Closed MRIs come in 1.5 and 3T. They are narrow but offer great resolution and less motion artifact especially with good technologists. 3T is necessary for many body imaging e ams such as multiparametric prostate MRIs to avoid using an endorectal coil.
Recently, a third option has become available called wide short bore MRI. These scanners have a shorter wider bore the patient enters. They still offer 1.5 and 3T capabilities as the narrow bore magnets and can accommodate larger patients and those with claustrophobia. Most hospitals are replacing their scanners with this newer generation. They are more expensive so many imaging centers are holding off on purchasing new equipment until their scanners are end of life.
Bottom line, the best quality scanner is closed MRI and the wide bore is more tolerable for patients.
There are different levels of image quality. You may not need the best to identify disc bulges which are easy to see. However, if you are looking for subtle nerve abnormalities you are going to want to generate the finest quality images with the ability to see great detail. Open MRs generate the lowest quality images. A 1.5 T (“T” stands for “Tesla” which is a unit of measurement that identifies the strength of the magnet) is better . A 3T magnet generates better quality images than a 1.5 T and a 7T magnet - usually only available in research facilities -gives even better image quality. 3T is the best commonly available. Open MR is designed for the claustrophobic- not best image quality though.
All the best.
Hope this helps.
Dennis Perez MD FACR