MRI Physics Questions and Answers
Latest Version Graded A+
What is the function of gradient echo sequences?
✔✔ To produce fast imaging with lower RF power requirements
Why is steady-state free precession (SSFP) used in MRI?
✔✔ To maintain continuous signal and enhance contrast in dynamic imaging
What is the role of phase cycling in MRI?
✔✔ To reduce artifacts caused by phase inconsistencies
How does increasing the number of slices in a 3D sequence affect scan time?
✔✔ It increases scan time but provides higher resolution images
Why is a high field strength beneficial for functional MRI (fMRI)?
✔✔ It improves sensitivity to small changes in blood oxygen levels
1
,How does increasing the number of phase encoding steps affect image quality?
✔✔ It improves spatial resolution but extends scan time
What is the primary factor affecting contrast in T2-weighted imaging?
✔✔ Differences in T2 relaxation times between tissues
How does T2 relaxation differ from T1 relaxation?
✔✔ T2 is transverse relaxation, while T1 is longitudinal relaxation
What is the function of the inversion time (TI) in MRI?
✔✔ To control the degree of tissue suppression in inversion recovery sequences
What is the primary purpose of the main magnetic field in MRI?
✔✔ To align hydrogen protons in the body
How does increasing the magnetic field strength affect image resolution?
✔✔ It improves resolution by increasing signal-to-noise ratio
2
, What is the role of radiofrequency (RF) pulses in MRI?
✔✔ To excite hydrogen protons and generate signals for imaging
Why is T1 relaxation also called spin-lattice relaxation?
✔✔ Because energy is transferred from protons to their surrounding environment
What happens when the repetition time (TR) is increased in an MRI scan?
✔✔ It allows more longitudinal relaxation, affecting image contrast
Why do different tissues have varying T2 relaxation times?
✔✔ Because molecular interactions and water content differ between tissues
What is the purpose of the 180-degree refocusing pulse in a spin-echo sequence?
✔✔ To correct dephasing caused by magnetic field inhomogeneities
How does decreasing the echo time (TE) affect T2 contrast?
✔✔ It reduces T2 contrast by minimizing transverse decay effects
3
Latest Version Graded A+
What is the function of gradient echo sequences?
✔✔ To produce fast imaging with lower RF power requirements
Why is steady-state free precession (SSFP) used in MRI?
✔✔ To maintain continuous signal and enhance contrast in dynamic imaging
What is the role of phase cycling in MRI?
✔✔ To reduce artifacts caused by phase inconsistencies
How does increasing the number of slices in a 3D sequence affect scan time?
✔✔ It increases scan time but provides higher resolution images
Why is a high field strength beneficial for functional MRI (fMRI)?
✔✔ It improves sensitivity to small changes in blood oxygen levels
1
,How does increasing the number of phase encoding steps affect image quality?
✔✔ It improves spatial resolution but extends scan time
What is the primary factor affecting contrast in T2-weighted imaging?
✔✔ Differences in T2 relaxation times between tissues
How does T2 relaxation differ from T1 relaxation?
✔✔ T2 is transverse relaxation, while T1 is longitudinal relaxation
What is the function of the inversion time (TI) in MRI?
✔✔ To control the degree of tissue suppression in inversion recovery sequences
What is the primary purpose of the main magnetic field in MRI?
✔✔ To align hydrogen protons in the body
How does increasing the magnetic field strength affect image resolution?
✔✔ It improves resolution by increasing signal-to-noise ratio
2
, What is the role of radiofrequency (RF) pulses in MRI?
✔✔ To excite hydrogen protons and generate signals for imaging
Why is T1 relaxation also called spin-lattice relaxation?
✔✔ Because energy is transferred from protons to their surrounding environment
What happens when the repetition time (TR) is increased in an MRI scan?
✔✔ It allows more longitudinal relaxation, affecting image contrast
Why do different tissues have varying T2 relaxation times?
✔✔ Because molecular interactions and water content differ between tissues
What is the purpose of the 180-degree refocusing pulse in a spin-echo sequence?
✔✔ To correct dephasing caused by magnetic field inhomogeneities
How does decreasing the echo time (TE) affect T2 contrast?
✔✔ It reduces T2 contrast by minimizing transverse decay effects
3
