Youtor
MRIT2T1Flair DWI
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Hi friends... • Welcome to Radiography Simplified. • #T1_relaxation #T2_relaxation #NMR • MRI uploaded video. • mri principle • • MRI principle ll Magnetic Resonance I... • mri components • • MRI ( components ) ll Magnetic resona... • mri introduction • • MRI introduction ll Magnetic resonanc... • Old video links • • Focal spot. • • Focal Spot in an x-ray tube ll Effec... • IVP • • IVP ll Intravenous pyelography ll Int... • Automatic processor • • Automatic film Processor l component... • X ray beam restrictor. • • X-ray beam restrictors ll Cone , Cyli... • Coherent scattering. • • COHERENT SCATTERING ll interaction of... • X- ray tube • • x-ray tube l components type l Radi... • Dark room • • Dark Room in radiography l feature l ... • Processing chemical • • x-ray film processing chemical l deve... • Intensifying screen • • Intensifying screen part -1 l constru... • X ray film • • Radiographic / x- Ray films l constru... • • Today topic is... • T1 relaxation T2 relaxation • ( magnetic resonance imaging) • T1 relaxation-: • 1) it is a loss of longitudinal. • magnetization along the axis. • 2) it happens along z axis • 3) hydrogen nuclei return to restingl state that is from higher energy state to lower energy state. • 4) it is also known as spin lattice relaxation. • 5) There is an energy transfer. • 6) T1 is a time constant. • It is the time it take longer chooral meditation to recover to 63% of it maximum value • T2 relaxation:- • 1) it is loss of transverse magnetization along xy plane. • 2) it is also known as spin-spin relaxation. • 3) T2 is a time constant. • 'It is the time taken to reduce the transverse magnetisation to 37% of the peak value' • It depends on -: • 1) external magnetic field inhomogeneities. • 2) intrinsic magnetic inhomogeneities of tissues. • MRI principle -: • It States that certain atomic nuclei demonstrate the ability to absorb and re-emit radio frequency when it • is placed in the magnetic field • Hydrogen is consist of a single proton. • Proton as spinning charged particle produces a magnetic field • so hydrogen act like a tiny magnet. • In a normal state all the hydrogen protons are oriented randomly • and cancel out each other so there will be no net magnetization. • When patient is placed in the magnetic field, • Most of the hydrogen proton line up in the direction of magnetic field Bo • and few line up in antiparallel direction resulting in net magnetization . • Precession frequency is represented by a formula called larmor equation. • It states that precession frequency is equal to Gamma multiplied by Bo. • When our pulse is applied perpendicular to the main magnetic field. • • Then absorption of energy takes place which flips the longitudinal magnetization in the direction of xy plane and there will be a loss of longitudinal magnetization. • And when RF pulse is switched off two things happen at the same time. • 1) regain longitudinal magnetization called T1 relaxation. • 2) lose of transverse magnetization known as T2 relaxation. • T1 relaxation :- • 1) it is also known as spin- lattice relaxation. • 2) it is is occur along the z axis. • 3) it involve transfer of energy. • 4)it is a slower process. • T2 relaxation:- • 1) it is also called spin spin relaxation. • 2) it's occur along xy plane • 4) it is a faster process. • Gradient coils are used to produce deliberate variation in the magnetic field. • There are three set of gradient coil for each directions. • The variation the magnetic field permit localisation of image slices as well as phase encoding and frequency encoding. • It is also responsible for the loud noise generated by the MR scanner. • During relaxation that is T1 and t2 signal are emitted out from the patient body. • Which is detected by the the RF receiver coils • Once the signal are are detected by the the RF receiver coil. • the signals are are turned to digital signal by analogue to digital converter. • the digital signal is then sent for image processing ( Fourier transform )and the the images displayed on the monitor. • • Thanks for watching 🙏 • Please like, share subscribe. • bye . • Take care.
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