Magnetic Resonance Imaging (MRI) Practice Test

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Study for the Magnetic Resonance Imaging (MRI) Test. Utilize flashcards and multiple choice questions with detailed hints and explanations. Get thoroughly prepared for your MRI exam!

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In MR imaging, what is the primary factor that influences image contrast?

Busyness of tissues
Relaxation times
Pulse sequence type
Magnetic field strength

The correct answer is: Relaxation times

The primary factor that influences image contrast in MR imaging is relaxation times. Relaxation times, which include T1 (spin-lattice relaxation time) and T2 (spin-spin relaxation time), are intrinsic properties of tissues that affect how protons return to equilibrium after being disturbed by the MRI pulse sequences. Different tissues in the body have varying T1 and T2 times, which influence how bright or dark an area appears on the MRI image. For example, fat has a shorter T1 and T2 time compared to water, leading to differences in signal intensity and thus contributing to contrast in the resulting images. By adjusting the imaging parameters in relation to these relaxation times, radiologists can enhance contrast to better visualize specific tissues or pathologies. Other factors, such as the type of pulse sequence used and magnetic field strength, also play a role in image quality and contrast but are secondary to the fundamental influence of relaxation times on the contrast observed in MR images.