Context:
What is magnetic resonance imaging? – An article in The Hindu Explained
Magnetic Resonance Imaging (MRI):
- An indispensable tool to look inside the human body without surgery.
- A non-invasive diagnostic procedure widely used to image the brain, the cardiovascular system, the spinal cord and joints, various muscles, the liver, arteries, etc.
- It is used to obtain images of soft tissues (non-calcified tissue) within the body.
- No long-term harm associated with scans.
- No threats – Once the magnetic fields are taken away, the atoms in the scanned part do not remain affected.
How does MRI work?
- MRI (Magnetic Resonance Imaging) procedure uses hydrogen atoms in the body part to be scanned to reveal an image.
- A hydrogen atom consists of one proton with one electron around it, and these atoms spin with axes pointing in random directions.
- Hydrogen atoms are abundant in fat and water, which are present almost throughout the body.
- The MRI machine resembles a giant doughnut, with a hole in the centre called the bore.
- Inside the MRI machine is a powerful superconducting magnet that produces a stable magnetic field around the body.
- Each hydrogen atom has a powerful magnetic moment, causing its spin axis to align with the magnetic field’s direction.
- The superconducting magnet applies a magnetic field such that the axes of roughly half of the hydrogen atoms are pointing one way and the other half the other way.
- The machine emits a radiofrequency pulse at the part under the scanner, exciting a small population of ‘excess’ atoms.
- When the pulse goes ‘off’, these atoms emit the absorbed energy and return to their original, lower energy states.
- A detector receives the emissions and converts them to signals, which are sent to a computer that recreates two- or three-dimensional images of the body part.
Applications:
- Brain Imaging: MRI identifies brain abnormalities and tracks conditions like Alzheimer’s and epilepsy.
- Cardiovascular Imaging: MRI produces detailed heart images, helping diagnose various heart conditions.
- Spinal Cord Imaging: MRI effectively visualises the spinal cord and related structures.
- Abdominal and Pelvic Imaging: MRI examines abdominal and pelvic organs, detecting abnormalities.
- Cancer Detection: MRI is crucial in observing and treating certain cancers.
Source: The Hindu
Previous Year Question
Consider the following statements:
DNA Barcoding can be a tool to:
1. assess the age of a plant or animal.
2. distinguish among species that look alike.
3. identify undesirable animal or plant materials in processed foods.
Which of the statements given above is/are correct?
(a) 1 only
(b) 3 only
(c) 1 and 2
(d) 2 and 3
Answer: (d)
Explanation:
Option 1 is not correct: Carbon dating is a technique used to determine the approximate age of once-living materials.
