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.

451 results found
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Situs inversus

Situs inversus, (rare plural: sitūs inversi) 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 ...
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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. Its objective is to accurately identify focal and diffuse abnormalities of the skeleton and to differentiate them from developmen...
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Small bowel follow through

Small bowel follow through (SBFT) is a fluoroscopic technique designed to obtain high-resolution images of the small bowel. The motility of the small bowel can also be grossly evaluated. Indications The small bowel follow through can be useful for evaluation of: strictures obstruction diver...
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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...
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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...
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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...
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Solitary pulmonary nodules

Solitary pulmonary nodule (SPN) is defined as a relatively well defined round or oval pulmonary parenchymal lesion equal to or smaller than 30 mm in diameter. It is surrounded by pulmonary parenchyma and/or visceral pleura and is not associated with lymphadenopathy, atelectasis, or pneumonia 9. ...
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Sonographic approach to dyspnea (mnemonic)

This mnemonic will help with the sonographic approach to the critically ill patient with dyspnea: 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 ou...
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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 color Doppler features favor malignancy in a lymph node. Gray scale parameters that favor malignancy size: larger-more likely malign...
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Sonographic Mulder sign

The sonographic Mulder sign is the ultrasound correlate of the clinical Mulder sign during examination of the forefoot to investigate causes of metatarsalgia associated with Morton neuroma 1. The intermetatarsal space is predominantly composed of fat inferiorly and also contains the neurovascula...
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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 etiologies. Injury to the spinal cord can be incomplete or complete and depends upon the mechanism of injury. This is important as differ...
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Split bolus technique

The split bolus technique is a CT imaging investigation used in patients with hematuria aiming to put together, in a single image acquisition, both the nephrographic and renal excretory phases and thus reducing the radiation dose of the study. It is a CT protocol adopted for some institutions fo...
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Standardized reports

Standardized 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 many cases, desirable. On the other hand in some instances standardized reports facilitate the creation of automated ...
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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...
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Sternoclavicular joint injection (technique)

Sternoclavicular joint (SCJ) injections under image guidance ensure precise delivery of an injectate into the joint and importantly that needle depth is under direct visualization.   Indications pain arthropathy, e.g. osteoarthritis diagnostic injection Contra-indications Absolute anaphyl...
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Subacromial bursal injection

Subacromial bursal corticosteroid injections, also known as subacromial-subdeltoid bursal injections, are used in patients with limited or no response to initial treatment with impingement syndrome, subacromial bursitis and/or rotator cuff disorders. Non-steroidal anti-inflammatory drugs (NSAIDs...
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...
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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...
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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

Sulcus angle (knee)

The sulcus angle is formed by the trochlear opening of the knee, measuring the angle between the medial and lateral facets. Classically described in axial x-rays of the knee performed at 30-45º of flexion (skyline view), it is valuable in both CT and MR studies. Interpretation Its normal value...
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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...
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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

T1 mapping - myocardium

T1 mapping is a magnetic resonance imaging technique used to calculate the T1 time of a certain tissue and display them voxel-vice on a parametric map. It has been used for myocardial tissue characterization 1-6 and has been investigated for other tissues 5. T1 is the spin-lattice or longitudin...
Article

T2 mapping - myocardium

T2 mapping is a magnetic resonance imaging technique used to calculate the T2 times of a certain tissue and display them voxel-vice on a parametric map. It has been used for tissue characterization of the myocardium 1-5 and has been investigated for cartilage 6,7 and other tissues 4. The T2 tim...
Article

Tanner-Whitehouse method

The Tanner-Whitehouse (TW) method is a way of assessing the bone age of children. There are several variations of this method, but all use a DP radiograph of the left hand and wrist to assess the relative maturity of the bones of the patient. The TW2 (Tanner-Whitehouse 2) methods 1: RUS (radiu...
Article

Tentorial angle

The tentorial angle is measured between a line connecting the nasion with the tuberculum sellae and the angle of the straight sinus. Normally it should measure between 27° and 52°. Abnormalities of the posterior fossa or base of skull can alter this. For example, this angle is elevated in achon...
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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 ionizing radiation. MRI is occasion...
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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...
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Thoracic spine radiograph (checklist)

The thoracic spine checklist is just one of the many pathology checklists that can be used when reporting to ensure that you always actively exclude pathology that is commonly missed; this is particularly helpful in the examination setting, e.g. the FRCR 2B rapid-reporting. Radiograph These ra...
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 . It involved resection of multiple ribs, allowed the apposition of parietal to the visceral or mediastinal pleura. Until...
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Tibial torsion

Tibial torsion refers to as the rotation or twist along the longitudinal axis of the lower leg or more specifically the tibial bone. Usage Internal tibial torsion is a cause of in-toeing gait a common rotational variant in toddlers, usually resolving spontaneously by the age of 5 years.  A sev...
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Tibiofibular clear space

The tibiofibular clear space (TFCS) is a radiographic measure and defined as the space between the groove of the distal tibial prominence and the medial margin of the distal fibula 1-3. Usage Together with the tibiofibular overlap (TFO) and the medial clear space the tibiofibular clear space h...
Article

Tibiofibular overlap

The tibiofibular overlap (TFO) is the overlapping area between the anterior distal tibial prominence and the medial edge of the distal fibula 1-3. Usage Together with the tibiofibular clear space (TFCS) and the medial clear space, the tibiofibular overlap space has been used in the diagnosis a...
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...
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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...
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Transmission (epidemiology)

Transmission, in the context of infectious disease, implies the passing of a pathogen from one host or reservoir of the pathogen to a new susceptible host. The term transmission is also used for the transfer of genes in genetic diseases. Instances of transmission can be divided into direct or i...
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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...
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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...
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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...
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Triangulation

Triangulation is a technique for localizing lesions seen on at least two views on 2D mammography. 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 lesion on the 90° later...
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 estriol Interpretation An abnormal test result doesn't indica...
Article

Trochlear depth (TD)

Trochlear depth (TD) measures the depth of the trochlear groove in relation to the femoral condyles. Usage Trochlear depth (TD) is used for the assessment of trochlear dysplasia, a dysplastic deformity of the femoral head, which is known risk factor for patellofemoral instability 1-6. A revie...
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Trochlear facet asymmetry (FA)

Trochlear facet asymmetry (FA) refers to the condition of the medial facet being abnormally small if compared to the lateral facet in trochlear dysplasia 1. Usage Facet asymmetry (FA) is also used as a measurement in magnet resonance imaging for trochlear dysplasia to make it more objective 1-...
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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...
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Tumor pseudoresponse

Tumor pseudoresponse, also known just as pseudoresponse, refers to the phenomenon of tumors 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 tumors imaging follow-up, especially fo...
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Tumors of the base of skull (differential diagnosis)

Tumors of the base of skull are histologically varied and are often challenging to preoperatively diagnose and treat. Exactly which tumors are considered to be tumors of the base of skull is debatable. The broadest definition would include any tumor that involves or abuts the base of skull, thu...
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Tumors that metastasize to bone (mnemonic)

Tumors that metastasize 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 th...
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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...
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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...
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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 stromal fibrosis, or both processes lead to the formation of cysts, disabling the drainage of the terminal ducts of the lobules. In al...
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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. The biopsy is gene...
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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...
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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...
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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...
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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 joints, tendons, and ligaments. Approach There are multiple possible approaches to imaging the wrist with ultrasound. The exa...
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 placental insufficiency and consequent intrauterine growth restriction (IUGR) or suspected pre-eclampsia.  Umbilical arter...
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Umbilical cord abnormalities

Abnormalities of the umbilical cord can be classified into 1: Morphologic abnormalities umbilical cord coiling hypocoiled umbilical cord hypercoiled umbilical cord straight umbilical cord umbilical cord length abnormalities long umbilical cord short umbilical cord umbilical cord thickne...
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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. Since a normal umbilical vein supplies a continuous forward flow of oxygenated blood to the fetal heart, the presence of pulsatility...
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...
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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)...
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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.  Clinical presentation painful urination strangury bloody, dark, cloudy urine urinary frequen...
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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...
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Ventral trochlear prominence

Ventral trochlear prominence describes and measures the bony surplus in the anterior femoral surface at the most superior or proximal aspect of the trochlea. Usage Ventral trochlear prominence is used for the assessment of trochlear dysplasia, a risk factor for patellofemoral instability 1-4 i...
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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

Videofluoroscopic swallow study

Videofluoroscopic swallow studies (also often called modified barium swallow studies) are a variation on traditional barium swallow studies. Although typical barium swallow studies / esophagrams evaluate the pharynx, the goal in these studies is to even more closely evaluate the oral cavity, pha...
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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...
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Voiding cystourethrography

Voiding cystourethrography (VCUG), also known as a micturating cystourethrography (MCU),  is a fluoroscopic study of the lower urinary tract in which contrast is introduced into the bladder via a catheter. The purpose of the examination is to assess the bladder, urethra, postoperative anatomy an...
Article

Volume doubling time

The volume doubling time (VDT) is an important volumetric parameter primarily used in lung cancer screening and follow-up by chest CT. Volume doubling time is defined as the time required for a growing nodule to double its volume. A longer VDT suggests a more benign course, whilst a short VDT is...
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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...
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Weight loss

A clinical presentation of weight loss is extremely common and often a source of marked anxiety for the patient. The commonest cause of unintentional weight loss (UWI) is gastrointestinal tract disease, and not malignancy. Terminology The published literature lacks a consistent definition of w...
Article

When to use italics

Making a decision about when to use italics in Radiopaedia.org articles and cases is important because the addition of bold and italic words in prose actually reduces readability. In literature, italics can be used for a number of things, including titles of works and foreign words. However, in...
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Wrist radiograph (an approach)

Wrist radiographs are ubiquitous on any night of the week in emergency departments, especially when pavements are icy! Choosing a search strategy and using it consistently is a helpful method to overcome common errors seen in diagnostic radiology. Systematic review Distal radial contour Check...
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 (checklist)

The wrist radiograph checklist is just one of the many pathology checklists that can be used when reporting to ensure that you always actively exclude pathology that is commonly missed; this is particularly helpful in the examination setting, e.g. the FRCR 2B rapid-reporting. Radiograph Wrist ...
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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