Magnetic teb gradients yog xav tau txhawm rau nkag mus rau lub teeb liab spatially. Lawv tsim ib qho kev sib txawv ntawm qhov sib nqus ntawm qhov sib nqus hauv ib qho kev taw qhia hauv qhov chaw. Qhov no variation nyob rau hauv magnetic teb siv tau ntxiv rau lub ntsiab magnetic teb, uas yog nyob deb zog ntau.
Magnetic field gradient ua dab tsi?
Magnetic Field Gradints, Spatial Frequencies thiab k-space
Raws li magnetic field gradients tsim sib txawv precession frequencies hla cov duab ntim, evolution nyob rau hauv ib tug gradient tshaj ib teev. lub sij hawm tsim ib tug spatial faib ntawm magnetization uas txawv raws gradient kev taw qhia.
MRI siv dab tsi?
Ib lub tshuab luam ntawv MRI siv cov hlau nplaum muaj zog heev ( txog 0.2 txog 3 teslas, lossis kwv yees li ib txhiab npaug ntawm lub zog ntawm cov hlau nplaum fridge), uas ua raws cov proton " tig. "
Lub luag haujlwm tseem ceeb ntawm cov gradients hauv MRI yog dab tsi?
Daim teb gradient no cuam tshuam lub ntsiab sib nqus hauv ib qho me me tab sis kwv yees tau. Qhov no ua rau lub resonance zaus ntawm protons txawv nyob rau hauv ib txoj hauj lwm ntawm txoj hauj lwm. Lub luag haujlwm tseem ceeb ntawm gradients yog tso cai spatial encoding ntawm MRI teeb liab, tab sis kuj tseem ceeb rau ntau yam kev siv lub cev.
Vim li cas cov hlau nplaum gradients tseem ceeb rau kev tsim duab?
Cov ntsiab lus tseem ceeb. Spatial encoding nyob rau hauv MR imaging siv magnetic gradients. Cov gradients no tso cai rau kev nkag siab ntawm cov ntaub ntawv spatial raws li cov ntaub ntawv spatial zaus. Cov ntaub ntawv no tau kos npe rau hauv k-qhov chaw kom qhov kev hloov pauv 2D Fourier rov tsim kho MR duab.
