Fetal atrial flutter is the second most common fetal tachyarrhythmia and can account for up to 30% of such cases 1-2.
As with other tachyarrthymias it is often detected in the 3rd trimester.
It has a typical atrial rate of 300-600 beats per minute (bpm)...
Fetal bradyarrhythmia refers to an abnormally low fetal heart rate (less than 100-110 beats per minute 3,7) as well as being irregular, i.e. irregular fetal bradycardia.
A fetal bradyarrhythmia can fall in to several types which include
fetal partial atrioventricular block (PAVB)
Fetal bradycardia refers to an abnormally low fetal heart rate, a potentially ominous finding. A sustained first trimester heart rate below 100 beats per minute (bpm) is generally considered bradycardic. The average fetal heart rate changes during pregnancy, however, and some consider the lower ...
Fetal cardiomegaly (FC) essentially refers to an enlarged fetal heart. It is variably defined with some sources stating the cut off as a fetal cardio-thoracic circumference above two standard deviations 7.
It can arise from a number of situations which include
congenital cardiac an...
Fetal cardiomyopathy refers to a very rare situation where a cardiomyopathy occurs in utero. It is often a diagnosis of exclusion where by definition there is an absence of an underlying congenital cardiac morphological anomaly.
The estimated incidence is variable with the high en...
Fetal chylothorax is defined as the presence of lymphatic fluid within the pleural cavity.
may show echogenic fluid in the pleural cavities
Some of the de...
Fetal enteric duplication cysts are enteric duplication cysts presenting in utero.
They result from an abnormal recanalisation of the gastrointestinal tract. They comprise of a two-layer smooth muscle wall and an internal epithelium of a respiratory or intestinal type. These cysts ma...
A fetal goitre is an enlargement of the thyroid gland in utero. It can occur with either hyper or hypothyroidism (and in isolated cases of euthyroidism 8).
The mechanism is different depending on whether the underlying cause is hyper or hypothyroidism.
Fetal hydrocephalus often refers to an extension of fetal ventriculomegaly where the ventricular dilatation is more severe. It is usually defined when the fetal lateral ventricular diameter is greater than 15 mm 1.
The estimated incidence is 0.5-3% per 1000 live births. There may ...
A fetal hydrocoele refers to an hydrocoele present in utero.
They may be sonographically identified in ~ 15% of male fetuses in the third trimester 6.
Often result from a patent processus vaginalis. They are more frequently unilateral.
Fetal parvovirus B19 infection is a type of in utero infection. In certain cases it can lead to intra-uterine fetal death.
It was first reported to be associated with fetal death and hydrops fetalis in 1984. Human parvovirus B19 is the only known parovirus virus pathogenic to human...
Fetal pericardial teratomas are rare pericardial teratomas that present in utero. They are an uncommon primary cardiac tumour occurring in a fetus.
It is a type of germ cell tumour and arises from multipotential cells derived from all three germinal layers. In contrast to ovarian ter...
Fibrillary astrocytomas are the most common type of diffuse low grade astrocytoma and as of the 2016 update to WHO classification of CNS tumours it no longer exists as a distinct entity, having been incorporated into the generic term diffuse astrocytoma 6.
Unlike the other variant...
Fibroadenoma is a common benign breast lesion and results from excess proliferation of connective tissue. Fibroadenomas characteristically contain both stromal and epithelial cells.
They usually occur in women between the ages of 10 and 40 years. It is the most common breast mass...
Fibrocartilaginous embolism (also known as nucleus pulposus embolism) is a rare cause of spinal cord ischaemia due to embolisation of nucleus pulposus material from intervertebral disc in a retrograde direction to a spinal artery or vein.
Fibrocartilaginous embolism is a diagnosis of suspicion....
Fibrocystic change of the breast (also known as diffuse cystic mastopathy) is a benign alteration in the terminal ductal lobular unit of the breast with or without associated fibrosis. It is seen as a wide spectrum of altered morphology in the female breast from innocuous to those associated wit...
Fibromatosis colli is a rare form of infantile fibromatosis that occurs within the sternocleidomastoid muscle (SCM).
There may be a slight male predilection. It typically presents a few weeks after birth.
Presentation is usually with torticollis and is most...
Fibromatosis of the breast (also known as an extra-abdominal desmoid tumour of the breast or mammary fibromatosis 4) is considered as a type of rare breast tumour. It is a non-metastasising benign but locally invasive stromal tumour 4. However, it can mimic more sinister types of breast cancer o...
Fibrosarcoma of the bone is a rare malignant bone tumor which may occur as a primary lesion, or secondarily after radiation treatment, dedifferentiation from other tumors 3 or pathologies such as Paget disease, bone infarction, or chronic osteomyelitis.
It is a distinct entity from...
Fibrosarcoma of the breast is a type of malignant stromal sarcoma that rarely occurs as a primary tumour within the breast.
A fibrosarcoma is composed of immature mesenchymal elements surrounded by a collagenous substance. It is a type of breast sarcoma with a predominant “herringbo...
Fibrosing colonopathy a condition characterised by progressive submucosal fibrosis, particularly of the proximal colon. It is associated with high dose lipase supplementation used to treat exocrine insufficiency of the pancreas, such as in treatment for cystic fibrosis.
It is more...
Fibrothorax is defined as fibrosis within the pleural space, and occurs secondary to the inflammatory response to one of the following events:
tuberculosis / tuberculous pleuritis - particularly as a late sequelae 3
asbestos related pleural disease
Fibrotic non-specific interstitial pneumonitis is a histological subtype of non-specific interstitial pneumonitis (NSIP). It is considered the more common form 1. This pattern manifests as chronic interstitial inflammation obscured by interstitial fibrosis (with dense collagen), a temporal homog...
Fibrous cortical defects (FCD) are benign bony lesions and are a type of fibroxanthoma, histologically identical to the larger non-ossifying fibroma (NOF).
Fibrous cortical defects typically occur in children (usually 2-15 years), and indeed are one of the most common benign bony ...
Fibrous meningiomas (also known as fibroblastic meningiomas) are the second most common histological subtype of meningioma, found in ~50% of all meningiomas, usually along with meningothelial histology (40%) or in isolation (7%). They are, for some reason, the most common intraventricular mening...
Fibular hemimelia is a congenital lower limb anomaly characterised by partial or complete absence of fibula and includes a spectrum ranging from mild fibular hypoplasia to complete fibular aplasia 1.
Although rare in occurrence, it is the most common congenital absence of long bon...
First branchial cleft cysts are a type of branchial cleft anomaly. They are uncommon and represent only ~7% of all branchial cleft cysts.
They are usually diagnosed in middle-aged women 3-4.
Their presentation can in the form of 3:
asymptomatic, e.g. inci...
The term fish vertebra (also codfish vertebra) describes the biconcave appearance of vertebrae (especially lumbar vertebrae).
sickle cell disease
thalassemia major (rarely)
Flail chest or flail thoracic segment occurs when three or more contiguous ribs are fractured in two or more places. Clinically, a segment of only one or two ribs can act as a flail segment, hence there is some controversy between the clinical and radiological definitions.
Flash filling hepatic venous malformations, also known as flash filling hepatic haemangiomas, are a type of atypical hepatic venous malformation (haemangioma), which due to its imaging features often raises the concern of a malignant process rather than a benign one.
It is importa...
Flavivirus encephalitis include a number of entities which characteristically involve the basal ganglia and thalami.
Typically these conditions present with a prodrome which is nonspecific but indicative of a viral infection. Symptoms include fever, myalgia, rash, rigors...
The presence of Flexner-Wintersteiner rosette is characteristic for retinoblastoma but is also seen in pineoblastoma and medulloepitheliomas.
Floating teeth is the description given to the appearances on imaging of teeth 'hanging in the wind' as a result of alveolar bone destruction around the root of the teeth.
They are uncommonly encountered, with a wide differential diagnosis - albeit that the underlying c...
Skeletal fluorosis is a chronic metabolic bone disease caused by ingestion of large amounts of fluoride through either water or food in geographic areas where high levels of fluoride occur naturally.
Described features include:
increased bone density: oste...
Focal areas of signal intensity (FASI), alternatively called focal abnormal signal intensity or unidentified bright objects, are bright areas on T2-weighted images commonly identified in the basal ganglia (often the globus pallidus), thalamus, brainstem (pons), cerebellum, and subcortical white ...
Focal brainstem gliomas are a relatively uncommon type of brainstem glioma, which carry a more favorable prognosis compared to the more common diffuse brainstem glioma. The name is a reflection of the imaging findings, which demonstrate a sharply demarcated mass with relatively frequent enhancem...
Focal cortical dysplasias (FCD) represent a heterogeneous group of disorders of cortical formation, which may demonstrate both architectural and proliferative features. They are one of the most common causes of epilepsy and can be associated with hippocampal sclerosis and cortical glioneuronal n...
Focal lymphoid hyperplasia of the lung refers to an abnormal accumulation of non-malignant lymphocytic aggregates within the lung.
It iwas previously known as pulmonary pseudolymphoma.
Clinical features can vary from being asymptomatic to various symptoms s...
Follicular lymphoma is a subtype of non-Hodgkin lymphoma (NHL) and is, in fact, the most common type.
Estimated to account for ~45% of all NHL cases 1. Higher rates in North America and Europe 4.
Nodal effacement by closely packed follicles containing small cleaved ce...
Follicular thyroid adenoma is a commonly found benign neoplasm of the thyroid consisting of differentiated follicular cells. It can not be differentiated from follicular carcinoma on cytologic, sonographic or clinical features alone 1.
Follicular thyroid adenoma is more commonly f...
Forked umbilical cord is rare anomaly of the umbilical cord, which can be detected on antenatal scan. The umbilical cord splits into two cords and contains three vessels in each of the bifurcated cords. This anomaly is seen associated with monochorionic twins.
Fournier gangrene is a necrotising fasciitis of the perineum. It is a true urological emergency due to the high mortality rate but fortunately the condition is rare.
Fournier gangrene is typically seen in diabetic men aged 50-70 but is rarely seen in women. Other than age, predisp...
Fracture healing occurs naturally after traumatic bony disruption. This process begins with hemorrhage and progresses through three stages:
This process can be supported by various treatment options with immobilisation a mainstay; inappropriate treatment m...
Frontoethmoidal encephalocoeles are second only to occipital encephalocoeles in terms of frequency, representing approximately 15% of all encephalocoeles. They represent meninges or brain tissue herniating through cranial defect in the anterior cranial fossa and typically result in facial defor...
Fundic gland polyps (FGP) are the most common type of gastric polyp.
FGPs occur most commonly in middle-aged females. They have been reported to be identified in ~1% of gastroscopies 3,4.
FGPs are usually an asymptomatic, incidental finding 1.
Gallbladder carcinomas are usually asymptomatic until they reach an incurable stage. As such, early incidental detection is important, if the occasional patient is to be successfully treated. The majority (90%) are adenocarcinomas, and the remainder are squamous cell carcinomas.
Gallbladder dysfunction, or functional gallbladder disorder, refers to biliary pain due to motility disturbance of the gallbladder without gallstones, biliary sludge, microlithiasis or microcrystals. The disorder has previous been known by several other names, including gallbladder dyskinesia, g...
Gallbladder hydrops refers to marked dilatation of the gallbladder due to chronic obstruction of the cystic duct results in accumulation of the sterile non-pigmented mucin.
Abdominal pain with palpable gallbladder without any signs of infection. In an asymptomatic patient...
Gallbladder perforations are a relatively rare complication that can occur in some situations but occurs most frequently as a result of acute cholecystitis. It can carry a relatively high mortality rate. It can also occur during laparoscopic cholecystectomies with the incidence of gallbladder pe...
Gallbladder polyps are elevated lesions on the mucosal surface of the gallbladder. The vast majority are benign, but malignant entities are possible. Gallbladder polyps may be detected on ultrasound, CT, or MRI, but are usually best characterized on ultrasound.
Gallbladder polyps ...
Gallbladder volvulus is a relatively rare condition in which there is a rotation of the gallbladder around the axis of the cystic duct and artery.
Symptoms are non-specific, however right upper quadrant pain and vomiting are similar to biliary colic. Laboratory evaluation...
Gallstone pancreatitis refers to pancreatitis caused by gallstones, specifically distal choledocholithiasis. Gallstones is the cause for 35-40% of acute pancreatitis but this number has a wide regional variance.
Gallstone pancreatitis has a higher incidence in women (compared to ...
Gallstones, also called cholelithiasis, are concretions that occur anywhere within the biliary system, most commonly within the gallbladder.
Gallstones (cholelithiasis) describes stone formation at any point along the biliary tree. Specific names can be given to gallstones dependi...
Gamma-aminobutyric acid (GABA) is the principle inhibitory neurotransmitter in the central nervous system 1 and as such, is one of the compounds examined in MR spectroscopy. It is present in the human brain at a concentration of about 1 mM, a whole order of magnitude lower than some of the more...
Ganglioneuromas are fully differentiated neuronal tumours that do not contain immature elements and potentially occur anywhere along the peripheral autonomic ganglion sites.
On imaging, usually, they present as well-defined solid masses and can be quite large at presentation. Generally, they a...
Gangrenous cholecystitis is the most common complication of acute cholecystitis, affecting ~15% (range 2-30%) of patients.
Gangrenous cholecystitis occurs as a result of ischaemia with necrosis of the gallbladder wall 4.
Gartner duct cysts develop from embryologic remnants of the Wolffian (mesonephric) duct. They are often noticed incidentally on ultrasound or MRI.
They may cause mass effect on adjacent structures.
Gartner duct cysts are located in the anterolateral ...
Gastric adenocarcinoma, commonly referred to as gastric cancer, refers to a primary malignancy arising from the gastric epithelium. It is the most common gastric malignancy.
Gastric cancer is rare before the age of 40, but its incidence steadily climbs after that and peaks in the...
Gastric antral vascular ectasia (GAVE), also known as watermelon stomach, is a rare condition affecting the stomach. It is one of the diagnoses to consider in older patients with severe anaemia and occult or profuse gastrointestinal bleeding (especially in those with cardiac, liver, or renal dis...
Gastric antral webs are a ring of mucosa in the distal stomach (gastric antrum) that can lead to gastric outlet obstruction. A circumferential ring of mucosa has also been termed a "gastric antral diaphragm".
Gastric antral webs are rare. There is an association with trisomy 21 an...
Gastric lipomas are a location-specific subtype of gastrointestinal lipomas and represent a rare benign mesenchymal tumours of the stomach. They can be definitively diagnosed on CT.
Gastric lipomas are rare, accounting for <5% of gastrointestinal lipomas and <1% of all gastric ne...
Gastric polyps are uncommon findings, even on endoscopy where they are encountered in only 2-6% of patients.
There are a number of gastric polyp subtypes 1-3:
virtually no malignant potential
typically small (<1cm), multiple, and sessile...
Gastric volvulus is a specific type of volvulus that occurs when the stomach twists on its mesentery. It should be at least 180° and cause bowel obstruction to be called gastric volvulus. Merely gastric rotation on its root is not considered gastric volvulus.
Gastrinomas are the second most common pancreatic endocrine tumour and the most common type in the setting of multiple endocrine neoplasia type I (MEN I).
Most gastrinomas are sporadic, although some are seen in the setting of multiple endocrine neoplasia type I (MEN I). In genera...
Gastrointestinal amyloidosis is relatively common, although symptomatic involvement is more rare. It is diagnosed if there is persistent gastrointestinal (GI) symptoms with endoscopic biopsy proven amyloid deposition.
Tends to affect middle-aged and older patients.
Gastrointestinal angiodysplasias or angioectasias are one of the most common causes of occult gastrointestinal bleeding.
Patients can present with symptoms and signs upper or lower gastrointestinal bleeding although they can commonly be an incidental finding.
Gastrointestinal neuroendocrine tumours (GI NETs) can be functional or non-functional:
functional NETs can be challenging to localise as:
they are often small in size at the time of diagnosis
arise in many sites throughout the body
non-functioning and/or malignant NETs often are larger at ...
Gastro-oesophageal reflux disease (GORD) is a spectrum of disease that occurs when gastric acid refluxes from the stomach into the lower end of the oesophagus across the lower oesophageal sphincter (LOS).
Minor reflux disease
In most patients with reflux disease, reflux is initiated...
Gastroschisis refers to extra-abdominal herniation (evisceration) of fetal or neonatal bowel loops (and occasionally portions or the stomach and or liver) into the amniotic cavity through a para-umbilical abdominal wall defect.
The estimated incidence is at around 1-6 per 10,000...
Gaucher disease (GD) is the most common lysosomal storage disease in humans. It is an autosomal recessive, multisystem disease arising from a deficiency of glucocerebrosidase or beta-glucosidase activity, resulting in accumulation of a glycolipid (glucocerebroside) within the lysosomes of macrop...
Gel bleed is a phenomenon associated with silicone breast implants.
Gel bleed refers to microscopic diffusion of silicone gel through the breast implant elastomer shell. The implant shell, made of silicone, is a semipermeable membrane that allows for the egress or bleed of silicone n...
Gemistocytic astrocytoma is a histologic subtype of low grade astrocytoma, with a poorer prognosis than other matched WHO grade tumours, and with no specific imaging features.
For a general discussion of clinical presentation, epidemiology, treatment please refer to the article on low grade as...
Geophagy is the intentional ingestion of earth, soil or clay and is a form of pica. This practice is not uncommon in the southern regions of the United States or provinces of Africa. It may be seen in pregnant or iron-deficient patients 3. Although geophagia may be seen in the context of a varie...
Germinal matrix haemorrhages, also know as periventricular-intraventricular haemorrhages (PVIH), correspond to the most common type of intracranial haemorrhage in neonates and are related to a perinatal stress affecting the highly vascularised subependymal germinal matrix. The majority of cases ...
The term germinoma usually refers to a tumour of the brain (WHO Classification of CNS tumours), but can also refer to similar tumours of the ovary and testis.
dysgerminoma of the ovary
seminoma of the testis
All three tumours share similar histology.
Gerstmann-Straussler-Scheinker disease is a very rare type of human transmissible spongiform encephalopathy. It manifests with dementia and/or ataxia and is due to a mutation in the prion protein (PRNP) gene, which is inherited in an autosomal dominant pattern.
Gerstmann syndrome, also known as angular gyrus syndrome, is a dominant hemisphere stroke syndrome consisting of four components:
agraphia or dysgraphia
acalculia or dyscalculia
Pure Gerstmann syndrome is said to be without aphasia.
History and ety...
Gestational choriocarcinoma (GC) is a type of choriocarcinoma that follows a gestational event. Similar to choriocarcinomas in general, it lies at the malignant end of the spectrum of gestational trophoblastic disease.
Approximately 50% of gestational choriocarcinomas arise from a pr...
Giant cell glioblastoma is a variant of glioblastoma (along with epithelioid glioblastoma and giant cell glioblastoma) recognised in the current (2016) WHO classification of CNS tumours 7. This tumour was previously called monstrocellular tumour due to the macro size of its cells.
Giant cell tumours of the tendon sheath (GCTTS), also known as pigmented villonodular tumour of the tendon sheath (PVNTS) or extra-articular pigmented villonodular tumour of the tendon sheath, are uncommon and usually benign lesions that arise from the tendon sheath. It is unclear whether these ...
Giant cerebral aneurysms are ones that measure >25 mm in greatest dimension.
Giant cerebral aneurysms account for ~5% of all intracranial aneurysms 1,3. They occur in the 5th-7th decades and are more common in females 2.
Patients can present with symptoms ...
Giant fibroadenomas are fibroadenomas weighing more than 500 grams or measuring >5 cm in size 2. They are usually encountered in pregnant or lactating women.
Gigantomastia (or macromastia) is a term given when there is massive breast enlargement. It is often associated with pregnancy.
Gigantomastia is a very common condition characterised by proliferation of either breast fatty tissue or glandular tissue or both, resulting in rapid increase in breas...
Glial cells, or neuroglia, are cells that surround the neurones of the central nervous system embedded between them, providing both structural and physiological support 1-3. Together they account for almost half of the total mass 1 and 90% of all cells of the central nervous system 3.
Glial fibrillary acid protein (GFAP) is a commonly used target for immunohistochemistry and is positive in many glial cells and tumours of glial origin. GFAP is the building block for intermediate filaments which are abundant in the cytoplasms particularly of astrocytes.
Gliomatosis cerebri is a rare growth pattern of diffuse gliomas that involves at least three lobes by definition. There often is an important discordance between clinical and radiological findings, as it may be clinically silent while it appears as a very extensive process radiologically.
Gliosarcomas are a variant of glioblastoma (along with epithelioid glioblastoma and giant cell glioblastoma) recognised in the current (2016) WHO classification of CNS tumours 9. They are highly malignant (WHO grade IV) primary intra-axial neoplasms with both glial and mesenchymal elements.
Gliosis is the focal proliferation of glial cells in the CNS in response to insult. By strict definition, gliosis is not synonymous with encephalomalacia which is the end result of liquefactive necrosis of brain parenchyma following an insult. Radiologically they share similar features and is of...
Globe rupture is an ophthalmologic emergency. A ruptured globe or an open-globe injury must be assessed in any patient who has suffered orbital trauma because open-globe injuries are a major cause of blindness.
In a blunt trauma, ruptures are most common at the insertions of the intraocular mus...
Globus pharyngeus is the subjective feeling of a lump in the throat which can have a variety of causes. In modern practice globus is often evaluated by flexible nasoendoscopy in the first instance since many patients present to otolaryngology services. If no cause is identified or if nasoendosco...
Glomus tympanicum paragangliomas (chemodectomas) are the most common middle ear tumour.
There is a female predominance (M:F = 1:3); presentation is most common when patients are more than 40 years old 1,2.
May be incidental but symptomatic masses produce ...
Glucagonomas are pancreatic endocrine tumours that secrete glucagon. Most lesions are malignant.
They are rare with an incidence of 0.000005%. Equal incidence in middle-aged men and women.
Most patients present with a necrolytic migratory rash and various ...
Gluteal injection site granulomas are a very common finding on CT and plain radiographs. They occur as a result of subcutaneous (i.e. intra-lipomatous) rather than intramuscular injection of drugs, which cause localised fat necrosis, scar formation and dystrophic calcification.
Once familiar wi...