What is inversion recovery in MRI?

Inversion recovery is a specific type of magnetic resonance imaging (MRI) sequence that begins with a 180-degree inversion pulse. This pulse inverts the longitudinal magnetization of tissue. After the inversion pulse, a delay is introduced before the application of a subsequent radiofrequency (RF) pulse, allowing for the recovery of the longitudinal magnetization. The time between the inversion pulse and the subsequent pulse can be adjusted to enhance the contrast of different tissues in the image based on their T1 relaxation times.

This technique is particularly useful for distinguishing between different types of tissues, as it can nullify the signal from certain tissues (like fat or water) at specific time intervals. By using inversion recovery techniques, such as FLAIR (Fluid Attenuated Inversion Recovery), radiologists are able to enhance contrast when assessing conditions like multiple sclerosis or cerebral edema.

The other options, while they describe valid MRI concepts, do not accurately define inversion recovery. For instance, reducing motion artifacts relates more to techniques like respiratory gating, T2 contrast enhancement is more associated with sequences that emphasize T2 weighting, and continuous imaging refers typically to techniques used in dynamic imaging rather than the specific mechanics of an inversion recovery sequence.