What Are The Pitfalls Of Datscan
DaTscan will appear abnormal in any disease in which there is a loss of dopamine nerve endings in the striatum. Therefore, Parkinson-plus syndromes, discussed in a prior blog, such as Progressive supranuclear palsy , Corticobasal ganglionic degeneration and Multiple system atrophy all typically demonstrate abnormal DaTscans. DaTscan therefore cannot be used to distinguish between these syndromes.
Every medical test has a false positive and a false negative rate. This means, that it is inevitable that in a certain percentage of people who have PD, the DaTscan will be read as normal and in a certain percentage of people without PD, the DaTscan will be read as abnormal. Results of any medical test that is performed, must therefore be considered within the entire clinical context.
What Are The Limitations Of The Test
Currently, DaTscan that is in clinical use is not quantitative, which means that the test is not designed to determine how impaired the dopamine system is just whether it is or not. This means that the test is not used to tell you whether the disease has progressed over time and is not used to follow a patients disease. It also is not used currently as a clinical test to screen for the disease before motor symptoms are evident. Because of these limitations, the search continues for additional measurable indicators, known as biomarkers, to help diagnosis and manage PD.
Tips and Takeaways
- DaTscan is a test that can help in the diagnosis of PD, although in most situations a clinical exam done by a neurologist offers the same information.
- Neurologists are skilled to diagnose PD through a clinical exam. While the exam to some may seem very basic and thus a PD diagnosis subjective or questionable, neurologists are well-trained to assess and diagnose with confidence.
- DaTscan may be useful in distinguishing PD from certain conditions, but not from others, so talk with your neurologist about whether DaTscan would be useful in your specific situation.
- DaTscan is not a test used for monitoring PD progression. It can be used to help clarify a PD diagnosis, but it is not a test you would undergo multiple times during the course of your disease.
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Dr. Rebecca Gilbert
Is Early Diagnosis Possible
Experts are becoming more aware of symptoms of Parkinsons that precede physical manifestations. Clues to the disease that sometimes show up before motor symptoms and before a formal diagnosis are called prodromal symptoms. These include the loss of sense of smell, a sleep disturbance called REM behavior disorder, ongoing constipation thats not otherwise explained and mood disorders, such as anxiety and depression.
Research into these and other early symptoms holds promise for even more sensitive testing and diagnosis.
For example, biomarker research is trying to answer the question of who gets Parkinsons disease. Researchers hope that once doctors can predict that a person with very early symptoms will eventually get Parkinsons disease, those patients can be appropriately treated. At the very least, these advances could greatly delay progression.
Parkinson’s Disease and Movement Disorders Center
Our center provides compassionate and timely treatment to patients with movement disorders, such as dystonia, ataxia, essential tremor and similar conditions. But our mission goes beyond patient care excellence. By offering educational events and support groups, we empower patients and caregivers to become better partners in their health.
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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.
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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Am I Convinced That I Have Pd
Three years after my diagnosis, I am still struggling to find relief from my symptoms and slow the progression of this disease. I exercise, eating a mostly vegan and gluten-free diet, take Sinemet , and use the Neupro transdermal patch. I am working with my current neurologist to fine-tune my medication cocktail.
I had wondered whether I did have PD since Ive never had an aha moment in which I feel somewhat normal after taking medications. People tell me I look fine and they dont observe any external signs of the disease. However, my tremors are internal and I feel horrible and constantly fatigued.
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.
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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.
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 .
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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.
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.
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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.
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.
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Passive Manipulation Of Limbs
To test for the presence of rigidity, we need to passively manipulate the limbs of the patient. However, If the disease is in its early stage or the symptoms are well controlled with medications, we may not be able to see rigidity. We will need to use some activation maneuvers, that basically consist in performing repetitive movements with the limb contralateral to the one that is being tested.
Also, there are two types of rigidity:
– Lead-pipe rigidity: where the tone is uniformly and smoothly increased throughout the entire range of movement
– Cogwheel rigidity: where a tremor is superimposed on the hypertonia, making the movement irregular due to intermittent increase and reduction of tone
Upper Extremity Testing
For the upper extremity the most sensitive joint where to check for rigidity is the wrist. To uncover rigidity, passively rotate the wrist and feel for a resistance to the movement. It is very important that the arm of the patient is fully relaxed when rotating the wrist. To do this, place your proximal hand under the patients forearm, while your distal hand grabs and rotates the wrist of the patient. When rigidity is present, the range of motion will be preserved but you will feel a resistance in performing the movement.
Wrist rotation with activation maneuver.
It is also possible to test for rigidity in the elbow by passively flexing and extending the forearm.
Elbow flexion-extension with activation maneuver.
Lower Extremity Testing
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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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 .
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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Other Tests Used To Diagnose Parkinsons Disease
Diagnosis of PD is generally made using a medical history and a physical exam. In addition to these tests, the patient presenting with Parkinsonian symptoms is usually given treatment with the medication levodopa. The relief of symptoms with levodopa is a sign that symptoms are caused by PD.6
An active area of research is discovering biomarkers, which are molecules in the blood, urine, or cerebrospinal fluid that can reliably diagnose Parkinsons disease.
The Role Of Mri And Datscan In Vascular Parkinsonism: A Case Report
A. Tran, M. Amin, R. Burns
Location: Exhibit Hall C
Objective: The role of MRI and DAT scan in Vascular Parkinsonism: A Case Report
Background: DaTscan has become a widely used clinical tool to help clinicians with challenging diagnoses. DaTscan can help distinguish idiopathic Parkinson Disease from secondary forms of Parkinsonism such as vascular Parkinsonism . The integrity of the nigrostriatal dopamine pathway can be assessed using single photon emission computed tomography with dopamine transporter radioligands. DaTscan would be abnormal in PD and normal in VD. While a meta-analysis by Brigo showed high sensitivity and specificity in differentiating PD and VD using DaTscan, reliance on DaTscan alone may be misleading in certain cases.
Methods: Case study
: Although DaTscan has been shown to have high sensitivity and specificity by many studies, the test has limitations because in most studies the gold standard used is the clinical diagnosis made by a movement disorders neurologist and not a neuropathological confirmation. Therefore, the true diagnosis is unknown false positive or false negative scans can occur, which highlights the needs for integration of various clinical findings and imaging tools . This case illustrates an abnormal DaTscan in a patient with VD.
References: Brigo F, et al. FP-CIT SPECT may be a useful tool to differentiate between Parkinsons disease and vascular or drug-induced parkinsonisms: A meta-analysis. Eur J Neurol 2014 21:1369-1376.
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