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:
metastases (meningeal carcinomatosis-...
Dural masses can be the result of a number of different tumors and conditions, although meningiomas are by far the most common. The differential of a dural mass includes:
primary dural lymphoma
solitary fibrous tumor of the dura
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...
Dysphagia refers to subjective awareness of difficulty or obstruction during swallowing. It is a relatively common and increasingly prevalent clinical problem. Odynophagia is the term for painful swallowing.
Fluoroscopy is the mainstay of imaging assessment but manometry can help evaluate the e...
Dystrophic soft tissue calcification is a type of soft-tissue calcification, which occurs in damaged or necrotic tissue, while the serum level of calcium and phosphorus are normal. It may progress to ossification, in which case a cortical and trabecular bone pattern is visible.
An often cited a...
Echogenic fetal lung lesions on antenatal ultrasound can be detected in a number of situations. They include:
Airway obstructions: lung are often enlarged and echogenic bilaterally
congenital high airways obstruction syndrome (CHAOS)
congenital tracheal stenosis
Echogenic renal pyramids in children can be due to many different causes.
Iatrogenic (most common cause)
Elevated diaphragm refers to the symmetrical elevation of both domes of the diaphragm.
There is some overlap with causes of an elevated hemidiaphragm.
poor inspiratory effort
An elevated hemidiaphragm may result from direct and indirect causes which include:
above the diaphragm 1
decreased lung volume
prior lobectomy or pneumonectomy
phrenic nerve palsy
contralateral stroke: ...
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...
Empty gestational sacs can be due to a number of causes:
anembryonic pregnancy (also known as "blighted ovum")
early pregnancy (intrauterine): by 5.5 weeks gestational age, a yolk sac should be identifiable by transvaginal ultrasound
pseudogestational sac with an ectopic pregnancy
Empyemas are purulent inflammatory collections within a body cavity. Contrast this with abscesses, which arise within parenchymal tissue, rather than occupying a pre-existing anatomical space.
Colloquially, the standalone term empyema is used to refer to thoracic empyemas but there...
Although sporadic viral encephalitis is most commonly due to herpes simplex virus 1 (HSV-1) the extended herpesvirus family consists of many other viruses many of which can also infect the central nervous system. Encephalitis due to herpesvirus family include 1:
herpes simplex virus 1 (HSV-1)...
Endobronchial metastases 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
Fluid in the endometrial cavity can result from a number of causes if excessive and associated with distension.
There are essentially three types of fluid:
hydrometra: simple fluid
hematometra: hemorrhagic content / clot
normal (i.e. physiological)
Endometrial microcalcifications can arise from a vast range pathologies but are usually of benign in etiology.
They have an increased incidence with older age, postmenopausal state, atrophic endometrium, and endometrial polyps.
In some cases they are associated wit...
Endosteal scalloping refers to the focal resorption of the inner layer of the cortex (i.e. the endosteum) of bones, most typically long bones, due to slow-growing medullary lesions.
It is important to note that although it is evidence of a slow non-infiltrative lesion, it does not equate to ben...
An enlarged/dilated azygos vein may result from a number of physiological as well as pathological causes. The enlarged azygos vein may be seen as a widened right paratracheal/paraspinal stripe on a frontal chest radiograph.
Spelling it "azygous" when referring to the vein is incorr...
Enlarged echogenic fetal kidneys can be associated with a number of pathologies that include:
autosomal recessive polycystic kidney disease (ARPKD) 1
autosomal dominant polycystic kidney disease (ADPKD) 3: the large cysts may not form in utero and the kidneys may initially appear as enlarged a...
There is a short list of causes for enlarged extraocular muscles. The differential can be narrowed by the clinical history, known systemic illness, pattern of specific muscles involved, the muscle morphology, as well as concurrent findings outside the muscles 3:
inflammatory, infectious, and de...
An enlarged posterior fossa 'CSF' space posterior to the cerebellum has a number of differentials that include:
mega cisterna magna
Careful attention to the cerebellum needs to paid as also to be considered are:
The differential of an enlarged pulmonary trunk/main pulmonary artery on chest radiography includes:
may appear prominent in young patients especially women
rotation of the heart
left lower lobe collapse
pulmonary arterial hyp...
Enlargement of sella turcica can be seen in situations including the following:
empty sella syndrome
slight globular enlargement of the sella with no erosion, destruction or posterior displacement of dorsum sellae
enlargement with erosion of anterior cortex of dorsu...
Enlargement of the cardiac silhouette on a frontal (or PA) chest x-ray can be due to a number of causes 1:
cardiomegaly (most common cause by far)
anterior mediastinal mass
prominent epicardial fat pad
AP projection (e.g supine radiographs taken w...
Enteritis (plural: enteritides) refers to inflammation of the small bowel. When associated with inflammation of the stomach, the term gastroenteritis is used which is usually caused by infection.
Epididymal calcification can be seen on ultrasound as hyperechoic foci within the epididymal head. If the calcifications are large enough, then they may demonstrate acoustic shadowing.
chronic epididymitis, e.g. bacterial, granulomatous (TB) or genital filariasis
Epididymal lesions are most commonly encountered on ultrasonography. Most epididymal lesions are benign; malignant lesions are rare.
They can comprise of
Benign solid lesions
adenomatoid tumor of the scrotum: most common epididymal mass 4
papillary cystadenoma of the e...
Epiglottic enlargement is often seen on lateral neck radiographs and it's accepted to confirm clinical suspicion of acute epiglottitis only on this finding 1. However, an enlarged epiglottitis has a wide range of differentials that should be considered.
Epiphora (plural: epiphoras) represents excessive tearing of the eye and is a common clinical presentation to ophthalmological practice. It is most frequently due to an obstruction of the nasolacrimal drainage apparatus. Less commonly, overproduction of tears may be responsible.
Epiphyseal lesions comprise tumors and other pathologies that occur around the epiphysis and any epiphyseal equivalent bone.
Common differential diagnoses include the following 2-4:
chondroblastoma: rare epiphyseal tumor found in young adults; it usually does not extend...
Ovarian epithelial tumors account for the majority of all ovarian tumors (60-70%) and their malignant forms represent >90% of ovarian cancers 1. They can range from being benign to highly malignant.
There is a difference in frequency of ovarian tumor subtypes depending on menopaus...
Erlenmeyer flask deformity (EFD), also known as metaphyseal flaring, refers to a radiographic appearance typically on a femoral radiograph demonstrating relatively reduced constriction of the diaphysis and flaring of the metaphysis as a result of undertubulation.
The name refers to the resembl...
Differential diagnosis of erosion of the superior aspects of the ribs include:
Erosion of the odontoid peg can result from a number of pathological entities:
rheumatoid arthritis: classic 1,2
systemic lupus erythematosus
calcium pyrophosphate arthropathy (CPPD): relatively common
non-inflammatory arthropathy: osteoar...
Erosive arthritis has a broad differential:
clinically an acute inflammatory attacks (swelling, erythema, pain) in postmenopausal woman
typically the interphalangeal joints, 1st carpometacarpal joint 6, but not the metacarpophalangeal (MCP) joints and large joints
Exophytic hepatic mass or tumor is a lesion which predominantly lies outside the margins of liver but originates from within the liver.
Causes include 1:
focal nodular hyperplasia
Exostoses are defined as benign growths of bone extending outwards from the surface of a bone. It can occur in any bone and be triggered by a number of factors. There are a number of examples of exostoses that occur due to local irritant stimuli:
exostosis of the external audit...
Expansile lytic bone lesions without cortical destruction can result from various benign and malignant neoplastic pathologies, causes include 1:
unicameral bone cyst
aneurysmal bone cyst (eccentric)
chondromyxoid fibroma (eccentric)
non-ossifying fibroma (eccentric)
Extra-axial masses of the intracranial compartment have a wide range of differentials, ranging from benign developmental cysts to malignant tumors.
choroid plexus papilloma/carcinoma
cranial nerve schwannoma
solitary fibrous ...
Extraconal orbital lesions include lesions which arise from structures within the extraconal orbital space and those extending from adjacent structures into the orbits.
dermoid cyst: most common lesion in pediatrics
lacrimial gland lesions
Extraneural spread of primary intracranial neoplasm is distinctly uncommon, occurring far less frequently than CSF spread.
The most frequent neoplasms to do so, in decreasing order of frequency, are:
Knowing extraskeletal musculoskeletal lesions by compartment is useful to help generate a meaningful differential diagnosis:
extraskeletal myxoid chondrosarcoma
The differential diagnosis for extratesticular cystic lesions includes:
loop of bowel from an inguinal hernia
Very rarely, a scrotal mesothelioma may present as a cystic mass.
Extratesticular scrotal masses (non-testicle and non-epididymis) are mostly mesenchymal in origin and benign 1.
lipoma (most common)
leiomyoma of the scrotum
granular cell tumor
fibrous hamartoma of infancy...
Facial palsy refers to the neurological syndrome of facial paralysis. It can result from a broad range of physiological insults to the facial nerve or its central nervous system origins. The most common causes of this is Bell palsy.
While facial palsy refers to the clinical presen...
Failed early pregnancy refers to the death of the embryo and therefore, miscarriage. The most common cause of embryonic death is a chromosomal abnormality.
Findings diagnostic of pregnancy failure
crown-rump length (CRL) of ≥7 mm and no heartbeat on a transva...
Intracranial fat is uncommon and a wide range of differentials should be considered.
intracranial dermoid cyst
quadrigeminal cistern lipoma
suprasellar cistern lipoma
cerebellopontine angle lipoma
choroid plexus li...
Fat containing breast lesions generally have some radiolucent component on mammography.
They are generally classified at BIRADS II lesions.
fat necrosis within the breast/oil cyst
intramammary lymph node: classically has a central fatty hilu...
Fat containing cardiac lesions have a limited differential diagnosis. These include 1-4:
normal aging/physiologic: mostly subepicardial, more in the right ventricle (especially right ventricular outflow tract) than left ventricle
lipomatous hypertrophy of the interatrial septum
Fat containing liver lesions represent a variety of benign and malignant liver lesions may contain macroscopic and/or intracytoplasmic fat in sufficient quantities enabling characterization on imaging studies. Most fat-containing liver lesions (80%) in patients with cirrhosis are malignant, most...
There are numerous fat-containing renal lesions, including:
renal cell carcinoma (often has calcifications when contains macroscopic fat)
renal or perirenal lipoma/liposarcoma
Non-mass lesions may also occasionally contain fat:
The differential of a fat containing solitary pulmonary nodule is very narrow.
In a well circumscribed smooth or lobulated mass (especially if it has been largely stable in size over time) presence of fat is essentially pathognomonic of a pulmonary hamartoma, and usually not further assessment ...
There is a long list of fat containing thoracic lesions. They may involve the mediastinum, lung, pleura or chest wall.
Differential diagnosis includes:
intrapulmonary: fat containing pulmonary lesions
Fatty mediastinal masses are relatively uncommon, and the differential diagnosis is brief, including 1-4:
benign mature teratoma
extravasation of lipid-rich hyperalimentation fluid 3
fibrofatty replacement of the central portion of mediastinal l...
Fetal anterior abdominal wall defects can occur with a number of pathologies.
limb body wall complex
omphalocele-radial ray (ORR) complex
Pentalogy of Cantrell
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 peritonitis...
Fetal bowel dilatation can occur from many causes, which include:
intestinal atresias: mainly distal
apple-peel intestinal atresia
megacystis microcolon hyperperistalsis syndrome 4
congenital chloride d...
Fetal brain tumors are uncommon and tends to have very different pathological spectrum than that observed in adults; in order of decreasing frequency:
fetal intracranial teratoma: most common tumor by far
astrocytoma/glioblastoma: next most common
craniopharyngioma: papillary type
Fetal cardiac tumors refer to primary cardiac tumors that can present in the in utero population.
Fetal cardiac tumors are rare; the prevalence, reported from autopsy studies of patients of all ages, varies from 0.0017-0.28 % 2.
Known cardiac tumor types that present ...
Fetal chylothorax is defined as the presence of lymphatic fluid within the pleural cavity of the fetus.
may show echogenic fluid in the pleural cavities
Fetal clenched hands are an antenatal ultrasound observation where the fetal hands are in a constant (permanently) clenched position as if being unable to extend.
Some authors 3 suggest that the abnormal posture results in part from:
muscle variations along the radial margin of the...
Fetal death in utero (FDIU), also known as intrauterine death (IUD), is the term used when the death of a fetus occurs after the 20th week of pregnancy. Prior to this, it is considered a miscarriage.
IUD is often also used as an abbreviation for an intrauterine contraceptive device...
Fetal intra-abdominal cystic lesions can arise from a number of physiological and pathological causes.
fetal gastric dilatation / fetal gastric bubble (can be pathological if there is a gastric outlet obstruction
normal fetal gallbladder
No color flow
Fetal intracranial calcification refers to intracranial calcification detected in utero. This can arise from a number of pathologies which include:
in utero infections
fetal toxoplasmosis infection: calcification tends to be randomly distributed
fetal cytomegalovirus infection1: calcificatio...
Fetal intracranial cystic lesions can arise from a number of pathologies, including:
fetal arachnoid cyst
fetal choroid plexus cyst
fetal connatal cyst
fetal porencephalic cyst
fetal interhemispheric cyst
fetal subependymal cyst
dorsal cyst of holoprosencephaly
Fetal intracranial hemorrhage may occur either within the cerebral ventricles, subdural space or infratentorial fossa.
Hemorrhages can occur in a number of situations:
mechanical trauma, e.g. maternal abdominal blunt or birth trauma
severe fetal hypoxia
background fetal thrombocyt...
Fetal intrahepatic calcification can be a relatively common finding. Calcifications in the liver can be single or multiple and in most cases in which isolated hepatic calcific deposits are detected, there is usually no underlying abnormality.
The presence of isolated intrahepatic calcification ...
Fetal limb bowing may be a feature of skeletal dysplasia, particularly if it is severe. A mild degree of lateral bowing of the femur can occur as part of normal variation.
Conditions associated with fetal limb bowing include:
campomelic dysplasia 1
thanatophoric dysplasia 2: particularly type...
Fetal pleural effusions (FPE) refer to an accumulation of pleural fluid in utero. It can refer to either a fetal chylothorax or a fetal hydrothorax.
A fetal pleural effusion can occur as part of hydrops fetalis, in association with other anomalies without hydrops or in isolation - pr...
Fetal rib fractures can be caused by certain skeletal dysplasias. These include:
osteogenesis imperfecta: type II - one of the classical causes of fetal rib fractures
achondrogenesis: type Ia - Houston-Harris sub type
Although rare, a number of tumors may be diagnosed antenatally. These fetal tumors are a diverse and a unique group of conditions, and include:
neuroblastoma: most common tumor overall
head and neck teratoma/epignathus
Fetal ventriculomegaly (ventricle width >10 mm) is an important finding in itself and it is also associated with other central nervous system abnormalities. For more information, see the main article fetal ventriculomegaly.
Fetal ventriculomegaly can be thought of in ter...
Fibropolycystic liver disease is a collective term for a group of congenital liver and biliary abnormalities resulting from abnormal development of the ductal plates. Disease in this group include:
congenital hepatic fibrosis
autosomal dominant polycystic disease
The differential for fibrous lesions is wide and includes:
osteofibrous dysplasia / adamantinoma
malignant fibrous histiocytoma / fibrosarcoma
Floating meniscus (also known as meniscal avulsion) occurs in acute traumatic settings when the meniscotibial coronary ligaments get disrupted leading to avulsion of the meniscus from the tibial plateau.
Displacement of the meniscus for 5 mm or more from the tibial p...
Flowing ossifications are seen in diffuse idiopathic skeletal hyperostosis (DISH).They are defined as heterotopic ossifications involving the anterior longitudinal ligament, paraspinal connective tissues and annulus fibrosus of at least four contiguous vertebral bodies and are originally describ...
Fluid-fluid level containing bone lesions are best seen on MRI, although with narrow window width they can also be appreciated on CT.
Their prevalence is estimated at ~3% of bone and soft tissue tumors 1.
Their presence is non-specific, as they are seen in...
Focal calvarial thinning can result from a number of causes. They include:
bilateral thinning of the parietal bones (normal variant) most common
mega cisterna magna
peripherally located tumors (e.g. oligodendroglioma)
Focal gallbladder wall thickening is an imaging finding that includes both benign and malignant etiologies.
gallbladder carcinoma: look for infiltration into adjacent organs, metastases, lymphadenopathy, bile duct dil...
Focal gas collection in right upper quadrant on plain radiographs can occur from a number of pathologies. Things to consider are:
enterobiliary fistula: common types include cholecystoduodenal fistula and cholecystocolic fistula. It may occur with:
gallstone ileus (being most common) 3
Focal hypodense hepatic lesions on a non-contrast CT scan can result from a number of pathological entities, including:
biliary hamartoma: von Meyenberg complexes 2
hepatoma/hepatocellular carcinoma (HCC)
Frontal bossing is a calvarial radiographic feature where the front of the skull appears protruding anteriorly. It is best appreciated on a sagittal or lateral image.
This feature can be seen in many conditions (in alphabetical order):
Gamuts in radiology refer to the complete list of differential diagnoses for any radiological finding. We include gamut as a section for articles on Radiopaedia.org.
History and etymology
According to Maurice Reeder, writing in the preface of his own eponymous text on gamuts, it was the trailb...
There are numerous causes of gas in the urinary bladder. In the hospital setting by far the most common is the recent placement of an indwelling urinary catheter. Other causes include 1:
indwelling urinary catheter is by far the most common cause
A gasless abdomen refers to a paucity of gas on abdominal radiography, and the specific cause can usually be identified when the patient's history is known. Common causes include:
small bowel obstruction
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 common than other malignancies as...
The causes of generalized increase in bone density in adult patients, also known as generalized or diffuse osteosclerosis, can be divided according to broad categories:
marrow cavity is narrowed by endosteal new bone
patchy lucencies due to the persist...
The causes of generalized increased bone density in pediatric patients can be divided according to a broad category of causes:
dense metaphyseal bands
cortex and flat bones may also be slight...
Causes of generalized increase in hepatic echogenicity include:
diffuse fatty change
cirrhosis: and/or coarsening
chronic hepatitis 3: and/or coarsening
diffuse infiltration or deposition
glycogen storage disease
Generalized osteopenia refers to osteopenia diffusely affecting the bones.
The differential diagnosis is wide and includes:
osteoporosis: decreased osteoid production
osteomalacia: undermineralisation of osteoid
The list of causes of a generalized periosteal reaction overlaps that of symmetrical periosteal reaction, and includes 1,2:
vascular stasis (common)
infantile cortical hyp...
Causes of generalized reduction of liver echogenicity on ultrasound include:
diffuse malignant infiltration
generalized increase in liver echogenicity
hepatic attenuation on CT
Giant cell carcinomas of the lung are a rare type of non-small cell lung carcinomas (NSCLC) classified under sarcomatoid carcinomas of the lungs.
They represent less than 0.5% of all NSCLC 2. There is a recognized association with smoking 1.
Symptoms are n...