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.

348 results found
Article

Sagittal balance (C7 plumb line)

Sagittal balance forms part of the plain radiographic assessment of spinal deformity including kyphotic or lordotic deformities and scoliosis. There are numerous ways of assessing this, using various bony landmarks and angles to evaluate whether or not a normal distribution of weight and stresse...
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Sagittal midline of the brain (an approach)

The sagittal midline of the brain is one of the most important sectional planes in neuroimaging. A good working knowledge of the normal neuroanatomy of the sagittal midline is essential so that the subtle abnormalities that may manifest here can be recognised. The neuroembryological development...
Article

Satisfaction of search error

Satisfaction of search (also known as SOS) error is a common error in diagnostic radiology. It occurs when the reporting radiologist fails to continue to search for subsequent abnormalities after identifying an initial one. This initial detection of an abnormality satisfies the "search for meani...
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

Scrotal scintigraphy

Scrotal scintigraphy is a radio-isotope examination of the scrotal contents, primarily in patients presenting with scrotal pain. Indications Although, ultrasound remains the mainstay of scrotal imaging, scintigraphy can be used where the diagnosis is unclear, since ultrasound appearances for s...
Article

Second trimester ultrasound scan

The second trimester scan is a routine ultrasound examination in many countries that is primarily used to assess fetal anatomy and detect the presence of any fetal anomalies.  The second trimester extends from 13 weeks and 0 days to 27 weeks and 6 days of gestation although the majority of thes...
Article

Selective internal radiation therapy

Selective internal radiation therapy (SIRT), also know as hepatic radioembolisation, is a relatively new and developing modality for treating non-resectable liver tumours. The procedure consists of a transcatheter injection of radioactive particles via the hepatic artery.  It is generally consi...
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 as predicted by the biparietal diameter (BPD). It can occur in isolation or in association with a number of other anomalies. The humeral length i...
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)

This is a basic article for medical students and other non-radiologists 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...
Article

Sigmoid volvulus versus caecal volvulus

The following points may be helpful to distinguish between sigmoid volvulus and caecal volvulus on plain film. Sigmoid volvulus arises in the pelvis (left lower quadrant) extends towards the right upper quadrant ahaustral in appearance sigmoid volvulus causes obstruction of the proximal lar...
Article

Situs inversus

Situs inversus, short form of the Latin “situs inversus viscerum”, is a term used to describe the inverted position of chest and abdominal organs. It is called situs inversus totalis when there is a total transposition of abdominal and thoracic viscera (mirror image of internal organs normal pos...
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

Sleeve gastrectomy

Sleeve gastrectomy is a bariatric surgical procedure involving resection of the greater curvature of the fundus and body of the stomach to leave approximately 15% of the original gastric volume (60 to 100 mL), thus creating a restrictive physiology. The postsurgical gastric pouch resembles a ban...
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Sleeve gastrectomy complications

Complications related to sleeve gastrectomy are often evaluated by imaging. For details about surgical procedure, please see the sleeve gastrectomy article.  Postoperative complications can be classified aetiologically or chronologically. Early complications staple line leakage clinical pres...
Article

Small bowel follow through

Small bowel follow through (SBFT) is a fluoroscopic technique designed to obtain high resolution images of the small bowel. The function of the small bowel can also be evaluated. Indications The small bowel follow through can be used for evaluation of small bowel abnormalities, including: str...
Article

Small pulmonary nodules (HRCT chest approach)

Small pulmonary lung nodules refer to an HRCT chest imaging descriptor for 5-10 mm lung nodules and are divided into three main categories based on their distribution pattern: centrilobular perilymphatic random Terminology Radiologists often informally refer to indeterminate small pulmonary...
Article

Sniff test

The fluoroscopic sniff test, also known as diaphragm fluoroscopy, is a quick and easy real time fluoroscopic assessment of diaphragmatic motor function (excursion). It is used most often to confirm absence of muscular contraction of the diaphragm during inspiration in patients with phrenic nerve...
Article

Solitary pulmonary nodule (an approach)

A solitary pulmonary nodule, according to the Nomenclature Committee of the Fleischner Society, is defined as a rounded opacity, well or poorly-defined on a conventional radiograph, measuring up to 3 cm in diameter and is not associated with lymphadenopathy, atelectasis, or pneumonia. Several r...
Article

Sonographic approach to dyspnoea (mnemonic)

This mnemonic will help with the sonographic approach to the critically ill patient with dyspnoea: CHEST Mnemonic C: collapsed lung (pneumothorax)  absence of anterior lung sliding, lung pulse, B-lines, or z-lines these artifacts arise from the pleural interface; their presence would rule o...
Article

Sonographic features of malignant lymph nodes

Lymphadenopathy is quite common, and it can be very difficult to differentiate malignant lymphadenopathy from reactive nodal enlargement. Several gray scale and colour Doppler features favour malignancy in a lymph node. Gray scale parameters that favour malignancy size: larger-more likely mal...
Article

Spinal cord injury

Spinal cord injury (SCI) can be traumatic or non-traumatic (i.e. neoplastic/stenosis) but the syndromes associated with spinal cord injury can be seen in all aetiologies. Injury to the spinal cord can be incomplete or complete and depends upon the mechanism of injury. This is important as diffe...
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

Standardised reports

Standardised reports may be a helpful starting point for reporting examinations. However, with practice and confidence, breaking away from the standard report is possible and, in most cases, desirable. The standard report may help to remember review areas and in times of increasing litigation m...
Article

Step-oblique mammography

Step-oblique mammography is an accurate technique for determining whether a mammographic finding visible on multiple images on only one projection (but not elucidated using standard additional mammographic projections) represents a summation artefact or a true mass and for precisely localizing t...
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

Submucosal leiomyoma in the exam

Getting a film with submucosal fibroid in the exam is one of the many exam set-pieces that can be prepared for.  Description Transabdominal and transvaginal pelvic ultrasound scans show an anteverted uterus with endometrium that is 7 mm wide and has a trilaminar appearance indicative of the pe...
Article

Subpleural reticulation

Subpleural reticulation is a type of reticular interstitial pattern where the changes are typically in a peripheral subpleural distribution (i.e. adjacent to costal pleural surfaces, located ≤1 cm from the pleura according to some publications 4). Pathology It can arise in a number of patholog...
Article

Supratentorial intracranial mass in an adult (an approach)

The identification of a supratentorial intracranial mass in an adult is a fairly common clinical scenario, the appropriate management of which relies heavily on preoperative imaging. Often important clues will be present in the clinical history (e.g. immunosuppression, systemic malignancy, durat...
Article

Systematic chest radiograph assessment (approach)

One approach to a systematic chest radiograph assessment is as follows: projection assessment of the technical adequacy tubes and lines cardiomediastinal contours hila airways, lungs and pleura bones and soft tissue review areas Following a systematic approach on every chest radiograph ...
Article

Tentorial angle

The tentorial angle is measured between a line connecting the nasion with the tuberculum sellae and the the angle of the straight sinus. Normally it should measure between 27° and 52°. Abnormalities of the posterior fossa / base of skull can alter this. For example this angle is elevated in ach...
Article

Testicular and scrotal ultrasound

Testicular and scrotal ultrasound is the primary modality for imaging most of the male reproductive system. It is relatively quick, relatively inexpensive, can be correlated quickly with the patient's signs and symptoms, and, most importantly, does not employ ionising radiation. MRI is occasion...
Article

The four "Ds" of radiology reporting

The four "Ds" of radiology reporting are the basic sequential tasks that a radiologist performs when reporting/reading a case, whether it be in training, the exam environment or in day-to-day clinical practice.  The 4 "Ds" Detect Describe Diagnosis or differential diagnoses Decision By sti...
Article

Thoracoplasty

Thoracoplasty is a surgical procedure that was originally designed to permanently collapse the cavities of pulmonary tuberculosis by removing the ribs from the chest wall 1-3 . The resection of multiple ribs, allows the apposition of parietal to the visceral or mediastinal pleura. Until supplant...
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

Transcatheter aortic valve implantation (TAVI)

Transcatheter aortic valve implantation or replacement (TAVI/TAVR) is a technique to replace the aortic valve through a transvascular or transapical approach. Compared to traditional open aortic valve replacement with sternotomy and a heart-lung bypass machine, the TAVI technique is less invasiv...
Article

Transrectal ultrasound

Transrectal ultrasound (TRUS) is a technique that is used most commonly to evaluate the prostate gland, including ultrasound-guided prostate biopsies depth of invasion of colon/rectal cancer (for staging purposes) It can also be used for guidance in placing a transrectal drain, or in rare pro...
Article

Transthoracic echocardiography views

A standard transthoracic echocardiogram consists of five standardized windows which are obtained in a standardized sequence 1. Obtaining views from the left parasternal, apical, subcostal, and suprasternal notch windows is mandatory for a complete echocardiography protocol. The right parasternal...
Article

Transverse view of abdomen

A transverse abdominal view is one of the standard views on fetal echocardiography and is very useful for assessing situs abnormalities. In case of situs solitus (normal situs), the stomach is on the left and liver on the right. The descending aorta lies anterior and to the left of the spine whi...
Article

Traumatic aortic injury in the exam

Getting a film with traumatic aortic injury in the exam is one of the many exam set-pieces that can be prepared for.  This is one of the cases you should look and not speak for 10 seconds as there tends to be a lot of findings on the film of patients with a traumatic aortic injury. Description...
Article

Triangle of safety

The triangle of safety is an anatomical region in the axilla that forms a guide as to the safe position for intercostal catheter (ICC) placement. With the arm abducted, the apex is the axilla, and the triangle is formed by the: lateral border of the pectoralis major anteriorly lateral border o...
Article

Triangulation

Triangulation is a technique for determining if a questionable structure is genuine or superimposition of structures. Technique hang the CC, MLO, and 90° lateral films (in that order) on the view box the nipple on each film must be at the same level use a ruler and place one end over the les...
Article

Triple screening

Triple screening refers to a screening blood test that is used to screen pregnant women for possible neural tube defects, Down syndrome and trisomy 18 in the developing fetus. It measures: alpha-fetoprotein Beta hCG unconjugated oestriol Interpretation An abnormal test result doesn't indic...
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

Tumour pseudoresponse

Tumour pseudoresponse, also known just as pseudoresponse, refers to the phenomenon of tumours appearing to respond to a specific treatment on imaging criteria, when the lesion actually remains stable or has even progressed. The term is largely used in brain tumours imaging follow-up, especially...
Article

Tumours of the base of skull (differential diagnosis)

Tumours of the base of skull are histologically varied and are often challenging to preoperatively diagnose and treat. Exactly which tumours are considered to be tumours of the base of skull is debatable. The broadest definition would include any tumour that involves or abuts the base of skull,...
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

Two diameter pocket method

The two diameter pocket (TDP) method is an alternative method of assessing amniotic fluid volumes on ultrasound. However, it is not thought to be a good predictor of adverse neonatal outcome 2. Sonographic assessment According to this method 1,2: TDP <15 cm2: indicative of oligohydramnios TD...
Article

Ultrasound assessment of carotid arterial atherosclerotic disease

Ultrasound assessment of carotid arterial atherosclerotic disease has become the first choice for carotid artery stenosis screening, permitting the evaluation of both the macroscopic appearance of plaques as well as flow characteristics in the carotid artery. This article focus on internal caro...
Article

Ultrasound evaluation of breast cysts

Ultrasound evaluation of breast cysts is the modality of choice. Obstruction of the ducts, often appearing as the result of epithelial hyperplastic processes or the stromal fibrosis, or both processes lead to the formation of cysts, disabling the drainage of the terminal ducts of the lobules. I...
Article

Ultrasound guided breast biopsy

Ultrasound guided percutaneous breast biopsy is a widely used technique for an accurate histopathological assessment of suspected breast pathology. It is a fast, safe and economical procedure. Indications Ultrasound guidance is limited to lesions visible on ultrasound study, such as:  BIRADS ...
Article

Ultrasound-guided FNA of the thyroid

Ultrasound-guided fine needle aspiration (FNA) of the thyroid refers to a minimally invasive procedure where in which tissue samples are collected from a thyroid nodule or other suspicious thyroid lesion. It is usually done on a outpatient basis and generally complications are very minimal. Pro...
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

Umbilical arterial Doppler assessment

Umbilical arterial (UA) Doppler assessment is used in surveillance of fetal well-being in the third trimester of pregnancy. Abnormal umbilical artery Doppler is a marker of uteroplacental insufficiency and consequent intrauterine growth restriction (IUGR) or suspected pre-eclampsia.  Umbilical ...
Article

Umbilical venous flow assessment

Umbilical venous flow in the physiological situation comprises of a monophasic non-pulsatile flow pattern in the umbilical vein with a mean velocity of 10-15 cm/s. The presence of pulsatility implies a pathological state unless in the following situations: early in pregnancy: up to ~13 weeks ge...
Article

Unilateral hypertranslucent hemithorax

Unilateral hypertranslucent hemithorax has many potential causes. It may be the result of rotation away from an optimal position or because of pathology. Rotation A unilateral hypertranslucent hemithorax may be caused by the positioning of the patient. Rotation away from the radiation beam alt...
Article

Urethrography

Urethrography refers to the radiographic study of the urethra using iodinated contrast media and is generally carried out in males.  Terminology When the urethra is studied with instillation of contrast into the distal/anterior urethra it has been referred to as retrograde urethrography (RUG)...
Article

Urinary tract infection

Urinary tract infection (UTI) is a common clinical condition involving the bladder (cystitis) and kidneys (pyelonephritis). It is commonly divided into 'uncomplicated' and 'complicated' infections.  Pathology UTIs occur when there is bacterial colonisation of the uroepithelium and a subsequent...
Article

Uteroplacental blood flow assessment

Uteroplacental blood flow assessment is an important part of fetal well-being assessment and evaluates Doppler flow in the uterine arteries and rarely the ovarian arteries. Pathology In a non-gravid state and at the very start of pregnancy the flow in the uterine artery is of high pulsatility ...
Article

Ventral cord syndrome

Ventral cord syndrome (also known as anterior cord syndrome) is one of the incomplete cord syndromes and affects the anterior parts of the cord resulting in a pattern of neurological dysfunction dominated by motor paralysis and loss of pain, temperature and autonomic function. Anterior spinal ar...
Article

Vermian maturity assessment (approach)

Radiological evaluation of the posterior fossa is an essential part of the routine fetal assessment, including vermian maturity assessment. Radiographic features Ultrasonography is a readily available diagnostic tool in the assessment of the fetal posterior fossa but is sometimes limited due t...
Article

Viva preparation

Viva preparation is key to successful completion of professional exams.  It is really important to think about the types of cases that you will be shown in the viva and preparing aurally for them. So, rather than learning sitting with your books, get a set of films, or using the Radiopaedia.org...
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Viva technique

Viva technique is hugely important when sitting oral examinations. You must remember that the examiners may well have been examining for several days and for hours at a time. They will have shown their films many times and will know them backwards! Moreover, their films will be beloved, so do no...
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)

This is a basic article for medical students and other non-radiologists 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 ...

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