Good question at 26:30- if Fourier transform is looking at differences in phase and plotting amplitude of each, it seems like an artificial placement of least phase induction at top/bottom extreme would have zero effect on transformed image. Great course, this is my only question so far.
Actually, I think you still have to put the least phase induction signal in the center according to the phase-encoding gradient that you apply. Reordering the signal of the phase-encoding slot of k-space would mess up the transformed image. However, Dr. Lipton's comment on inverting the highest (or higher) amplitude signal to the periphery of k-space was also very misleading, I supposed he meant that we might be able to put the higher amplitude signal (with the correct phase-encoding gradient, that is the lowest phase induction signal in the center and the highest out at the periphery) inverted to enhance the edge definition of the acquired image. However, this is somewhat contradictory, because as you go along higher in the phase encoding steps (ie, stronger phase encoding gradient) the amplitude of the signal should get lesser and lesser, so I supposed the inverted method that Dr. Liipton mentioned was actually referring to relative signal amplitudes that have similar phase encoding steps (or gradient). Or maybe it is possible to acquire the samples (for example in a fast spin echo sequence) with a higher phase encoding gradient early in the echo train length while the signals are still high, in such a way, that you would have a signal with higher amplitude than the ones that follow (with lower phase encoding gradient). I hope Dr. Lipton can answer our confusion because it is really hard to find information on the internet regarding the inverted ordering method (22:14) that he mentioned. Aside from this question that I have, this is the best MRI course that anyone would need to understand the wonders of this amazing imaging modality. ~ from an ophthalmologist standpoint.
Good question at 26:30- if Fourier transform is looking at differences in phase and plotting amplitude of each, it seems like an artificial placement of least phase induction at top/bottom extreme would have zero effect on transformed image. Great course, this is my only question so far.
Actually, I think you still have to put the least phase induction signal in the center according to the phase-encoding gradient that you apply. Reordering the signal of the phase-encoding slot of k-space would mess up the transformed image. However, Dr. Lipton's comment on inverting the highest (or higher) amplitude signal to the periphery of k-space was also very misleading, I supposed he meant that we might be able to put the higher amplitude signal (with the correct phase-encoding gradient, that is the lowest phase induction signal in the center and the highest out at the periphery) inverted to enhance the edge definition of the acquired image. However, this is somewhat contradictory, because as you go along higher in the phase encoding steps (ie, stronger phase encoding gradient) the amplitude of the signal should get lesser and lesser, so I supposed the inverted method that Dr. Liipton mentioned was actually referring to relative signal amplitudes that have similar phase encoding steps (or gradient). Or maybe it is possible to acquire the samples (for example in a fast spin echo sequence) with a higher phase encoding gradient early in the echo train length while the signals are still high, in such a way, that you would have a signal with higher amplitude than the ones that follow (with lower phase encoding gradient).
I hope Dr. Lipton can answer our confusion because it is really hard to find information on the internet regarding the inverted ordering method (22:14) that he mentioned.
Aside from this question that I have, this is the best MRI course that anyone would need to understand the wonders of this amazing imaging modality. ~ from an ophthalmologist standpoint.
videos are extremely informative and consists quality knowledge. thank you for uploading the course
Bro how come after application of phase encoding gradient before second 180 pulse only one k space is filled
I wish this guy was like my grandpa or something..
man you are a legend!
your grandmother might object
great , thanks voor the video