MAGNETIC RESONANCE IMAGEING

 

MAGNETIC RESONANCE IMAGEING

 

MAGNETIC -  in magnetic field

RESONANCE= whenever two different energy levels exits within a physical system there will be transition of energy from one state to another its called resonance ……

IMAGING= all three planes

MRI is a medical IMAGEING TECHNIQUE USED IN RADILOGY TO FROM IMAGE OF ANATOMY AND THE PHYSIOLOGICAL PROCESSES OF THE BODY

MRI IS BASED ON NMR PHENOMENON

NMR= NUCLEAR MAGNETIC RESONANCE

Certain atomic nuclei demonstrate the ability to absorb s re-emit radiofrequency energy when it is placed in magnetic field

Radiofrequency pulse in the range of 1_80 MHz

= history

. NMR was described in 1946 by FELIX BOLCH and EDWARD PURECELL

.in 1970 s RAYMOND DAMODION invented on apparatus s method to use NMR Safely and accurately to scan the human body and named it “IDOMINTABLE’’

( RAYMOND  DAMODION = FATHER OF MRI)

. in 1977 PAUL C LAUTERBER S SIR PETER MANSFIELD CAME WITH ON IDEA OF USING GRADIENT COILS

And development of echo planer imaging from these new ideas they took the first clinical scan in very short time [ 15-23 MINUTUS]

. PAUL C LAUTERBER AND SIR PETER MANSFIELD SHARED THE NOBEL PRIZE FOR DEVELOMENT OF MRI IN 2003

[PRINICIPLE OF MRI]

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. MRI TECHNOLOGY FORMS IMAGE WITH REFERENCE TO THE HYDROGEN ATOM PRESENT IN THE HUMAN BODY

. WHY WE TAKE HYDROGEN ATOM AS REFERENCE……?

FIRSTLY  AS NMR PHENOMENON WE NEED AN ATOMIC NUCLI PASSING AN ODD NUMBER OF PROTONS OR NEUTRONS AND HYDROGEN ATOM HAS SINGLE PROTON WHICH SPINS AROUND THE NUCLEUS RESULTING PRODUCTION OF MAGNETIC FIELD

 

THE MOST ABUNDENT NUCLEI IN HUMAN BODY IS HYDROGEN   (10     H+ IN EACH CUBIC CM OF TISSUE )

 HOW DOES MRI WORKS ON THE BASIS OF NMR  ?

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 MRI GOES THROUGH FOLLOWING STEPS TO MAKE AN FINAL IMAGE

[1] MAGNETIC FIELD

[2] RESONANCE

[3] RELAXATION

[4] IMAGE RESONSTRUCTION AND DISPLAY

 

 

1 MAGNETIC FIELD

……………………………= ORDINARRY WITH NO EXTERNAL INTERFERENCE HYDROGEN NUCLEI IN HUMAN BODY ARE SITUATEDIN A RANDOM MANNER AND THIR MAGNETIC MOMENT CANCEL EACH OTHER TO GIVE AN OVER ALL MAGNETIGATION OG ZERO

                                                                                WHEN HUMAN BODY IS PLACED IN A STRONG MAGNETIC FIELD SACH AS MR SCANNER SPINNNIG NUCLEI MAY POSITION THEMSELVES IN TWO ORIENTATION WITH RESPECT TO FIELD PARALLEL ( WITH THE FIELD ) OR ANTI_ PARALLEL  ( AGAINST FIELD)

SPIN UP ATOMIC NUCEI WILL BE ORIENTED ON LOW ENERGY STATE AND SPIN DOWN NUCLEI WILL BE ORIENTED ON HIGH ENERGY STATE

= the net magnetization is the same of individual magnetic moments aligned parallel to external field in excess of those aligned against the external magnetic field and ex