Should I Get A Datscan Or Pet Scan To Confirm My Diagnosis Of Parkinsons Disease
You can find out more about NPFs National Medical Director, Dr. Michael S. Okun, by also visiting the NPF Center of Excellence, University of Florida Center for Movement Disorders & Neurorestoration.
This past month, the FDA approved DaTscan , a radiopharmaceutical agent which is injected into a patients veins in a procedure referred to as SPECT imaging. DaTscan is an important addition because it is anticipated to be more widely available than other techniques and it has received several major endorsements from leading scientists.
One of the most frequently asked questions about Parkinsons disease on NPFs Ask the Doctor web-based forum is whether or not to pursue DaT or PET scanning to confirm a diagnosis of Parkinsons disease. In this months Whats Hot column, we offer a review of the subject in light of the recent FDA approval.
The new DaT scans use a substance that tags a part of a neuron in the brain where dopamine attaches to it, showing the density of healthy dopamine neurons. Thus, the more of the picture that lights up, the more surviving brain cells. If the parts of the brain where dopamine cells should be remain dark in the scan, an expert reader may diagnose early brain degeneration. This could mean either Parkinsons disease or parkinsonism.
An example DaTscan is shown below and it demonstrates essential tremor on the left , and a parkinsonian syndrome on the right .
Tests Used In Establishing The Cause Of Parkinsonism
PET is a radiotracer-based method that can assess the in vivo function of the dopaminergic and other neurotransmitter systems. DOPA PET is a reliable tool to establish nigrostriatal cell loss but not very practical in clinical practice because the technique is only available in a limited number of centers, is expensive, and expertise in cerebral PET imaging is essential .
DAT SPECT imaging – a practical, less expensive, and more widely available technique than DOPA PET – has been incorporated in most centers as diagnostic tool . DAT tracers like FP-CIT are typically used. Recent studies have shown that DAT SPECT imaging might be a sensitive method to establish nigrostriatal dopaminergic degeneration . For example, people with subclinical and even preclinical PD already have clear deficits of the nigrostriatal pathway . Also, if the scan does not show a nigrostriatal deficit, it is highly unlikely that the patient suffers from symptoms caused by nigrostriatal cell loss . SPECT with tracers labeling postsynaptic dopamine D2/3 receptors shows a relatively low diagnostic accuracy, 59 to 80% sensitivity and 46 to 50% specificity in differentiating PD from non-neurodegenerative diseases .
Hyperechogenicity in the area of the midbrain has been consistently found in 79 to 90% of patients with PD using TCS . However, in 6 to 12% of healthy volunteers, hyperechogenicity of the substantia nigra is also found . This is even higher in patients with essential tremor .
Would I Still Have Gotten A Datscan
It was important for me to have confirmation other than my symptoms of abnormalities in my brain. I think this scan can be used as a baseline to follow my disease progression.
So, yes, I would have still gotten this test, although the $2,000 out-of-pocket cost upfront may have given me pause.
Note: Parkinsons News Today is strictly a news and information website about the disease. It does not provide medical advice, diagnosis or treatment. This content is not intended to be a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your physician or another qualified health provider with any questions you may have regarding a medical condition. Never disregard professional medical advice or delay in seeking it because of something you have read on this website. The opinions expressed in this column are not those of Parkinsons News Today or its parent company, BioNews Services, and are intended to spark discussion about issues pertaining to Parkinsons disease.
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What’s Hot In Pd An Update On Dat Scanning For Parkinsons Disease Diagnosis
In 2011, the FDA approved a diagnostic test for Parkinsons disease. The DaTscan is a radiopharmaceutical agent which is injected into a patients veins in a procedure referred to as SPECT imaging. DaTscan, when it was approved, was considered an important addition to the armamentarium of the bedside clinician. In 2011 I wrote a Whats Hot column on DAT scanning, and this month I will update that posting and bring everyone up to date on the impact of this test.
One of the most frequently asked questions about Parkinsons disease on NPFs Ask the Doctor web-based forum is whether or not to pursue DaT or PET scan to confirm a diagnosis of Parkinsons disease. The short answer is that the DaT test is over-used in clinical practice, and is only FDA approved to distinguish potential Parkinsons disease from essential tremor. In fact, the test only tells the clinician if there is an abnormality in the dopamine transporter, and does not actually diagnose Parkinsons disease . PET is also overused, though it can be a more powerful diagnostic tool when in the right expert hands.
The new DaT scans use a substance that “tags” a part of a neuron in the brain where dopamine attaches to it, thus showing the density of healthy dopamine neurons. Thus, the more of the picture that “lights up”, the more surviving brain cells. Dark areas could mean either Parkinsons disease or parkinsonism.
Selected References
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 Parkinsons 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 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 patients 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.
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How Does Predicting Parkinsons Disease Severity Help Doctors And Patients
Parkinsons is a progressive disease patients symptoms gradually get worse over time. However, some develop more debilitating symptoms more rapidly than others. At the moment, doctors are unable to predict an individual patients clinical course, or make a prognosis of a persons disease when they are newly diagnosed.
Being able to make predictions by looking at the data on the initial scan allows the doctor to anticipate, and therefore treat severe symptoms early on. Especially such symptoms as cognitive impairment, psychosis and falling.
If doctors can predict the likely course of a disease, they can design more informative clinical trials, the authors added. Volunteers could be placed into groups according to their predicted disease progression.
Prior studies had tried to see whether the DaTscan might be used for Parkinsons disease diagnosis. This study provides the most compelling evidence yet that this type of brain scan could be used to predict the progression of Parkinsons, both its long-term motor and non-motor progressions.
What To Expect During A Datscan
Before the DaTscan, it is essential to discuss the patients medical history with the doctor. For instance, some medications may interfere with the imaging and may need to be discontinued.
The radioactive agent that is injected into the patients bloodstream before the imaging takes some time to reach the striatum region of the brain where cells carrying DaT are usually found. After injection, the patient may need to wait for three to six hours before receiving the SPECT scan to visualize DaT distribution in the brain. The scan itself can take 45 minutes to an hour.
The radiologist will then send the brain scans to the neurologist who will explain the results to the patient.
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Diagnosis Of Parkinsons Via Datscan And Clinical Exam Are Similarly Accurate
Despite the DaTscan being available to help diagnose Parkinsons, in most clinical situations, a DaTscan will not add information to what can be gleaned from the clinical exam. One study actually demonstrated that the accuracy of diagnosis in early PD was the same whether the diagnosis was reached using clinical exam or using DaTscan.
How A Diagnosis Is Made
The bedside examination by a neurologist remains the first and most important diagnostic tool for Parkinsons disease . Researchers are working to develop a standard biological marker such as a blood test or an imaging scan that is sensitive and specific for Parkinsons disease.
A neurologist will make the diagnosis based on:
- A detailed history of symptoms, medical problems, current and past medications. Certain medical conditions, as well as some medications, can cause symptoms similar to Parkinsons.
- A detailed neurological examination during which a neurologist will ask you to perform tasks to assess the agility of arms and legs, muscle tone, gait and balance, to see if:
- Expression and speech are animated.
- Tremor can be observed in your extremities at rest or in action.
- There is stiffness in extremities or neck.
- You can maintain your balance and examine your posture.
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Referral To A Specialist
If your GP suspects Parkinson’s disease, you’ll be referred to a specialist.
This will usually be:
- a neurologist, a specialist in conditions affecting the brain and nervous system
- a geriatrician, a specialist in problems affecting elderly people
The specialist will most likely ask you to perform a number of physical exercises so they can assess whether you have any problems with movement.
A diagnosis of Parkinson’s disease is likely if you have at least 2 of the 3 following symptoms:
- shaking or tremor in a part of your body that usually only occurs at rest
- slowness of movement
- muscle stiffness
If your symptoms improve after taking a medication called levodopa, it’s more likely you have Parkinson’s disease.
Special brain scans, such as a single photon emission computed tomography scan, may also be carried out in some cases to try to rule out other causes of your symptoms.
How Does A Datscan Help With The Diagnosis Of Parkinsons
A datscan only helps with the clinical diagnosis of Parkinsons Disease by ruling out similar conditions. The following US site explains how:. http://www.memorialcare.org/about/stories/datscan-imaging-clearer-picture-parkinsons I have read up on ET at it doesnt seem to be that.
I mentioned a DaTscan, but he said the test is not entirely conclusive. He also indicated that DaTscan results likely would not change his prescribed course of treatment for me. His view was that the best way to confirm a PD diagnosis is to give a patient the medication levodopa to see if PD symptoms disappeared.
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Dat Scan In Daily Practice Making Pd Differential Diagnosis Easier
Correctly diagnosing Parkinsons disease can be challenging, especially when based solely on medical history and physical examination techniques. While these form the basis of any diagnosis, Tao Xie, Chicago, USA, during a corporate-sponsored symposium at MDS 2018, explained how he uses DaT scan, in his everyday clinical practice.
DaT scan is a single photon emission computer tomography nuclear imaging technique which uses a 123Iodine – labelled ligand bound to the dopamine transporter to visualize functioning at the presynaptic dopaminergic neural terminal. A reduced DaT signal reflects presynaptic functional dopaminergic neuron loss.
When Do You Get Results From A Pet Scan For Parkinsons
PET scans are usually more extensive and detailed than similar tests that are available. Despite this, test results can usually be given within one to two days after the scan. National Parkinson Foundation: Should I get a DaT scan or PET scan to confirm my diagnosis of Parkinsons disease? Radiology-Info.org: PET Scan and Parkinson Disease.
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What Doctors Look For When Diagnosing Parkinsons
Certain physical signs and symptoms noticed by the patient or his or her loved ones are usually what prompt a person to see the doctor. These are the symptoms most often noticed by patients or their families:
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Shaking or tremor: Called resting tremor, a trembling of a hand or foot that happens when the patient is at rest and typically stops when he or she is active or moving
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Bradykinesia: Slowness of movement in the limbs, face, walking or overall body
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Rigidity: Stiffness in the arms, legs or trunk
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Posture instability: Trouble with balance and possible falls
Once the patient is at the doctors office, the physician:
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Takes a medical history and does a physical examination.
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Asks about current and past medications. Some medications may cause symptoms that mimic Parkinsons disease.
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Performs a neurological examination, testing agility, muscle tone, gait and balance.
Response To Parkinsons Drugs
After examining you, and depending on the severity of your symptoms, your specialist may suggest you take medication for Parkinsons. If your symptoms improve after taking Parkinsons medication for a few weeks or months, your specialist may confirm a Parkinsons diagnosis. However, some people with other forms of parkinsonism will also respond well to these drugs.
Your specialist may suggest you have a scan to help make a diagnosis. However, scans alone cant make a definite diagnosis of Parkinsons, so they are not commonly used.
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What Is Essential Tremor And How Is It Different To A Parkinsons Tremor
A tremor is a rhythmical, involuntary movement that affects a part of the body, such as the hand.
Essential tremor is the most common type of tremor. Its most noticeable when your hands are doing something and it usually affects both the right and left sides of the body equally. Essential tremors often lessen when your body is resting.
Unlike an essential tremor, a Parkinsons tremor is most obvious when the affected body part is resting and tends to be less noticeable with movement. It usually starts on one side of the body and may progress to the other side as Parkinsons develops.
The time it takes to get a diagnosis can vary from person to person. Some people may receive a diagnosis of Parkinsons quite quickly, but for others it may be a long process. This can be due to a number of things, including your medical history, your age and what symptoms you have.
Your specialist may wish to rule out other causes of your symptoms first and see how you respond to treatment. This may take some time, and, as already mentioned, there is currently no definitive test for Parkinsons.
How you respond to treatment may help your specialist make a diagnosis. Keeping a diary or record of your symptoms will give the specialist more information to guide their decision.
Because the symptoms of Parkinsons are sometimes similar to other forms of parkinsonism, people can sometimes be misdiagnosed.
What Is A Datscan
A DaTscan is an imaging drug, also called Ioflupane I 123 or phenyltropane, that acts as a radioactive tracer for dopamine transporters within the brain. This drug was approved by the FDA in 2011. It may help distinguish the diagnosis of essential tremor from Parkinson’s syndromes, like Parkinsons disease or Parkinsons disease dementia.
The drug is administered during the SPECT scan. This scanning technique gathers images of a particular area in the brain called the striatum, a cluster of neurons in the subcortical basal ganglia of the forebrain. The striatum helps facilitate the transportation of dopamine.
DaTscan is injected into the patients bloodstream and eventually circulates to the brain. The tracer attaches itself to a molecule found on dopamine neurons in the striatum called the dopamine transporter . The patient then undergoes a SPECT scan which will produce an image of the dopaminergic neuron terminals that remain available in the striatum.
In patients with a diagnosis of Parkinsons disease, or parkinsonism , this area of the brain will show dark. This indicates the loss of dopamine-containing nerve cells within the brain, a hallmark of the disease.
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Data Extraction And Quality Assessment
Data were extracted by two reviewers independently and were recorded in absolute numbers. Where proportions only were reported the absolute figure was recalculated. Data on clinical utility following imaging with DaTscan, scan technical characteristics ), and baseline characteristics of studied patients were extracted . Change in diagnosis was defined as any change in the patients assigned or suspected diagnosis following disclosure of the results of the imaging scan. Change in management was defined as any changes that the study authors recorded as changes in treatment or further investigations, such as drug changes , referral for counselling or physical therapy following the disclosure of DaT imaging results. Results were compared, and discrepancies between the two reviewers were resolved in a meeting.
Risk of bias assessment was carried out on all studies using an adapted form of the QUADAS-2 checklist amended by the study authors to fit studies of clinical utility, rather than diagnostic accuracy. A copy of the amended QUADAS-2 checklist is provided in Supplementary data . The risk of bias assessment was used independently of the quantitative meta-analysis.