Acetabular protrusio (also known as acetabular protrusion) is intrapelvic displacement of the acetabulum and femoral head, so that the femoral head projects medial to the ischioilial line. It should be differentiated from coxa profunda.
Protrusio acetabuli is divided into two types, ...
Sclerotic clavicles have many causes:
trauma: fractured clavicle
arthritis: osteoarthritis, seronegative arthritides
osteitis condensans of the clavicle 1
Pleural effusion tends to be used as a catch-all term denoting a collection of fluid within the pleural space. This can be further divided into exudates and transudates depending on the biochemical analysis of aspirated pleural fluid (see below). Essentially it represents any pathological proces...
Perifissural lung nodules (PFNs) are a type of intrapulmonary nodules. They commonly represent intrapulmonary lymph nodes 1. There is some overlap with the term perilymphatic pulmonary nodules since the latter can be perifissural.
PFNs are typically seen as well...
Pulmonary nodules are small, rounded opacities within the pulmonary interstitium. Pulmonary nodules are common and, as the spatial resolution of CT scanners has increased, detection of smaller and smaller nodules has occurred, which are more often an incidental finding.
Pear-shaped (or teardrop-shaped) bladder is one whose normal round or ovoid shape has been extrinsically compressed to resemble a pear. The pear may be inverted or upright, depending on how the excess pelvic tissue compresses the bladder.
Causes of a pear-shaped bladder in...
The differential for peripheral or ring enhancing cerebral lesions includes:
demyelination (incomplete ring)
tumefactive demyelinating lesion (incomplete ring)
Bone age assessment is used to radiologically assess the biological and structural maturity of immature patients from the hand and wrist x-ray appearances. It forms an important part of the diagnostic and management pathway in children with growth and endocrine disorders. It is helpful in the di...
Erosive arthritis has a broad differential, including:
clinically an acute inflammatory attacks (swelling, erythema, pain) in postmenopausal woman
typically includes the DIPs, PIPs 1st CMC joint 6, but not the metacarpophalangeal (MCP) joints and large joints
Basal ganglia calcification is common and is seen in approximately 1% of all CT scans of the brain, depending on the demographics of the scanned population. It is seen more frequently in older patients and is considered a normal incidental and idiopathic finding in an elderly patient but should ...
Intracranial calcifications are common in certain locations and often are of no clinical concern.
The two most commonly encountered types of calcification include:
normal age-related intracranial calcifications
intracranial arterial atherosclerosis
Concerning calcifications are much less co...
The differential diagnosis for masses of the cauda equina region is often considered separately to the remainder of the spinal cord. It is often difficult to determine whether masses in this region are intramedullary or intradural-extramedullary.
Most common tumours
Seronegative spondyloarthritides, also known as spondyloarthropathies or spondyloarthritis, are a group of musculoskeletal syndromes linked by common clinical features and common immunopathologic mechanisms. The subtypes of spondyloarthritis are usually distinguished on the basis of the patient’...
Abdominal hernias (herniae also used) may be congenital or acquired and come with varying eponyms. They are distinguished primarily based on location and content. 75-80% of all hernias are inguinal.
Content of the hernia is variable, and may include:
small bowel loops
mobile colon segments (s...
There are numerous primary pancreatic neoplasms, in part due to the mixed endocrine and exocrine components.
Classification based on function
exocrine: ~99% of all primary pancreatic neoplasms
pancreatic ductal adenocarcinoma ~90-95%
intraductal papillary muc...
Carotid artery stenosis also referred as extracranial carotid artery stenosis, is usually caused by an atherosclerotic process and is one of the major causes of stroke and transient ischemic attack (TIA) 1.
This article refers to stenosis involving carotid bulb and the proximal segment of inte...
Elevated hemidiaphragms can result from many causes:
above the diaphragm 1
decreased lung volume
phrenic nerve palsy
contralateral stroke: usually middle cerebral artery distribut...
Periportal hyperechogenicity can result from many causes including:
schistosomiasis of the portal region
recurrent pyogenic cholangitis (oriental)
inflammatory bowel disease: has been described to give "echo-rich" periportal cuffing 2
It may also be observed in ...
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 ...
Bartholin gland tumours represent neoplasms of the Bartholin glands.
squamous cell carcinoma of the Bartholin gland: tends to be the most common histological subtype
adenocarcinoma of the Bartholin gland
adenoid cystic carcinoma of the Bartholin gland
Companion shadows are smooth, homogeneous, radiopaque shadows running parallel along the bones. In a study of 700 chest radiographs, Ben Felson found that 75% had companion shadows on the lower ribs 3.
They appear secondary to soft tissues and intercostal muscles running ...
Visceral artery aneurysms are abnormal focal dilatations of arteries supplying abdominal organs. Visceral artery aneurysms include both true aneurysms and pseudoaneurysms.
Owing to different clinical manifestations and a unique, specific, pathology, renal artery aneurysms are discussed separate...
Bilateral renal enlargement can arise from a number of causes which include 1:
diabetic nephropathy (common)
renal involvement with lymphoma
acute interstitial nephritis
vasculitis / autoimmune
autosomal recessive polycystic kidneys (ARPKD)
adult dominant polycys...
Internal hernias due to gastric bypass surgery are more common after laparoscopic gastric bypass than after an open procedure.
It is a particularly sinister complication with variable, nonspecific clinical presentations. Most patients report a combination of postprandial...
Bird fancier lung refers to a type of hypersensitivity pneumonitis occurring as a response to avian antigens (usually inhaled proteins in the dust of bird feathers and droppings). It can have acute, subacute and chronic clinical presentations.
For a broad discussion on this entity, please refer...
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...
Oesophageal dysmotility refers to the pathological disruption of the normal sequential and coordinated muscle motion of the oesophagus to transport food from the oropharynx to the stomach. It is an umbrella term used to refer to the common pathophysiological endpoint of dysmotility that can be c...
Dynamic tracheal collapse refers to collapse of the trachea during expiration. It is perhaps best assessed on CT in the end expiratory phase. An inspiratory series is also useful for comparative purposes. The term excessive dynamic airway collapse (EDAC) refers to abnormal and exaggerated bulgin...
Reeder and Felson's Gamuts in Radiology is a general radiology textbook which was first published in 1975. The current publisher is Springer.
The first edition was edited and, primarily, written by Ben Felson and Maurice M Reeder. Additional contributors were Elias "Lee" G Theros, Herbert E Par...
Facial fractures are commonly caused by blunt or penetrating trauma at moderate or high levels of force. Such injuries may be sustained during a fall, physical assault, motor vehicle collision, or gunshot wound. The facial bones are thin and relatively fragile making them susceptible to injury.
Bile duct dilatation can be due to several aetiologies.
Variable, depending on underlying cause, but usually:
right upper quadrant pain
Harmonic imaging is useful when assessing the biliary system, as it improves the clarity ...
Abnormally thickened endometrium on imaging may occur for a number of reasons which may be categorised based on whether or not they are related to pregnancy. Aetiologies may also be classified based on whether the patient is premenopausal or postmenopausal.
The gamut for cystic lung disease is long, but includes:
pulmonary Langerhans cell histiocytosis
lymphoid interstitial pneumonia
cystic lung disease
Endobronchial metastases (EBMs) are an uncommon form of intrathoracic metastases. They are much less common than intrapulmonary metastases.
The clinical presentation varies and includes:
post-obstructive pneumonitis from distal obstruction
Pericardial calcification usually occurs in patients with a history of pericarditis.
previous trauma or prior pericarditis
later sequelae of rheumatic heart disease
malignant pericardial involvement (e.g. mediastinal teratoma)
On chest radiography, location of...
Clavicle tumours may be malignant or benign.
osteoma: uncommon, sclerotic, hamartomatous surface lesion
enchondroma: rare, geographic, intramed...
Primary tracheal and endobronchial lesions are generally rare and can be either malignant or benign. The majority of these lesions are malignant.
primary malignant endobronchial lesions
squamous cell carcinoma: commonest malignant lesion in tr...
Hiccups (or hiccoughs), medical term singultus, are an unpleasant phenomenon, experienced by everyone on occasion, and usually self-limiting. However the much rarer intractable chronic form can be extremely debilitating.
Hiccups are a symptom that has probably been experienced by ...
The liver is one of the most frequently damaged organs in blunt trauma, and liver trauma is associated with a significant mortality rate.
In blunt abdominal trauma, the liver is injured ~5% (range 1-10%) of the time 1,3.
Patients can present with right uppe...
Artifacts can present in a variety of ways including abnormal shadow noted on a radiograph or degraded image quality and have been produced by artificial means from hardware failure, operator error and software (post-processing) artifacts.
There are common and distinct artifacts for film, comp...
Endometrial ablation is a minimally invasive surgical procedure that involves the destruction of the uterine endometrium commonly performed for menorrhagia in premenopausal or perimenopausal women.
It has evolved has an alternative to hysterectomy and is associated with good outcomes and patien...
The lissencephaly-pachygyria spectrum is useful in describing the spectrum of diseases that cause relative smoothness of the brain surface and includes:
agyria: no gyri
pachygyria: broad gyri
lissencephaly: smooth brain surface
It is a basket term for a number of congenital cortical malforma...
Acute occlusion of the basilar artery may cause brainstem or thalamic ischaemia or infarction. It is a true neuro-interventional emergency and, if not treated early, brainstem infarction results in rapid deterioration in the level of consciousness and ultimately death.
There is broad differential for cyst like lesions around the knee.
The list includes:
popliteal synovial cyst - Baker's cyst
intra-articular ganglion cyst
ACL ganglion cyst
PCL ganglion cyst
Hoffa fat pad ganglion cyst
extra-articular ganglion cyst
Pulmonary fibrosis is a descriptive term given when there is excess of fibrotic tissue in lung. It can occur in a wide range of clinical settings and can be precipitated by a multitude of causes. The term should not be confused with idiopathic pulmonary fibrosis which is a progressive fibrotic l...
Spinal metastases is a vague term which can be variably taken to refer to metastatic disease to any of the following:
vertebral metastases (94%)
may have epidural extension
intradural extramedullary metastases (5%)
intramedually metastases (1%)
Each of these are discussed separately. Below ...
Generalised osteopenia refers to osteopenia diffusely affecting the bones.
The differential diagnosis is wide and includes includes:
osteoporosis: decreased osteoid production
osteomalacia: undermineralisation of osteoid
Hypertrophic osteoarthropathy (HO) is a syndrome characterised by periosteal reaction of the long bones without underlying bone lesion. There is a broad range of manifestations, although it tends to be symmetric and involving the appendicular skeleton. Accompanying abnormal soft tissue prolifer...
Mixed lytic and sclerotic bone metastases are seen in a number of malignancies:
breast carcinoma: typically sclerotic but 25% are mixed
lung carcinoma: typically lytic but 15% are mixed
carcinoma of the cervix
prostate carcinoma: typically sclerotic but 15% are mixed
Mucoid impaction, also referred to as mucus plugging or bronchocele, airway filling by mucoid secretions and can be obstructive or non-obstructive. It is a common pathological finding in chest imaging.
Mucoid impaction may result from either obstructive or non-obstructive ...
Sclerotic or blastic bone metastases can arise from a number of different primary malignancies including 1-5:
prostate carcinoma (most common)
breast carcinoma (may be mixed)
transitional cell carcinoma (TCC)
mucinous adenocarcinoma of the gastroint...
Male breast disease includes a wide spectrum of conditions. Many conditions and entities that affect the female breast may also affect the male breast.
male breast cancer
pseudogynaecomastia: fat deposition within the...
Gynaecomastia refers to a benign excess of the male breast tissue, that is usually reversible. It is not a risk factor per se for developing male breast cancer.
While it can occur at any age, it tends to have greater prevalence in two groups: adolescent boys and older men (some pu...
Diffuse alveolar haemorrhage (DAH) is a subset of diffuse pulmonary haemorrhage when bleeding is diffuse and directly into the alveolar spaces. It can occur in a vast number of clinical situations and can be life threatening.
Blood tends to fill alveolar spaces at multiple sites.
A J-shaped sella is a variant morphology of the sella turcica, whereby the tuberculum sellae is flattened, thus forming the straight edge of the "J". The dorsum sellae remains rounded and forms the loop of the "J".
Differential diagnosis for a J-shaped sella includes 1,2...
It is common for radiologists to be asked to distinguish between cerebral toxoplasmosis and primary CNS lymphoma (PCNSL) in patients with HIV/AIDS. Treatment is clearly different and thus accurate interpretation of CT and MRI is essential.
In many instances, the imaging appearance is classic an...
Coin lesion refers to a round or oval, well-circumscribed solitary pulmonary lesion. It is usually 1-5 cm in diameter and calcification may or may not be present 1,3. Typically but not always the patient is asymptomatic 1.
The differential diagnosis for such lesions is ...
The atlantodental interval (ADI), as the name suggests, is the horizontal distance between the anterior arch of the atlas and the dens of the axis, used in the diagnosis of atlanto-occipital dissociation injuries and injuries of the atlas and axis.
It is the distance (in mm) between the posteri...
Hydroxyapatite crystal deposition disease (HADD) is a disease of uncertain aetiology characterised by periarticular and intra-articular deposition of hydroxyapatite (HA) crystals.
The shoulder is the most frequently involved site with classic calcific tendinitis presentation.
There are a number of splenic lesions and anomalies:
Benign mass lesions
splenic cyst (mnemonic)
splenic haemangioma: commonest benign sp...
Cavitating pneumonia is a complication that can occur with a severe necrotising pneumonia and in some publications it is used synonymously with the latter term 2. It is a rare complication in both children and adults.
Cavitation associated with Mycobacterium tuberculosis is separately discusse...
Viral encephalitides are the result of brain parenchymal infection by a number of different viruses, many of which have similar presentations and imaging features. Specific diagnosis often requires PCR.
For viral infection of the meninges, please refer to the general article on viral meningiti...
Tracheomalacia, or sometimes described as tracheobronchomalacia, is a common incidental finding on imaging of the chest of older patients and manifests as an increase in tracheal diameter as well as a tendency to collapse on expiration. Generally, more than 70% collapse of the trachea during exp...
Pulmonary aspergillosis is a collective term used to refer to a number of conditions caused by infection with a fungus of the Aspergillus species (usually Aspergillus fumigatus).
There are a number of recognised pulmonary forms, the number depending on the author 1,3-4 . Each form has specific ...
Right heart strain (or more precisely right ventricular strain) is a term given to denote the presence of right ventricular dysfunction usually in the absence of an underlying cardiomyopathy. It can manifest as an acute right heart syndrome.
Right heart strain can often occur as a re...
An orbital mass carries a relatively wide differential:
lacrimal gland or duct tumours
rhabdomyosarcoma of the orbit
optic nerve meningioma
optic nerve glioma
optic nerve schwannoma
developmental orbital cysts 3:
Barium meal has been frequently used to differentiate malignant and benign gastric ulcers:
Features suggesting benign gastric ulcer
outpouching of ulcer crater beyond the gastric contour (exoluminal)
smooth rounded and deep ulcer crater
smooth ulcer mound
smooth gastric folds that reach the...
Tension pneumothoraces occur when intrapleural air accumulates progressively in such a way as to exert positive pressure on mediastinal and intrathoracic structures. It is a life-threatening occurrence requiring both rapid recognition and prompt treatment to avoid a cardiorespiratory arrest.
RASopathies are a class of developmental disorders caused by germline mutations in genes that encode for components or regulators of the Ras/mitogen activated protein kinase (MAPK) pathway.
As a group, RASopathies represent one of the most common malformation syndromes, with an in...
Pathological fractures are fractures that occur in abnormal bone. Although the term can be used in the setting of a generalised metabolic bone disease, it is usually reserved for fractures through a focal abnormality. The abnormality may be malignant or non-malignant in nature.
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 ...
Metastases from breast cancer can be a frequent finding in routine onco-radiological practice.
With the universal use and acceptance of screening mammography, the isolated clinical presentation from metastases from breast carcinoma has become rare in clinical practice. Hi...
Gunshot injuries often require imaging assessment, and this evaluation has both clinical relevance (assessment of organ damage, surgical planning and prognostication), and often also forensic implications.
Incidence of gunshot injuries to the head is increasing in some countries, ...
The paediatric curriculum is one of our curriculum articles and aims to be a collection of articles that represent the core paediatric knowledge.
Topics pertaining to paediatric radiology, including paediatric neuroradiology and fetal radiology, although there will be some cross cov...
Greenstick fractures are incomplete fractures of long bones and are usually seen in young children, more commonly less than 10 years of age. They are commonly mid-diaphyseal, affecting the forearm and lower leg. They are distinct from torus fractures.
Greenstick fractures ...
Trauma is a leading cause of mortality in pregnancy. Pregnancy increases the incidence and severity of abdominal trauma in females.
Trauma affects up to 7% of pregnancies, and the incidence of pregnancy in level 1 trauma patients is estimated to be ~2% 1.
The term ampullary tumour generally refers to either benign or malignant neoplasms that arise from the glandular epithelium of the ampulla of Vater, including 1:
ampullary adenoma (adenoma of ampulla of Vater)
ampullary carcinoma (carcinoma of ampulla of Vater)
According to some authors, ampu...
Scoliosis is defined as an abnormal lateral curvature of the spine. It is quite common in young individuals and is often idiopathic and asymptomatic. In some cases, however, it is the result of underlying structural or neurological abnormalities.
By definition, a scoliosis is any lateral spina...
Pseudocyst of the humerus, also referred as a humeral head pseudolesion, is a normal anatomical variant due to increased cancellous bone in the region of the greater tuberosity of the humerus which is seen as a lucent lesion on radiography.
Hyperaemia and disuse caused by shoulder problems (suc...
Pneumoretroperitoneum is by definition presence of gas within the retroperitoneal space.
Pneumoretroperitoneum is always abnormal and has a relatively small differential:
perforated retroperitoneal hollow viscus
peptic ulcer disease
blunt or penetrating abdominal trauma
Testicular microlithiasis (TM) is a relatively common condition that represents the deposition of multiple tiny calcifications throughout both testes.
The most common criterion for diagnosis is that of five microcalcifications in one testicle, although definitions have varied in the past. In t...
The differential for cystic lesions of the pancreas includes:
intraductal papillary mucinous neoplasm (IPMN)
serous cystadenoma uncommonly uni/macrolocular
simple pancreatic cyst
pancreatic cysts occur in association with
von Hippel Lindau syndrome
In many centers, laparoscopic Roux-en-Y gastric bypass has become the most common bariatric procedure for morbid obesity.
In this operation, the stomach is stapled or divided to form a small pouch (typically <30 mL in volume), which empties into a Roux limb of the jejunum of varying length (ty...
Fragility fractures are the result of forces that would not fracture a normal bone. They can occur in the context of very low energy (i.e. minimal) trauma such as falling from standing height, or they may be no identifiable preceding trauma. There is overlap between fragility fractures and insuf...
Congestive hepatopathy includes a spectrum of hepatic derangements that can occur in the setting of right-sided heart failure (and its underlying causes). If there is subsequent hepatic fibrosis the term cardiac cirrhosis may be used. The condition can rarely occur as a result of non-cardiac cau...
Joint ankylosis has a relatively broad differential including 1-5:
chronic reactive arthritis
juvenile idiopathic arthritis
Intra-uterine contraceptive devices (IUCD) are one of the most frequently used methods of contraception throughout the world. It prevents pregnancy by:
thinning the endometrial lining
preventing sperm motility
There are two main types of IUCDs:
non-hormonal metallic ...
Spinal fractures are usually the result of significant trauma to a normally formed skeleton, or the result of trauma to a weakened spinal column. Examples include:
Jefferson fracture: ring fracture of C1
hangman fracture: bilateral pedicle or pars fracture of C2
Rupture of a berry aneurysm, also known as a saccular aneurysm, can cause either a subarachnoid haemorrhage (SAH), cerebral haematoma and/or intraventricular haemorrhage.
Berry aneurysms form 97% of aneurysms of the central nervous system. Up to 80% of patients with a spontaneous ...
Non small-cell lung cancer represents a heterogeneous group of lung cancers that do not have small-cells on histology. They are thus separated, as small cell carcinoma of the lung has distinctive management implications. The major histological types include:
adenocarcinoma of lung
Elevated prolactin can be due to a number of causes, including elevated production/secretion as well as reduced inhibition.
Prolactin is controlled by numerous homeostatic mechanisms, with tonic secretion of prolactin inhibitory hormone (dopamine) by the hypothalamus having a dominant effect 1...
Non-neoplastic solid lesions of the pancreas (NNSLP) are conditions which may mimic pancreatic neoplasms on imaging. They include:
intrapancreatic accessory spleen
peripancreatic lymph node
congenital anomalies, such as prominent pancreatic ...
Pachymeningeal enhancement, also known as dura-arachnoid enhancement 4, refers to a dural and outer layer of arachnoid pattern of enhancement seen following contrast administration and may occur in the conditions listed below: