Radiology MRI physics course

Explore how MRI uses superconducting main magnets cooled by liquid helium to 4 kelvin, with gradient coils encoding spatial fields and RF coils (B1) matching precession frequency for imaging.

Explore spin, resonance, and precession in MRI, showing how the magnetic field drives hydrogen precession and why hydrogen uniquely responds.

Understand how hydrogen atoms precess in MRI, using the gyromagnetic ratio and B0 to set resonance, and how RF pulses flip magnetization to produce measurable transverse signals.

Explore T2 spin-to-spin relaxation and the free induction decay, and explain how T2* and TE affect tissue contrast due to inhomogeneities.

Explore t1 relaxation as the regrowth of longitudinal magnetization after a radiofrequency pulse, contrasted with t2 relaxation and transverse magnetization loss.

Differentiates T1, T2, and proton density MRI signals using spin-echo images and explains how varying TR and TE create contrasts among fat, CSF, and muscle.

Apply slice selection in MRI by using a gradient and a radiofrequency pulse matched to the local Larmor frequency to localize signals along the z axis.

Learn how the frequency encoding gradient localizes signal along the x axis by varying the Larmor frequency with the readout gradient and Fourier transforming the data to form the image.

Describe how the phase encoding gradient creates a phase change along the y axis to encode signal in k-space, enabling two-dimensional image formation with frequency encoding gradient and slice selection.

Understand k-space as the spatial frequency domain where raw MRI data are stored, and learn how sampling trajectories, center versus periphery frequencies, and the Fourier transform shape image quality.

Learn how the field of view and matrix size set MRI resolution and image quality. See how bandwidth and Nyquist limit prevent aliasing artifacts from signals outside field of view.

Explore how bandwidth influences the signal-to-noise ratio and image resolution in MRI, considering field of view, matrix size, sampling rate, and Nyquist limit.

Understand how aliasing and wraparound artifacts arise in MRI, and how field of view, oversampling, bandwidth, Nyquist limit, and parallel imaging with coils reduce these artifacts and improve image quality.

Learn how the chemical shift artifact arises from fat–water Larmor frequency differences and how bandwidth and matrix adjustments reduce it in MRI.

Explore the spin echo pulse sequence in MRI, from conventional 90°-180° refocusing to fast spin echo, detailing phase and frequency encoding, T2 contrast, and artifact considerations.

This lecture explains gradient echo sequence, contrasts it with spin echo, and shows how dephasing and rephasing gradients reveal T2* signals and blooming artifacts for brain hemorrhage or calcification.

Learn how the flip angle, especially the Ernst angle, shapes signal in gradient echo MRI by balancing transverse recovery and longitudinal magnetization, versus spin-echo dynamics and T2* effects.

Master coherent, incoherent, and steady-state free precession gradient echoes, including residual transverse magnetization and rewinder rephasing, for rapid cardiac imaging and angiography.

Apply a 180-degree inversion before the 90-degree excitation to invert magnetization and null signals from fat with stair. Use flare to null CSF and optimize T1 difference, aiding lesion detection.

Learn chemical shift selective fat saturation through targeted radiofrequency pulses and spoiler gradients to null fat signals while preserving water signal.

Explore fast spin echo and echo planar imaging, showing how multiple lines of k-space fill reduce examination time with 180-degree refocusing pulses, phase encoding gradients, and gradient-echo strategies.

Discover diffusion weighted imaging and the ADC map, explain isotropic and anisotropic diffusion, restricted diffusion, and how ADC differentiates true restriction from artifacts.

Demonstrates high velocity signal loss and time of flight in MRI, explaining how blood velocity, saturation bands, and pulse sequence parameters shape signals in vessels like the aorta and IVC.

Explain time of flight flow related enhancement in MRI angiography, where vessels appear bright due to inflow, independent of direction, and how saturation bands suppress one-direction signals.

Explore spin phase effects that dephase moving blood in MR angiography and learn how gradient moment nulling compensates flow-induced dephasing to recover signal.

Explain phase contrast MR angiography and velocity encoding MR angiography, showing how phase shifts differentiate moving blood from stationary tissue and how velocity selection avoids aliasing.

Learn contrast-enhanced MR angiography with gadolinium, which shortens T1 to brighten vessels, enables 3d rapid gradient imaging, bolus injection timing, and arterial visualization with peak concentration guidance.

Explore magnetic resonance spectroscopy by measuring voxel metabolites such as NAA, choline, and lactate while suppressing fat and water signals with chemical shift selective methods. Compare pathology to normal tissue.