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 for a J-shaped sella includes 1,...
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).
Jaccoud arthropathy (JA) is a deforming non erosive arthropathy characterised by ulnar deviation of the second to 5th fingers with MCP subluxation.
It was traditionally described as occurring post rheumatic fever. It is also seen in association with systemic lupus erythematosus (SLE)...
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.
Jackstone calculus is the name assigned to the appearance of a subset of urinary calculi.
Jackstone calculi are almost always composed of calcium oxalate dihydrate. They are nearly always created, and thus, located, in the bladder rather than the upper urinary tract.
They are compos...
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...
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 preganglionic parasympathetic fibres, from the inferior salivary nucleus, which eventually enter the otic ganglion.
Jacobson nerve en...
Jaffe-Campanacci syndrome is characterised by:
multiple non-ossifying fibromas of the long bones and jaw
café au lait spots
hypogonadism or cryptorchidism
giant cell granuloma of the jaw
Japanese encephalitis (JE) is one of many viral encephalitides and results from infection with the Japanese encephalitis virus.
At the onset of the disease patients present with severe rigors, fevers and headache. As it progresses to the acute encephalitic stage, meningo-...
The Jarcho-Levin syndrome (JLS) or spondylothoracic dysostosis is a rare autosomal recessive heterogeneous disorder which can occur to variable severity.
It is primarily characterized by a short neck, short trunk and a constricted thorax (narrow fetal thorax) due to multi...
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 dete...
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.
A typical mechanis...
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...
Jejunal atresia is a congenital anomaly characterised by obliteration of the lumen of the jejunum. 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.
This article will focus on jejuna...
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...
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...
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.
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 ...
The jejunum is arbitrarily defined as the proximal two-fifths of the small intestine and is, on average, ~300 cm 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 appearanc...
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
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...
It is common to identify a number of forms of jewellery on radiographs.
umbilical and genital rings
Jod-Basedow phenomenon is hyperthyroidism following iodine intake in a person with long term underlying thyroid disease.
Jod-Basedow phenomenon occurs due to either overactivation of the entire thyroid gland, or more commonly autonomous nodules within the gland after iodine repletion...
Johanson-Blizzard syndrome is a disorder of ectodermal dysplasia with a wide variability in its manifestations. It is thought to have autosomal recessive inheritance.
There is a wide variability in the clinical presentation, but common features are:
low birth weight
The Johansson classification of periprosthetic hip fractures was the first classification system proposed and is the simplest. It is based on the level of fracture in relation to the prosthesis.
type I: fracture proximal to tip of prosthesis with stem still in contact with medullary canal
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).
It was reported that ~70% of adults have been exposed to this virus, however no clinic...
Joint ankylosis has a relatively broad differential including 1-5:
chronic reactive arthritis
juvenile idiopathic arthritis
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...
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.
Joints can be classified into three broad types according to the tissue that binds them.
A Jones fracture is an extra-articular fracture at the base of the fifth metatarsal.
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.
The fracture is ...
Joplin neuromas are rare compression traumatic neuromas, involving the proper digital nerve of the great toe (a branch of the medial plantar nerve).
Pain and tenderness at the first digit metatarsophalangeal joint. More common in soccer players and in patients post bunion...
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.
When associated with anomalies of the kidneys, liver and/or eyes then the term Joubert ...
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:
Juberg-Hayward syndrome (JHS), also known as the oro-cranio-digital syndrome, is a rare autosomal recessive syndrome characterised by the association of the following:
cleft lip and palate
minor vertebral and rib anomalies 4
horseshoe kidneys 4
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...
The jugular bulb is the connection between the sigmoid sinus and the internal jugular vein.
The sigmoid and inferior petrosal sinuses empty into the jugular bulb, which continues as the internal jugular vein. It lies in the pars vascularis, which occupies the posterolateral aspe...
The jugular foramen courses anteriorly, laterally, and inferiorly as it insinuates itself between the petrous temporal bone and the occipital bone.
The jugular foramen is usually described as being divided into two parts by a fibrous or bony septum, called the jugular spine, into...
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.
In those without neurofibromatosis type 2 (NF2), they tend to present between the 3rd to 6th decades of life. There is...
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.
glomus jugulare is the most common tumour of jugular fossa
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.
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 ...
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...
Jumper's knee is a chronic insertional injury of the posterior and proximal fibres of the patella tendon, at the site of its origin at 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...
Junctional parenchymal defects in renal imaging are a normal variant.
It results from the incomplete embryonic fusion of renunculi.
It can be seen as a triangular echogenic cortical defect, frequently seen in upper lobe parenchyma. The defect is th...
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...
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.
Juvenile granulosa cell tumours of the ovary (JGCT) are a less common subtype of granulosa cell tumour of the ovary (~5% of cases). They are classified as ovarian sex cord / stromal tumours.
It typically occurs in premenarchal girls and young women. The mean age of presentation is...
Juvenile idiopathic arthritis (JIA), also known as juvenile rheumatoid arthritis, is the most common chronic arthritic disease of childhood and corresponds to a group of different subtypes.
The estimated incidence is ~13 per 100,000 per annum 3. By definition, symptoms must start ...
Juvenile nasopharyngeal angiofibromas (JNA) are a rare benign but locally aggressive vascular tumour.
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 ...
Staging of juvenile nasopharyngeal angiofibromas is performed with cross-sectional imaging and relies on the identification of local tumour extent, and invasion of adjacent spaces. For a discussion of this entity please refer to the parent article: juvenile nasopharyngeal angiofibroma.
Juvenile osteoporosis (JO) refers to osteoporosis occurring in children.
It can arise from a number of causes.
osteoporosis pseudoglioma syndrome
Juvenile papillomatosis (JP) of the breast is a relatively common benign localised proliferative lesion in the breast.
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.
Juvenile polyposis syndrome, also referred as familial juvenile polyposis, is one of the polyposis syndromes and consists of hundreds of juvenile polyps.
Presentation in the second decade is most common 2.
Rectal bleeding, bowel obstruction and intussuscept...
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)
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.
They tend to present around the 2nd to 4th decades. There is a recognised m...
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).
Typically it occurs in adu...
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...
Juxtaglomerular cell tumour (JGCT) is an infrequent renal tumour of the juxtaglomerular cells. These cells secrete renin and often cause severe hypertension and hypokalaemia.
JGCT affects all age groups, but is most common in adolescents and young adults, with peak prevalence in t...
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 ...