MRI Practice Test 2025 – Complete Exam Prep Guide

To determine the number of times the repetition time (TR) must be repeated for one number of excitations (NEX) given a phase resolution of 192, it's essential to understand the concepts of phase encoding and NEX in MRI.

Phase resolution refers to the number of lines of k-space data that can be acquired in one phase encoding step. When you require a phase resolution of 192, it means that you need to collect 192 different phase-encoded lines of data during the imaging process. In a typical MRI sequence, for each TR, you can acquire data for a specific phase encoding step.

When only 1 NEX is being utilized, it implies that you are collecting data for each of the phase encoding steps in a single repetition of the TR. Consequently, to achieve the full phase resolution of 192, you must repeat the TR one time for each of the 192 phase encoding steps.

Thus, if the required phase resolution is 192, the TR must be repeated 192 times to obtain the necessary data points for each of those lines. This is why the correct answer is 192.