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.

57 results found
Article

Abnormal ultrasound findings in rheumatological diseases (definitions)

The OMERACT ultrasound group published a consensus in 2005 of widely accepted definitions of abnormal ultrasound findings in rheumatological diseases: erosion: an intra-articular discontinuity of the bone surface that is visible in two orthogonal planes joint effusion: abnormal hypoechoic or a...
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Achondrogenesis 1B

Achondrogenesis type Ib, also known as Parenti-Fraccaro subtype, is a subtype of achondrogenesis and is an extremely rare skeletal dysplasia (chondrodysplasia).​​ Pathology Undersulphation has a pronounced effect on the composition of the extracellular matrix of cartilage, and this has been sh...
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Acromiohumeral interval

Acromiohumeral interval is a useful and reliable measurement on AP shoulder radiographs and when narrowed is indicative of rotator cuff tear or tendinopathy.  Pathology Measurements of the acromiohumeral interval in the following intervals are suggestive of pathology 1-2: >12 mm: shoulder dis...
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Amsterdam wrist rules

The Amsterdam wrist rules are validated clinical decision rules for determining which patients require radiographic imaging (wrist radiography) for acute wrist pain following trauma. The initial study evaluated 882 patients and were published in 2015 1. The decision rules assessed different clin...
Article

Ankle (AP view)

Ankle AP view is part of a three view series of the distal tibia, distal fibula, proximal talus and proximal metatarsals. Patient position the patient may be supine or sitting upright with their leg straighten on the table the foot is in dorsiflexion the toes will be pointing directly toward...
Article

Blumensaat line

Blumensaat line is the line drawn along the roof of the intercondylar notch of the femur as seen on lateral radiograph of the knee joint. It can been used for: indicating the relative position of the patella as normally this line intersects the lower pole of the patella suggesting ACL injury a...
Article

Böhler angle

Böhler angle, also written as Bohler angle or Boehler angle, is also called the calcaneal angle or tuber joint angle 1, and is the angle between two lines tangent to the calcaneus on the lateral radiograph. These lines are drawn tangent to the anterior and posterior aspects of the superior calca...
Article

Canadian C-spine rules

Canadian C-spine rules are a set of guidelines that help a clinician decide if cervical spine imaging is not appropriate for a trauma patient in the emergency department. The patient must be alert and stable. There are three rules: is there any high-risk factor present that requires cervical s...
Article

Cases in radiology (video tutorials)

The cases featured in these video lectures are specifically selected to teach important concepts in radiology over a broad range of topics. The tutorials vary in difficulty from basic to advanced. For maximum learning, try the cases for yourself in Radiopaedia quiz mode first.  We love this ser...
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Chest x-ray: disability (summary)

Chest x-ray review is a key competency for medical students, junior doctors and other allied health professionals. Using A, B, C, D, E is a helpful and systematic method for chest x-ray review where D refers to disability and specifically fractures and dislocations. Reference article This is a...
Article

Coracoclavicular distance

The coracoclavicular (CC) distance is an indicator of the integrity of the coracoclavicular (CC) ligament. Radiographic features The CC distance is assessed on a frontal radiography of the shoulder or clavicle or the coronal projection or a CT or MRI as the distance between the superior cortex...
Article

Coxa magna

Coxa magna is the asymmetrical, circumferential enlargement and deformation of the femoral head and neck. Definitions in the literature vary but enlargement with asymmetry >10% in size is a reasonable cut-off for diagnosis 1.  Pathology Aetiology Legg-Calve-Perthes disease transient synoviti...
Article

Coxa profunda

Coxa profunda refers to a deep acetabular socket. On pelvis x-rays it is seen as the acetabular fossa being medial to the ilioischial line. It should be differentiated from protrusio acetabuli, where the femoral head is seen additionally medial to the ilioischial line. Coxa profunda is much more...
Article

Describing a fracture (an approach)

Describing a fracture is a basic requirement when making an assessment of a plain radiograph. There are many ways to approach the assessment of the radiograph; this is just one approach. I: Describe the film What film (or films) are you looking at? Check the who, what, why, when, and where. I...
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Elbow radiograph (summary approach)

Elbow radiographs are common plain films that are obtained frequently in the emergency department. Summary approach alignment anterior humeral line drawn down the anterior surface of the humerus should intersect the middle 1/3 of the capitellum if it does not, think distal humeral fracture...
Article

Enchondroma vs low grade chondrosarcoma

Distinguishing between enchondromas and low-grade conventional chondrosarcomas is a frequent difficulty as the lesions are both histologically and radiographically very similar. It is important to remember, though, that differentiating between them may be a moot point since both can either be c...
Article

Evaluation of recurrent bone tumours

Recurrent bone tumours are a common complication post curettage or resection. Radiographic features Radiographs taken pre- and postoperatively are sufficient for evaluation of recurrence based on the following features: osteolytic changes cortical changes matrix mineralisation (characterist...
Article

First metatarsal axis

The first metatarsal axis is represented by a line drawn down the longitudinal axis of the shaft of the first metatarsal. It can be drawn on lateral and DP radiographs and is used to measure the: first metatarsal inclination angle talo-first metatarsal angle
Article

Foot (lateral view)

The lateral projection is part of the three view series examining the phalanges, metatarsals and tarsal bones that make up the foot.  The lateral projection additionally examines the talocrural joint. Patient position the patient may be supine or upright depending on comfort  the affected le...
Article

Foot radiograph (an approach)

Foot radiographs are commonly performed in Emergency departments, usually after sport-related trauma and often with a clinical request that states lateral border pain. Remember to check the whole film, though. Often, a foot x-ray is also requested for the investigation of osteomyelitis, arthriti...
Article

Gissane angle

Gissane angle, also known as the "critical angle", is an angular measurement made directly inferior to the lateral process of the talus. It is formed by the downward and upward slopes of the calcaneal superior surface. It is better seen on a lateral plain film of the calcaneus and hindfoot. Its ...
Article

Hindfoot equinus

Hindfoot equinus describes abnormal plantarflexion (calcaneotibial angle >90°)  of the foot that occurs in the hindfoot. It occurs in congenital talipes equinovarus and congenital vertical talus.
Article

Imaging of gunshot injuries

Gunshot injuries often require imaging assessment, and this evaluation has both clinical relevance (assessment of organ damage, surgical planning and prognostication), and often also forensic implications. Epidemiology Incidence of gunshot injuries to the head is increasing in some countries, ...
Article

Intermetatarsal angle

The intermetatarsal (IM) angle refers to the angle measured between the 1st and 2nd metatarsal shaft on an axial view of the foot. In normal situations it is considered to be under 9°. The angle can increase with hallux valgus and metatarsus adductus deformities.
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...
Article

Low grade osteosarcoma

Low grade osteosarcoma is an uncommon subtype of osteosarcoma accounting less than 1% of all osteosarcomas. Epidemiology Low grade osteosarcoma affects individuals of higher age group as compare to the other subtypes of osteosarcoma. The usual age of presentation is 19 to 54 years with the mea...
Article

Magnetic resonance neurography

Magnetic resonance neurography (MRN) is a relatively new non-invasive imaging technique for dedicated assessment of peripheral spinal nerves. It is used to assess peripheral nerve entrapments and impingements as well as localization and grading of nerve injuries and lesions. Dedicated high-res...
Article

McGregor line

The McGregor line is a modification of the Chamberlain line and is used in the evaluation of basilar invagination when the opisthion is not identified on plain radiographs. It refers to a line connecting posterior edge of the hard palate to the most caudal point of the occipital curve. If the t...
Article

Midfoot equinus

Midfoot equinus is an abnormality in foot alignment where there is abnormal plantarflexion of the foot in the midfoot. Related pathology Midfoot equinus occurs as a component of congenital talipes equinovarus.
Article

Monoarticular arthropathy

Monoarticular arthropathy can result from a number of causes: infectious arthritis gout HADD (hydroxyapatite deposition disease) traumatic arthritis secondary osteoarthritis avascular necrosis PVNS synovial osteochondromatosis osteochondritis dissecans
Article

MRI of the brachial plexus

MRI of the brachial plexus is used to provide a causal diagnosis for brachial plexopathies. It provides clear structural analysis of the brachial plexus, its intraneural integrity, as well as surrounding structures 1,3. Related pathology brachial plexus injuries grading of brachial plexus inj...
Article

NEXUS criteria

NEXUS (National Emergency X-Radiography Utilization Study) is a set of validated criteria used to decide which trauma patients do not require cervical spine imaging. Trauma patients who do not require cervical spine imaging: alert and stable no focal neurologic deficit no altered level of co...
Article

Normal radiographic measurements of the shoulder

Normal radiographic measurements of the shoulder are important in evaluation of the osseous relationships in plain film radiography. Normal measurements do not rule out pathology, and must be considered in the context of other findings and the clinical presentation. AC joint space: 2-4 mm  inc...
Article

Osteolytic lesions with septations and trabeculations (differential)

Differential diagnosis of lytic bone lesions with septations and trabeculations include 1: benign lesions unicameral bone cyst aneurysmal bone cyst giant cell tumour non-ossifying fibroma intraosseous lipoma fibrous dysplasia Brown tumour ameloblastoma adamantinoma haemophilic pseudot...
Article

Ottawa ankle rules

The Ottawa ankle rules are a clinical decision-making strategy for determining which patients require radiographic imaging for ankle and foot injuries. Proper application has high (97.5%) sensitivity and reduces the need for radiographs by ~35% 1,2,4.  There are two components, assessing for an...
Article

Ottawa knee rules

The Ottawa knee rules are a clinical decision-making strategy for determining which patients require radiographic imaging for knee pain. A patient with knee pain qualifies for a radiograph if: 55 years or older point tenderness at the fibular head isolated point tenderness of the patella in...
Article

Paediatric elbow radiograph (an approach)

Paediatric elbow radiographs are commonly encountered in the emergency department and, when approached in a systematic fashion, are not as difficult to interpret as most people think! Systematic review Ossification Check that the ossification centres are present and in the correct position. T...
Article

Radiographic evaluation of anterior cruciate ligament reconstruction

Radiographic evaluation of anterior cruciate ligament (ACL) reconstruction involves: femoral component a line is drawn along the posterior cortex of the femur a second line is drawn along the roof of the intercondylar notch of the femur (Blumensaat line) the point of intersection of these tw...
Article

Reverse total shoulder arthroplasty

Reverse total shoulder arthroplasty (RTSA) is a type of total shoulder replacement. It is often the preferred method when there has been advanced damage to the rotator cuff as seen in rotator cuff arthropathy. Procedure The reverse total shoulder flips the normal mechanical arrangement of the ...
Article

Scapholunate interval

The scapholunate interval is the radiographic measurement of the scapholunate joint on PA wrist projections. Abnormal widening is indicative of injury to the scapholunate ligament that occurs with scapholunate dissociation.  In adults, the normal value is usually taken as <2 mm, with an interva...
Article

Shortened fetal humerus

Shortened fetal humerus is a morphological description and is usually defined when the humeral length falls below the 5th percentile or less than 0.9 predicted by the bipareital diameter (BPD). It can occur in isolation or in association with a number of other anomalies. The humeral length is n...
Article

Shoulder radiograph (an approach)

Shoulder radiographs are common films to see in the Emergency Department, especially during the weekend after sporting events. Systematic review Glenohumeral joint articular surfaces should be parallel the humeral head should be on the glenoid in any other view if the humeral head lies unde...
Article

Shoulder radiograph (summary approach)

Shoulder radiographs are commonly performed for shoulder injury assessment and followup. Using a standard system to approach the x-ray means it is much more likely you will find the abnormality. Summary approach alignment glenohumeral joint - shoulder dislocation the humeral head is adjacent...
Article

Skeletal survey

A skeletal survey is a series of radiographs, performed systematically to cover the entire skeleton or the anatomic regions appropriate for the clinical indications. A typical skeletal survey includes bilateral anteroposterior (AP) and posteroanterior (PA) projections of hands, forearms, humeru...
Article

Sports injuries (cricket)

Cricket is a popular game in Commonwealth countries, injuries in this game can be associated with three aspects of the game: bowling, batting or fielding. Radiologists should know the different kind of injuries related to this game for a better clinical association. Injuries can range from a mus...
Article

Subcutaneous calcification (differential)

Subcutaneous calcification can be associated with a number of disorders. The list includes: dermatomyositis Ehlers-Danlos syndrome pseudoxanthoma elasticum basal cell nevus syndrome subcutaneous lipodystrophy venous thrombosis as a manifestation of systemic lupus erythematosus varicose v...
Article

Trabecular pattern of proximal femur

Trabecular pattern of proximal femur refers to the five groups of trabeculae that are demonstrable within the femoral head and neck. Basic concept Trabecula is a supportive and connective tissue element which form in cancellous bone. Trabeculae develop in a normal bone and also in a healing bo...
Article

Tuberculosis (musculoskeletal manifestations)

Musculoskeletal tuberculosis is always secondary to a primary lesion in the lung. Epidemiology The prevalence of the disease is around 30 million globally and 1-3% of the 30 million have involvement of their bones and/or joints. Mycobacterium tuberculosis is responsible for almost all of the c...
Article

Tuberculous arthropathy

Tuberculous arthropathy is a type of musculoskeletal manifestation of tuberculosis (TB) and a common cause of infectious arthritis in developing countries. Any pathological joint lesion where the exact diagnosis is equivocal should be considered tubercular in origin unless proven otherwise. Ple...
Article

Tumours that metastasise to bone (mnemonic)

Tumours that metastasise to bone may be remembered using the mnemonic "lead kettle" spelled PBKTL (lead is Pb on the Periodic Table). PB-KTL Mnemonic P: prostate B: breast K: kidney T: thyroid L: lung For females, breast and lung are the most common primary sites; nearly 80% of cancers t...
Article

Ultrasound of the elbow

Ultrasound of the elbow allows high-resolution imaging of elbow anatomy while simultaneously allowing dynamic evaluation of the joint, tendons, and ligaments. Approach There are multiple possible approaches to imaging the elbow with ultrasound. A typical protocol is as follows 1: Anterior elb...
Article

Ultrasound of the knee

Ultrasound of the knee allows high-resolution imaging of superficial knee anatomy while simultaneously allowing dynamic evaluation of some of the tendons and ligaments. Knee ultrasound is somewhat limited compared with ultrasound examinations of other joints because the cruciate ligaments and th...
Article

Ultrasound of the wrist

Ultrasound is a useful imaging modality for evaluation of the wrist, allowing high-resolution imaging of anatomy while simultaneously allowing dynamic evaluation of the joint, tendons, and ligaments. Approach There are multiple possible approaches to imaging the wrist with ultrasound. The exam...
Article

Weightbearing foot series (an approach)

Reporting a weightbearing foot series can be a daunting process if you are inexperienced and often results in the films being left for somebody else to report. This article attempts to demystify the whole process by providing a structured approach to their reporting. Technique The weightbearin...
Article

Wrist radiograph (an approach)

Wrist radiographs are ubiquitous on any night of the week in emergency departments, especially when pavements are icy! Systematic review Distal radial contour Check the contour of the distal radius: AP the distal radial articular surface should cup the carpals the articular surface should ...
Article

Wrist radiograph (approach)

Wrist x-rays are commonly used for the assessment of the wrist following trauma. This is usually a fall onto an outstretched hand. Systematic review It is useful to have a systematic approach; I tend to start proximally and work distally looking at structures on both views together: distal ra...
Article

Wrist radiograph (summary approach)

Wrist radiographs are commonly used for the assessment of the wrist following trauma.  Summary approach alignment AP distal radius and ulna have smooth joint surface carpal arcs are smooth carpal bones do not overlap apart from pisiform and trapezium metacarpals do not overlap and distal...

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