Mri scanner machine in radiology department

MRI scanner machine in a radiology department, essential for noninvasive diagnostic imaging.

About this subject

Magnetic resonance imaging (MRI) is a medical imaging technique that uses strong magnetic fields and radio waves to generate detailed images of organs and tissues inside the body. Unlike X-rays or computed tomography, MRI does not involve ionizing radiation, making it particularly safe for repeated scans and vulnerable populations such as children and pregnant women (though its use during pregnancy is limited to high-benefit cases). The equipment consists of a large cylindrical magnet that creates a stable magnetic field, typically 1.5 to 3 Tesla (T) in standard clinical machines. During the exam, the patient lies still inside the scanner while radiofrequency pulses excite hydrogen protons in the body; as they return to equilibrium, these protons emit signals captured by antennas and transformed into three-dimensional images by computational algorithms.

In Brazil, MRI is widely available in public and private hospitals, especially in large urban centers like São Paulo, Rio de Janeiro, and Belo Horizonte. The Unified Health System (SUS) offers the exam in high-complexity units, although waiting lists can be long. The technology is crucial for diagnosing neurological diseases (such as multiple sclerosis and brain tumors), musculoskeletal conditions (ligament injuries and herniated discs), and cardiovascular issues (cardiac function assessment). A notable fact: the first human MRI scanner was developed in the 1970s, and in 1977 the first whole-body scan was performed on a patient. Since then, advances have reduced acquisition times from hours to minutes, and spatial resolution has increased significantly, allowing visualization of millimeter-sized structures.

The radiology department where the machine is installed follows strict safety protocols. Due to the extremely powerful magnetic field, ferromagnetic metal objects such as keys, credit cards, and electronic devices are prohibited. Patients with metal implants like pacemakers or aneurysm clips require prior evaluation. The loud noise generated during the scan (up to 120 dB) requires ear protection. Additionally, the machine uses liquid helium to cool the superconducting magnet to near -269 °C, requiring specialized maintenance. The image, captured on an overcast day with soft daylight, shows the equipment in a central position, highlighting its tubing and the retractable table where the patient is positioned.

Frequently Asked Questions

How long does an MRI scan take?

The duration ranges from 20 to 60 minutes, depending on the body part and protocol complexity. Cranial scans are usually faster, while spine or joint studies may take longer.

Can anyone undergo an MRI?

No. People with pacemakers, cochlear implants, aneurysm clips, or other ferromagnetic metal devices cannot undergo MRI without medical evaluation. It is also contraindicated during the first trimester of pregnancy unless benefits outweigh risks.

What is the difference between MRI and CT?

MRI uses magnetic fields and radio waves, with no ionizing radiation, providing better soft tissue contrast. CT uses X-rays, is faster, and is preferred for emergencies and bone evaluation.