Testing For Parkinsons Disease
There is no lab or imaging test that is recommended or definitive for Parkinsons disease. However, in 2011, the U.S. Food and Drug Administration approved an imaging scan called the DaTscan. This technique allows doctors to see detailed pictures of the brains dopamine system.
A DaTscan involves an injection of a small amount of a radioactive drug and a machine called a single-photon emission computed tomography scanner, similar to an MRI.
The drug binds to dopamine transmitters in the brain, showing where in the brain dopaminergic neurons are.
The results of a DaTscan cant show that you have Parkinsons, but they can help your doctor confirm a diagnosis or rule out a Parkinsons mimic.
Side Effects Requiring Immediate Medical Attention
Along with its needed effects, ioflupane I 123 may cause some unwanted effects. Although not all of these side effects may occur, if they do occur they may need medical attention.
Check with your doctor or nurse immediately if any of the following side effects occur while taking ioflupane I 123:
Incidence not known
- Difficulty with breathing or swallowing
- reddening of the skin, especially around the ears
- swelling of the eyes, face, or inside of the nose
- unusual tiredness or weakness
Prepping For The Datscan
After a few minutes, a young and artsy-looking woman appears and invites me to follow her into the bowels of the imaging center, to the prep room. She has short, spiky blonde hair with light pink streaks. We sit down and she asks me a series of questions as she checks boxes and writes short notes on a printed form. At one point I interrupt her.
How often do you do a DaTscan? I ask.
Rarely and were one of the few places in town that has the machine its expensive. You must have good insurance, she says.
She gives me a Xanax tablet to relax me and prepares an injection of a radioactive isotope, iodine 123. It will make my head glow for the camera when she sticks me into a machine that wraps around my head like its the contents of a burrito. Watching her work, I try to absorb the multicolored peace sign tattooed on the inside of her pale wrist. I wonder why she chose it and whether it helps her feel calm. The drug kicks-in and I begin to feel more relaxed. I show her the slight tremor in my index finger, and her forehead wrinkles and her lips puff out. After a moment of silence, she says, They ordered this scan for that?
My head begins to hurt. My scalp burns.
Try not to move, he says.
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Using Datscan To Diagnose Parkinson Disease
Am Fam Physician. 2021 Jun 1 103:647-648.
Original Article: Parkinson Disease
To the Editor: The article by Dr. Halli-Tierney and colleagues summarized the diagnosis and treatment of Parkinson disease well. Although the diagnosis is mostly clinical, in more uncertain cases, the addition of a DaTscan can be helpful.1 By confirming normal dopamine activity, the DaTscan can differentiate drug-induced Parkinson-like syndromes from actual Parkinson disease. For atypical presentations that mimic stroke or depression, the finding of diminished dopamine transport can redirect the differential diagnosis and treatment back to Parkinson disease.2 Clinicians should inquire about the closest DaTscan capability in their area. We have sent patients from our tribal health center to a tertiary medical center for their DaTscan because nearby imaging programs do not offer them.
Rasagiline , as a highly selective monoamine oxidase-B inhibitor, works only in the central nervous system and does not block amine oxidation in the gut therefore, it does not provoke malignant hypertension or other excess stimulant adverse effects. Rasagiline has been found by some to slow the progression of Parkinson disease.
Kenneth Renwick, MD, MPH
Datscan Imaging: A Clearer Picture Of Parkinson’s
Parkinsons disease affects one in every hundred people over the age of 60. Until recently, however, doctors had to rely on a clinical evaluation, combined with blood tests and brain studies, to diagnose this common movement disorder. But the results were often inconclusive because there was no test to distinguish Parkinsons disease and related disorders from other conditions that have similar symptoms. As a result, effective treatment could sometimes be delayed while the patient and physician searched for answers.
Now, a recently introduced nuclear imaging test called DaTscan is helping specialists at Orange Coast Memorial evaluate patients with suspected parkinsonian syndromes, of which PD is the most common. The test is especially important because it helps distinguish PD and allied disorders from a look-alike condition called essential tremora disorder characterized by trembling of the hands, head, and occasionally the arms and legs. Although Parkinsons disease and essential tremor both involve involuntary shaking movements that are similar, these disorders require very different treatments, says Daniel Truong, M.D., a internationally known neurologist and medical director of The Parkinsons and Movement Disorder Institute at Orange Coast Medical Center. DaTscan allows us to rule out essential tremor and other non-parkinsonian conditions, which can help lead to a more accurate and timely diagnosis and treatment.
Changes In The Brain
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Role Of Dat Scan In Early Diagnosis And Management
Sensitivities and specificities of DaT scan use are as follows:
- Differentiating essential tremor from PD sensitivity 93% specificity 100%
- Differentiating dementia with Lewy bodies from AD or other dementia sensitivity 93% specificity 86%
In clinically-uncertain Parkinsonian syndrome, 53% accuracy in early diagnosis without the scan versus 86-90% accuracy with the scan has been reported.
In clinically-uncertain Parkinsonian syndrome, 53% accuracy in early diagnosis without the scan versus 86-90% accuracy with the scan has been reported
In general, Dr Tao reported, 50% or more of patients have their clinical management changed following DaT scan changed, depending on whether the technique is being used by a MDS specialist or not. Non-specialists tend to change clinical management strategies in a greater proportion of patients than specialists.
50% or more of patients have their clinical management changed following DaT scan changed
Essential tremor is not difficult to diagnose in most patients but can sometimes be challenging if it is present with symptoms mimicking Parkinsonism. And, he reminded the audience, patients with a long-standing essential tremor are also more likely to develop PD and, therefore, become ET/PD.
Cases demonstrate value of DaT scan in clinical practice
Dr Tao warned that certain medicines that bind to the dopamine transporter can interfere with diagnosis, including cannabis, and need to be discontinued prior to DaT scan.
What Happens During A Datscan
During a DaTSCAN, a very small amount of tracer, specific for the organ or tissue to be scanned, is injected into a vein by a nuclear medicine technologist. Images may be taken during the injection, immediately after the injection, or following a delayed period to allow the tracer to distribute to the organ or tissue of interest. The gamma rays emitted by the tracer are detected by a special camera that is positioned near the organ or part of the body being imaged.
You will need to remain very still for the camera, but it will not touch you. The radiation from a nuclear medicine procedure is comparable to that received during a routine X-ray. The tracer only remains in the body for a short period of time before being eliminated in the urine or stool.
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Why Would My Doctor Order A Datscan
Your doctor may order a DaTSCAN to confirm or rule out a diagnosis, or to see how a medication is affecting your brain or internal organs. SPECT scans may also be ordered to help diagnose or monitor conditions affecting the bones and the internal organs, especially the heart and the brain, and even to manage and stage cancer.
DaTSCAN allows physicians to see which areas of the brain are responding to various stimuli, making it particularly helpful in confirming diagnoses as movement disorders such as Parkinsons Disease, Parkinsonian Syndrome, and Essential Tremor. DaTSCAN can also be helpful in diagnosing and treating traumatic brain injury , attention deficit disorder , attention deficit hyperactivity disorder , and more.
Effective And Efficient Diagnosis Of Parkinsonism: The Role Of Dopamine Transporter Spect Imaging With Ioflupane I
DaSupplements and Featured Publications
Am J Manag Care. 2004 20:S97-S109 Parkinsons disease is a common neurological illness associated with significant patient and payer burden. Its accurate diagnosis is challenging and misdiagnosis is common.1-3 Additionally, overdiagnosis of PD has been observed when only clinical symptoms were used to assess uncertain cases.4 Although experts in movement disorders are able to achieve greater diagnostic accuracy than their primary care or general neurology counterparts, they are still uncertain about the diagnosis in many patients. Adding to this, access to experts may be limited, thus further reducing opportunities for diagnosis.5 Imaging technology has improved considerably in recent years. The 2011 approval by the US Food and Drug Administration of the radiopharmaceutical ioflupane I-123 injection for striatal dopamine transporter visualization using single-photon emission computed tomography offers a new biomarker that can assist in differentiating conditions associated with nigrostriatal degeneration from those movement disorders without this degeneration .6 This publication is based on a roundtable discussion involving a multidisciplinary panel of experts with experience in movement disorders, nuclear imaging, managed care, and patient advocacy, and provides clinical criteria and algorithms to help guide managed care organizations and practitioners in the appropriate use of DaTscan imaging.
Overview of Parkinsons Disease
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New Diagnostic Standards For Parkinsons
Until recently, the gold-standard checklist for diagnosis came from the U.K.s Parkinsons Disease Society Brain Bank. It was a checklist that doctors followed to determine if the symptoms they saw fit the disease. But thats now considered outdated. Recently, new criteria from the International Parkinson and Movement Disorder Society have come into use. This list reflects the most current understanding of the condition. It allows doctors to reach a more accurate diagnosis so patients can begin treatment at earlier stages.
When Is Datscan Helpful
There are situations in which DaTscan can be very helpful in securing a diagnosis when neurologic exam findings are not clear-cut. Although DaTscan cannot distinguish PSP, CBGD, and MSA from PD, studies suggest that it may be able to distinguish drug-induced parkinsonism and vascular parkinsonism from PD.
The FDA indication for DaTscan is for distinguishing between PD and essential tremor . Usually it is quite straightforward for a neurologist to distinguish between the tremors of ET and the tremors of PD. PD tremors occur at rest and are accompanied by slowness and stiffness of the limb, whereas ET tremors occur with action and are not accompanied by slowness and stiffness of the limb. However, some people may have mixed tremor features making the diagnosis more difficult. In those cases, a DaTscan can be very useful.
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How Do I Prepare For My Datscan
Your doctor will review your medical history, and provide general instructions before scheduling your procedure. There is no specific prep for DaTSCAN, and there are only 3 simple instructions. Youll need to drink plenty of fluids the day before and the day of your procedure. The day before your procedure youll need to pick up your medication, and youll need to take your medication as prescribed the night before your procedure. On the day of your procedure, you will arrive early for an injection. After receiving your injection, you may leave and return when scheduled for your procedure.
Who Is Datscan For
DaTscan is not necessary for every Parkinsons patient. For most, the distinct clinical symptoms such as slowness of movement, tremors, and stiffness are sufficient to reach a diagnosis, and the information generated through the scan may not be new and will not alter their treatment plans.
However, in patients with unclear symptoms that overlap with other neurological conditions and for those who do not respond to treatment, DaTscan can be necessary to reach a diagnosis.
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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.
Datscan: A Test To Help In The Diagnosis Of Parkinsons
In 2011, the Food and Drug Administration approved an imaging test to help diagnose PD. In this test, a radioactive tracer, Ioflupane 123I, also known as DaTscan, is injected into the blood, where it circulates around the body and makes its way into the brain. It attaches itself to the dopamine transporter, a molecule found on dopamine neurons. Several hours after the tracer has been injected, special imaging equipment scans the head to detect the presence of DaTscan.
People with PD will typically have a smaller signal in a part of the brain called the striatum, where the ends of the dopamine neurons are meant to be. Here is a normal scan on the left, which would indicate a healthy dopamine system, next to an abnormal scan on the right, which would indicate an unhealthy dopamine system.
It is important to note that conventional MRI imaging will appear normal in PD and is therefore not helpful in confirming the diagnosis. Other atypical parkinsonian conditions, such as vascular parkinsonism however, can have abnormalities on MRI, so the test may be done to rule out other diagnoses.
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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 .
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:
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
Bradykinesia: Slowness of movement in the limbs, face, walking or overall body
Rigidity: Stiffness in the arms, legs or trunk
Posture instability: Trouble with balance and possible falls
Once the patient is at the doctors office, the physician:
Takes a medical history and does a physical examination.
Asks about current and past medications. Some medications may cause symptoms that mimic Parkinsons disease.
Performs a neurological examination, testing agility, muscle tone, gait and balance.
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On The Day Of The Exam
- Drink plenty of fluids and go to the bathroom frequently
- Wear loose comfortable clothing, since you will need to lie still for a period of time.
- Please bring a list of all medications that you are taking name and dosage.
- We want to make your waiting time as pleasant as possible. Consider bringing your favorite magazine, book or music player to help you pass the time.
- Please leave your jewelry and valuables at home.
Before Taking This Medicine
You should not receive DaTscan if you are allergic to ioflupane I-123. Tell your doctor if you have ever had any type of reaction to another contrast agent, or to iodine.
To make sure DaTscan is safe for you, tell your doctor if you have ever had:
a thyroid disorder
if you have ever had an allergic reaction to potassium iodide or Lugol’s Solution.
Older adults may need kidney function tests before receiving DaTscan. Your kidney function may also need to be watched closely after you have received this medicine.
It is not known whether this medicine will harm an unborn baby. Tell your doctor if you are pregnant.
You should not breastfeed within 6 days after using ioflupane I-123. If you use a breast pump during this time, throw out any milk you collect. Do not feed it to your baby.
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How Is Datscan Given
DaTscan is given as an infusion into a vein. A healthcare provider will give you this injection about 3 to 6 hours before your radiologic test.
At least 1 hour before you are treated with DaTscan, you will be given a liquid drink that contains medicine to protect your thyroid from harmful radioactive effects of ioflupane I-123.
Drink plenty of liquid before you receive DaTscan, and for at least 48 hours afterward. Follow your doctor’s instructions about the types and amount of liquids you should drink before and after your test. Ioflupane I-123 is radioactive and it can cause dangerous effects on your bladder if it is not properly eliminated from your body through urination.
Expect to urinate often during the first 48 hours after your test. You will know you are getting enough extra fluid if you are urinating more than usual during this time. Urinating often will help rid your body of the radioactive iodine.