All acronyms

Abdominal Aortic Aneurysm

Aneurysm of abdominal aorta; risk of rupture if greater than 5.5 centimetres

Arterial blood gas

A blood test used to assess oxygenation, carbon dioxide and acid-base status.

Anterior Cerebral Artery

Cerebral artery supplying medial brain; arises from internal carotid artery

Anterior Cruciate Ligament

Primary ligament preventing anterior tibial translation at knee

American College of Radiology

Professional organisation setting imaging standards and guidelines

Apparent Diffusion Coefficient

Quantitative map derived from DWI showing water diffusion

Adenosine diphosphate

A nucleotide formed when ATP loses one phosphate group.

As Low As Reasonably Achievable

Principle minimising radiation exposure while maintaining diagnostic quality

Alanine aminotransferase

A liver-associated enzyme measured in liver function testing.

Anteroposterior

Standard frontal projection view

Acoustic Radiation Force Impulse

Technique using short-duration acoustic pulses to assess tissue stiffness

Alberta Stroke Programme Early CT Score

10-point scoring system assessing extent of early ischaemic changes on computed tomography or magnetic resonance imaging

Aspartate aminotransferase

An enzyme found in liver, muscle and other tissues.

Adenosine triphosphate

A high-energy molecule used as a cellular energy currency.

Area Under Curve

Summary statistic of receiver operating characteristic curve; probability test correctly ranks random positive versus negative

Avascular Necrosis

Bone death from loss of blood supply

Abdominal X-Ray

Plain radiograph of the abdomen

Barium

Barium contrast used in fluoroscopic GI studies

Breast Imaging Reporting and Data System

Standardised reporting system for breast imaging with scores 0 to 6

Blood-Oxygen-Level Dependent

Contrast mechanism used in fMRI based on paramagnetic deoxyhaemoglobin

Blood pressure

The pressure exerted by circulating blood on arterial walls.

CT Colonography Reporting and Data System

Reporting system for computed tomography colonography findings

Cervical vertebra 1

First cervical vertebra (atlas)

Cervical vertebra 2

Second cervical vertebra (axis); features prominent odontoid process

Cervical vertebra 5

Fifth cervical vertebra; common level for cervical myelopathy

Cervical vertebra 6

Sixth cervical vertebra

Cervical vertebra 7

Seventh cervical vertebra (vertebra prominens); most prominent on physical exam

Cone Beam CT

CT using cone-shaped X-ray beam; common in dental and ENT imaging

Common Bile Duct

Duct formed by confluence of common hepatic duct and cystic duct; terminates at ampulla of Vater

Contrast-Enhanced CT

CT performed with intravenous contrast agent

Contrast-Enhanced Ultrasound

Ultrasound with microbubble contrast agents to assess tissue vascularity

Common Hepatic Duct

Bile duct formed by confluence of right and left hepatic ducts

Confidence Interval

Range of values containing true population parameter with specified probability (typically 95 percent)

Carcinoma in situ

A pre-invasive epithelial malignancy that has not breached the basement membrane.

Core Needle Biopsy

Image-guided biopsy using 14 to 18 gauge needle for tissue samples

Central nervous system

The brain and spinal cord.

Cryptogenic Organising Pneumonia

Reversible airway-centred inflammation; computed tomography shows consolidations and bronchial wall thickening

Chronic obstructive pulmonary disease

A chronic respiratory condition characterised by persistent airflow limitation.

Cardiopulmonary resuscitation

Emergency chest compressions and rescue measures used in cardiac arrest.

Colorectal cancer

Cancer arising from the colon or rectum.

C-reactive protein

An inflammatory marker measured in blood tests.

Computed Tomography

Cross-sectional imaging using X-ray and computer reconstruction

CT Angiogram

CT with IV contrast during arterial phase to image blood vessels

CT Colonoscopy

Virtual colonoscopy using CT to visualise colon lumen

CT Dose Index Volume

Volume-averaged CT dose metric (units milligrays)

CT Pulmonary Angiogram

CT with IV contrast to image pulmonary arteries

Chest X-Ray

Radiograph of the thorax

Diffuse Axonal Injury

Microscopic axonal tearing from shearing forces in severe head trauma

Dynamic Contrast-Enhanced

Rapid serial imaging after gadolinium injection to assess perfusion and permeability

Ductal carcinoma in situ

A non-invasive malignant proliferation confined to breast ducts.

Dual-Energy CT

CT using two X-ray energy spectra for material-specific characterisation

Disproportionately Enlarged Subarachnoid-space Hydrocephalus

Magnetic resonance imaging finding in normal pressure hydrocephalus

Dual-Energy X-Ray Absorptiometry

Alternative acronym for DXA

Digital Imaging and Communications in Medicine

Universal standard for digital medical imaging file format and communication

Dose-Length Product

CT dose metric combining CTDIvol and scan length (units milligrays times centimetre)

Dose Reference Level

Typical dose level for a standard imaging procedure used for dose comparison

Digital Subtraction Angiography

High-resolution vessel imaging using digital subtraction technique

Diffusion Tensor Imaging

Diffusion-weighted technique measuring anisotropic diffusion along white matter tracts

Deep Vein Thrombosis

Blood clot in deep veins of leg or arm

Diffusion-Weighted Imaging

MRI sequence sensitive to water motion (Brownian diffusion)

Diffusion-Weighted Imaging with Background Body Signal Suppression

Diffusion-weighted imaging technique suppressing background body signal for improved lesion visualisation

Dual-Energy X-Ray Absorptiometry

Imaging technique measuring bone mineral density

Electrocardiogram

A recording of the heart’s electrical activity over time.

Extradural Haematoma

Blood between skull and dura mater

End-Diastolic Velocity

Blood velocity at end of diastole on Doppler ultrasound

Ejection Fraction

Percentage of left ventricular volume ejected with each contraction

Extended FAST

FAST protocol plus additional views to assess for pneumothorax

Endoscopic Retrograde Cholangiopancreatography

Fluoroscopic endoscopic procedure combining endoscopy and X-ray for biliary intervention

Endovascular Aneurysm Repair

Minimally invasive stent-graft placement for abdominal aortic aneurysm repair

F1 Score

Harmonic mean of precision and recall; balances sensitivity and positive predictive value

Focused Assessment with Sonography in Trauma

Rapid bedside ultrasound protocol assessing free fluid in four views

Full blood count

A common blood test measuring red cells, white cells and platelets.

Fluorodeoxyglucose

Fluorine-18 labelled glucose analogue (18F-fluorodeoxyglucose) for positron emission tomography imaging

Fluid-Attenuated Inversion Recovery

T2-like sequence with cerebrospinal fluid suppression using inversion recovery

Fleischner Society

Society guidelines for management of incidentally discovered pulmonary nodules on computed tomography

Functional MRI

MRI measuring brain activation using BOLD contrast during tasks or at rest

Fine Needle Aspiration

Image-guided biopsy using 25 to 27 gauge needle for cytology

Fine Needle Aspiration Cytology

Fine needle aspiration with cytology analysis

Field of View

Spatial extent of magnetic resonance imaging acquisition; larger field of view shows more anatomy but lower resolution

Gallbladder

Pear-shaped organ storing and concentrating bile

Glasgow Coma Scale

A clinical scale used to assess level of consciousness.

Glomerular filtration rate

A measure of kidney filtration function.

Ground Glass Opacity

Computed tomography finding showing hazy opacity without obscuring underlying vessels

Glenohumeral

Shoulder joint between humeral head and glenoid fossa

Gastrointestinal Stromal Tumour

Mesenchymal tumour of gastrointestinal tract; KIT-positive; arise from Cajal cells

Hepatic Artery

Artery supplying liver; arises from celiac trunk as common hepatic artery

Glycated haemoglobin

A blood marker reflecting average blood glucose over roughly the previous two to three months.

Hepatocellular Carcinoma

Primary liver cancer; usually develops in cirrhotic liver

Heart rate

The number of heart beats per minute.

High-Resolution CT

Thin-slice CT with optimised reconstruction for lung parenchyma detail

Hysterosalpingogram

Fluoroscopic contrast study of uterus and fallopian tubes

Hounsfield Unit

Scale of CT radiodensity (water equals 0 HU, air equals minus 1000 HU, bone approximately plus 1000 HU)

Hepatic Vein

Veins draining liver to inferior vena cava; three major (right, middle, left)

Internal Carotid Artery

Major artery to brain; arises from common carotid bifurcation

Intraclass Correlation Coefficient

Statistical measure of agreement or reliability between observers or repeated measurements

Immunohistochemistry

A laboratory technique using antibodies to detect antigens in tissue sections.

Intrahepatic Duct

Bile ducts within the liver

Idiopathic Pulmonary Fibrosis

Progressive idiopathic lung fibrosis; computed tomography shows usual interstitial pneumonia pattern

Intraductal Papillary Mucinous Neoplasm

Mucinous lesion in pancreatic duct; malignant potential varies

Interventional Radiology

Minimally invasive image-guided procedures (biopsy, ablation, embolisation, stenting)

Inferior Vena Cava

Largest vein carrying deoxygenated blood from lower body to right atrium

Intervertebral Disc

Fibrocartilage disc between vertebral bodies

Intravenous Pyelogram

Contrast study of kidneys and urinary tract

Intravenous Urogram

Alternative term for intravenous pyelogram

Jugular venous pressure

A clinical sign used to estimate right atrial pressure.

Cohen's Kappa

Measure of inter-rater agreement for categorical data; accounts for chance agreement

Kidneys, Ureters, Bladder

Plain radiograph of the lower abdomen and pelvis

Lumbar vertebra 1

First lumbar vertebra

Lumbar vertebra 2

Second lumbar vertebra

Lumbar vertebra 5

Fifth and lowermost lumbar vertebra; largest lumbar body

Lateral

Side-to-side projection view

Lateral Collateral Ligament

Ligament on lateral (outer) side of knee

Low-Dose CT

Reduced-dose CT screening for lung cancer in high-risk patients

Lactate dehydrogenase

An enzyme involved in the conversion between lactate and pyruvate.

Liver Imaging Reporting and Data System

Standardised reporting system for liver nodules in cirrhotic patients

Left Lower Lobe

Inferior lobe of left lung

Loss of Cortical Outline

Disruption of the sharp cortical margin of bone, indicating cortical erosion or destruction

Left Upper Lobe

Superior lobe of left lung; contains 4 to 5 segments

Lung CT Screening Reporting and Data System

Reporting system for lung nodules on low-dose computed tomography screening

Left Ventricular Ejection Fraction

Ejection fraction specific to left ventricle

Middle Cerebral Artery

Major cerebral artery supplying lateral brain; most common site for stroke

Matthews Correlation Coefficient

Correlation coefficient between observed and predicted binary classifications

Medial Collateral Ligament

Ligament on medial (inner) side of knee

Myocardial infarction

Myocardial injury caused by ischaemia, commonly known as a heart attack.

Minimum Intensity Projection

Reconstruction showing minimum pixel intensity along projection path

Maximum Intensity Projection

Reconstruction showing maximum pixel intensity along projection path

Multiplanar Reconstruction

Reformatted CT images in coronal, sagittal, and oblique planes

MR Angiography

MRI technique for vessel imaging without gadolinium (TOF) or with gadolinium (contrast-enhanced)

MR Cholangiopancreatography

Non-invasive MRI technique visualising biliary and pancreatic ducts using heavy T2 weighting

Modified RECIST

Modified RECIST criteria adapted for hepatocellular carcinoma and immunotherapy trials

Magnetic Resonance Imaging

Imaging using magnetic field and radio waves to produce detailed anatomical and functional images

MR Spectroscopy

Technique measuring metabolite concentrations in tissue voxels

MR Spectroscopy

Alternative abbreviation for MR spectroscopy

Multiple Sclerosis

Autoimmune demyelinating disease; magnetic resonance imaging shows T2 lesions in brain and spinal cord

Musculoskeletal

Imaging of bones, joints, and soft tissues

Microwave Ablation

Image-guided thermal ablation using microwave energy

No Abnormality Detected

Indicates normal imaging findings; completely negative study

Nicotinamide adenine dinucleotide

An electron carrier involved in redox reactions and metabolism.

Non-Enhanced CT

CT performed without intravenous contrast

Neuroendocrine Tumour

Tumours from neuroendocrine cells; slow-growing often; chromogranin A marker

No Further Action

Imaging finding does not require additional imaging or clinical follow-up

Neck Imaging Reporting and Data System

Reporting system for neck masses and lymph nodes

Normal Pressure Hydrocephalus

Triad of gait disturbance (magnetic gait), cognitive decline, urinary incontinence; normal cerebrospinal fluid pressure

Negative Predictive Value

Probability that a negative test result is truly negative

Non-Small Cell Lung Cancer

Majority of lung cancers; includes adenocarcinoma, squamous, large cell types

Non-Specific Interstitial Pneumonia

Computed tomography pattern less specific than usual interstitial pneumonia; ground-glass dominant with reticular component

Ovarian-Adnexal Reporting and Data System

Reporting system for adnexal masses on ultrasound

Osteoarthritis

Degenerative joint disease; X-ray shows osteophytes, joint space narrowing, sclerosis

Orthopantomogram

Panoramic dental radiograph

Probability value

Probability of observing results as extreme as those observed assuming null hypothesis is true

Posteroanterior

Standard posterior-to-anterior projection

Picture Archiving and Communication System

Computer system for storing, retrieving, and distributing medical images

Posterior Cerebral Artery

Cerebral artery supplying posterior brain; arises from basilar artery

Posterior Cruciate Ligament

Ligament preventing posterior tibial translation at knee

Pancreatic Ductal Adenocarcinoma

Most common pancreatic malignancy; aggressive with poor prognosis

Pulmonary Embolism

Blood clot in pulmonary artery; life-threatening; diagnosed on computed tomography pulmonary angiogram or ventilation-perfusion scan

PET Response Criteria in Solid Tumours

Response criteria using positron emission tomography for assessment of therapy response

Positron Emission Tomography

Imaging using positron-emitting radiopharmaceuticals to assess metabolic activity

Combined PET and CT

Integrated imaging combining PET metabolic data with CT anatomical information

Prostate Imaging Reporting and Data System

Standardised reporting system for multiparametric prostate magnetic resonance imaging with scores 1 to 5

Peripherally Inserted Central Catheter

Central venous catheter inserted via peripheral arm vein

Peripheral nervous system

The nerves and ganglia outside the brain and spinal cord.

Point-of-Care Ultrasound

Bedside ultrasound performed at point of care by non-radiologists for diagnosis or guidance

Positive Predictive Value

Probability that a positive test result is truly positive

Peak Systolic Velocity

Maximum blood velocity during systole on Doppler ultrasound

Percutaneous Transhepatic Biliary Drainage

Image-guided catheter placement through liver into biliary system for drainage

Papillary Thyroid Carcinoma

Most common thyroid cancer; usually indolent with good prognosis

Portal Vein

Vein carrying blood from gastrointestinal tract to liver; formed by confluence of superior mesenteric vein and splenic vein

Perfusion-Weighted Imaging

MRI technique measuring tissue perfusion using susceptibility effects from gadolinium or BOLD contrast

Renal Artery

Artery supplying kidney; arises from abdominal aorta at L1 to L2

Radiation Absorbed Dose

Unit of absorbed radiation dose (1 Gy equals 100 rad)

Reporting and Data System

Standardised framework for imaging reports and risk stratification

Renal Cell Carcinoma

Most common renal malignancy; arises from proximal tubular epithelium

Response Evaluation Criteria in Solid Tumours

Standardised criteria for measuring tumour response to therapy

Radiofrequency Ablation

Image-guided thermal ablation using alternating electrical current

Resistive Index

Doppler parameter calculated as (peak systolic velocity minus end diastolic velocity) divided by peak systolic velocity

Radiology Information System

Software system managing radiology workflow, orders, scheduling, and reporting

Right Lower Lobe

Inferior lobe of right lung; contains 3 segments

Right Middle Lobe

Middle lobe of right lung (unique to right side)

Receiver Operating Characteristic

Curve plotting sensitivity versus one minus specificity at various thresholds

Respiratory rate

The number of breaths per minute.

Rotator Cuff

Four muscles (supraspinatus, infraspinatus, teres minor, subscapularis) providing shoulder stability

Right Upper Lobe

Superior lobe of right lung; contains 3 segments

Renal Vein

Vein draining kidney to inferior vena cava

Sacral vertebra 1

First sacral vertebra; fused component of sacrum

Subarachnoid Haemorrhage

Blood in subarachnoid space (between arachnoid and pia mater)

Systolic blood pressure

The arterial pressure during ventricular contraction.

Small Cell Lung Cancer

Aggressive small cell carcinoma; associated with smoking

Subdural Haematoma

Blood between dura and brain surface

Superior Mesenteric Artery

Major artery arising from abdominal aorta, supplying small intestine, proximal colon

Signal to Noise Ratio

Ratio of signal intensity to noise; higher signal to noise ratio indicates better image quality

Space-Occupying Lesion

Any mass or lesion that displaces or replaces normal tissue

Single Photon Emission Computed Tomography

Nuclear imaging using single-photon emitters (technetium-99m, iodine-123) with rotating detector to create 3D images

Peripheral oxygen saturation

An estimate of haemoglobin oxygen saturation measured by pulse oximetry.

Shaded Surface Display

3D surface reconstruction with shading for depth perception

Standardised Uptake Value

Quantitative measure of radiotracer uptake normalised to body weight and injected dose

Maximum Standardised Uptake Value

Peak standardised uptake value within a lesion or region

Transabdominal Scan

Ultrasound with transducer on abdominal wall

Transoesophageal Echocardiogram

American abbreviation for transoesophageal echocardiogram

Thyroid Imaging Reporting and Data System

Reporting system for thyroid nodules on ultrasound

Temporomandibular joint

The joint between the temporal bone and mandible.

Transoesophageal Echocardiogram

Cardiac ultrasound with transducer placed in oesophagus for high-resolution imaging

Testicular Ultrasound

Ultrasound of the scrotum and testicular contents

Transvaginal Ultrasound

Ultrasound using transducer placed in vagina for high-resolution pelvic imaging

Ultrasound

Real-time imaging using sound waves without radiation, dynamic, operator-dependent