CAT scans are particularly dangerous when used on children. Despite their reduced size, they may receive adult-sized doses of x-rays, up to five times of what is necessary, leaving them prone to cancer. In the US, where 600,000 children under 15 receive CAT scans every year, an estimated 500 die as a result.89 Furthermore, although all the early studies showed that CAT scans reduced diagnosis time, helped doctors to understand their diagnosis, reassured doctors about their diagnosis or treatment plans and avoided the need for other tests, very few demonstrated that this knowledge in any way reduced illness, shortened hospital stay or prevented death.90
There are also questions of accuracy. Despite the dangers of high-dose radiation in children, particularly of their sexual organs, it is often used to diagnose cerebral (brain) hernia after lumbar puncture for meningitis. Nevertheless, one study found that one-third of children with hernias were misdiagnosed as normal.91 As with other contrast mediums, the dyes used can permanently damage the kidneys.92
Despite any real demonstration of value, other than as a diagnostic toy, use of CT scanning has moved briskly apace. Patients who have a seizure are scanned, even before a clinical history is taken, to rule out alcohol withdrawal.93 So beloved is this gadgetry that it has even been used to research the cause of the common cold, the researchers concluding that their study patients had – wait for it – swelling of the mucous membranes.94 Besides megadoses of radiation, CT scans (indeed all x-rays) have long been known to cause cataracts and other lens opacities, such as nuclear sclerosis,95 and could affect thyroid function.96
MRI SCANS
The dangers of CAT scans and the use of computers led to the development of nuclear magnetic resonance, which developed into magnetic resonance imaging (MRI). This screening procedure was hailed as a promising alternative to x-rays for providing detailed pictures of soft body tissue, particularly the brain and spinal cord.
In MRI, you are placed inside a massive cylindrical magnet weighing up to 500 tons – large enough to envelope the entire body. While you are inside the magnet a quick pulse is applied, creating a magnetic field some 50,000 times stronger than that of the earth.97 The effect of this is to excite the nuclei of atoms within body cells. These hyped-up nuclei produce radiofrequency echoes, which get translated into images on a computer.
The MRI scan works by focusing on the water molecules, which largely make up the tissues of your body. The scan excites the hydrogen and oxygen molecules and, as they begin moving in a certain pace and direction, the scanner is able to detect and measure them and then reconstruct a picture of your body from them, displaying it in real time on a television monitor. Although it was originally believed that the good ‘pictures’ afforded by MRI would eliminate the need for injectible dyes, this hasn’t proved so. Contrast agents are needed to detect brain tumours, for example. Unlike the contrast materials used for CAT scans, which contain iodine, those used for MRI are magnetically-active substances.
Currently, the only MRI contrast materials approved by the American Food and Drug Administration are chelates, containing a rare earth element called gadolinium. When injected into a patient’s veins, this works similarly to iodine contrast agents, but is supposed to be far safer, with severe reactions occurring in about 1 in 350,000 patients.
MRI is mainly used to view the nervous system, for suspected strokes, brain tumours, multiple sclerosis, brain infections such as meningitis, epilepsy, developmental disorders of the brain such as hydrocephalus, and problems of the spinal cord or vertebrae. Its advantages over CAT scans are that it shows better tissue contrast, enables you to get images in multiple planes, has no radiation, employs a safer contrast medium, and enables you to view veins and the top and front joining of the skull. The big drawback is that you must undergo a much longer scanning time, and results can be flawed if you move at any time during the procedure. However, these days the latest MRI scanners can work faster and take in more detail in one go.98 MRI is reputed to be fairly accurate for detecting multiple sclerosis; one study of MS patients showed a 95–99 per cent accuracy in detecting the disease.99
But, again, large question marks remain about its accuracy. According to a medical textbook on CT and MRI, many initial reports that MRI gave more detailed images than CT were ‘overly optimistic’. All the initial fanfare, which came from individual cases of patients, could not be confirmed by subsequent larger studies using full scientific methods. The earlier studies turned out not to be well controlled.100
Lately, MRI has shown to be less than accurate in detecting early prostate cancer101 or coronary artery disease.102 It is now thought that MRI is better than CT for the brain and spine, because of its ability to take shots of the top of the head and front of the skull and to detect subtle tissue changes, but CT is better for studying any sort of trauma – such as blows to a body part – or the bones or calcium.
The problem is that no one yet knows the likely long-term effects of subjecting the body to a magnetic field powerful enough to send magnetic objects flying across the room. So far, the National Radiological Protection Board has sounded a warning about the heating effects of the magnetic field and its ability to influence magnetic matter inside the body or to damage tissues.
Microbiologist Wendell Winter and colleagues at the University of Texas Health Center at San Antonio stated that exposure to these types of electromagnetic fields may not be totally harmless. They subjected a number of living things to a range of electromagnetic fields and found that they stimulated the growth rate of cancer cells.103
Research on chick embryos has demonstrated that they are at risk with the increased temperatures; female mice chronically exposed showed changes in their white blood cell count. Other animal studies show that MRI can cause birth defects in the eyes104 and damage to the ears.105 In the States, several patients with pacemakers died when the magnetic forces altered them.106
Another potential danger concerns any metallic substances on your body. Complications can occur if you have any metal prostheses or implants, surgical clips or artificial heart valves, you are wearing any metal object, like a watch, have any metal on your clothing, wear a shade of eye shadow that contains metallic substances or even have your ATM card in your wallet.
One of the big problems with MRI scannings is claustrophobia. Up to one-third of patients given MRI scans have felt so claustrophobic that the tests had to be abandoned.107 ‘After an MRI scan for my neck, I had appalling claustrophobia (during it), with memory loss,’ writes Jill from Aberdeen. ‘I kept crying, shaking, couldn’t write, stammered, had nightmares for two weeks afterwards. It was 55 minutes of hell – worse than the two previous CAT scans. It must affect the brain cells with all that magnetism.’
Perhaps
