The energy used to form MRI images is ____________ the patient's tissues.

The correct answer indicates that the energy used to form MRI images is emitted from the patient's tissues. In MRI, the primary source of the imaging signal comes from the hydrogen nuclei present in the body's tissues. When a patient is placed in the magnetic field, radiofrequency (RF) pulses are delivered to excite these hydrogen protons. As they return to their equilibrium state, they emit energy in the form of signals, which are then detected by the MRI system to create images.

This emission process is crucial to the formation of MRI images, as it is the emitted signals that provide information about the different types of tissues, their characteristics, and their arrangement within the body. This helps in distinguishing between various tissue types based on their magnetic properties and the behavior of the protons when subjected to magnetic fields and RF pulses.

Understanding this fundamental concept is essential for interpreting how MRI technology operates and how images are generated from the interactions between the magnetic field and the body's tissues.