Articles

Articles are a collaborative effort to provide a single canonical page on all topics relevant to the practice of radiology. As such, articles are written and edited by countless contributing members over a period of time. A global group of dedicated editors oversee accuracy, consulting with expert advisers, and constantly reviewing additions.

55 results found
Article

J shaped sella

A J-shaped sella is a variant configuration of the sella turcica, where 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 Differential diagnosis for a J-shap...
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J sign

The J sign refers to the appearance of the inferior glenohumeral ligament in the presence of a humeral avulsion of the glenohumeral ligament (HAGL lesion). The normal U-shaped inferior glenohumeral recess is retracted away from the humerus, appearing as a J (right shoulder).
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Jaccoud arthropathy

Jaccoud arthropathy (JA) is a deforming non erosive arthropathy characterised by ulnar deviation of the second to 5th fingers with MCP subluxation. Pathology It was traditionally described as occurring post rheumatic fever. It is also seen in association with systemic lupus erythematosus (SLE)...
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Jack and Jill lesion

Jack and Jill lesion refers to simultaneous bucket handle tears of medial and lateral menisci with intercondylar notch displacement of the fragments which appear as quadruple sign on coronal MRI images.
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Jackstone calculus

Jackstone calculus is the name assigned to the appearances of a sub-set of urinary tract calculi. Pathology These stones have a loose crystalline lattice of calcium oxalate dihydrate which allows them to be easily fragmented with various forms of lithotripsy, despite their formidable appearanc...
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Jacobsen syndrome

Jacobsen syndrome (also known as the chromosome 11q deletion syndrome) is a rare chromosomal anomaly that results from deletion of the terminal region of chromosome 11. It results in intellectual disabilities, a distinctive facial appearance and a variety of physical problems including heart def...
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Jacobson nerve

Jacobson nerve is the tympanic branch of the glossopharyngeal nerve (CN IX) and arises from the inferior ganglion of the glossopharyngeal nerve. It also carries parasympathetic fibers from the otic ganglion.  It enters the middle ear cavity via the inferior tympanic canaliculus and contributes ...
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Jaffe-Campanacci syndrome

Jaffe-Campanacci syndrome is characterised by: multiple non-ossifying fibromas of the long bones and jaw café au lait spots intellectual disability kyphoscoliosis hypogonadism or cryptorchidism ocular malformations cardiovascular malformations giant cell granuloma of the jaw Differentia...
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Japanese encephalitis

Japanese encephalitis (JE) is one of many viral encephalitides and results from infection with the Japanese encephalitis virus. Clinical presentation At the onset of the disease patients present with severe rigors, fevers and headache. As it progresses to the acute encephalitic stage, meningo-...
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Jarcho-Levin syndrome

The Jarcho-Levin syndrome (JLS) or spondylothoracic dysotosis is a rare autosomal recessive heterogenous disorder which can occur to variable severity. Clinico-pathological spectrum It is primarily characterized by a short neck, short trunk and a constricted thorax (narrow fetal thorax) due to...
Article

Jaundice

Jaundice refers to a clinical sign of hyperbilirubinemia (>2.5 mg/dl) which has many causes. It is often a clue to a diagnosis. It can be largely divided into two types: non-obstructive, i.e. pre-hepatic and hepatic causes obstructive, i.e. post-hepatic causes Imaging has a major role in d...
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Jefferson fracture

Jefferson fracture is the eponymous name given to a burst fracture of C1. It was originally described as a four-part fracture with double fractures through the anterior and posterior arches, but three-part and two-part fractures have also been described. Pathology Mechanism A typical mechanis...
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Jejunal and ileal branches of superior mesenteric artery

The jejunal and ilieal branches of the superior mesenteric artery are variable in number. The pass in the two layers of the mesentery to the jejunum and ileum and progressively divide and join in a series of anastomosing arcades. From the arcades, straight arteries (also known as vasa recta) pa...
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Jejunal atresia

Jejunal atresia (JA) is a congenital anomaly characterized by closure of the jejunuum. The site of the atresia can be anywhere from the ligament of Treitz to the junction of the jejunum and ileum. At times there can be more than one atretic segment. Demographics and clinical presentation It ha...
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Jejunocolic bypass

Jejunocolic bypass was an early form of bariatric surgery. It is no longer performed due to severe side effects. For this bypass, the proximal small bowel (jejunum) is transected and anastomosed to the colon (such as the transverse colon). The other end of the small bowel is closed and the dist...
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Jejunoileal bypass

Jejunoileal bypass is an older form of bariatric surgery that was developed to be an improvement on jejunocolic bypass. It is no longer performed due to severe side effects. For this bypass, the proximal small bowel (jejunum) is divided ~35 cm past the ligament of Treitz, and the proximal end i...
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Jejunoileal diverticula

Jejunoileal diverticula, also referred just as jejunal diverticula or diverticulosis as most of the diverticula are located in the jejunum, are outpouchings from the jejunal and ileal wall on their mesenteric border that represent mucosal herniation through sites of wall weakening 1. See also ...
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Jejunoileal fold pattern reversal

Jejunoileal fold pattern reversal (a.k.a. jejunisation of the ileum) is one of the signs of coeliac disease, and is seen on small bowel follow-through studies as well as CT. The pattern is one of increased number of ileal folds and reduced number of jejunal folds 1,2, and is considered positive ...
Article

Jejunum

The jejunum is arbitrarily defined as the proximal two-fifths of the small intestine and is, on average, ~300cm in length. The primary method of evaluation of the small bowel is small bowel follow-through examination (SBFT). On SBFT the jejunum has a delicate feathery appearance, and is located ...
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Jejunum vs. ileum

There are a few differences that can help differentiate jejunum and ileum 1-3: jejunum is slightly wider (< 3 cm) than ileum (<2 cm) jejunum folds (valvulae conniventes) are thicker (2-3 mm) than ileum folds (1-2 mm) jejunum folds are also more numerous and deeper than ileum folds
Article

Jersey finger

Jersey finger (also called Rugby finger or Sweater finger) describes a type of injury where there is avulsion of the flexor digitorum profundus (FDP) at the base of the distal interphalangeal joint (DIP) 1. Most commonly affects the 4th digit as the FDP insertion into the ring finger is anatomi...
Article

Jewellery on radiographs

It is common to identify a number of forms of jewellery on radiographs. These include: nipple rings umbilical and genital rings ear-rings belts
Article

Jod-Basedow phenomenon

Jod-Basedow phenomenon is hyperthyroidism following iodine intake in a person with long term underlying thyroid disease. Pathology Jod-Basedow phenomenon occurs due to either overactivation of the entire thyroid gland, or more commonly autonomous nodules within the gland after iodine repletion...
Article

Johanson-Blizzard syndrome

Johanson-Blizzard syndrome is a disorder of ectodermal dysplasia with a wide variability in its manifestations. It is thought to have autosomal recessive inheritance. Clinical presentation There is a wide variability in the clinical presentation, but common features are: low birth weight hyp...
Article

John Cunningham virus

John Cunningham (JC) virus is an ubiquitous double-stranded DNA virus member of the polyomaviridae family 1. It is the aetiological agent of the progressive multifocal leukoencephalopathy (PML). Epidemiology It was reported that ~70% of adults have been exposed to this virus, however no clinic...
Article

Joint effusion

This article is dedicated to the humble joint effusion, particularly the plain radiographic appearances. A joint effusion is defined as an increased amount of fluid within the synovial compartment of a joint. There is normally only a small physiological amount of fluid. Abnormal fluid accumulat...
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Joints

Joints, also known as articulations, are a form of connection between bones. They provide stability to the skeletal system as well as allowing for specialised movement. Gross anatomy Joints can be classified into three broad types according to the tissue that binds them.  Structural types fi...
Article

Jones fracture

Jones fractures occur at the base of the fifth metatarsal.  Pathology It is a transverse fracture at the base of the fifth metatarsal, 1.5 to 3 cm distal to the proximal tuberosity at the metadiaphyseal junction, without distal extension.  Mechanism The fracture is believed to occur as a res...
Article

Joplin neuroma

Joplin neuromas are rare compression traumatic neuromas, involving the proper digital nerve of the great toe (a branch of the medial plantar nerve). Clinical presentation Pain and tenderness at the first digit metatarsophalangeal joint. More common in soccer players and in patients post bunion...
Article

Joubert syndrome

Joubert anomaly, also known as vermian aplasia or molar tooth midbrain-hindbrain malformation, is an autosomal recessive disorder where there is a variable degree of cerebellar vermal agenesis.  Terminology When associated with anomalies of the kidneys, liver and/or eyes then the term Joubert ...
Article

Joubert syndrome related disorders (JSRD)

Joubert syndrome related disorders (JSRD), one of a growing group of related disorders known as ciliopathies, refers to the combination of Joubert syndrome and involvement of the liver, kidneys and/or eyes. Various combinations of these have been given their own syndromes, including 1,2: Varadi...
Article

Juberg-Hayward syndrome

Juberg-Hayward syndrome (JHS) (also knwon as the oro-cranio-digital syndrome) is a rare autosomal recessive syndrome characterised by the association of  growth retardation microcephaly cleft lip and palate minor vertebral and rib anomalies 4 horseshoe kidneys 4 thumb anomalies triphalang...
Article

Judet and Letournel classification for acetabular fractures

The Judet and Letournel classification is the most widely used classification of acetabular fractures. It is based on three radiographic views (anteroposterior view, obturator oblique view and Iliac oblique view)  and classifies acetabular fractures into ten major fracture patterns, which cons...
Article

Jugular foramen

The jugular foramen courses anteriorly, laterally, and inferiorly as it insinuates itself between the petrous temporal bone and the occipital bone. Gross anatomy The jugular foramen is usually described as being divided into two parts by a fibrous or bony septum, called the jugular spine, into...
Article

Jugular foramen schwannoma

Jugular foramen schwannomas are a rare type of intracranial schwannoma that presents as a jugular fossa mass. As the name implies it involves the jugular foramen. Epidemiology In those without neurofibromatosis type 2 (NF2), they tend to present between the 3rd to 6th decades of life. There is...
Article

Jugular fossa

The jugular fossa is a depression situated on the inferior surface of petrous temporal bone posterior to the inferior opening of carotid canal. It lodges the jugular bulb. Anteriorly, lies the jugular foramen. Related pathology glomus jugulare is the most common tumour of jugular fossa
Article

Jugular fossa masses

Jugular fossa masses comprise a range of pathological lesions that arise from or extend into the jugular fossa in the skull base. Although not a common location for tumours it is not unusual for jugular fossa lesions to be discovered incidentally on cross sectional imaging. Terminology Althoug...
Article

Jugular spine

The jugular spine is a small sharp bony ledge which separates the two parts of the jugular foramen - pars nervosa anteriorly and pars vascularis posteriorly. It is an important landmark, as masses of the jugular foramen (e.g. glomus jugulare) will erode this spine, helping distinguish them from ...
Article

Jugular venous catheters

The internal jugular vein is a preferred site for venous access for large lumen, long-term central venous catheters for chemotherapy, haemofiltration and plasma exchange.  Typically, the right internal jugular is used as its vertical course straight down into the superior vena cava via the righ...
Article

Jumper's knee

Jumper's knee is a chronic insertional injury of the posterior and proximal fibres of the patella tendon, where they insert into the inferior pole of the patella. Many authors equate jumper's knee to the adult form of Sinding-Larsen-Johansson disease 1 . Some suggest instead that jumper's knee ...
Article

Junctional parenchymal defect of kidney

Junctional parenchymal defects in renal imaging are a normal variant. Pathology It results from incomplete embryonic fusion of renunculi. Radiographic features Ultrasound It can be seen as an triangular echogenic cortical defect, frequently seen in upper lobe parenchyma. The defect is the e...
Article

Junctional zone

Junctional zone is a region representing the inner myometrium and is a very important imaging feature in pelvic MR imaging for interpretation of various pathologies. In its intact state, it is usually visualised as a low T2 signal layer beneath the endometrium. This low signal intensity is thou...
Article

Juvenile fibroadenoma of the breast

A juvenile fibroadenoma of the breast is a term given to a fibroadenoma presenting in children or adolescents. These may account for ~0.5-2% of all fibroadenomas, and are rapidly growing masses that cause asymmetry of the breast, distortion of the overlying skin, and stretching of the nipple. 1...
Article

Juvenile granulosa cell tumour of the ovary

A juvenile granulosa cell tumour of the ovary (JGCT) is a less common subtype of granulosa cell tumour of the ovary (~5% of cases). They are classified as ovarian sex cord / stromal tumours. Epidemiology It typically occurs in premenarchal girls and young women. The mean age of presentation is...
Article

Juvenile idiopathic arthritis

Juvenile idiopathic arthritis (JIA), also known as juvenile rheumatoid arthritis, is the most common chronic arthritic disease of childhood and correspond to a group of different subtypes. Epidemiology The estimated incidence is ~13 per 100,000 per annum 3. By definition, symptoms must start b...
Article

Juvenile nasopharyngeal angiofibroma

Juvenile nasopharyngeal angiofibromas (JNA) are a rare benign but locally aggressive vascular tumour. Epidemiology Juvenile nasopharyngeal angiofibromas occur almost exclusively in males and usually in adolescence (~15 years). They account for only 0.5% of all head and neck tumours 2, but are ...
Article

Juvenile osteoporosis

Juvenile osteoporosis (JO) refers to osteoporosis occurring in children. Pathology Aetiology It can arise from a number of causes. primary conditions osteogenesis imperfecta Bruck syndrome osteoporosis pseudoglioma syndrome Ehlers-Danlos syndrome Marfan syndrome homocystinuria seconda...
Article

Juvenile papillomatosis of the breast

Juvenile papillomatosis (JP) of the breast is a relatively common benign localised proliferative lesion in the breast. Epidemiology As the name implies, it is mainly seen in young women (mean age ~19-23 years 4,6) and is unusual in women over 30 years old. Clinical presentation Patients pres...
Article

Juvenile polyposis syndrome

Juvenile polyposis syndrome (familial juvenile polyposis) is one of the polyposis syndromes and consists of hundreds of juvenile polyps. Epidemiology Presentation in the second decade is most common 2. Clinical presentation Rectal bleeding, bowel obstruction and intussusception are common pr...
Article

Juxta-articular ganglion cyst

Juxta-articular ganglion cyst refers to a ganglion cyst which abuts an articular surface. They can be located within the bone (intraosseous ganglion cyst) or within the soft tissues (soft tissue ganglion cyst)
Article

Juxta-cortical chondroma

Juxta-cortical chondromas, also known as periosteal chondromas, are rare benign chondral tumours that arise from the periosteum of tubular bones. They are thought to account for ~2% of benign bone tumours. Epidemiology They tend to present around the 2nd to 4th decades. There is a recognised m...
Article

Juxta-cortical chondrosarcoma

Juxta-cortical chondrosarcomas (also known as periosteal chondrosarcomas) are indistinguishable histologically from conventional medullary chondrosarcomas, and are therefore graded into low, intermediate or high grade tumours (see chondrosarcoma grading). Epidemiology Typically it occurs in ad...
Article

Juxtacortical

Juxtacortical is a general term and merely denotes 'next to cortex' and can be used in a variety of context depending on the structure (e.g. bone, brain, kidney etc..).  Juxtacortical brain lesions The term juxtacortical is most commonly encountered in the brain in the context of multiple scle...
Article

Juxtaglomerular cell tumour

Juxtaglomerular cell tumour (JGCT) is an infrequent renal tumour of the juxtaglomerular cells. These cells secrete renin and often cause severe hypertension and hypokalaemia. Epidemiology JGCT affects all age groups, but is most common in adolescents and young adults, with peak prevalence in t...
Article

Juxtaphrenic peak sign

The juxtaphrenic peak sign or diaphragmatic tenting refers to the peaked or tented appearance of a hemidiaphragm which can occur in the setting of lobar collapse. It is caused by retraction of the lower end of diaphragm at an inferior accessory fissure (most common 1), major fissure or inferior ...

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