Nuclear Medicine


“Go and look at your toes, John,” my Mother used to tell me when she was choosing shoes. So I would obediently trot off to the X-ray machine.

Not that I was ever really obedient but I liked the X-ray machine because you could see your toes wiggle. The machine was a bit like an old fashioned wooden upright coin-weighing machine with an opening for your feet and a viewing glass to peer down at your bones, suddenly bereft of shoes, socks, and skin through the magic of X-rays. I thought my toe bones wiggled magnificently.

No longer are these machines available in shoe stores to check whether the shoes fit your feet scaremongers drove them away. But they were among the most original of medical imaging techniques available to us. Now we have many other techniques and scaremongers are still out there trying to turn off progress. Most of the new imaging techniques are nuclear in character and scaremongers cannot tell nuclear bombs from nuclear science just as they cannot distinguish between a TV cartoon and wisdom.

But the spigot is open and so much benefit flows from medical imaging that the scaremongers have generally moved on, bleating, to other irrationalities.

The X-ray – we all know. Although not as instant as in older shoe stores, it is still digitally fast. The doctor can see bone images within 5 to 10 minutes of asking. He sees bone the hard stuff through which the X-rays cannot penetrate to the film, so unfortunately he cannot see the soft stuff such as muscles. X-rays are great to see fractures but cannot see meniscus tears or blood.

Of course, a blood analysis provides a chemical image of the body but it is an average image referring to the instantaneous average condition. It will tell you whether you have high cholesterol or perhaps confirm something like gout with a high uric acid count, but otherwise it is very limited.

Ultra-sound imaging is immediate. Its principal benefit is that the soft tissue image can be seen in movement. High-frequency sound detects soft tissue and by creating a triangular section mapping tissue in a two dimensional plane one can see movement. It’s particularly good for finding blood clots or things, which you might not have expected in the womb.

Then came the Nuclear Magnetic Resonance Imaging system and the scaremongers bleated once more. Baaa! Baaa! However, removing the word nuclear’ was sufficient to satisfy them and the MRI is now an established medical tool.

With the patient lying at the center of a magnet, in conjunction with radio wave pulses of energy, the MRI scanner can pick out a very small point inside the patient’s body and ask it, essentially, “What type of tissue are you?” The point might be a cube that is half a millimeter on each side. By rapidly scanning and constructing composite images the MRI scanner provides an unparalleled view inside the body. It can see soft tissue, fat, muscles, tendons, menisci, nerves, glands, and even flowing blood. The two-dimensional scans on innumerable slices give a three dimensional view.

There are other imaging techniques, several of which involve injecting radioisotope-tagged markers that can be traced by counters outside the body. All are non-invasive.

A PET Scan for example involves positron radiation from radioactive tracers attached to, say, glucose that is taken up differently by healthy and cancerous tissues. A CT-scan also measures radioactivity from tracers in the body. All these techniques can be tailor made for the patient’s specific problem. They replace the scalpel of prior investigative surgery.

Recently, my knee became very painful. Ouch! So because I had recently come back from a long flight, a blood clot was suspected. Ultra-sound imaging showed that wasn’t true. Phew! A blood test showed that all my chemicals lay within normal bounds so it couldn’t be an excess of uric acid. An X-ray next showed a small piece of loose bone in the joint so an MRI was called for to give better information about other possible loose items such as pieces of meniscii.

It told me that there were no other loose pieces in the knee and, moreover, the single piece of bone wasn’t irritating or doing any harm. It showed me that I had very little arthritic degradation. Instead it showed that the patella (kneecap) was a little worn on the moving surface caused by imbalance. It was a typical runner’s knee to be cured by physiotherapy.

My message to you is to find out more about these techniques and use them. Remember when the doctor has a negative result and doesn’t find anything it is a very positive result for you.

So, “what can you see, John?” a great more than ever before, thus saving the use of the diagnostic knife. But it is not quite so much fun as watching your toe-bones wiggle.