Radiology High Yield

Must Know Points Before Exams

•William Roentgen discovered X-rays
•Father of Interventional Radiology : Charlies Dotter
•Father of medical USG : John Wild
•Father of Obstetric USG : Sir Ian Donald
•Attenuation of x ray depend on Absorption Coefficient
•Radiation exposure is measured by Dosi Meter
•GRID used in X ray to reduce scattered radiation
•Contrast in x ray depend on Kv
•Radioactivity was discovered by Curie (1896)
•Pantomography : is a special radiographic technique used for CURVED SURFACES
•GAMMA RAYS : Discovered by Henry Becquerel , high energy ionizing radiation , maximum penetrating power . radiation sickness is mostly due to gamma rays
•Cesium -137, cobalt and Radium predominantly emit gamma rays , natural soure : Phosphorus 40.
•Most ionizing radiation are Alpha rays .
•Infra Red Rays are used in Placental localization , Thermography , Orbital pneumotography , intra cerebral infract diagnosis
•USG is sound with frequency > 20,000 cycles/sec , MC used frequency 1MHz to 20 MHz , principle : PIEZO ELECTRIC CRYSTAL ACTIVATION
•USG is non mutagenic , contrast used is sonavist
•Echocardiography uses high frequency sound waves .
•Transesophageal echocardiography is used to evaluate patients with suspected aortic dissection
•CT scan was invented by Hounsfield
•Spiral CT uses Slip ring technology , in routine spiral CT splice thickness is 10mm , Routine spiral CT : 1rotation/1section/1sec
•Multi Detector CT scan : IOC for Pulmonary Embolism , Aortic aneurysm, Aortic dissection
•Most accurate investigation for Aortic Dissection : MRI
•CEREBRAL ANEURYSM IOC : Angiography
•CARDIC CT SCAN : Coronary calcium scoring or AGATSON scoring is done for patients with asymptomatic CAD
•HRCT is specialized technique used to evaluate lung parenchyma which uses Bone Algorithm
•HRCT IOC : ILD , Miliary TB, Bronchectasis
•Box car ventricles or Butter fly ventricles : on MRI is seen in HUNTINGTONS CHOREA
•Eye of tiger appearance on MRI : HALLEVORDEN SPATZ DISEASE
•Brain infract earliest detected by dw- MRI
•IOC Acute brain hemorrhage : CT SCAN
•IOC Acute head injury : CT-SCAN
•IOC stroke : CT-SCAN
•Pop corn calcification on chest x ray : Hamartoma
•Pop corn calcification on mammography : Fibroadenoma
•Cancer missed on mammography : LCIS
•MRI discovered by SIR PETER MANSFIELD & PAUL LATENBEUR
•MRI works on principle of Gyro Magnetic Property of Proton
•MC contrast agent used in MRI Gadolinium DTPA, magnetic field strength : 0.2-7 tesla , routine MRI : 1.5 tesla
•Time of flight technique : MRI
•Salt and pepper skull : Hyperthyroidism
•Salt and pepper appearance on MRI : Glomus Tumor
•Carotid body tumor : LYRE sign on angiography
•Corpus callosum agenesis on MRI : Racing car appearance
•Corpus callosum Lipoma on X ray : Bracket shaped calcification
•Elevated NAA levels on MR Spectroscopy : CANAVANS DISEASE
•MRCP is initial investigation for : Biliary stricture, Carolis disease, Choledochal cyst
•SCIWORA : spinal cord injury with out obvious radiological abnormality
•MRI IOC for stress fracture , Bone Bruise, occult bony injury
•CT SCAN IOC : ankle , temporal bone, acetabular fractures
•Minimum amount of pleural fluid identified in lateral decubitus postion : 25 ml
•Right heart border : RA,SVC,IVC
•Left heart border : LV, Auricle, PA , Aortic Knuckle
•Left atrial enlargement : BED FORD SIGN
•LV enlargement : HOFFMAN RIGLER SIGN
•CT finding of Endo-Bronchial spread of TB : TREE IN BUD SIGN
•Scadding criteria : grading criteria for Sarcoidosis
•FACE OF GAINT PANDA ON MRI of Brain : Wilsons disease
•Aspergillus : air cresent sign / Mondas sign
•ABPA : Gloved Finger of Simon app
•HALO sign on CT scan : invasive Aspergillosis
•Reverse Halo Sign : Cryptogenic organizing pneumonia
•Hydatid Cyst : USG – Cart wheel app , CXR – water lily sign , Cumbo sign
•Dropping lily sign on IVP : Duplication with non functional upper pole
•Polo Mint sign on CT scan : Portal vein thrombosis
•Safe and accurate for fetal viability at 6 wks : USG
•Doppler- pregnancy for IUGR
•MOYA MOYA disease PUFF OF SMOKE app
•IOC for Blunt abdominal trauma : CECT
•FAST : focused assessment & sonography in trauma
•PACS : picture archiving & communication system
•Minimum Blood detected by FAST 200ml
•USG – Pneumothorax :STRATOSPHERE SIGN
•MCU IOC for VUR , PUV , posterior urethral evaluation
•IOC for renal and splenic injury : CECT
•IOC urinary stones : NCCT , Stones detected only on Ureteroscopy : INDINAVIR stones
•RENAL TB : IOC – CECT
•Renal TB on IVP : moth eaten calyces , thimble bladder , Putty /cement kidney / Auto –nephrectomy
•Egg in a cup app on IVP : Papillary Necrosis
•AR – PCKD – sun ray appearance / Striated Nephrogram
•AD-PCKD- Swiss cheese Nephrogram
•ADPCKD on IVP : Spider leg app
•Multi cystic dysplastic kidney on IVP : is not visualized , on USG : Soap Bubble app
•Horse Shoe kidney on IVP : Flower Vase app , Hand-shake sign
•Bouquet of flowers on IVP : Medullary Spongy Kidney
•Multiple sclerosis MRI : Dawson’s Fingers
•On MRI Metachromatic Leuko-dystrophy shows : TIGROID PATTERN LEOPARD SKIN APP
•Parkinsons disease –MRI – Absene of swallow tail app
•Progressive Supranucler Palsy – MRI – HUMMIMG BIRD App
•Medulloblastoma has CSF drop metastasis , MRI : Sugar Coating App
•Ring Enhancing Lesion of brain : Toxoplasmosis , brain abscess, tuberculoma, metastasis, Neurocysticercosis
•Solid Homogenous Enhancing Lesion in Brain : Lymphoma (AIDS)
•Meningioma : MRI : Dural tail sign , X ray – shows calcification and hyperosteosis of skull bone
•Vestibular schwannoma MRI : ICE CREAM CONE app
•Spinal Neurofibroma : MRI – DUMBELL SHAPED NEUROFIBROMA
•Osteosarcoma : Codman triangle , Sun Ray app on x ray
•Chondroblastoma HPE : chicken wire calcification
•Enchondroma : x ray – O’Ring sign
•Fibrous Dysplasia : x ray- Ground Glass app
•Vertebral Haemangioma : X ray : corduroy app , vertical striations are present . CT scan POLKA DOT sign
•Simple bone cyst : fallen leaf sign on x ray
•Beveled Edges of skull on x ray : Histocytosis
•Punched out lytic lesions of skull : Multiple Myeloma
•Earliest X ray finding of TB spine : Rarefaction of end plate -> disc space narrowing
•Spool shaped vertebrae is feature of – Pyknodysostosis
•Molten candle wax appearance seen in- Melorheostosis

Paget’s disease:

oCotton wool skull
oIvory vertebra (also seen in – metastasis)

Ankylosing spondylitis:

oBamboo spine
oRomanus sign/ Dagger sign
oSquaring of vertebrae (picture frame vertebra)
oIntervertebral disc calcification.

•Bare orbit sign seen in – Neurofibromatosis
•Earliest seen in rickets – Loss of provisional zone of calcification
•Looser’s zones or pseudo fractures is the hallmark feature of – Osteomalacia.
•Rugger jersey spine seen in Renal osteo-dystrophy, Osteopetrosis.
•Achalasia cardia : Bird beak app , Pencil tip app
•Ca Esophagus : Rat tail app
•IOC for swallowing disorder : Videoscopy
•Duodenal ulcer : Trifolate Duodenum
•IOC CHPS : USG
•Bening Gastric Ulcer : spoke wheel app
•Malignant Gastric Ulcer : Carmen’s meniscus sign / Carmen kirkliv complex
•Acute Pancreatitis –IOC CECT
•Chronic Pancreatitis –IOC : MRCP ( chain of lake app)
•Periampullary ca of pancreas : Frost Berg Reverse 3 Sign
•Bowel TB : string sign , Inverted Umbrella sign / fleschner’s sign , conical ceacum , goose neck ileum .
•Ulcerative Colitis : Earliest barium finding : Mucosal granularity , collar button ulcer , lead pipe app colon
•Crohn’s disease : Earliest barium finding : Apthous Ulcer , rose thorn app, string sign of kantor
•IOC Meckel’s Diverticulum : Tc 99 Per technetate scan
•Ischemic Colitis : Ba Enema : thumb print sign
•Thumb sign on neck X ray : Epiglottis
•Sigmoid volvus : X ray : coffee bean sign , bird of prey sign on Ba enema

Radiation and Radiotherapy:

o1Particulate/corpuscular: alpha, beta ,proton , neutron
o2Electro magnetic: X-rays’s , gamma rays , cosmic rays .
oMost common cause of outdoor radiation – cosmic.
oMost common cause of indoor radiation – radon.
oMost common cause of endogenous (human body)– potassium

Radiation exposure limits:

oNatural radiation / anum: 0.1 rad / anum
oFatal dose – single exposure – 500 REM
oMinimum dose required for systemic effect: 100 Rem
oMaximum permissible dose for normal population – 5 rads / anum
oMaximum permissible dose for a pregnant female who is occupationally exposed: 0.5 rads /anum .
oMinimum dose required for teratogenicity: 5 rads

Sensitivity and resistance:

oMost radio sensitive tissue: bone marrow
oLeast radio sensitive tissue: brain / nervous tissue
oMost radio sensitive cell: lymphocyte
oMost radio resistant: platelets / RBC
oMost radio sensitive stage of cell cycle – G2 M > M
oMost radio resistant stage of cell cycle – late S phase