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Coronal balance

Coronal balance is one of the features that needs to be assessed on long spine radiographs obtained for spinal deformity, particularly scoliosis. It measures whether or not the upper spine is located over the midline (normal) or off to one side. To assess coronal balance, a vertical (plumb) li...

Coronary Artery Disease - Reporting and Data System - SCCT/ACR/NASCI (2016)

Coronary Artery Disease - Reporting and Data System (CAD-RADSTM) classification is proposed by the Society for Cardiovascular Computed Tomography (SCCT), the American College of Radiology (ACR), and the North American Society for Cardiovascular Imaging (NASCI), last updated in 2016. This recomm...

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 Etiology Legg-Calve-Perthes disease transient synovitis...

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...

Crohn disease vs ulcerative colitis

Due to the overlap in clinical presentation of Crohn disease (CD) and ulcerative colitis (UC), imaging often has a role to play in distinguishing the two. Distinguishing features include: bowel involved CD: small bowel 70-80%, only 15-20% have only colonic involvement UC: rectal involvement 9...

CT angiography of the cerebral arteries

CT angiography of the cerebral arteries is a noninvasive technique allows visualization of the internal and external carotid arteries and vertebral arteries and can include just the intracranial compartment or also extend down to the arch of the aorta. By using multidetector CT (MDCT) after int...

CT cisternography

Computed tomography (CT) cisternography is an imaging technique used to diagnose CSF rhinorrhea or CSF otorrhea (CSF leaks), as CT allows the assessment of the bones of the base of skull. Procedure pre-contrast CT is performed with thin slices 3-10 mL of an iodinated non-ionic low-osmolar co...

CT cystography

CT cystography is a variation of the traditional fluoroscopic cystogram. Instead of anterograde opacification of the urinary collecting system (as with CT urography), contrast is instilled retrograde into the patient's bladder, and then the pelvis is imaged with CT. Indications suspected bladd...

CT enterography

Computed tomographic (CT) enterography is a non-invasive technique for diagnosis of small bowel disorders. Advantages evaluates the entire thickness of the bowel wall offers information about the surrounding mesentery, the mesenteric vasculature and the perienteric fat detect occult gastroi...

CT head (an approach)

The approach taken to interpreting a CT scan of the head is no doubt different depending on the circumstances and the reading clinician, however, most radiologists will go through the same steps. What follows is merely a suggested approach to interpreting a CT of the head. An important aspect ...

CT head (subdural window)

The subdural (blood) window can be used when reviewing a CT brain as it makes intracranial hemorrhage more conspicuous, and may help in the detection of thin acute subdural hematomas that are against the calvaria. It is a wider setting than the standard non-contrast window, and there are a numbe...

CT perfusion in ischemic stroke

CT perfusion in ischemic stroke has become established in most centers with stroke services as an important adjunct, along with CT angiography (CTA), to conventional unenhanced CT brain imaging. It enables differentiation of salvageable ischemic brain tissue (the penumbra) from irrevocably dam...

CT polytrauma (approach)

Below is an approach used for the "primary survey" of a CT polytrauma/multitrauma (also called trauma CT or whole body CT), often performed at the CT console with the patient still on the CT table. It allows rapid communication of significant findings to the trauma team as well as the decision ...

CVC position on chest x-ray (summary)

This is a basic article for medical students and other non-radiologists Chest x-ray CVC (central venous catheter) position should be assessed following initial placement and on subsequent radiographs. Reference article This is a summary article; for a more in-depth reference article see centr...

Cystography

Cystography is a fluoroscopic study that images the bladder. It is similar to a voiding cystourethrogram (VCUG), and the difference between the studies is primarily one of emphasis; a cystogram focuses on the bladder and a VCUG focuses on the posterior urethra. The study has been adapted to CT a...

Deductive echocardiography

Deductive echocardiography is a step-by-step approach in diagnosing and differentiating congenital heart disease. Parameters assessed position of heart levocardia dextrocardia viscero-atrial situs solitus inversus ambiguus ventricular loop D-loop L-loop conotruncus normal transpos...

Deep brain ultrasound therapy

Deep brain ultrasound (DBUS) therapy is a form of precision medicine using a technique based on the principle of high-intensity focused ultrasound (HIFU), also referred to as focused ultrasound surgery (FUS). Technique The method combines two main components 1: guidance component MRI of the ...

Deepest vertical pocket method

The deepest (maximal) vertical pocket (DVP) depth is considered a reliable method for assessing amniotic fluid volume on ultrasound 1,2. It is performed by assessing a pocket of a maximal depth of amniotic fluid which is free of an umbilical cord and fetal parts. The usually accepted values are...

Densitometric vertebral fracture assessment

Densitometric vertebral fracture assessment (VFA) is an image of the lumbar and thoracic spine acquired on dual energy x-ray absorptiometry (DXA) scanners, for the purpose of diagnosing osteoporotic vertebral fractures. Terminology The technique is available on DXA scanners under a variety of...

Denver criteria for blunt cerebrovascular injury

The Denver criteria are a set of screening criteria for blunt cerebrovascular injury (BCVI) in trauma used to reduce the need for CT angiography and its associated radiation exposure. Screening criteria The screening protocol criteria 1,3 for BCVI are divided into signs and symptoms of BCVI a...

Describing a bone lesion

Describing a bone lesion is an essential skill for the radiologist, used to form an accurate differential diagnosis for neoplastic entities, and occasionally non-neoplastic. In addition to patient demographics, the radiographic features of a bone lesion are often the primary determinant of non-h...

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 radiograph What radiograph (or radiographs) are you looking at? Check the who, what, why, w...

Determination of atrial situs

Atrial situs refers to the relative position of the cardiac atria in relation to abdominal viscera and the midline. Pathology Identification of atrial situs is an important initial step in the antenatal and postnatal diagnosis of cardiac structural and situs anomalies. Radiographic features ...

Diagnostic HRCT criteria for usual interstitial pneumonia (UIP) pattern - Fleischner society guideline (2018)

In 2018, the Fleischner Society provided updated diagnostic HRCT criteria for usual interstitial pneumonia (UIP) pattern based on literature review and the expert opinion of members. As a part of this white paper, diagnostic HRCT criteria for usual interstitial pneumonia (UIP) pattern were updat...

Diastolic dysfunction (point of care ultrasound)

Assessment for diastolic dysfunction is an advanced application of point-of-care ultrasonography, most commonly used as a supplemental non-invasive estimate of left atrial pressure in hemodynamically complex patients 1. Of note, this article will discuss the simplified, binary approach used in c...

Diffuse pulmonary nodules

Diffuse pulmonary nodules are usually seen as multiple pulmonary nodular opacifications on a HRCT chest scan. They can signify disease processes affecting either the interstitium or the airspace. They can range from a few millimetres to up to 1 cm and when very small and numerous there can be so...

Diffuse pulmonary nodules on HRCT (an approach)

A number of differentials must be kept in mind while approaching diffuse pulmonary nodules. Interpretation is easier if nodules are the only abnormality. These differentials can be narrowed down based on the several criteria: Based on appearance miliary nodules miliary tuberculosis silic...

Digastric line

The digastric line, also known as the biventer line, has been described and used to evaluate basilar invagination on frontal skull plain film and coronal CT images. The digastric line is drawn between right and left digastric grooves, which are located medial to the mastoid apices. These are co...

Dolan's lines

Dolan's lines are the collective name given to three lines described by Dolan and Jacoby 1 that aid in evaluating for maxillofacial fractures on an occipitomental skull radiograph. They are usually used as an adjunct to McGrigor-Campbell lines. orbital line traces the inner margins of the later...

Elbow radiograph (summary approach)

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

Empyema vs pulmonary abscess

Distinguishing between an empyema and a peripherally located pulmonary abscess is essential. Lung abscesses are usually managed with prolonged antibiotics and physiotherapy with postural drainage whereas an empyema usually requires percutaneous or surgical drainage. Radiographic features Plai...

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...

Endometrial polyp in the exam

Getting a film with endometrial polyp in the exam is one of the many exam set-pieces that can be prepared for. Description Transabdominal and transvaginal pelvic ultrasound images in a lady with post-menopausal bleeding show an anteverted uterus with focal increased endometrial thickness to 1...

Enlargement of the cardiac silhouette

Enlargement of the cardiac silhouette on a frontal (or PA) chest x-ray can be due to a number of causes 1: cardiomegaly (most common cause by far) pericardial effusion anterior mediastinal mass prominent epicardial fat pad expiratory radiograph AP projection (from supine radiographs taken ...

Enteroclysis

Enteroclysis is a gastrointestinal technique designed to provide improved evaluation of the small bowel. The conventional fluoroscopic technique is not widely used since it is somewhat invasive, time and labor intensive, and not particularly pleasant for the patient. The exam also requires a deg...

Epistaxis

Epistaxis (plural: epistaxes) is the medical term for a nosebleed, and is very common in clinical practice with a broad differential diagnosis. Anterior epistaxes mainly bleed from Kiesselbach's plexus and posterior epistaxes (5% of all epistaxis) from Woodruff's plexus. Epidemiology Epistaxis...

Errors in diagnostic radiology

Errors in diagnostic radiology occur for a variety of reasons related to human error, technical factors and system faults. Classification Renfrew classification This classification was proposed by Renfrew et al. 5 in 1992, and at the time of writing (July 2016) remains the most widely accept...

Evacuation proctography

Evacuation proctography (defecography) is a fluoroscopic technique to evaluate pelvic floor disorders. The technique traditionally involves fluoroscopy and barium, but an analogous MRI technique has also been developed (see: MR defecating proctography). Indications incomplete or obstructed def...

Evaluation of recurrent bone tumors

Recurrent bone tumors 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 (characteristi...

Exam set-pieces

Exam set-pieces refer to those cases that can be considered likely to turn up in the exam setting and can be prepared for. In the oral exam, having a prepared "speech" for these set-pieces allows the candidate to focus less on the stress of describing what is in front of them and more on conside...

Expiratory HRCT

Expiratory HRCT is an useful method for detecting small airway obstructive disease in which the air remain trapped in the small airways even after the expiration and appear as mosaic attenuation. Indication Ideally, an expiratory HRCT scan should be performed in all obstructive airway diseases...

Extradural hematoma vs subdural hematoma

Differentiating extradural (EDH) from subdural (SDH) hemorrhage in the head is usually straightforward, but occasionally it can be challenging. SDHs are more common and there are a few distinguishing features which are usually reliable. Pathology History and mechanism of injury Extradural hem...

Femur length

Fetal femur length (FL) is one of the basic biometric parameters used to assess fetal size. Femur length together with biparietal diameter, head circumference, and abdominal circumference are computed to produce an estimate of fetal weight. In the second trimester this may be extrapolated to an ...

Fetal abdominal circumference

Abdominal circumference (AC) is one of the basic biometric parameters used to assess fetal size. AC together with biparietal diameter, head circumference, and femur length are computed to produce an estimate of fetal weight. In the second trimester this may be extrapolated to an estimate of gest...

Fetal cardiothoracic circumference ratio

Fetal cardiothoracic (C/T) circumference ratio is a parameter than can be used in assessment of fetal cardiac and thoracic/chest wall anomalies. It is the ratio of the cardiac circumference to the thoracic circumference and may be easily measured on fetal ultrasound/echocardiography. Radiograp...

Fetal MCA systolic/diastolic ratio

Fetal MCA systolic/diastolic (S/D) ratio is an important parameter in fetal middle cerebral arterial Doppler assessment. It is a useful predictor of fetal distress and intrauterine growth restriction (IUGR). Interpretation Normal During pregnancy the middle cerebral (and other intracranial)...

Fetal middle cerebral arterial Doppler assessment

Fetal middle cerebral arterial (MCA) Doppler assessment is an important part of assessing fetal cardiovascular distress, fetal anemia or fetal hypoxia. In the appropriate situation it is a very useful adjunct to umbilical artery Doppler assessment. It is also used in the additional work up of: ...

Fetal middle cerebral arterial peak systolic velocity

The fetal middle cerebral arterial (MCA) peak systolic velocity (PSV) is an important parameter in fetal MCA Doppler assessment. Sonographic assessment The fetal MCA should be sampled~2 mm from the origin of the fetal internal carotid artery and the angle of the ultrasound beam and the directi...

Fetal middle cerebral artery pulsatility index

The fetal middle cerebral artery (MCA) pulsatility index (PI) is a key parameter used in fetal middle cerebral arterial Doppler assessment. It is calculated by subtracting the end diastolic velocity (EDV) from the peak systolic velocity (PSV) and then dividing by the time averaged (mean) velocit...

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

Flattening of the diaphragm

Flattening of the diaphragm is the most sensitive sign on chest radiographs for the presence of hyperinflation of the lungs, usually due to emphysema 1-2. The normal dome of each hemidiaphragm should rise at least 1.5 cm above a line connecting the costophrenic angle posteriorly and sternophren...

Fleischner Society pulmonary nodule recommendations

The Fleischner Society pulmonary nodule recommendations are for the follow-up and management of pulmonary nodules detected incidentally on imaging. The guideline does not apply to patients <35 years or with a history of cancer or immunosuppression. The initial guideline was released in 2005 1; s...

Fluid-fluid levels in bone tumors

Fluid-fluid levels in bone tumors is a commonly encountered finding, both in benign as well as malignant bone tumors, and can be used to differentiate between the two. Method of assessment On the sagittal T2W image: measure the length of the largest fluid-fluid level (A) measure the maximum ...

Fluoroscopic evaluation of esophagectomy

Fluoroscopic evaluation of esophagectomy is an important study, given the high rate of complication following esophagectomy (~10-20% rate of leak). Although the approach will differ slightly depending on the type of esophagectomy performed, the principles are similar. Procedure Preprocedural e...

Focal areas of signal intensity (brain)

Focal areas of signal intensity (FASI), alternatively called focal abnormal signal intensity or unidentified bright objects (UBO), are bright areas on T2-weighted images commonly identified in the basal ganglia (often the globus pallidus), thalamus, brainstem (pons), cerebellum, and subcortical ...

Focus‐assessed transthoracic echocardiography

FATE (focus‐assessed transthoracic echocardiography) is a goal-directed protocol used in critical care for indications such as haemodynamic instability, shock, and pulseless electrical activity (PEA) arrest 1. The protocol is designed as a series of questions as follows: does the left ventricl...

Focused Assessment with Sonography for Trauma (FAST) scan

Focused Assessment with Sonography for Trauma (FAST) scan is a point-of-care ultrasound examination performed at the time of presentation of a trauma patient. It is invariably performed by a clinician, who should be formally trained, and is considered as an 'extension' of the trauma clinical a...

Follicular monitoring

Follicular monitoring or follicular study is a vital component of in-vitro fertilization (IVF) assessment and timing. It basically employs a simple technique for assessing ovarian follicles at regular intervals and documenting the pathway to ovulation. Physiology Journey to ovulation begins d...

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...

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...

Forbidden areas in mammography

In breast imaging, forbidden, check or review areas are zones that, according to Tabár, require special attention in mammographic interpretation. These are: on a mediolateral oblique (MLO) view the "milky way" (retromammary fat): a 3-4 cm wide band parallel to the edge of the pectoral muscle ...

Four chamber cardiac view (fetal)

The four chamber cardiac view is an important and routinely performed view in both fetal echocardiography as well as on a standard second trimester anatomy scan. Detectable pathology The four chamber view can only detect some of the congenital cardiac anomalies (~64% according to one study 2) ...

Frontal horn width to intercaudate distance ratio

Frontal horn width to intercaudate distance ratio (FH/CC) is used in assessing patients with suspected Huntington disease. On the same axial plane obtained on the ACPC (anterior commissure and posterior commissure) line, the ratio between the distance between the caudate heads (where they are ...

Functional endoscopic sinus surgery

Functional endoscopic sinus surgery (FESS) is a type of paranasal sinus surgery performed intranasally using a rigid endoscope. Its primary objective is to restore physiological ventilation and mucociliary transport 1. Paranasal sinus imaging is crucial in preoperative planning and is also incr...

Fundoplication

Fundoplications are forms of antireflux surgery used as a second line of treatment of gastroesophageal reflux disease after failure of medical treatment and first line of treatment of paraesophageal hernia. Technique A gastric fold is wrapped around the distal esophagus which enforces the lowe...

Geographic appearance

Geographic appearance is a term used in imaging, and other clinical fields (e.g. histopathology) to describe lesions with a well-circumscribed margins with adjacent tissues. The term derives from the somewhat similar appearance of the outline of countries on a map or the clear demarcation forme...

Giant breast masses

Many patients, particularly in developing countries, can present late with giant breast masses. They may be single or multiple and either benign or malignant. Many of these conditions are indistinguishable on physical examination alone. Some of these lesions require mastectomy while others can b...

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 ...

Glioblastoma vs cerebral metastasis

Differentiating a glioblastoma (GBM) from a cerebral metastasis is a frequent challenge, with profound surgical, workup and treatment implications. Unfortunately distinguishing between the two entities is not always straightforward. This article addresses helpful imaging features to aid in dis...

Global cortical atrophy scale

The global cortical atrophy (GCA) scale, also known as the Pasquier scale, is a qualitative rating system developed to assess cerebral atrophy, especially in the context of neurodegenerative diseases. It evaluates atrophy in 13 brain regions assessed separately in each hemisphere and resulting i...

Ground-glass opacification

Ground-glass opacification/opacity (GGO) is a descriptive term referring to an area of increased attenuation in the lung on computed tomography (CT) with preserved bronchial and vascular markings. It is a non-specific sign with a wide etiology including infection, chronic interstitial disease an...

Gynecological ultrasound set-pieces

The clinical history will nearly always lead to a short differential or the answer. Show off to the examiner that you have a structured approach to reporting and managing the patient. Structured approach uterus: size, version and shape (normal or variant which you should elaborate on and say w...

Hematospermia

Hematospermia (less commonly hemospermia) refers to the presence of blood in semen or ejaculatory fluid. It is a symptom that can cause great anxiety in patients despite usually being of benign etiology. Pathology Etiology Benign urogenital infections including sexually transmitted disease, ...

Hematuria (pediatric)

Hematuria in a child is evaluated differently than in an adult in two main respects: there is a lower likelihood of a malignancy (renal or bladder) causing the hematuria preference is given to nonionizing radiation Pathology Hematuria can be considered in three main forms: "gross" hematuria...

Hemorrhage exclusion sign (prostate)

The hemorrhage exclusion sign can be a useful MRI finding following prostate biopsy. Pathology The normal prostate produces high concentrations of citrate, which among other properties, acts as an anticoagulant 1. As tumor cells are dysfunctional, they will produce lower levels of citrate than...

Hemorrhage on MRI

Hemorrhage on MRI has highly variable imaging characteristics that depend on both the age of the blood, the type of hemoglobin present (oxy- deoxy- or met-), on whether or not the red blood cell walls are intact and the specifics of the MRI sequence. Although MRI is often thought of as not being...

Hemorrhagic infarct vs intracerebral hemorrhage

Hemorrhagic infarct or hemorrhagic transformation of an infarct is seen following breakdown of the lamina of the microvessels. Intracerebral hemorrhage (ICH) may overlap with a hemorrhagic infarct and hence needs to be differentiated as the line of treatment will vary. Differentiating points ...

Hemorrhagic intracranial tumors

Various types of brain tumors may cause hemorrhage. Increased tumor vascularization with dilated, thin-walled vessels and tumor necrosis are the most important mechanisms of hemorrhage. The list includes: glioblastoma pituitary adenoma ependymoma central neurocytoma choroid plexus carcinoma...

Head and neck cancer therapy response interpretation (Hopkins criteria)

The head and neck cancer therapy response interpretation (Hopkins criteria) is a qualitative system of interpretation for therapy response assessment using PET-CT. Background Widely used options for therapy response assessment are clinical examination, histopathology, CT and MR imaging, howev...

Hepatobiliary contrast agents and LI-RADS

LI-RADS (Liver Imaging Reporting and Data System) is both a set of standardized terminology and a classification system for imaging findings in liver lesions. The LI-RADS score for a liver lesion is an indication of its relative risk for hepatocellular carcinoma (HCC). The classification system ...

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.

Hyperechoic liver lesions

A hyperechoic liver lesion on ultrasound can arise from a number of entities, both benign and malignant. A benign hepatic hemangioma is the most common entity encountered, but in patients with atypical findings or a risk for malignancy, other entities must be considered. Benign hepatic hemangi...

Hysterosalpingogram

Hysterosalpingogram (HSG) is a fluoroscopic examination of the uterus and the Fallopian tubes, most commonly used in the investigation of infertility or recurrent spontaneous abortions. Indications Infertility to assess uterine morphology and tubal patency. Contraindications pregnancy activ...

Idiopathic interstitial pneumonias: HRCT chest approach

The approach to HRCT chest in patients with suspected idiopathic interstitial pneumonia (IIP) is with the aim to: make sure an appropriate study requested i.e. HRCT chest with optimal individually adjusted protocol and ensure adequacy of the HRCT chest quality (see imaging protocol below) meti...

Imaging in liver transplantation

Imaging in liver transplantation is aimed to evaluate donor and recipient for successful transplantation and its outcome. Pre-transplant evaluation Donor volume of liver parenchymal disease (diffuse or focal) vascular anatomy arterial variations venous variations biliary anatomy Recipie...

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, ...

Incidental lung nodules

Incidental lung nodules are encountered commonly in normal clinical practice on CT. The risk of developing cancer in very small nodules (<5 mm) is very low. However, clear-cut recommendations are still not in place with high variation in practice amongst reporting radiologists 1. As a result, it...

Increased retrosternal airspace

Increased retrosternal airspace is an indicator of hyperinflation of the lungs and is usually due to emphysema. The thickness of the space between the ascending aorta and the posterior margin of the sternum (3 cm inferior to the sternomanubrial joint) and is normally no more than 2.5 cm 1 altho...

Infertility in the exam

It is important to have a systematic way of approaching a case with subfertility in the exam. Ultrasound is the initial examination of choice. Always say that you would further assess the uterus with 3D ultrasound. You may also say that in my department we would perform a sonohysterogram or HS...

Intercaudate distance to inner table width ratio

Intercaudate distance to inner table width ratio (CC/IT) is used in assessing patients with neurodegenerative diseases that affect the caudate nuclei. It is best known for assessing individuals with suspected Huntington disease but is in no way specific for the diagnosis, also seen in other less...

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.

Interscalene brachial plexus block

An interscalene brachial plexus block is indicated for procedures involving the shoulder and upper arm. History Ultrasound-guided brachial plexus nerve blocks entered the literature in 1989, when Ting et al. detailed their success with axillary nerve blocks in 10 patients 3. Indications redu...

Interseptal distance

The interseptal distance (ISD) is a measurement used to assess septal area atrophy as a marker for neurodegenerative conditions in patients with memory problems 1. It is proposed that atrophy of the septal nuclei can commonly be seen in conditions associated with hippocampal atrophy, particular...

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