauma. The Macklin effect accounts for ~40% of severe blunt traumatic pneumomediastinum. Exclusion of tracheobronchial and oesophageal causes of pneumomediastinum is mandatory to exclude con...
A gastric duplication cyst is a rare congenital foregut duplication cyst affecting the stomach. It accounts for less than 10% of all gastrointestinal duplications. The most common site of gastrointestinal tract duplication cysts (GTDCs) is the ileum, followed by oesophagus, large bowel and jejun...
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...
The foramen caecum represents a primitive tract between the anterior cranial fossa and the nasal space. It is located along the anterior cranial fossa, anterior to the cribriform plate of the ethmoid bone and posterior to the frontal bone, within the frontoethmoidal suture. It lies at a variable...
Crohn disease, also known as regional enteritis, is an idiopathic inflammatory bowel disease characterised by widespread discontinuous gastrointestinal tract inflammation. The terminal ileum and proximal colon are most often affected. Extraintestinal disease is common.
Epibasal fractures of the thumb (also called pseudo-Bennett fracture) are two-piece fractures of the proximal first metacarpal bone. They are usually stable, depending on the degree of displacement, and often do not require surgery. It is important to distinguish them from intra-articular fractu...
Renal cortical nephrocalcinosis is ~20 times less common than medullary nephrocalcinosis.
renal cortical necrosis: common 2
toxaemia of pregnancy
extracorporeal shock wave lithotripsy (ESWL)
Myxoid uterine leiomyomas are a relatively rare pathological subtype of uterine leiomyomas.
They are not to be confused with myxoid degeneration of a uterine leiomyoma which is a different entity.
Myxoid leiomyomas contain abundant myxoid material between smooth muscle ...
Vaginal leiomyomas are an extremely rare entity and fall under extra-uterine pelvic leiomyomas.
They are extremely rare with only ~ 300 cases reported in literature 3.
It may occur anywhere along the vaginal canal and is usually localized, mobile, non-tender, and circ...
Benign metastasising leiomyomas are a rare metastatic phenomenon that is observed when a pelvic leiomyoma is present.
Women who have undergone hysterectomy for leiomyomas are most commonly affected.
Patients are usually asymptomatic at presentation. A histo...
Intravenous leiomyomatosis (IVLM) is characterised by the extension into venous channels of histologically benign smooth muscle tumour arising from either the wall of a vessel or from a uterine leiomyoma.
Intravenous leiomyomatosis should not be confused with benign metastasising l...
Leiomyomas of the uterine cervix are an unusual variation in terms of location for a uterine leiomyoma.
They are rare and account for ~5% (range 0.6-10%) of uterine leiomyomas 1,4.
Clinical symptoms of cervical leiomyomas, including hypermenorrhea, dysmenor...
Parasitic leiomyomas are considered a type of extra-uterine leiomyoma and present as peritoneal pelvic benign smooth-muscle masses separate from the uterus.
It likely originates as a pedunculated subserosal leiomyoma that twists and torses from its uterine pedicle. The contact with ...
Lesions of the corpus callosum are uncommon and arise from multiple different aetiologies. The lesions can be classified according to underlying pathophysiology 4-6.
agenesis of the corpus callosum
enlarged perivascular spaces
tubonodular pericallosal lipoma: associated with dysge...
Autoimmune encephalitis, also known as autoimmune limbic encephalitis, is an antibody-mediated brain inflammatory process, typically involving the limbic system, although all parts of the brain can be involved.
Autoimmune encephalitis can be divided broadly into two groups, based on whether or...
The Castellvi classification is used for lumbosacral transitional vertebra (LSTV):
type I: enlarged and dysplastic transverse (at least 19 mm)
type II: pseudoarticulation of the transverse process and sacrum with incomplete lumbarisation/sacralisation; enlargemen...
Thorotrast is a radioactive radiographic contrast agent containing thorium dioxide first produced in Germany in 1928 and was in use until the 1950s. It was used primarily for cerebral angiography, and 90% of the estimated 50,000-100,000 patients who received it were studied for this purpose.
Menkes disease, also known as trichopoliodystrophy or Kinky hair kinky vessel syndrome, is an X-linked recessive disorder that results in a derangement in copper handling. It results in low copper levels and subsequently, deficiency in copper-dependant mitochondrial enzymes.
Transposition of the great arteries (TGA) is the most common cyanotic congenital cardiac anomaly presenting during the newborn period, with cyanosis in the first 24 hours of life. It accounts for up to 7% of all congenital cardiac anomalies 1 and can be assessed with echocardiography, gated car...
Tetralogy of Fallot (TOF) is the overall most common cyanotic congenital heart condition with many cases presenting after the newborn period. It has been classically characterised by the combination of ventricular septal defect (VSD), right ventricular outflow tract obstruction (RVOTO), overridi...
A useful mnemonic to remember the causes of corpus callosum hyperintensity is:
I MADE A PHD
I: infections (e.g. tuberculosis, varicella, rotavirus, HSV)
M: Marchiafava-Bignami syndrome
A: AIDS encephalopathy
D: diffuse axonal injury and diffuse vascular injury
Gastric metastases are rare, found in less than 2% of patients who die of a carcinoma 6.
Usually affects the middle-aged and elderly population. Affects males and females equally without predilection.
The patient may be asymptomatic, but the most common sig...
Sesamoids, also known as sesamoid bones, are focal areas of ossification within tendons as they pass over joints 1. They can also occur in ligaments and usually measure a few millimeters in diameter. Their function is purported to be to alter the direction of the tendon and modify pressure, ther...
Broad ligament leiomyomas are extra-uterine leiomyomas that occur in relation to the broad ligament.
Broad ligament leiomyomas are also referred as a type of parasitic leiomyomas 5.
While in most cases broad ligament leiomyomas are asymptomatic, patients ma...
Subserosal uterine leiomyoma is a subtype of uterine leiomyoma that often exophytically projects outwards from a subserosal location. While its exact definition may vary, a leiomyoma is often called subserosal if >50% of the fibroid protrudes out of the serosal surface of the uterus 2.
Intramural uterine leiomyoma is the most common type of uterine leiomyoma in terms of location. They are centred primarily within the myometrium. A large intramural uterine leiomyoma can, however, have a submucosal or subserosal component.
They are usually asymptomatic; h...
The bridging vessel sign refers to an appearance of vessels coursing from the uterus into an adjoining pelvic mass (a vascular bridge). This sign helps to differentiate a pedunculated subserosal uterine leiomyoma from other juxtauterine masses of ovarian, adnexal or bowel origin.
Colour and pow...
Adrenal haemorrhage can result from a variety of traumatic and non-traumatic causes. When unilateral, it is often clinically silent. In contrast, bilateral adrenal haemorrhage can lead to catastrophic adrenal insufficiency.
The large majority of patients with unilateral a...
Diffuse or disseminated peritoneal leiomyomatosis, also known as leiomyomatosis peritonealis disseminata, is an exceedingly rare benign disorder characterised by multiple vascular leiomyomas growing along the submesothelial tissues of the abdominopelvic peritoneum.
It is usually d...
Submucosal leiomyomas of the uterus refer to a subtype of uterine leiomyoma that primarily projects into the endometrial cavity. They are least common albeit the most symptomatic type of leiomyoma.
Submucosal leiomyomas can be a common source of abnormal uterine bleeding ...
Echogenic fetal bowel is an observation in antenatal ultrasound imaging, in which fetal bowel appears to be brighter than it is supposed to be. It is a soft marker for trisomy 21 and has several other associations. When observed, it needs to be interpreted in the context of other associated abno...
Pancreatic metastases are uncommon and are only found in a minority (3-12%) of patients with widespread metastatic disease at autopsy . They account for only 2-5% of all pancreatic malignancies.
Although essentially any primary may eventually deposit in the panaceas the most common primaries en...
Hypervascular liver lesions may be caused by primary liver pathology or metastatic disease.
hepatocellular carcinoma (HCC)
most common hypervascular primary liver malignancy
early arterial phase enhancement and then rapid wash out
rim enhancement of c...
Ulcerative colitis is an inflammatory bowel disease that not only predominantly affects the colon, but also has extraintestinal manifestations.
Typically ulcerative colitis manifests in young adults (15-40 years of age) and is more prevalent in males but the onset of disease after...
Causes of neonatal distress can be broadly split into intrathoracic, extrathoracic and systemic:
respiratory distress syndrome (RDS)
transient tachypnoea of the newborn (TTN)
meconium aspiration syndrome
bronchopulmonary dysplasia (BPD)
patent ductus arteriosus (PDA)...
Concha bullosa (plural: conchae bullosae) (also known as middle turbinate pneumatisation) is a common finding and although associated with deviation of the nasal septum, it is usually of little clinical importance.
Concha bullosa is a normal variant and is one of the most common v...
Perianal abscess refers to a formed infective-inflammatory collection within the perianal region. It forms part of the broader group of anorectal abscesses. They are often associated with perianal fistulae and are components of grades 2 and 4 fistulae of the St James’ University Hospital classif...
Os trigonum is one of the bony ossicles of the foot and can be mistaken for a fracture.
It sits posterior to the talus on the lateral foot radiograph and represents a failure of fusion of the lateral tubercle of the posterior process. It is estimated to be present in ~7% of adults 1. The ossic...
Diverticulitis is one of the presentations of diverticular disease and is most often a complication of colonic diverticulosis. Differentiating one from the other is critical since uncomplicated diverticulosis is mostly asymptomatic and acute diverticulitis is a potentially life-threatening illne...
Colonic diverticulosis refers to the presence of multiple diverticula. It is quite distinct from diverticulitis which describes inflammation and infection of one or multiple diverticula.
Diverticulosis is very common in westernised countries and is typically found in older individ...
Calcific tendinitis (or calcific tendonitis) is a self-limiting condition due to deposition of calcium hydroxyapatite within tendons, usually of the rotator cuff. It is a common presentation of the hydroxyapatite crystal deposition disease (HADD).
Typically this condition affects...
Intracranial epidermoid cysts are relatively common congenital lesions which account for about 1% of all intracranial tumours. They result from inclusion of ectodermal elements during neural tube closure, and typically present in middle age due to mass effect on adjacent structures. Their conten...
The ovaries are paired female gonads of the reproductive and endocrine systems. They lie within the ovarian fossa on the posterior wall of the true pelvis.
The ovaries are ovoid in shape and measure approximately 1.5-3.0 cm x 1.5-3.0 cm x 1.0-2.0 cm (length x width x thickness) ...
Spina bifida occulta is the mildest form of spina bifida and is a type of neural tube defect.
While typically referring to asymptomatic posterior fusion defects, some authors 5 use it as a broad term that encompasses closed spinal defects such as:
Posterior vertebral fusion anomalies are relatively common and should not be mistaken for fractures. They are thought to be both pathological (e.g. spondylolysis) but are typically asymptomatic and incidental, and considered as anatomical variants. There are six types of posterior vertebral fusi...
Fetal intra-abdominal cystic lesions can arise from a number of entities:
fetal gastric dilatation / fetal gastric bubble (can be pathological if there is a gastric outlet obstruction
normal fetal gallbladder
No colour flow
fetal choledochal cyst
fetal hepatic cyst ...
RAD-AID (also known as RAD-AID International) is a US-based international non-profit organisation established to advance the provision of imaging services for medically-underserved populations in the developing world.
As of July 2018, RAD-AID comprises over 6,000 volunteers...
Caisson disease is an uncommon diving-related decompression illness that is an acute neurological emergency typically occurring in deep sea divers.
Diving-related decompression illness is classified into two main categories 3:
arterial gas embolism secondary to pulmonary decompression barotra...
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...
Renal infarction results from interruption of the normal blood supply to part of, or to the whole kidney. The main imaging differential diagnosis includes pyelonephritis and renal tumours.
The demographics of affected patients will depend on the underlying cause, although as most ...
There are numerous terms used in radiology that are worth knowing and this is list of some of them.
sine qua non
Exophytic is a descriptive term used by radiologists/pathologists to describe solid organ lesions arising from the outer surface of the organ of origin.
Literally exophytic only refers to those lesions arising from the outer surface, however radiologists and pathologists use the term to include...
Periportal halo or periportal collar sign is a zone of low attenuation seen around the portal veins on contrast-enhanced CT or hypoechogenicity on liver US. Periportal halos may occur around the central portal veins or their peripheral branches and occurs on both sides of the portal triads.
Fetal ascites refers to the accumulation of free fluid in the fetal abdomen. It is often considered under the same spectrum of hydrops fetalis.
any condition that results in hydrops fetalis
additional causes include
bowel perforation (e.g. meconium peritoniti...
Haemangiopericytoma is a term formerly used to describe a continuum of mesenchymal tumours with elevated cellularity found throughout the body in soft tissue and bone. After many years of controversy, haemangiopericytomas have been shown to not only share histological features similar to solitar...
Marie S Curie (1867-1934) was a Polish-born, French scientist known for her work in discovering radioactivity. Her work shaped medicine, warfare and scientific research for countless generations, earning her Nobel prizes in both physics and chemistry 1,3.
Maria Salomea Skłodowska wa...
Cortical desmoids, also known as cortical avulsive injuries or the Bufkin lesion, are a benign self-limiting entity. This is a classic "do not touch" lesion, and should not be confused with an aggressive cortical/periosteal process (e.g. osteosarcoma).
Cortical desmoid is a misnom...
Intramuscular myxomas are a rare benign type of soft tissue myxoma most commonly seen in middle-aged women. On imaging, they are often seen in large muscles from the thighs, buttocks, or shoulder girdle, and present as well-defined cystic-like lesions with a surrounding rim of fat.
Bronchopulmonary dysplasia (BPD) refers to late pathological lung changes that develop several weeks later in infants on prolonged ventilation.
BPD and chronic lung disease of prematurity (CLDP) have often been used interchangeably to describe the condition post-treatment of premat...
The oblique pelvis otherwise known as the Judet view is an additional projection to the pelvic series when there is suspicion of an acetabular fracture.
The Judet view is comprised of two projections, first the iliac oblique for assessment of the posterior column and anterior wall of the acetab...
Fetal ovarian cysts refer to an ovarian cyst detected antenatally in a female fetus. They are relatively uncommon and are usually diagnosed in the 3rd trimester 5.
From autopsy studies they are found in up to 30% of fetuses 1.
The exact aetiology is not well known at t...
D-dimer is a commonly tested biological marker which is produced by the enzymatic breakdown of cross-linked fibrin which forms the fibrous mesh of a blood clot. The measurement of d-dimer in the circulation acts as a marker of coagulation and fibrinolysis, which can be useful in the diagnosis of...
Heterotopic pregnancy is a rare situation when there is an intra-uterine and extra-uterine (i.e. ectopic) pregnancy occurring simultaneously.
The estimated incidence in the general population is estimated at 1:30,000 (for a naturally conceived pregnancy 7). The incidence among pat...
The water-lily sign is seen in hydatid infections when there is detachment of the endocyst membrane which results in floating membranes within the pericyst that mimic the appearance of a water lily.
It is classically described on plain radiographs (mainly chest X-ray) when the collapsed membran...
This article contains a list of commonly used medical abbreviations and acronyms that start with the letter T and may be encountered in medicine and radiology (please keep in alphabetic order).
A - B - C - D - E - F - G - H - I - J - K - L -M - N - O - P - Q - R - S - T - U - V - W - X - Y - Z ...
Hydatid cysts result from infection by the Echinococcus, and can result in cyst formation anywhere in the body.
There are two main species of the Echinococcus tapeworm 1,2:
pastoral: dog is a main host; most common form
sylvatic: wolf is a main h...
The cervical enlargement is the source of the spinal nerves that contribute to the brachial plexus and supply the upper limbs.
It is one of two symmetrical enlargements which occupy the segments of the limb plexuses, the other being the lumbosacral enlargement for the lumbar and ...
Avascular necrosis of the hip is more common than other sites, presumably due to a combination of precarious blood supply and high loading when standing.
The most common presenting symptom is a pain in the region of affected hip, thigh, groin, and buttock. Although few p...
Diffuse idiopathic pulmonary neuroendocrine cell hyperplasia (DIPNECH) is an extremely rare pulmonary disorder at the benign end of the neuroendocrine cells proliferation spectrum. It is mainly seen in non-smoker middle age females with a history of chronic cough or asthma.
On imaging, it is c...
Niemann-Pick disease (NPD) is actually a collection of a number of distinct autosomal recessive lysosomal storage diseases. They are divided into two groups of two based on the underlying metabolic deficiency:
deficiency of acid sphingomyelinase 1,3,4
Niemann-Pick disease type A (NPD-A)
Niemann-Pick disease type A (NPD-A) is one of a group of autosomal recessive lysosomal lipid storage disorders (see Niemann-Pick disease) that presents in early childhood and usually progresses to death within a few years. It shares the same enzyme deficiency as Niemann-Pick disease type B (NPD-...
Niemann-Pick disease type c (NPD-C or just NPC) is an autosomal recessive lysosomal storage disorder classed under Niemann-Pick disease on account of clinical similarities, namely hepatosplenomegaly and variable involvement of the central nervous system.
NPD-C is inherited as a a...
Niemann-Pick disease type B (NPD-B), along with Niemann-Pick disease type A (NPD-A), is an autosomal recessive disorder due to acid sphingomyelinase deficiency resulting in abnormal storage of sphingomyelin.
Common manifestation of NPD-B include hepatosplenomegaly, thrombocytopaenia and variabl...
Sydney D Rowland (1872-1917), was the founder and editor of the Archives of Clinical Skiagraphy, the first regular journal of radiology to be published anywhere in the world.
Sydney Domville Rowland was born on 29th March 1872.
His undergraduate preclinical studies were at Downing ...
Progressive multifocal leukoencephalopathy (PML) is a demyelinating disease which results from the reactivation of John Cunningham virus (JC virus) infecting oligodendrocytes in patients with compromised immune systems. It is considered the most common clinical manifestation of John Cunningham v...
Cystic lesions of liver carry a broad differential diagnosis. These include:
simple hepatic cyst
adult polycystic liver disease
infectious: inflammatory conditions
pyogenic hepatic abscess
amoebic hepatic abscess
Carotid body tumour, also known as a chemodectoma or carotid body paraganglioma, is a highly vascular glomus tumour that arises from the paraganglion cells of the carotid body. It is located at the carotid bifurcation with characteristic splaying of the ICA and ECA.
Archives of Clinical Skiagraphy was the first radiology scientific journal in the world with its first edition issued in May 1896. This is only six months after the discovery of x-rays by Wilhelm Roentgen on 8th November 1895.
Its founder and editor was Sydney D Rowland (1872-1917), a...
Tumours of the chest wall are varied, some of which are found most often in this region. They can be divided into benign and malignant tumours and into those which arise in the ribcage and those of soft tissue density.
Benign tumours include 1,3-4:
Intrabiliary rupture of hepatic hydatid cyst is a common complication associated with hepatic hydatid cysts. It is important to appreciate the direct and indirect signs of this condition.
The radiological features of intrabiliary rupture of a hepatic hydatid cyst can be c...
Elastofibroma dorsi is a benign soft-tissue tumour with a characteristic location and imaging appearance.
It is more frequently seen in older women, with a reported female predilection of 5-13:1. The estimated mean age at diagnosis is around 65-70 years.
Scaphotrapeziotrapezoidal (STT or triscaphe joint) arthritis is common, occurring in ~40% of wrist radiographs. It is typically degenerative (i.e. osteoarthritis) and presents with radial-sided wrist pain in patients over 50 years.
Subcortical U-fibres, also known as short association fibres, represent connections between adjacent gyri of the brain, located within the cortex or immediately deep to it in the very outer parts of the subcortical white matter 1.
They are among the last parts of the brain to myelinate, as lat...
Gastric outlet obstruction is a syndrome resulting from mechanical obstruction of stomach emptying.
Gastric outlet obstruction can be due to malignant or benign causes.
adenocarcinoma (second most common 4)
lymphoma (less commonly than other malignancies...
Pulmonary metastases are common and the result of metastatic spread from a variety of primary tumours via blood or lymphatics.
This article describes haematogenous pulmonary metastases with lymphangitis carcinomatosis discussed separately.
The epidemiology will match that of the ...
Testicular choriocarcinoma is a type of non-seminomatous germ cell tumour.
Incidence peaks at around 20-30 years of age.
Can be variable with some patients initially presenting with metastates.
It is most commonly detected as a component of a m...
Spontaneous splenic rupture (SSR) (or atraumatic splenic rupture) is rare, especially when compared to traumatic splenic rupture.
The pathogenesis of atraumatic splenic rupture is not well understood. Splenomegaly is present in almost all patients (~95%), although rupture of normal ...
An anterior labroligamentous periosteal sleeve avulsion (ALPSA) lesion is similar to a Bankart lesion, in that it too is usually due to anterior shoulder dislocation and involves the anterior inferior labrum.
Unlike the Bankart lesion in which the labrum and glenoid periosteum are avulsed from...
An os supratalare is an accessory ossicle of the foot located at the superior aspect of the talar head or neck. It has a reported incidence of ~1% (range 0.2-2.4%) 1. It is almost always asymptomatic.
os supranaviculare is also anatomically seen in close proximity to th...