Simplify the following text for a Grade 13 native English-speaking person.
Original: Magnetic resonance imaging ( MRI ) , nuclear magnetic resonance imaging ( NMRI ) , or magnetic resonance tomography ( MRT ) is a medical imaging technique used in radiology to visualize detailed internal structures .
Simplified: Magnetic resonance imaging ( MRI ) , or nuclear magnetic resonance imaging ( NMRI ) , is are machines that doctors use to give a visual representation of soft tissue , ( flesh ) , inside the body . Magnetic resonance uses nuclear magnetic resonance to generate these images .