Digital Subtraction Angiography (DSA) is an invasive procedure

Ultrasound is beneficial in bowel-related pathologies

Most CT examinations do not require contrast media

Patients with metal implants have an absolute contraindication for MRI

Gastrografin is injected intravenously

Extravasation of contrast media can result in compartment syndrome

Asthmatic patients are at higher risk of adverse reaction to iodinated contrast media

Intravenous injection of high-osmolar contrast media produces flushing sensation

Low-osmolar contrast media is used in MRI

Low back pain – MRI lumbar spine

Intussusception – Ultrasound abdomen

Traumatic intracranial bleed – MRI brain

Intestinal obstruction – Barium enema

Renal stone – CT renal phase

Can visualize soft tissue, blood vessels, and bone in any part of the body

Trauma cases use contrast-enhanced CT

Multiple exposures of CT increase cancer risk

CT is used in guided procedures such as needle biopsy

Dental fillings can cause streak artefacts

Spinal cord injury is best visualized using CECT spine

Cerebral angiography can be performed using non-contrast MR

Acute intracranial bleeds are detected by non-contrast CT brain

Brain abscess is diagnosed using contrast-enhanced MRI

Skull base fractures are detected by non-contrast CT

Mechanical ventilation may cause iatrogenic pneumothorax

Lobar pneumonia shows air bronchogram

COPD chest radiographs may appear normal

Drowning may cause pulmonary oedema

Congestive cardiac failure may present with normal cardiac size

Caecum > 6 cm is abnormal

Central location of bowel dilatation is typical

Abdominal radiograph can reliably differentiate mechanical from pseudo-obstruction

Commonest cause is inguinal hernia

Coffee-bean sign suggests sigmoid volvulus

Cystic duct joins the common hepatic duct to form the common bile duct

Mesenteric infarction may cause air in the portal venous system

Percutaneous cholecystostomy is indicated for gallbladder empyema

Contrast-induced pancreatitis is a complication of MRCP

Triphasic CT can diagnose hepatic artery pseudoaneurysm

Plain radiography is commonly used in musculoskeletal imaging

CT and MRI are good for vascular imaging

CT scan is best for bony delineation

Ultrasound is not operator-dependent

Barium swallow is a real-time imaging technique

• Air can be used as contrast media

• Oral contrast does not cause allergic reaction

• Intravenous contrast is contraindicated in renal impairment

• Nephrogenic fibrosis does not occur in renal failure patients

• Skin burn is a deterministic effect

• 28-day rule applies for female patients undergoing CT

• Inverse square law applies to radiation dose

• ALARA principle applies to all radiation imaging

• Pregnancy is an absolute contraindication in radiology imaging

• Barium follow-through is used for large bowel study

• Bird’s beak sign indicates hiatal hernia

• Three air-fluid levels indicate small bowel obstruction

• Left lateral decubitus view is first-line for pneumoperitoneum

• Toxic megacolon is a contraindication for barium enema

• PA chest X-ray is routine for children < 5 years old

• Acute subdural haemorrhage raises suspicion of non-accidental injury

• Inhaled foreign bodies are usually radio-opaque on plain X-ray

• Aerobilia is characteristic of necrotizing enterocolitis

• Meticulous collimation reduces radiation dose

• Ultrasound is not sensitive in diagnosing liver pathology

• Percutaneous cholecystostomy is indicated for gallbladder empyema

• Nephrogenic fibrosis is most likely in renal failure

• Hepatomegaly

• Phrenic nerve palsy

• Diaphragmatic eventration

• Pneumothorax

• Pleural effusion

• Radiology is absolutely contraindicated in pregnancy regardless of indication

• Minimal radiation dose is used in all patients

• Limit of ionising radiation for a patient is 20 Gy

• Collimation reduces radiation exposure

• Contraindicated in toxic megacolon

• Barium suspension is used in upper and lower GI imaging

• Barium swallow is indicated for haematochezia

• IV contrast is optional for liver abscess

• Low-osmolar contrast can be used for colon anastomosis imaging

• Sail sign is normal in children

• Pleural effusion is a feature of transient tachypnoea of newborn (TTN)

• Extradural haemorrhage raises suspicion of non-accidental injury

• Children are more radiosensitive than adults for the same dose

• Double-bubble sign suggests pneumoperitoneum

• Ultrasound is first-line for intestinal obstruction

• Colonic diameter is used to assess pathology

• Bowel ischaemia may cause portal venous air

• Pericardial effusion

• Pleural effusion

• Enlarged hilar nodes

• Aortic unfolding

• Enlarged mediastinal nodes

• Normal diaphragmatic curvature is 1.5 cm

• Right hemidiaphragm crosses anterior 6th rib at midpoint

• Left hilum is higher than right hilum

• Carina angle is < 60° (65°)

• Right descending artery should not exceed 16 mm

• Liver cirrhosis can be diagnosed with ultrasound

• Acoustic enhancement = reduced echogenicity adjacent to attenuating lesion

• Echogenicity is the ability to produce echo

• Curvilinear probe is used for deep structures

• High-frequency probe is used in musculoskeletal imaging

• Plain radiography is commonly used in musculoskeletal imaging

• CT and MRI are good for vascular imaging

• CT scan is best at showing bony delineation

• Ultrasound is not operator-dependent

• Barium swallow is a real-time imaging technique

• Air is a contrast medium

• Oral contrast does not cause allergic reactions

• IV contrast cannot be given to renal impairment patients

• Nephrogenic fibrosis does not occur in renal failure

• Skin burn is a deterministic effect

• 28-day rule applies to female CT patients

• Inverse square law applies to radiation dose

• ALARA principle applies universally

• Pregnancy is an absolute contraindication

• Barium follow-through is for large bowel

• Bird’s beak sign = hiatal hernia

• Three air-fluid levels = small bowel obstruction

• Left lateral decubitus = first test for pneumoperitoneum

• Toxic megacolon contraindicates barium enema

• PA chest X-ray is routine < 5 years

• Acute subdural haemorrhage = non-accidental injury

• Inhaled FBs usually radio-opaque

• Aerobilia = necrotizing enterocolitis

• Collimation reduces dose

Ultrasound not sensitive for liver disease

Percutaneous cholecystostomy for empyema

Nephrogenic fibrosis common in renal failure

Refraction

Shadowing

Enhancement

Reverberation

Mirror image

Hepatomegaly

Phrenic palsy

Eventration

Pneumothorax

Pleural effusion

CT only for head & body

USG/MRI = non-radiation

Most CT = no contrast

XR/CT = ionising radiation

Angiography = invasive

Iodine = most used IV contrast

LOCM = for anastomosis / leaks

Barium suspension = GI assessment

Gastrografin = GE fistula

Contrast optional for liver abscess

Contraindicated in pregnancy

Minimal dose used always

Limit 20 Gy

Collimation reduces dose

XR = first-line spine

MRI > CT for skull fracture

Non-contrast CT for hydrocephalus

Contrast MRI for brain abscess

Barium follow-through = large bowel

Bird’s beak = hiatal hernia

Three air-fluid levels = SBO

Left lateral decubitus = pneumoperitoneum

Toxic megacolon contraindicates barium

Sail sign = normal (3 y/o)

Pleural effusion = TTN

Extradural haemorrhage = non-accidental injury

Children more radiosensitive

AXR diagnoses cholelithiasis

Mesenteric infarction → portal venous air

USG diagnoses cirrhosis

MRCP → pancreatitis

Triphasic CT → hepatic pseudoaneurysm

Diaphragm excursion = 1.5 cm

Carina angle < 60°

Right descending artery < 16 mm

Right hemidiaphragm crosses 6th rib

Left hilum higher

Curvilinear = deep structures

High freq = MSK

USG = no ionising radiation

Echogenicity = echo production

Acoustic enhancement = reduced amplitude

Mediastinal nodes

Aortic unfolding

Enlarged hilar nodes

Pleural effusion

Pericardial effusion

Gamma & X-ray = EM waves

Terrestrial radiation = natural source

Stochastic effects = dose-dependent

Non-stochastic example = radiation sickness

Nuclear therapy → patient as source

Water-soluble CM = mucosal imaging

Positive CM = useful in USG (false)

All positive CM = iodine

Barium contraindicated in perforation

Rectal contrast used in pelvic CT

MRI uses ionising radiation

MRI more time-consuming than CT

Diagnostic US intensity = safe

Angiography = real-time imaging

CT cannot visualise intracranial vessels

Bat’s wing = pulmonary oedema

Cavitation = post-primary TB

Air bronchogram = pulmonary haemorrhage

Sternal fractures visible in PA CXR (false)

Erect film → improves pneumothorax detection

Left atrial appendage forms cardiac margin

Right hemidiaphragm apex 3 cm lower

Right hilum higher

PA CXR usually done supine

Underpenetration → opaque film

Cystic duct + common hepatic duct → CBD

Triphasic CT → hepatic pseudoaneurysm

Multiphase CT → HCC vs haemangioma

MRCP → pancreatitis complication

USG diagnoses acute pancreatitis

Caecum > 7 cm = abnormal

Inverted V sign = LBO

Barium swallow = dysphagia

Pneumoperitoneum easily detected supine AXR

Normal kidney on US excludes pyelonephritis

KUB XR assesses kidney size

KUB XR shows normal orientation

CTU for renal trauma

KUB XR detects 80–90% renal stones

CXR: multiple air-filled cysts + mediastinal shift = congenital diaphragmatic hernia

Extradural haemorrhage = non-accidental injury

Thymus seen up to 5 years

Collimation reduces dose

MRA = choice for subarachnoid haemorrhage

USG screens carotid stenosis

MRI > CT for skull fracture

USG screens brain abnormality in 6 y/o

Crescent-shaped hyperdensity on CT = subdural haemorrhage

CT rules out brain abscess & tumour

Fluoroscopy & angiography use radiation

Carotid Doppler uses sound waves

First-line for intestinal obstruction = USG

DSA is non-invasive

CT contraindicated with metallic implants

CT good for bone fractures

All positive CM iodine-based

MRI uses iodine contrast

Dehydration = risk factor

Barium used in suspected perforation

Nephrogenic systemic fibrosis = gadolinium complication

Neck lesion first-line = USG

MRI delineates brain tumour

CT differentiates embolic vs haemorrhagic stroke

MRI delineates head/neck fractures

Non-traumatic SAH → CT angiogram

Aerobilia vs portal venous gas = same features

GB wall thickening avoided with 4 hr fasting

Multiplanar CT excludes tumour vs haemangioma

MRCP → pancreatitis complication

Percutaneous drainage not indicated in GB emphysema

Normal US kidney excludes pyelonephritis

First-line IO = USG

LBO = peripheral with haustrations

Barium indicated in anastomotic leaks

Gas under diaphragm

Double bubble sign

Thumbprint sign

Urachus sign

Inverted T sign

Sail sign in 2 y/o = pathological

Extradural haemorrhage = NAI

NEC = aerobilia + pneumoperitoneum

Organs in children more radiosensitive

FB aspiration better on expiratory film

Consolidation = ill-defined opacity

Wide-based opacity = lung lesion

Lung contusion → consolidation

Small pleural effusion better seen lateral view

RML collapse better in apical view

Oblique view detects rib fractures

Right pneumothorax better seen in left decubitus

X-ray & gamma = EM spectrum

Latent period of 40 yrs for stochastic effect

Stochastic severity proportional to dose

AP CXR higher dose than AP abdomen

Lung fibrosis = stochastic

CT better than XR for mediastinal mass

HRCT detects PE

RUL collapse typical on CXR

USG has no role in loculated effusion drainage

V/Q scan useful in PE

Multiphase CT distinguishes tumour vs haemangioma

Fasting ≥ 4 hrs avoids false GB thickening

Emphysematous cholecystitis detected by USG

MRCP disadvantage = no parenchymal assessment

MRCP → pancreatitis complication

Sphincterotomy

Bowel ischaemia

Patulous sphincter (elderly)

Passage of gallstone

Malignancy/trauma

Rigler’s sign

Football sign

Ligamentum teres sign

Urachus sign

Lucent liver sign

MRI uses ionising radiation

MRI slower than CT

Diagnostic US has no side effects

Nuclear imaging → patient emits radiation

Fluoroscopy shows real-time movement

28-day rule for women of childbearing age

ALARA applies to staff + patients

Aluminium best protection for gamma rays

CT detects early stroke

Choroid plexus calcification = normal

MRI detects SAH

Basal ganglia loss = ACA haemorrhage

DWI/ADC detects SAH