Physics of the Future: How Science Will Shape Human Destiny and Our Daily Lives by the Year 2100 by Michio Kaku Page B
Authors: Michio Kaku
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not too far away, when a person would be able to pass his personal MRI-MOUSE over his skin and look inside his body any time of the day. Computers would analyze the picture and diagnose any problems. “Perhaps something like the Star Trek tricorder is not so far off after all,” he has concluded.
(MRI scans work on a principle similar to compass needles. The north pole of the compass needle immediately aligns to the magnetic field. So when the body is placed in an MRI machine, the nuclei of the atoms, like compass needles, align to the magnetic field. Now a radio pulse is sent into the body which makes the nuclei flip upside down. Eventually, the nuclei flips back to its original position, emitting a second radio pulse or “echo.”)
The key to his mini-MRI machine is its nonuniform magnetic fields. Normally, the reason the MRI machine of today is so bulky is because you need to place the body in an extremely uniform magnetic field. The greater the uniformity of the field, the more detailed the resulting picture, which today can resolve features down to a tenth of a millimeter. To obtain these uniform magnetic fields, physicists start with two large coils of wire, roughly two feet in diameter, stacked on top of each other. This is called a Helmholtz coil, and provides a uniform magnetic field in the space between the two coils. The human body is then placed along the axis of these two large magnets.
But if you use nonuniform magnetic fields, the resulting image is distorted and useless. This has been the problem with MRI machines for many decades. But Blümich stumbled on a clever way to compensate for this distortion by sending multiple radio pulses into the sample and then detecting the resulting echoes. Then computers are used to analyze these echoes and make up for the distortion created by nonuniform magnetic fields.
Today, Blümich’s portable MRI-MOUSE machine uses a small U-shaped magnet that produces a north pole and a south pole at each end of the U. This magnet is placed on top of the patient, and by moving the magnet, one can peer several inches beneath the skin. Unlike standard MRI machines, which consume vast amounts of power and have to have special electrical power outlets, the MRI-MOUSE uses only about as much electricity as an ordinary lightbulb.
In some of his early tests, Blümich placed the MRI-MOUSE on top of rubber tires, which are soft like human tissue. This could have an immediate commercial application: rapidly scanning for defects in products. Conventional MRI machines cannot be used on objects that contain metal, such as steel-belted radial tires. The MRI-MOUSE, because it uses only weak magnetic fields, has no such limitation. (The magnetic fields of a conventional MRI machine are 20,000 times more powerful than the earth’s magnetic field. Many nurses and technicians have been seriously hurt when the magnetic field is turned on and then metal tools suddenly come flying at them. The MRI-MOUSE has no such problem.)
Not only is this ideal to analyze objects that have ferrous metals in them, it can also analyze objects that are too large to fit inside a conventional MRI machine or cannot be moved from their sites. For example, in 2006 the MRI-MOUSE successfully produced images of the interior of Ötzi the iceman, the frozen corpse found in the Alps in 1991. By moving the U-shaped magnet over Ötzi, it was able to successively peel away the various layers of his frozen body.
In the future, the MRI-MOUSE may be miniaturized even more, allowing for MRI scans of the brain using something the size of a cell phone. Then, scanning the brain to read one’s thoughts may not be such a problem. Eventually, the MRI scanner may be as thin as a dime, barely noticeable. It might even resemble the less-powerful EEG, where you put a plastic cap with many electrodes attached over your head. (If you place these portable MRI disks on your fingertips and then place them on a person’s head, this would
(MRI scans work on a principle similar to compass needles. The north pole of the compass needle immediately aligns to the magnetic field. So when the body is placed in an MRI machine, the nuclei of the atoms, like compass needles, align to the magnetic field. Now a radio pulse is sent into the body which makes the nuclei flip upside down. Eventually, the nuclei flips back to its original position, emitting a second radio pulse or “echo.”)
The key to his mini-MRI machine is its nonuniform magnetic fields. Normally, the reason the MRI machine of today is so bulky is because you need to place the body in an extremely uniform magnetic field. The greater the uniformity of the field, the more detailed the resulting picture, which today can resolve features down to a tenth of a millimeter. To obtain these uniform magnetic fields, physicists start with two large coils of wire, roughly two feet in diameter, stacked on top of each other. This is called a Helmholtz coil, and provides a uniform magnetic field in the space between the two coils. The human body is then placed along the axis of these two large magnets.
But if you use nonuniform magnetic fields, the resulting image is distorted and useless. This has been the problem with MRI machines for many decades. But Blümich stumbled on a clever way to compensate for this distortion by sending multiple radio pulses into the sample and then detecting the resulting echoes. Then computers are used to analyze these echoes and make up for the distortion created by nonuniform magnetic fields.
Today, Blümich’s portable MRI-MOUSE machine uses a small U-shaped magnet that produces a north pole and a south pole at each end of the U. This magnet is placed on top of the patient, and by moving the magnet, one can peer several inches beneath the skin. Unlike standard MRI machines, which consume vast amounts of power and have to have special electrical power outlets, the MRI-MOUSE uses only about as much electricity as an ordinary lightbulb.
In some of his early tests, Blümich placed the MRI-MOUSE on top of rubber tires, which are soft like human tissue. This could have an immediate commercial application: rapidly scanning for defects in products. Conventional MRI machines cannot be used on objects that contain metal, such as steel-belted radial tires. The MRI-MOUSE, because it uses only weak magnetic fields, has no such limitation. (The magnetic fields of a conventional MRI machine are 20,000 times more powerful than the earth’s magnetic field. Many nurses and technicians have been seriously hurt when the magnetic field is turned on and then metal tools suddenly come flying at them. The MRI-MOUSE has no such problem.)
Not only is this ideal to analyze objects that have ferrous metals in them, it can also analyze objects that are too large to fit inside a conventional MRI machine or cannot be moved from their sites. For example, in 2006 the MRI-MOUSE successfully produced images of the interior of Ötzi the iceman, the frozen corpse found in the Alps in 1991. By moving the U-shaped magnet over Ötzi, it was able to successively peel away the various layers of his frozen body.
In the future, the MRI-MOUSE may be miniaturized even more, allowing for MRI scans of the brain using something the size of a cell phone. Then, scanning the brain to read one’s thoughts may not be such a problem. Eventually, the MRI scanner may be as thin as a dime, barely noticeable. It might even resemble the less-powerful EEG, where you put a plastic cap with many electrodes attached over your head. (If you place these portable MRI disks on your fingertips and then place them on a person’s head, this would
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