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SPECT OVERVIEW   | HEAR Dr. Kohn

 

SPECT TECHNOLOGY

 

The use of a brain SPECT scan is based on the principal of blood flow.  Areas of increased blood flow take up more Radioactive tracer than areas of less blood flow. Blood flow in the brain is directly related to brain activity. Areas or regions of interest in the brain are related in their demand for blood flow which can be imaged with this specific nuclear test.

 

The basis of the brain image comes from the temporary uptake of radioactive particles; from the blood into the brain tissue. The radioactive particles are tagged" to a drug that flows into the brain. These particles come from the radioactive decay of the element Technetium; TC99. The SPECT Gamma camera system collects these particles and passes them to a complex system which reconstructs a working image of the brain. This snapshot view of the imagination is referred to as a functional image. SPECT is an abbreviation of this process described above:

  Single Photon Emission Computerized Tomography.  

Advances in the field of nuclear medicine over the past 30 years have improved the image quality with these cameras through the modifications of both the camera design and the radiopharmaceuticals developed. The triple headed camera designed by Picker-Marconi is the one that Dr. Kohn uses. Images are acquired in  less than thirty minutes with excellent visualization of the cortex and subcortical regions of interest.
 

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  ADHD BASELINE & ACTIVATION

 

The clinical diagnosis of ADHD is not determined by reliance on brain SPECT imaging.  This test is helpful at times, in viewing the response of the brain at rest and during a continuous performance test; baseline and activation.

 

At times patients with ADHD demonstrate less blood flow to the frontal cortex areas when performing the activation test,  The normal response is the opposite; greater activation - blood flow in the frontal cortical are during this test. 

Normal Patient       

Baseline Scan       

 

   Little Activity         

During Rest          

 

Normal Patient        

Activation Scan        

 

Activity Increases after  Performance Test      

 

 

  ADD Patient        

Baseline Scan      

 

Activity During Rest    

ADD Patient         

Activation Scan      

 

Activity Decreases after  Performance Test      

  

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  SPECT PROCEDURE

 

The procedure takes nearly one hour.  The first 30 minutes requires the patient to relax  before and after the intravenous injection of "Ceretec".  The later 30 minutes requires the patient to rest comfortably on the image table.  

 

An activation study involves injection of Ceretec two to four minutes after a computerized working memory test has begun. When the task is completed the patient then moves to the image table for the same procedure as described above.

 

The state of brain activity during the two minutes following each injection is captured on the scan.  This is referred to as a "functional image".  The actual scan is acquired  30 minutes after the injection.

 

 

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  HOW DR. KOHN USES SPECT TECHNOLOGY

 

S P E C T is used  as a tool in the clinical evaluation process to help view areas of brain activity and relate them to presenting symptoms. Symptoms and signs are clustered based in part, on the brain networks activated. 

 

Symptoms include those observations made by the person or parent, etc while signs refer to those findings noted on clinical examination. Common symptoms include sadness, anger, rage, worry, obsessions-compulsions, fear- panic, fatigue, loss of motivation or will, distractibility, inattention. Common signs include weight loss, agitation, mood lability, illogical, tangential, circumstantial thinking, etc. 

 

 A " network" refers to a system  in which specific properties are common to its components and the interaction of the parts in the system  is essential for the overall property of the system to be maintained. There are natural and man made networks. The most well known man made system is the INTERNET. In nature we think of examples such as spider webs or water ways in which, although parts are separate, there is an overall interaction that form the basis of the operation of the system. 

 

The human brain has developed a system of interconnections that coordinate the many functions that make us who we are; our personality, our aptitude, our interests, our emotional state, etc.  The tug and pull between muscles that move bones occurs differently in the brain. The working of one brain part occurs in coordination with many other parts. Like a traffic officer that directs cars to move in and out of an intersection; brain systems allow one part to function or " come on line" while influencing another part to decrease its function or " come off line".

 

Using SPECT imaging in the field of neurology and psychiatry allows visualization of the components of the many systems that run our emotional state, our motivation level, our concentration and memory ability and more. Brain parts form a network of interacting pieces that maintain the examples I mentioned. 

 

There are very specific parameters set up for measuring brain activity in these networks based on mathematical computations. Each image is acquired through a sequence of steps that accepts and discards the " radioactive counts" of the TC99m radiotracer in accordance with the accuracy limitations of the SPECT GAMMA CAMERA  that measure these counts. The result of the computations is a display that is seen on a scale of color. We use the geographical color scale at the University of Illinois in Chicago because it allows accurate separation of degrees of brain activity. Activity is recorded as relatively more than or less than or normal.

 

Based on the model of networks, brain activation states and my experience comes a very important statement. There is NO one simple "Signature Pattern" of a specific diagnosis! 

 

There are patterns that are common to each diagnosis and patterns that often overlap. Often this is seen clinically as the phenomenon of Co morbidity. This means that more than one condition can be present at one time.  

 

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  WHAT DOES DR. KOHN DO?

 

Dr. Kohn evaluates and treats children, adolescents,
    adults and seniors with the following disorders:
- The spectrum of Attention Deficit Hyperactive Disorder 

- The spectrum of Pervasive Developmental Disorder;
    Autism, Aspergers syndrome.

- Unipolar and Bipolar Depression

- Anxiety states; Panic, Obsessive-Compulsive
   Disorder, Social phobia-anxiety

- Epilepsy and Non-epileptic seizure equivalents;
   Rage, Impulse control disorders

- Post Traumatic Stress Disorder
- Migraine and common headaches 
- Schizophrenia
- Dementia; and memory loss
- Stroke
- Multiple Sclerosis
- Parkinson's Disease
- Child and Adolescent Behavior Disorders

 

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