Why are Some MRIs Open and Some are Not?
The highest field-strength scanners all use what are known as “superconducting” magnets. The reason such magnets are known as superconductors or “supercons” is that their magnets are comprised of miles and miles of special wire which, when immersed in a bath of liquid helium and initial connection to a power source, is capable of conducting electricity indefinitely, even when disconnected from the power source. In order for this phenomenon to occur, the liquid helium must be maintained at a temperature of about minus 273.15 degrees Celsius, very close, in other words, to absolute zero, and the liquid helium must be replenished periodically. The architecture associated with such a magnet requires that the patient be positioned in the center of the magnet with the magnet coils surrounding the patient. Thus, superconducting magnets are always shaped like a cylinder and the patient being scanned is positioned in a narrow, hollow tube in the center of the cylinder. This architecture is necessarily much less conducive to an open environment. It is therefore much more confining for the patient and, for some, much more claustrophobic. The architecture of vertical-field scanners are not restricted in the same way by the magnet design. After Dr. Damadian constructed Indomitable, his prototype scanner, he determined that for commercial development of his scanner, he would forsake the superconducting type of magnet he had used for that machine, which required periodic, costly refilling with liquid helium, and that his next scanner would use a permanent magnet. Later, because of weight considerations that he had to overcome when he developed the world’s first mobile MRI scanner, he also designed a water-cooled, vertical-field electromagnet. All of these commercial units have been “open” in their design and as the scientists at FONAR have developed more and more efficient magnet designs and coil systems, they have been able to increase that openness even more. For a long time, FONAR scanners have been known as the ones in which patients could spread out their arms and relax, free of claustrophobia. And in FONAR’s latest machine, the QUAD 7000, the vertical dimension within the patient gap has been increased by nearly 50 percent to its greatest height ever, unmatched by any other manufacturer. For that reason, radiologists sometimes have to refer large or claustrophobic patients to FONAR machines, even if they are located some distance beyond the nearest competitive machine. If you are a larger patient, you shouldn’t have to be crammed into an MRI scanner with a shoehorn. If large patients who weigh 300 to 400 pounds fit into FONAR scanners but not those others, it stands to reason that a person weighing 130 pounds or 180 pounds will feel much less confined in a FONAR scanner. Fortunately, there’s another option-the FONAR MRI Scanner. Some patients who are claustrophobic simply cannot tolerate lying down for extended periods of time in the confining spaces typical of most MRI scanners. Because of their claustrophobia, they often refuse to enter the scanner, even though an MRI may well prove critical for the accurate diagnosis of their illness. Even though these patients often admit their fear is irrational, for them it’s a fact of life. If you are a patient with claustrophobic tendencies, you shouldn’t have to endure unnecessary anxiety just to get an MRI. Remember, however, that not all “open” MRI scanners are created equal. Most of them are underpowered and thus of diminished image quality. In some cases, that diminished image quality could be enough to cause a radiologist to miss an important detail, critical perhaps to an accurate diagnosis. A FONAR scanner provides both power and openness.