Fundamental Principles and Mechanism of MRI

MRI (Magnetic Resonance Imaging): A diagnostic tool specifically used to examine soft tissues within the human body.
Key Components: The machine consists of a magnet, radio waves, a gradient, and a computer.
Biological Basis: The human body is composed of $60\%$ water ( $H_2O$ ). Hydrogen atoms within these molecules act as tiny magnets sensitive to magnetic fields.

Magnetic Alignment: A large magnet creates a unified magnetic field. While molecules are usually arranged randomly, they align with the field's frequency when the patient is inside the scanner.
Gradient Function: This component divides the magnetic field into sections of varying strengths to isolate specific body parts, such as the brain.
Low Energy Molecules: These are water molecules that do not initially align with the magnetic field and are the primary focus for generating images.

Radio Wave Resonance: Radio waves are emitted at the same frequency as the magnetic field. The low energy molecules absorb this energy to move into alignment with the field.
Energy Release: Once the radio waves stop, the molecules release the absorbed energy as they return to their original positions.
Image Translation: The computer detects these energy signals and uses software to translate the data into three-dimensional images for medical diagnosis.