Seminal vesicle cysts can be congenital or acquired.
Age of presentation of congenital seminal vesicular cysts is during the period of greatest reproductive activity i.e. in second and third decades of life, while acquired cysts are most often seen in the elderly age group.
An ectopic kidney, also known as renal ectopia, is a congenital renal anomaly characterized by the abnormal location of one or both of the kidneys.
They can occur in several forms:
cross fused renal ectopia
ectopic thoracic kidney
The estimated incidence of an ec...
The ethmoidal air cells, also known less commonly as the ethmoidal sinuses, form one of the four pairs of paranasal sinuses. They are located within the single, midline ethmoid bone.
location: between the orbit and the nasal cavity, within the ethmoid labyrinth of the ethmoid bone
Myometrial cysts are cysts seen in the myometrium and these can be differentiated appropriately based on location and sonological or Doppler features.
They can arise from variable etiology and include:
adenomyosis: these cysts are most often seen in the endomyometrial junc...
The paranasal sinuses usually consist of four paired air-filled spaces. They have several functions of which reducing the weight of the head is the most important. Other functions are air humidification and aiding in voice resonance. They are named for the facial bones in which they are located:...
The maxillary sinus (or antrum of Highmore) is a paired pyramid-shaped paranasal sinus within the maxillary bone which drains via the maxillary ostium into the infundibulum, then through hiatus semilunaris into the middle meatus. It is the largest of the paranasal sinuses.
A bifid ureter, or ureter fissus, is an example of incomplete duplication of a duplex collecting system and is an anatomical variant.
Multiple seemingly unrelated terms for blind-ending bifid ureters are currently in use and there is no consensus on terminology in the literature. T...
Broca's area (Brodmann area 44) is an area of the lateral frontal lobe in the dominant hemisphere concerned with the production of speech.
Broca's area is located in the posterior inferior frontal gyrus (pars opercularis and pars triangularis) of the dominant hemisphere, anterior...
The petromastoid (or subarcuate) canal is a channel in the petrous temporal bone that joins the mastoid antrum to the posterior cranial fossa. It contains the subarcuate artery and vein 1.
The canal has been categorized by its size 1:
type I - invisible
type II - less than 0.5...
The frontal lobe is by far the largest of the four lobes of the cerebrum (other lobes: parietal lobe, temporal lobe, and occipital lobe), and is responsible for many of the functions which produce voluntary and purposeful action.
The frontal lobe is the largest lobe accounting fo...
Iselin disease is a benign and self-limiting condition, defined as apophysitis of the base of the 5th metatarsal.
It is most commonly seen in males with sport injuries and is often also seen in adolescents.
It is due to repetitive traction of the peroneus brevis tendo...
Umbilical cord coiling index is defined in terms of the number of 360-degree spiral course of umbilical vessels. This can be described in two main ways:
the number of coils per one centimeter of length of cord.
Normocoiled: one coil for a length of five centimeters.
Hypercoiled: more than one...
Forked umbilical cord is a rare anomaly of the umbilical cord, which can be detected on an 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.
Thymic rebound hyperplasia is considered a from of true thymic hyperplasia.
In periods of bodily stress the thymus may acutely shrink to 40% of its original volume (depending on the severity and duration of the stress). During the recovery phase it can grow back to its original size ...
Wilhelm C Roentgen (1845-1923) was a German physicist who is celebrated globally for his discovery of x-rays on 8 November 1895.
Wilhelm Conrad Roentgen (Röntgen in German) was born on 27 March 1845 in Lennep, Germany. He attended the primary and secondary school run by Martinus Her...
Persistent hypophyseal canal, also known as the craniopharyngeal canal when larger than 1.5 mm in diameter, is a rare congenital defect characterized by communication through the central skull base between the nasopharynx and the pituitary fossa.
There are a number of terms that r...
Antonio Egas Moniz (1874-1955) 1 was a pioneering Portuguese neurologist that is notable in radiology history for his development of cerebral angiography in 1927.
He is also known as the developer of prefrontal leucotomy (now better known as a lobotomy) for which he received a Nobel Prize in 1...
The anterior commissure - posterior commissure line (AC-PC line), also known as the bicommissural line, has been adopted as a convenient standard by the neuroimaging community, and in most instances is the reference plane for axial imaging in everyday scanning. The creation of a standard image p...
The diaphragma sellae is one of the folds (or reflections) of the dura mater. It covers the sella turcica and forms the roof over the pituitary fossa 1.
The diaphragma sellae consists of two horizontal leaves of dura mater on the sphenoid bone. It extends from the tuberculum sell...
The subdural space (epiarachnoid space) is a potential space that exists between the meningeal layer of the dura mater and the inner arachnoid mater of the leptomeninges which are adherent to each other 1.
The meningeal layer of dura mater is usually adherent to the underlying ar...
The coracoid process is an anteriorly projecting hook-like process on the superolateral edge of the scapula that projects anterolaterally.
coracobrachialis from the medial apex
short head of biceps brachii from the lateral apex
pectoralis minor from the m...
The extradural (epidural) space is a potential space between the cranial bones and the endosteal layer of the dura mater, which is otherwise adherent to the cranial bone.
The extradural space is a potential space inside the cranial vault and is not normally appreciable unless th...
Ureteritis refers to inflammation of the ureter, it is rare and is often associated with cystitis or pyelonephritis 1.
Patients may present with symptoms of cystitis or pyelonephritis with suprapubic/flank pain, dysuria, hematuria and/or fever. White cell count may also ...
The glenoid or glenoid cavity or fossa is the shallow depression of the scapula found on the lateral angle.
glenoid labrum: the cavity has a fibrocartilaginous structure on its margin called the glenoid labrum which is continuous superiorly with the tendon of the lo...
The foramen magnum is the largest foramen of the skull and is part of the occipital bone 1. It is oval in shape with a large anteroposterior diameter 2.
The foramen magnum is found in the most inferior part of the posterior cranial fossa 3. It is traversed by vital structures inc...
Elastography is a newer technique that exploits the fact that a pathological process alters the elastic properties of the involved tissue. This change in elasticity is detected and imaged using elastography.
Sono-elastography is the term used when ult...
Congenital limb amputation is the absence of a fetal limb or part of a limb that usually occurs due to disruption of vascular supply.
Congenital amputations occur in 0.5 (range 0.03-1) per 1000 live births 2.
They are slightly more common in the upper limb (60%) than ...
Supernumerary kidneys, also known as accessory kidneys, are a rare congenital anomaly of the urogenital system, where there are one or two additional kidneys.
Less than 100 cases have been documented in the medical literature.
Many conditions have been found to be a...
Intracranial arterial beading represents alternating areas of constriction in the intracranial arteries that gives the appearance of beads strung together.
The various conditions where this may be seen are:
cerebral vasospasm post...
Bowing fractures are incomplete fractures of tubular long bones in pediatric patients (especially the radius and ulna) that often require no intervention and heal with remodeling.
Bowing fractures are almost exclusively found in children. However, there have been several case repo...
Doppler shift or Doppler effect is defined as the change in frequency of sound wave due to a reflector moving towards or away from an object, which in the case of ultrasound is the transducer.
When sound of a given frequency is discharged and subsequently reflected from a source th...
The sensory innervation of the meninges is primarily by meningeal branches of both the trigeminal and vagus nerves with a smaller contribution from the upper cervical spinal nerves 1,2. The supratentorial dura mater is mainly supplied by the ophthalmic division of the trigeminal nerve 3. Like th...
Oroantral fistulas are a pathological communication between the oral cavity and the maxillary sinus (antrum).
The term oroantral fistula is similar to but not synonymous with the term oroantral communication (OAC). An oro-antral fistula refers to an "epithelialized" pathological un...
Pulmonary pseudomonas aeruginosa infection is an uncommon cause of community-acquired pneumonia but can be a common cause of nosocomial pneumonia. It becomes increasingly important in critically ill and ventilated patients.
Pneumonia due to Pseudomonas aeruginosa can occurs as several distinct ...
The blood supply of the meninges generally concerns the blood supply of the outer layer of dura mater rather than the inner layer of dura mater, arachnoid or pia mater which do not require a large blood supply. There are several arteries that supply the dura in the anterior, middle, and posterio...
Amniotic fluid embolism is a special type of pulmonary embolism where the embolus is comprised of amniotic fluid. It can be a highly fatal complication of pregnancy, with an 80% maternal mortality rate.
It is thought to complicate 1/8,000-80,000 pregnancies.
Wilson Mikity syndrome (WMS) refers to chronic lung disease in premature infants, characterized by early development of cystic interstitial emphysema (PIE). This is now sometimes considered as part of the spectrum of bronchopulmonary dysplasia.
History and etymology
Almost 51 years ago, Wilson...
Pulmonary coccidioidomycosis, also known colloquially as valley fever, refers to lung involvement of the dimorphic fungus Coccidioides spp, mainly Coccidioides immitis and Coccidioides posadasi.
Coccidioidomycosis is endemic to many parts of North, Central, and South America 1. Wh...
The pia mater is the innermost layer of the meninges and together with the arachnoid mater is referred to as the leptomeninges. It is closely related to the surface of the brain and unlike the arachnoid mater extends into the sulci 1.
The pia mater is separated from the arachnoid...
Glass foreign bodies may be present if they are ingested, inserted, or as a result of an injury. All glass is radiopaque 7.
The prevalence of glass foreign bodies in wounds from injury has been recorded at a rate of 1.5% in superficial (subcutaneous) wounds and 7.5% of deeper woun...
Klebsiella pneumonia, also known as Friedländer pneumonia, refers to pneumonia resulting from an infection from the organism Klebsiella pneumoniae.
There tends to be a higher prevalence in older patients with alcoholism and debilitated hospitalized patients 3.
Supratentorial ependymomas are an uncommon type of ependymoma, found within the cerebral hemispheres, either remote to or abutting the ventricles.
They have distinct molecular features compared to both posterior fossa ependymomas and spinal ependymomas.
Overall, supratentorial ...
Harmonic imaging is a technique in ultrasonography that provides images of better quality as compared with conventional ultrasound technique.
Harmonic imaging exploits non-linear propagation of ultrasound through the body tissues. The high pressure portion of the wave travels faster th...
The cranial meninges (singular: meninx) surround the brain and are made up of three layers (from outermost to innermost):
The dura mater can also be known as the pachymeninx. The arachnoid mater and pia mater are collectively known as the leptomeninges 3....
The falx cerebelli is a small infolding of the dura in the sagittal plane over the floor of the posterior cranial fossa. It partially separates the two cerebellar hemispheres 1.
The falx cerebelli is attached posteriorly in the midline to the internal occipital crest of the occip...
The extrapleural air sign is one of the many signs of pneumomediastinum, and was first described by Lillard and Allen in 1965. It is defined as the presence of gas between the parietal pleura and the diaphragm. On a lateral projection, the gas forms a radiolucent pocket of gas posterior to the d...
The clavicle, also colloquially known as the collarbone, is the only bone connecting the pectoral girdle to the axial skeleton and is the only long bone that lies horizontally in the human skeleton.
The clavicle is roughly "S-shaped" with a flattened, concave, lateral...
The tentorium cerebelli (plural: tentoria cerebellorum) is the second largest dural fold after the falx cerebri. It lies in the axial plane attached perpendicularly to the falx cerebri and divides the cranial cavity into supratentorial and infratentorial compartments 1. It has free and attached ...
The properitoneal fat, also known as the preperitoneal space, is a fat containing space in the abdomen.
Posteriorly it lies deep to the transversalis fascia, and fills the posterior pararenal space. Laterally it thickens and forms the properitoneal fat pad, which is the anterior extension of po...
Metaphyseal corner fractures, also known as classical metaphyseal lesions (CML) or bucket handle fractures, are observed in young children, less than 2 years old. It is suggestive of non-accidental injury (NAI).
This injury is not only the fracture most specific for NAI, it is al...
Erb palsy, also known as brachial plexus birth palsy, is a form of obstetric brachial plexus injury as a result of complications during delivery.
The most common cause is due to excessive lateral traction or stretching of the fetal head and neck in opposite directions du...
Transplant renal arterial pseudostenosis is uncommon. It is a lesion in the iliac artery proximal to the implantation of the transplant renal artery.
Uncommon, although as the population of renal transplant recipients has become older and more diabetic, the incidence of this disea...
The CT comma sign is a characteristic sign seen in head trauma. It is the presence of concurrent epidural and subdural hematomas, which gives the characteristic appearance of this sign as a "comma" shape.
Gangrenous cholecystitis is the most common complication of acute cholecystitis, affecting ~15% (range 2-30%) of patients.
systemic inflammatory response syndrome 5
Thoracic manifestations of systemic lupus erythematosus can be variable.
For a general discussion, and for links to other system specific manifestations, please refer to the article on systemic lupus erythematosus.
pleuritis: considered one of the c...
The coronal suture is the cranial suture formed between the two parietal bones and the frontal bone. At the junction of coronal, sagittal and frontal sutures is the anterior fontanelle which is open at birth and usually fuses at around 18-24 months after birth.
Fusion of the coronal suture occu...
Prosencephalon (plural: prosencephala or prosencephalons) or forebrain is one of the primary divisions of neural tube.
Later the forebrain further separates into the telencephalon (cerebrum) and diencephalon (thalamus and related structures).
At about 8 weeks of intrauterine life, the prosenc...
The falx cerebri (plural: falxes/falces cerebrorum) is the largest of the four main folds (or septa) of the intracranial dura mater, separating the cerebral hemispheres 1.
The falx cerebri is a double-fold of dura mater that descends through the interhemispheric fissure in the m...
The arachnoid mater forms the middle layer of the meninges and together with the pia mater is sometimes referred to as the leptomeninges.
The arachnoid mater is a membrane that comes into direct contact with the dura mater and is separated from the pia mater by a CSF-filled spac...
The sphincter of Oddi (also known as the sphincter of ampulla or choledochal sphincter) is a complex of four smooth muscle sphincters within the duodenal wall. It surrounds, and helps fix to the duodenum, the duct of Wirsung, common bile duct and the ampulla of Vater 1,2.
When relaxed it allow...
Pulmonary graft versus host disease (GvHD) is one of the thoracic manifestations that can complicate hematopoietic stem cell transplantation. Pulmonary GvHD can be broadly divided into acute and chronic disease 1-4:
acute pulmonary GvHD
pulmonary involvement is rare
the median time of onset o...
A mnemonic for remembering the symmetric vs asymmetric causes of sacroiliitis is:
P: psoriatic arthritis
A: ankylosing spondylitis
I: inflammatory bowel disease related
R: reactive (e.g. reactive arthritis)
The outside letters P and R (letters are far apart) are the asymmetr...
The gut signature sign is an ultrasound term used to describe the appearance of the gastrointestinal wall.
The bowel wall has five layers, composed of alternating hyperechoic and hypoechoic appearances. Anatomically these layers are as follows (innermost to o...
The suprasternal space (of Burns) is a space of the inferior neck.
Inferior to the hyoid bone, the superficial or investing layer of the deep cervical fascia divides into anterior and posterior leafs to attach to the respective borders of the suprasternal (jugular) notch, forming...
The styloid apparatus, found within the parapharyngeal space, refers to the structures derived from the second branchial arch (see branchial apparatus) along with associated ligaments and muscles:
styloid process of the temporal bone
lesser horn of the hyoid bone
Riolan's bouquet (white flowe...
The stylohyoid ligament forms part of the styloid apparatus. The origin is at the styloid process of the temporal bone and it inserts into lesser horn of the hyoid bone.
The stylohyoid ligament provides part of the origin for the middle pharyngeal constrictor muscle and styloglossus muscle. It ...
The canalis basilaris medianus (median basal canal), also known as clival canal, median clival canal, or inferior median clival canal, refers to a number of anatomic variant midline canals in the clivus, typically involving the basioccipital portion.
These canals are generally we...
Thoracic manifestations in Behçet disease have a wide spectrum of appearances.
The reported prevalence of thoracic involvement of Behçet disease is thought to range around 1-8% 2.
Chest HRCT can demonstrate the entire spectrum of thoracic manifestation...
The 5-F rule refers to risk factors for the development of cholelithiasis in the event of upper abdominal pain:
fair: more prevalent in the Caucasian population 1
fat: BMI >30 kg/m2 and hyperlipidemia 3,4
fertile: one or more children
forty: age ≥40 years
cholelithiasis can occur in...
Pulmonary fat embolism is a specific subtype of pulmonary embolism where the embolic particles are composed of fat.
It usually occurs in the context of a long bone fracture and may occur in 1-3% of patients with simple tibial or femoral fractures and up to 20-33% of individuals with ...
Acute spinal cord ischemia syndrome is uncommon, but usually presents with profound neurological signs and symptoms, and the prognosis is poor.
Acute spinal cord ischemia syndrome represents only 5-8% of acute myelopathies 4,5 and <1% of all strokes 7. The demographic of affected...
Snake eyes, also known as snail eyes, is a term used to refer to the appearance of the facial nerve on coronal CT within its canal in the petrous temporal bone as the tympanic segment doubles back next to the labyrinthine segment. Anteriorly, these two segments converge at the geniculate ganglio...
Takotsubo cardiomyopathy, also known as stress cardiomyopathy, apical ballooning syndrome, or broken heart syndrome, is a condition characterized by transient regional abnormal cardiac wall motion, not confined to a single coronary arterial territory.
It has been described predomi...
The double delta sign is a feature that has been described in a bucket handle meniscal tear when the inner meniscal fragment flipped anteriorly adjacent to the anterior horn of the donor site and is referred to as a displaced bucket handle tear. The original location of the posterior horn remain...
A cyamella is a rare sesamoid bone that exists as a normal variant within the popliteus tendon, characteristically located at the lateral aspect of the distal femur in the popliteal groove.
Cyamella is best seen on the AP view of plain radiograph as opposed to fabella, which is best appreciated...
Mycoplasma pneumonia is a type of community-acquired pneumonia caused by the organism Mycoplasma pneumoniae. It is usually grouped under atypical pneumonia.
It is relatively common in the pediatric population where it is considered the most common community-acquired pneumonia in 5...
Intrapulmonary lymph nodes, or pulmonary lymph nodes, are normal lymph nodes found within the lung parenchyma itself. They are commonly found during the assessment of CTs of the chest and are, sometimes, difficult to distinguish from pulmonary nodules.
The pulmonary lymph nodes are divided into...
The spinal cord is the part of the central nervous system that is found within the spinal canal of the vertebral column. The cord extends from the corticomedullary junction at the foramen magnum of the skull down to the tip of the conus medullaris within the lumbar cistern. It is lined by spinal...
The dual or double rim sign is seen on MRI in approximately 75% of cerebral abscesses and is helpful in distinguishing an abscess from a glioblastoma.
On both susceptibility weighted imaging (SWI) and T2WI it consists of two concentric rims surrounding the abscess cavity, outer one of which is...
Os radiostyloideum (or persistent radial styloid) is an accessory ossicle of the wrist located adjacent to the radial styloid process and lateral to the mid-portion of the scaphoid.
This should not be confused with another bony ossicle in the wrist, os styloideum (part of a carpal boss), which...
Os supratrochleare dorsale, also called os supratrochleare posterius is an accessory ossicle of the elbow located in the olecranon fossa of the humerus 1. It may become symptomatic due to trauma during elbow extension and as such may require surgical removal 2.
Pulmonary mesenchymal cystic hamartomas (PMHCs) are a rare subtype of pulmonary hamartomas.
They usually comprise multiple bilateral cysts and nodules. The cyst walls are lined with normal respiratory epithelium and the nodules are permeated by scattered airways that are also lined w...
Os paratrapezium is an accessory ossicle located between distal radial aspect of the trapezium and the base of the 1st metacarpal 1.
Differential diagnoses include loose bodies secondary to trapreziometacarpal joint osteoarthritis or secondary to trauma (e.g. Bennett's fracture) 2.
Pulmonary gas emboli are a specific type of pulmonary emboli that, while rare, should be kept in mind especially with the use of automatic injectors and interventional procedures. The seriousness of the problem will depend on both the amount and rate of injected air in the circulatory system.
The os triangulare (also known as the os intermedium antebrachii or os triquetrum secundarium) is an accessory ossicle located between the ulnar styloid, lunate and triquetrum 1,2.
They may be unilateral or bilateral and the main differential diagnosis is non-union of an ulnar styloid process f...
Adrenal metastases are the most common malignant lesions involving the adrenal gland. Metastases are usually bilateral but may also be unilateral. Unilateral involvement is more prevalent on the left side (ratio of 1.5:1).
They are present at autopsy in up to 27% of patients with ...
Meth mouth is the name given to the overt dental disease that is one of the signs of chronic methamphetamine use.
Clinical examination often reveals blackened, stained, rotting or crumbling teeth. Serial studies only a few years apart may show a striking deterioration in ...
Jackstone calculus is the name assigned to the appearance of a subset of urinary calculi, a rare bladder stone with spiculated and stippled edges3.
Jackstone calculi are almost always composed of calcium oxalate dihydrate. They are nearly always created, and thus, located, in the bla...
Chronic pulmonary emboli are mainly a consequence of incomplete resolution of pulmonary thromboembolism.
vascular CT signs include
direct pulmonary artery signs
calcified thrombus - calcific pulmonary ...
Idiopathic dilatation of the pulmonary trunk is a rare congenital anomaly comprising pulmonary trunk enlargement with or without dilatation of the right and left pulmonary arteries.
For this diagnosis, exclusion of pulmonary and cardiac diseases (mainly pulmonary valve stenosis) and confirmatio...
Aberrant arachnoid granulations, also known as arachnoid pits, are arachnoid granulations that penetrated the dura but failed to migrate normally in the venous sinus. They are most often located in the greater wing of the sphenoid bone and may be seen in idiopathic intracranial hypertension. Occ...
Head and neck manifestations of sarcoidosis can have three main forms:
orbital involvement: orbital sarcoidosis
parotid gland involvement
laryngeal sarcoidosis 2
nodal involvement: cervical lymphadenopathy in sarcoidosis
Hepatic infarction is an extremely rare situation because the liver has a dual blood supply from the hepatic artery and portal vein. Hepatic infarction can occur when there is both hepatic arterial and portal vein flow compromise but most cases are due to acute portal venous flow compromise 11.