Investigations

Imaging: An introduction for parents of children with JIA

Susan Luxford-Moore, BSc (Hons) Diagnostic Radiography

Throughout the process of your child being diagnosed with Juvenile Idiopathic Arthritis (JIA), and possibly after diagnosis, it is more than likely that they will require a visit to the Radiology Department for some imaging examinations. This article will look at the four main methods of imaging used and what to expect during each of these examinations.

The people you meet in the Radiology Department will mostly be radiographers and radiologists. Radiographers are healthcare professionals who will take x-rays and perform some types of scans. Radiologists are doctors who have specialist training in imaging. They interpret the images and make a report on what can be seen. This report is sent back to the doctor who originally requested the examination to help aid in the diagnosis or treatment plan. Radiologists will also perform some scans.

X-ray

X-rays are essentially photographs of the inside of the body. They provide a good overview of the area and are a quick and easy process. They are very helpful when looking at bones but also some soft tissue areas, such as the lungs.

The x-ray room usually has dimmed lighting and, depending on the body part being examined, your child may be asked to lie down on a table or stand against a special board. The radiographer will then bring the ‘camera’ over and shine a light on the area being examined. Once they are ready and the patient is in the correct position, they will go behind a screen and take the x-ray. It is very important for your child to keep still, as otherwise the image will be fuzzy! Parents are often allowed to accompany their child into the room, unless they are pregnant, and will be asked to wear a lead coat to prevent them from receiving a radiation dose. The lead coat is quite heavy but you will only have it on for a few minutes.

X-ray examinations do use ionising radiation but the dose is so small that parents should not worry about it having an effect on their child. Many protocols are in place to keep the dose to an absolute minimum and to make sure only the area under examination is exposed to the radiation.

X-rays are also sometimes used to help during procedures, such as joint injections, so the doctor/surgeon can check the position of where they are going to inject, or place an implant.

Ultrasound Scan

As the name suggests, this type of scan uses sound waves to produce the images. There is no radiation involved. Ultrasound scans are very good at looking at soft tissue structures as well as inside joints.

The room is dimly lit to allow the images to be seen clearly on the monitor. The patient will be asked to lie up on the examination table and a special type of gel is then applied to the area being examined and the radiographer, or radiologist, will move a ‘probe’ over this to obtain the images. Again, this is a painless and quick procedure and, as a parent, you will usually be able to stay with your child throughout the examination.

Ultrasound scans can also be used to help guide doctors during procedures such as joint injections.

Computed Tomography (CT) Scan

CT scans use radiation to take multiple images of the body in different orientations: side-to-side, back-to-front, and top-to-toe. These images can then be looked at individually or reconstructed into a 3D image. CT scans are used to examine various parts of the body including bones, organs, and blood vessels.

The scanner itself is shaped like a ring doughnut, and the table moves through the centre of it. The table moves back and forth whilst the images are acquired but, again, it is important the patient remains very still throughout the examination. These scans are usually relatively quick and painless but it does depend on the area being scanned as to how long they take.

However, the use of CT scans in children is limited as much as possible due to the fact that CT scans do give a slightly higher radiation dose. Should your child be referred for a CT scan, do not worry as the doctors will have discussed this and decided this is the best examination for them. Like x-rays, the radiation dose is kept as low as possible throughout the scan.

Magnetic Resonance Imaging (MRI) Scan

MRI scanning does not use radiation. Instead, a very strong magnet and radio frequency pulses are used to create the images. This type of scan is useful for examining most parts of the body, including joints, internal organs, and blood vessels. It gives particularly good soft tissue detail. MRI scans also take multiple images in different orientations to help give a detailed picture of the area.

Prior to the scan you will be asked to complete a safety questionnaire about your child. It will ask about any implants or recent surgery your child may have had. Generally, the scan is safe for most people to have but there are certain implants, like pacemakers, that are not allowed in the scanning area. The scanner itself is like a short tube and the table goes inside. Often a piece of equipment may be placed over, or around, the body part which is being examined. This is called a ‘coil’ and helps obtain the images. Depending on which area is being scanned the patient may be positioned head first or feet first inside the scanner. Once the table is in position it may only move slightly until it comes out again at the end of the examination. When the scanner is working it is very noisy, like a road drill, so the patient will be provided with headphones to wear as ear protection. Usually these also allow music to be listened to during the scan, so it is worth taking your favourite CD. Some MRI departments also give patients the option to watch a DVD during the scan. These scans take a minimum of around fifteen minutes and, again, it is really important to keep still.

As a parent you will usually be able to accompany your child into the scan room and stay with them for the duration of the scan. However, you must be able to comply with the safety requirements prior to entering the scanning area too. You will also be provided with ear protection to wear. Due to the length of time some scans take and the fact that is it so important to keep still, some children will undergo their MRI scan under a general anaesthetic. This is dependent on the age of the child and the body part being examined, so each hospital will advise accordingly. In this instance parents are not usually able to accompany their child during the scan.

Contrast Agents

Sometimes it is necessary to administer a contrast agent or ‘dye’ to help provide extra information. The contrast agent that is used in CT scans is iodine based, whilst a gadolinium-based agent is used during MRI scans. Both are injected into a vein, usually in the arm. You will also be asked safety questions relating to these agents prior to the scan. The iodine-based contrast can sometimes give patients a metallic taste in their mouth, or a flushing feeling over their body, but these do not last for long. The MRI contrast does not usually have any side-effects although it may feel a little cold as it is injected in. Both are colourless and will pass naturally as they are excreted through the kidneys. Contrast agents are sometimes required to be taken orally in a drink prior to the scan, if areas such as the bowel are being examined.

Contrast agents will help show areas of inflammation, infection, and blood flow. They can also help distinguish scar tissue in the cases of patients who have had recent surgery. The radiologist will usually decide if it is necessary to administer these depending on the clinical history of the patient.

A Final Word

Ask about anything that is concerning you, or your child, prior to the examination, no matter how silly it may seem. If worries can be reduced then children are likely to be more co-operative and better images are obtained, aiding their diagnosis and treatment.