A DaTSCANTM is a nuclear medicine scan which images the dopamine transporter in the brain and is used in the diagnosis of Parkinson’s disease and Dementia with Lewy Bodies.
Parkinson’s disease affects one in 500 people, mostly over the age of 50, but younger people can get it too. The main symptoms of Parkinson’s are tremor, rigidity and slowness of movement and the diagnosis is usually made clinically. Traditional CT and MRI scans of the brain are not able to distinguish Parkinson’s disease and related disorders from other conditions with similar symptoms. Often, the initial symptoms of the disease are vague, making diagnosis extremely challenging. This can lead to delays in diagnosis and treatment.
|NICE guidelines recommend using DaTSCAN in patients with tremor where it is not possible to clinically differentiate Parkinson’s disease from benign essential tremor.|
Patients with Parkinson’s Disease typically begin to experience symptoms after losing 80 percent of the dopamine in their basal ganglia, the region of the brain involved in motor control and movement. DaTSCANTM assists doctors in differentiating between movement disorders that share similar symptoms, such as benign essential tremor. The scan is able to detect the early neuronal degeneration which can occur in Parkinson’s disease and can clinically reclassify the diagnosis in 10-30% of patients.
Whilst DaTSCAN can differentiate Parkinson’s disease from benign essential tremor, the scan can also be positive in a number of variants of Parkinson’s. These are referred to as Parkinson’s plus syndromes and include multiple system atrophy, progressive supranuclear palsy and corticobasal degeneration.
Dementia with Lewy Bodies
Dementia with Lewy Bodies is a type of dementia that shares symptoms with both Alzheimer’s disease and Parkinson’s disease. It may account for around 10 per cent of all cases of dementia but tends to be underdiagnosed. Lewy Bodies are tiny deposits of protein in the nerve cells of the brain. Their presence is linked to low levels of dopamine and a loss of connections between cells.
The symptoms a person experiences will depend partly on where the Lewy bodies are in the brain. Lewy bodies in the striata are closely linked to problems with movement. These are the main feature of Parkinson’s disease. Lewy bodies in the outer layers of the brain are linked to problems with mental abilities (cognitive symptoms), which are characteristic of Dementia with Lewy Bodies.
Symptoms in Dementia with Lewy Bodies include problems with attention and alertness which fluctuate over the course of the day. Visual hallucinations are also common and can be very distressing. Up to two thirds of people with Dementia with Lewy Bodies have movement problems. These symptoms are those of Parkinson’s disease, and include slowness and rigidity of movement with a blank facial expression.
- Provide an early diagnosis of Dementia with Lewy Bodies
- Prevent exposure to medications that may aggrevatesympotms or cause severe reactions.
- Identify commonly occurring and treatable disorders (such as REM sleep behaviour disorder).
|NICE guidelines recommend using DaTSCAN to establish the diagnosis in those with suspected Dementia with Lewy Bodies if the diagnosis is in doubt.|
How does the DaTSCANTM work?
The radiopharmaceutical, or tracer, which is used in DaTSCANTMis Iodine-123 Ioflupane. It is injected into the vein after administering a thyroid blocking agent in the form of oral potassium iodide. This is to prevent unnecessary accumulation of the radiopharmaceutical in the thyroid gland.
The DaTSCANTM binds to the presynaptic dopamine transporters in the brain, in particular the striatal region of the brain. In Parkinson’s disease and Dementia with Lewy Bodies there is a marked reduction in dopaminergic neurons in the striatal region. The tracer binds to the dopamine transporters and gives a semi-quantitative measure and spatial distribution of the transporters.
The scan itself is a single photon emission computed tomography (SPECT) scan of the brain. The patient lies down on the examination couch with their head positioned in the headrest. Often a gentle head restraint is used to minimise motion. The gamma camera rotates around the patient’s head for approximately 30-45 minutes. During this time, it is important that the patient lies still as a three-dimensional image of the distribution of the dopamine receptors in the brain is being created.
Most patients will tolerate the scan very well, and we are used to performing the scans in patients with a tremor. In patients with suspected dementia, it is very useful to liaise with a carer to make sure the patient can attend the appointment. It is also reassuring for the patient to have their carer next to them during the scan.
The scan will be reported by one of our specialist radiologists who have experience in DaTSCANs.
Are you required to make any special preparations?
Please also inform us if you have an allergy or sensitivity to iodine.
If you are taking drugs for the treatment of Attention Deficit Hyperactivity Disorder (ADHD) or Attention Deficit Disorder (ADD), antipsychotics, antidepressants, cocaine, weight-loss medications or smoking-cessation medications, please inform us when making your appointment.
You may eat and drink normally. If you leave the department, you do not need to take any special precautions, but if you stay in the department then you should use the special toilet for nuclear medicine patients.Your technologist will show you where the toilet in the department is.
Are there are any risks?
As the gamma rays are like X-rays, there are small risks associated with being exposed to radiation. However, the radiation decays away over a few hours and the amount of radiation used in medical imaging is very low. This is comparable to the natural radiation we all receive from the environment over about 2 years. In fact, the risks from missing a disorder by not having a scan may be considerably greater than the risks of the radiation. If you are concerned about the risks of the radiation, please speak to a member of our team.
If you are pregnant or breastfeeding
If you are pregnant, or think you may be pregnant, you mustinform the department before attending, and certainly before the radiopharmaceutical is administered.
If you are breastfeeding, please inform the department before attending and you will be advised as to whether you will need to take any precautions.
Can you bring a relative/friend?
Yes, you can, but for reasons of safety, they may not be able to accompany you into the examination room, except in very special circumstances. Please do not bring children with you as they will potentially be exposed to radiation from other patients.
Arriving for your appointment
When you arrive for your appointment, please go to the reception desk, after which you will be shown where to wait until collected by a technologist.
The technologist will explain the procedure, and you have the opportunity to ask any questions. You may be asked some questions about your health, or whether you have had this examination before.
The technologist will then give you the injection of radiopharmaceutical preparation into a vein, generally the one near your elbow. This is just like having blood taken.
There is then a two- to three-hour wait to allow the tracer to be absorbed by the kidneys, during which time you may leave the department.
What happens during the scan?
The DaTscantakes approximately 45 minutes, but after injection of the radiopharmaceutical you will need to wait 3-6 hours before the radiopharmaceutical concentrates in the brain.
One hour before the exam, you will receive a drug to allow you to safely take the iodine required for the scan.
Before the scan, DaTscan will be injected through an intravenous (IV) line into your arm.
For the imaging test, you will be asked to lie on a table and a technologist will position your head in a headrest. A flexible restraint may be placed around your head to help you to not move your head during the scan.
The gamma camera will be positioned above you and you must remain very still for about 30 minutes while images are taken. The scanner will be very close to your head, but will not touch your head.
Will it be uncomfortable?
No. Apart from the injection, you will not feel anything.
How long will it take?
It takes 3-6 hours while the radiopharmaceutical is absorbed into the brain. The scanning process usually takes 30-45 minutes, and your time in the department will be less than one hour in total.
Can I listen to music while I have my scan?
Your technologist will ask you whether you would like to listen to music during your scan. You may bring in a CD or select music from our selection.
Are there any after-effects?
No, the injection causes no side-effects, nor will you feel sleepy. You can drive home afterwards and go about your normal activities.
In addition to mothers who are breastfeeding, parents with young children should notify the radiographer, who will explain that it is advisable not to have prolonged close contact with them for the rest of the day. This is to avoid them being exposed to unnecessary radiation.
When will you get the results?
The scan will be examined after your visit and a written report on the findings will be sent to your referring doctor within 7 days.
The radiopharmaceutical required for this examination is ordered especially for you. If you cannot attend your appointment, please let the department know as soon as possible, so that we can use it for someone else.
We hope that this leaflet has answered your questions, but remember that this is only a starting point for discussion about your treatment with the doctors looking after you. Make sure you are satisfied that you have received enough information about the procedure.