MRI scan plays an important role in the diagnosis of a high number of diseases. Depending on the character of your disease, doctor can choose a different strength of the magnet of the MRI scanner to get an image of your body. During MRI examination a very strong magnet creates a radio waves directed at you inside the MRI scanning machine. These radio waves send signals to your body and afterwards receive them back. The returning signals are converted into images by a computer attached to the MRI machine.
What is the difference between MRI scanners?
The quality of an MRI scan depends on signal and magnetic field strength. Strength of the magnetic field is measured in Tesla or “T”. Usually, MRI scanners have between 0.23T and 3.0T – a 3.0T MRI machine has much more signal than a 0.3T machine. In general, we can divide MRI scanner into two groups: low-field MRIs and high-field MRIs.
Low-field MRIs (0.23T – 0.3T)
Group of low-Field MRI scanners with a range of 0.23T-0.3T usually represent open MRI scanners. These types of MRI machines are more suitable for patients with claustrophobia or due to weight restrictions for a closed MRI. In comparison with high-field MRI scanners, low-field MRIs have decreased image quality and require a longer scanning time.
High-field MRIs (1.5T to 3.0T)
Nowadays, a 1.5T MRI represents a standard in a clinical setting. 1.5T MRI scanner is faster in comparison to lower strength MRIs (e.g. 1.2T MRI machines) and is ideal for patients requiring abdominal and chest MRI scan. The main advantages of higher-signal MRI machines combines shorter time of examination and higher quality of the images.
3T MRI scanners provide extremely clear images and can often be done faster, decreasing overall time of the examination. Both mentioned features makes an advantage for the patient in terms of diagnosis and comfort. 3T MRI machine is more suitable for imaging musculoskeletal system, structures of the nervous system, small bones and vessels. In these cases, the minute details may be crucial to diagnosis, such as:
- traumatic brain injuries
- epilepsy and brain function disorders
- accurate pre-operative mapping of brain tumors
- joint cartilage and surrounding structures
- detailed imaging of ligaments, tendons and nerves
However, 3T MRI scanner is not always the best choice for every patient and every possible diagnosis. 3T MRI scans have an increased rates of artifacts (any objects that appear in the image, but are absent in the original object). Common are “flow” artifacts due to occurence of blood or fluid. Compared to a 1.5T MRI machines, more noise and additional heat can also be a challenge with 3T MRIs.