General 2 Flashcards
-ve contrasts
Air
Water
Mannitol
They make tissue black
+ve contrast
Make tissue white
MRI contrast agents(CA)
Gadolinium based
-gadoxetic acid
-gadobenate dimeglumine
(Hepatobiliary specific gd ca )
Given I v
Excreted through kidney and go
In tissues based on vascularity
They dec t1rt so image white
And dec t2rt so image black
And post contest mri is always t1mri
MRCP
No dye as water in bile ducts acts as contrast so MRCP is t2wmri
Gd CA
Does not cross Bbb
So dura seeen normally
But if leptomeningeal enhancement seen - sign of meningitis
Gd crosses placenta so not in pregnancy
In CKD where GFR <30ml/min Gd causes nephrogenic systemic fibrosis - chronic scleroderma like illness so RFT imp before giving this CA
Usg contrast agents
Levobist
Sonoview
Are micro bubbles injected I v
Depend on vascularity of tissue and so used for vascular characterisation
Characterise focal liver lesion
Triphasic scan in HCC
Excreted through lungs
Iodinated water soluble contrast agents
Emits iodine so xrays used
Can be:
Ionic monomer (3:2)- urograffin, gastrograffin, ditrizoate HOCM
Ionic dimer(6:2) - ioxoglate LOCM
Non ionic monomer (3:1)- iohexol (omnipeg)LOCM
Non ionic dimer (6:1)- iodioxanol (visiprove) isoosmolar CM
ADR of CA
-anaphylactoid reaction (non ige mediated hsn)
Tt is 1:1000 im adrenaline
-contrast induced nephropathy where contrast induced AKI when CA >.5mg/dl
And contrast induced nephropathy when CA >1mg/dl
Happens when rft is compromised, osmaolartiy of CA more and renal excretion of CA is there
Mets
CA lung - adrenal for non symptomatic
Brain for symptomatic
Small cell CA - brain
Non small cell CA - adrenal
Tt of cin
-hydration of pt
-isoosmolar CA use
-drugs like
N acetyl cysteine (mc)
Theophylline
Na HCO3 (2nd mc)
Ascorbic acid
NOT MANNITOL AND DIURETICS
Haemofiltration is protective and not hameodialysis
Renal excretion in
CECT
IVP
CT ANGIO
ANGIOGRAPHY
Nuclear scans
Gamma camera has sodium iodide detectors activated by thallium
Energy of gamma rays - 140 kilo e volt
T1/2 of tc- 6hrs
Types of nuclear scans
- Tc DTPA- for gfr measurement
- Tc MAG3- for renal function (gfr and tubular secretion measurement)
- Tc DMSA - tells about structure of kidney cortex, if scar present or amount of functioning renal parenchyma
- Tc pertechnate- for gastric mucosa (meckels diverticulum is activity in peri umbilical or right iliac fossa), salivary gland (where it picks up warthins tumor as hot spot) and thyroid
Thyroid
I123 used for thyroid scanning where it’s t1/2 is 13 hrs but not present in India so pertechnate scan used
I131- used for thyroid ablation where it’s t1/2 is 8 days
Other scans
MIBG - pheochromocytoma
SestaMIBI scan- parathyroid adenoma
HIDA scan - biliary atresia
-gold standard to diagnose acute cholecystitis but IOC Is USG
Selenium methionine scan- for pancreas
MDP- bone scan for osteoblastic activity
Octreotide scan- also cld somatostain receptor scintigraphy used for neuroendocrine tumors
Heart
Thallium scan -for myocardial perfusion -reversibility if myocardial ischemia -to diff viable and non viable myocardium Non invasive test for this is FDG PET
MUGA scan- for ventricular function (where it sees contractility of ventricles ejection fraction)
Pet scan
18 FDG (flouro deoxyglucose) where it’s t1/2 is 110min
It competes with glycolysis so it dec as it is metabolised by hexokinase so before performing do blood sugar as dec glucose so hypoglycaemia can occur
Principle of pet- annihilation where positron combines with e and neutral charge and mass is released as energy of 511kev
FDG marker of glycolysis
Pet scan activity
Carcinoid and bronchoalveolar CA don’t show activity on it as no glycolysis
Brain and brown fat show inc activity normally so interscapular area and nape of neck show inc acitivity
Glucose metabolism in tumor is by GLUT3 present in brain and placenta normally so brain and brain tumor show same activity but radiation induced necrosis in brain and recurrence can be picked up on pet
Inherent soft tissue resolution poor with
Pet so CT-pet used where pet CT >CECT for staging of cancers
Flouro dopa pet - in Parkinsonism and pheochromocytoma
Alphabeta amyloid pet - in Alzheimer’s
Psma pet- in prostate specific membrane ag so in prostate CA
DOTANOC, DOTA TOC and DOTATATE- affinity for somatostatin r so NET used
IOC
Acute Sah- NCCT
Diagnose case of acute SAH- angiography (to see cause of SAH)
Acute pancreatitis- serum lipase and amylase
Assess severity of AP- CECT
DIagnose myelomalacia- MRI
Staging lung CA- pet CT > CECT
Pancoast tumor(compress brachial plexus and sympathetic ganglia)- MRI
POtts spine diagnosis- CT guided biopsy
Extent of Potts spine- mri
Mc site of epidermoid cyst in Brain
Cp angle
Application of MR to imagine done by
Lauterber
