DAT Scan: Can it Really Tell Me I have PD? : By Dr. De Leon

Dat Scan (Ioflupane I 23 injection also known as phenyltropane) is a radio pharmaceutical agent injected into the veins of a patient known as SPECT nuclear medicine test. When this test was approved in was under the premise that it will be an added tool in the armamentarium of the neurologists/ movement disorder specialist to help decipher difficult cases.

So, the answer to the question…can it tell you have PD? – NO!

The test can’t confirm you have PD! – it can only tell if there is abnormality in the dopamine system which can include any and all of the Parkinson’s plus syndromes including Parkinson’s disease. If abnormal it means there is a problem in the dopamine system period.

Furthermore, like any test is user dependent. My husband who is a neuroradiologist in a small community who has extensive experience in reading PETs for lots of disease and specializes in the brain would not give an accurate reading of a DATSCAN as his colleagues up the road in Houston at the medical center who do hundreds of them.  Since the only PET scans of the brain that have been FDA approved are for diagnosis of dementia- there are standard things that the radiologists look for by guidelines set by the Academy of Radiology who also mandate general training in reading of these tests across the border to all practicing radiologist to maintain their credentials. However, no such mandate has been given in the reading in SPECT or DAT scans  for diagnosis of PD and only those that are in academic centers who have seen hundreds of these studies are actually the only ones qualified to give an expert opinion as to the “quantitative” measure of the uptake in the brain.

If you have received a diagnosis of PD from an expert specialists in movement disorders and are improving or responding to dopamine therapy there is no reason or gain by getting a Dat scan. Likewise, if someone suspects of Parkinsonism due to PSP, MSA etc. no added benefit will be obtained by getting this scan, you might in fact be wasting your money ($2500 to $5000) and time.

This test was only intended to be used as another diagnostic tool to help decipher between dopamine and non dopamine diseases which can mimic PD. Now it is over used unfortunately for the wrong reasons. The FDA only intended to be used to differentiate between essential tremors and PD. In my humble professional opinion, Dat scans are not required for treatment or diagnosis and only place for a Dat scan is in academics for studies or in rare cases where a procedure like DBS or Pallidotomy is being considered and physician is not sure if treating essential tremors vs. PD; which if this is the case, I would be reluctant to have a brain surgical procedure when clinical diagnosis is in question! This invariable will lead to poor outcome… many other treatments can be employed until diagnosis is certain.

Another thing because the trace used to measure dopamine activity is radioactive and expensive is not ordered till the day or night before the test. Thus, if you decide to cancel at the last minute because not feeling well you are causing the facility to lose a lot of money and some facilities may even charge you for it. If you have history of thyroid disease or take thyroid replacement you may not be able to do the test.

So short and long …Doing a DAT SCAN CAN NOT TELL ANYONE THEY HAVE PD – do not be fooled by those that claim otherwise!!! Parkinson’s unfortunately still remains primarily a clinical diagnosis and ONLY way to diagnosed with 100% certainty is brain biopsy or at autopsy. However, there is a caveat, with more studies being done in academic centers understanding and standardization of DAT scan reading is increasing slowly among those involved in the field. at the same time we are slowly gaining knowledge of PD and its varying presentations. Therefore, it is conceivable that in the near future, we might be able to combine the knowledge of two to predict and detect patients who will develop PD.

According to a new study, Danna Jennings, MD, Clinical Research Director at the Institute for Neurodegenerative Disorders in New Haven, and colleagues have attempted to do just this via the Parkinson Associated Risk Syndrome (PARS) study to identify a large-scale cohort of individuals at risk for Parkinson’s disease using olfactory testing and DAT imaging. What they have found is that although no one had PD symptoms at baseline despite abnormal DAT scans or reduced ability to smell ; 46% of individuals with loss of sense of smell combined with a deficit on the DAT scan have shown to develop clinical features of Parkinson’s disease within four years.

“The knowledge that comes from this study will have important implications for the recruitment of individuals for future neuroprotective trials,” stated Dr. Anthony Lang, Director of the Movement Disorders Clinic at Toronto Western Hospital. Remember, in a previous blog “Thinking Outside the Brain for a Parkinson’s Cure,” I commented that often trials fail or are doomed to fail from the start when it comes to finding neuroprotective agents because we often don’t even have the right diagnosis. If we are able to successfully predict who will develop PD from these early markers: 1) we can institute treatment a lot earlier in hopes of retarding or slowing progression and 2) trials may have a greater chance of success than previously; because we may no longer have to wait until a patient’s disease evolves to the motor stage causing obvious manifestations of Parkinson’s disease in order to include in “early –stage” trials which by definition is no longer early since by then these patients have lost at least 50% of their dopamine producing neurons.

Source: Olfactory Testing and DAT Imaging May Lead to Early Detection of Parkinson’s disease. Neurology Reviews. 2014 22(8):18-21.

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Dr. M. De Leon is a movement disorder specialist on sabbatical, PPAC member and research advocate for PDF (Parkinson’s Disease Foundation); Texas State Assistant Director for PAN (Parkinson’s Action Network). You can learn more about her work at http://www.facebook.com/defeatparkinsons101 you can also learn more about Parkinson’s disease at www.pdf.org or at www.wemove.org; http://www.aan.org, http://www.defeatparkinsons.blogspot.com All materials here forth are property of Defeatparkinsons. without express written consent, these materials only may be used for viewers personal & non-commercial uses which do not harm the reputation of Defeatparkinsons organization or Dr. M. De Leon provided you do not remove any copyrights. To request permission to reproduce release of any part or whole of content, please contact me at deleonenterprises3@@yahoo.com contributor http://www.assisted-living-directory.com Contributor http://www.lavozbrazoriacounty.com

 

Categories: biomarkers in parkinson's, parkinson's disease, parkinsons health and beauty tips, research, research in parkinson's diseaseTags: , , ,

3 Comments

  1. Jan Mueller

    I was diagnosed about 14 months ago w PD based in DaT scan. Only clinical symptoms are right hand tremor and R.E.M. Sleep behavior disorder which I have had since I can remember. In fact two of my children have sleep behavior issues ranging from night terrors at a young age, sleepwalking, and vivid dreams and waking hourly as adults. Not quite sure what to do at this point. Neurologist says PD but admits no progression in the last year. My primary physician says not PD but hasn’t diagnosed anything. Several other physicians have said not PD but nobody is willing to throw me a diagnosis or give me advice. Not willing to take any medication as long as I feel I am functional but do not know where to go for advice at this point. Any suggestions?

    • I am sorry that you are in a conundrum..it can be very confusing. unfortunately, we as neurologists/mds still are bound by our clinical criteria before committing to diagnosis, if dat scan abnormal means there is some dopamine abnormality most likely however this could be any of the dopamine syndromes including pd, msa, psp. surely you could be one of those rare patients that have only rest tremors ( extremely rare) but I really would not expect huge changes within 14 months for regular pd… one of my suggestions would be to treat rest tremor with amantadine , artane or even dopamine agonist ( not as good as other two for tremors) but in case it does turn out to be pd you would not have depleted/stressed your brain/body as much.. discuss thoroughly with your physician particularly pros and cons of treatment and no treatment…best of luck ..I hope I shed some insight….

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