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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A STIR sequence with a T1 time of 160ms will null signal from fat at which field strength?

1.0T
1.5T
3.0T
1.2T

The correct answer is: 1.5T

In a STIR (Short Tau Inversion Recovery) sequence, the purpose is to null the signal from fat by applying an inversion pulse at a specific time (T1) after the fat's T1 relaxation time. The selected T1 time of 160 ms is intended to correspond to the T1 relaxation of fat at a given magnetic field strength. At 1.5T, which is a commonly used field strength in MRI, the T1 time for fat is approximately 250 ms. With the given T1 time of 160 ms for the STIR sequence, this would effectively null the fat signal because it aligns closely with the fat’s T1 relaxation characteristics at that field strength. At lower or higher field strengths, the T1 of fat changes, and the inversion time might not appropriately match the T1 of fat, resulting in inadequate nulling. Therefore, for this scenario, 1.5T is the correct answer, aligning the T1 chosen in the STIR sequence to effectively select optimal time for nulling fat signal.