* Plan to Compare MOST-EEG to SPECT Brain Imaging: Parkinson’s Disease Drug Study
admin | Wednesday, January 6th, 2010 | No Comments »For some studies, MOST-EEG might be an attractive alternative to SPECT nuclear brain imaging. This is for 3 main reasons: (1) MOST-EEG is inexpensive relative to SPECT, (2) MOST-EEG requires data collection procedures that are less complex than SPEC (no radio-tracers, or nuclear medicine protocols), and (3) MOST-EEG offers high-time resolution functional analysis that reveals the time-coordination among active areas of the brain. To show that MOST-EEG can be used in place of SPECT in some studies, it is necessary to evaluate MOST-EEG in replications of some prior SPECT studies. This article proposes such a replication with the addition of a drug comparison component, and compares the requirements of SPECT and MOST-EEG.
Why it is Worthwhile Using MOST-EEG Instead of SPECT
It is worthwhile using MOST-EEG in place of SPECT methods in some studies for reasons relating to the additional complexities, resources, and costs associated with SPECT that do not exist for MOST-EEG. Using SPECT to investigate brain function requires:
- a radio isotope tracer that participants ingest prior to scanning,
- a facility to store and prepare radioactive materials,
- a time-sensitive paradigm that considers the half-life and uptake of the tracer,
- a physically large radio isotope scanner (expensive to purchase, operate and maintain),
- and a facility to house the isotope scanner.
In contrast, all that is required to use MOST-EEG to investigate brain function is:
- EEG equipment (small in size, inexpensive to purchase, inexpensive to operate and maintain).
In addition to its simplicity and low cost, MOST-EEG provides information that SPECT does not. This includes: (1) millisecond resolution time-varying changes in brain function, and (2) estimates of coordination relationships among active areas of the brain.
Hence, MOST-EEG is an attractive alternative to SPECT because it minimizes the costs and complexities associated with data acquisition and facilitates estimates of time-varying brain function and functional coordination among areas of the brain. An example result obtained using MOST-EEG is available on http://www.spatialbrain.com (opens new window). Figure 1 below shows a comparison of SPECT equipment (left-side) and the equipment used for MOST-EEG (right-side).
 SPECT Camera (Hospital Facility) |
 EEG Equipment (Office) |
The Study We Propose
Multiple investigations using MOST-EEG which yield results that are comparable to past SPECT results can demonstrate that MOST-EEG is indeed an alternative to SPECT. The remainder of this article proposes one such investigation composed of 3 parts. These parts include: (1) a replication of a SPECT study of Parkinson’s disease using MOST-EEG, (2) a drug comparison to show how MOST-EEG can reveal differences and similarities among drug therapies, and (3) evaluation of how a drug currently under development affects brain function.
(1) The Replication
In the original study we wish to replicate, Hanakawa et al. (1999) used SPECT to identify areas of the brain that participants with Parkinson’s disease used to compensate for behavioral effects of the disease. In the original study, Hanakawa et al. (1999) showed that study participants with Parkinson’s disease that were off their medication used different parts of their brain to walk on a treadmill (marked with transverse lines) than healthy control participants. This result illustrates two important concepts: (1) persons with Parkinson’s disease compensated for the disease by using visual characteristics of their environment, and (2) during this compensation, participants used other parts of their brain that are not utilized under ‘normal’ treadmill walking conditions. During compensation (with transverse lines present on the treadmill belt), participants with the disease walked with the same cadence as healthy controls. When these transverse lines were not present on the treadmill, participants with Parkinson’s disease did not demonstrate compensation– they walked with a high-cadence shuffle in order to keep up with the movement of the belt on the treadmill. In essence, they clearly did not present the same behaviour when transverse lines were not present.
The protocol for the Hanakawa study required participants to ingest the tracer prior to walking on the treadmill. Participants then took part in the behavioral component of the experiment by walking on the treadmill. Participants walked on the treadmill in two experimental conditions. In the first condition participants walked with parallel lines present on the treadmill belt. In the second condition, participants walked with transverse lines present on the belt. After walking on the treadmill, participants were placed in a SPECT scanner to detect gamma radiation sources for brain image construction. Those areas of the brain that metabolized the most tracer would be the strongest sources for the brain scan. The SPECT results that were published in the Hanakawa paper are illustrated in Figure 2 below.
Figure 2. These results illustrate SPECT-detected brain activation related to the transverse line – parallel line condition. These results illustrate areas of the brain used by healthy controls (left-side) and the areas of the brain that were used to compensate by participants with Parkinson’s disease (right-side).
Why we Believe that MOST-EEG can be used to Replicate Results
In our prior research investigation the cognitive brain function associated with spatial navigation while playing video games, we found active areas of the brain in a pattern similar to those found by Hanakawa. In essence, both studies revealed what appears to be a ‘dorsal’ stream of information processing in the right hemisphere. A comparison of the two studies is presented below in Figure 2.
 Hanakawa Result using SPECT |
 MOST-EEG Result |
We are optimistic that we can replicate the results using MOST-EEG, however, while positive results are likely, it is important to mention some important differences between MOST-EEG that could lead to a negative result. First, there are differences in the signal-to-noise ratio properties between SPECT and MOST-EEG. While we know these differences exist, the size and direction of the difference is not known. However, there are way in which extra noise in the case of MOST-EEG can be compensated for. In addition, MOST-EEG does not model activities originating from the cerebellum and hence function in the cerebellum will be overlooked in a replication study using MOST-EEG.
(2) Comparison of on-the-market Pharmaceuticals
Once data for the replication study has been collected, we will examine two Parkinson’s disease drug therapy scenarios. We will investigate the brain function in an on-drug comparison of two different drugs, (Levodopa and a dopamine agonist such as cabergoline) to determine which therapy can be related to brain function that is closest to those of healthy controls.
(3) Evaluating an Experimental Drug (In Development)
We will also incorporate an ‘investigational’ drug in the study to see how it relates in the comparison of the two market approved drugs examined. This will help demonstrate how MOST-EEG can be used to learn more about how a drug ‘in development’ affects brain function.
ABV Sciences is Soliciting a Partner For this Study
ABV Sciences is currently looking for a partner to do this investigation. Preferably, this partner will have an interest in the development of a pharmaceutical therapy for Parkinson’s disease. Please send inquires and requests for more information to Dr. Zeman (pzeman@abvsciences.com)
More Information about SPECT
The paragraphs below provide a brief description of SPECT technology: what it is, what equipment is required to use it to learn about brain function, and how much it costs.
Why SPECT?
Similar to X-ray Computed Tomography (CT) or Magnetic Resonance Imaging (MRI), Single Photon Emission Computed Tomography (SPECT) allows us to visualize functional information about a patient’s specific organ or body system.
How does SPECT manage to give us functional information?
Internal radiation is administered by means of a pharmaceutical which is labeled with a radioactive isotope. This so called radiopharmaceutical, or tracer, is either injected, ingested, or inhaled. The radioactive isotope decays, resulting in the emission of gamma rays. These gamma rays give us a picture of what’s happening inside the patient’s body.
How do these gamma rays allow us to see inside?
By using the most essential tool in Nuclear Medicine, the gamma camera. The gamma camera can be used in planar imaging to acquire 2-dimensional images, or in SPECT imaging to acquire 3-dimensional images.
What is SPECT?
SPECT is short for Single Photon Emission Computed Tomography. As its name suggests (single photon emission), gamma ray emissions are the source of information, rather than X-ray transmissions as used in conventional Computed Tomography.
How are these gamma rays collected?
The Gamma camera collects gamma rays that are emitted from within the patient, enabling us to reconstruct a picture of where the gamma rays originated. From this, we can determine how a particular organ or system is functioning.
How Much Does SPECT Cost?
A SPECT gamma camera costs $400,000 to $600,000 USD.
Applied Brain and Vision Sciences was founded to change the way we understand brain function and treat brain diseases. Simply, we believe there is a ‘better’ way to diagnose and treat brain disease and dysfunction. We believe that through appropriate therapies and objective measures of functional brain activity during the course of these therapies, we can significantly impact lives.
| For more information about our technology and our web portal access to our technology, visit our TECH/EEG Portal Page. |
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