As a Tampa Bay area traumatic brain injury attorney, it is a function of my job to learn as much as possible about the different imaging studies utilized to illustrate traumatic brain injuries. Please follow my blog both on this site and at www.dolmanlaw.com to learn more about the ever evolving area of medicine concerning closed head injuries and traumatic brain injuries as well as how this is affecting plaintiff lawyers who seek to demonstrate such injuries to juries throughout the State of Florida.
PET (Positron Emission Tomography) relies on a radionuclide (an isotope) with a half life of twenty minutes that is injected into the body with an intravenous drip of glucose. The patient is then provided a number of cognitive tasks, which will provide stress (activity) to specific sections of the brain when forced to perform mental work. The healthy areas of the brain will absorb large portions of the radioactive glucose and will show up as a bright orange or read when the patient’s head is placed under the gamma camera. The areas of the brain that are damaged or dying will in turn absorb very little of the fluid and will display as blue or purple under the gamma camera.
PET scans provide very dynamic illustrations of injury to the working brain. Many brain injuries illustrated by PET scan would be missed utilizing a less sensitive imaging like a CT or MRI scan. Further, the PET scan helps illustrate damage and deficits in the areas of the brain that control memory, mood, concentration, ability to analyze and many other critical areas that make up what is known as “executive thinking.”
PET scans are admissible in the State of Florida to prove up the existence of a brain injury and there is a long line of case law in support of such. With a proper foundation created by utilizing a sound expert, a Florida traumatic brain injury attorney can utilize this dynamic study and show 3D color images of the brain with great clarity to the jury.
SPECT (Single Photo Emission Computed Tomography) Scan is a nuclear diagnostic imaging test that measures regional changes in the brain’s activity. A radioactive tracer is injected and absorbed as it circulates through the blood stream. A camera is utilized to snap photos of how the tracer is being absorbed and this information is transmitted to a computer which will display cross sectional images of blood flow in the brain.
SPECT Scans are much cheaper that a PET Scan but the images are not nearly as precise and it does not serve as strong as a demonstrative aid as does the PET. However, SPECT scans are more readily available than PET. The biggest difference between the two imaging studies is that the tracer stays in your blood stream in a SPECT as opposed to being absorbed into tissue as in a PET Scan. Thus, the images are limited to where the blood actually flows.
FMRI (Functional MRI)
A functional MRI of the brain is a non-invasive diagnostic study providing high- resolution reports of neural activity detected by blood oxygen level dependent signal. Again, this study examines the brain’s response to specific tasks but does not require an isotope injection and the scanning time is much quicker. FMRI’s are not used as commonly as PET or SPECT Scans for diagnosing traumatic brain injury. The criticism of FMRI is it’s inherent limitations in spatial and temporal resolution. Due to the rapid scanning time, the images are often less clear. MRI’s are more of a structural test and display less information about the internal tissue. MRI’s cannot be used if the patient has ventilation equipment or pacemaker as a result of the magnetic field.
Diffusion Tensor Imaging (DTI)
Diffusion Tensor Imaging (hereinafter referred to as “DTI”), is an MRI which utilizes magnetic pulses to measure the diffusion (outward movement) of molecules of water in relation to brain fiber in six different planes. It measures the diffusion of water through brain tissue and allows the Radiologist to estimate the damage to nerve fibers that connect the white matter of the brain.
The predominant theory behind DTI scans is the ability to detect “white matter lesions.” White matter lesions are cells that are dead or damaged within the brain tissue. DTI isolates water movement within the brain, enabling physicians to isolate specific regions of the brain that are functioning improperly. Typical MRI’s cannot track the movement of water molecules. This new technology is not only useful in the medical field but now can be a tool, utilized by plaintiff’s lawyers to illustrate an injury to the brain. The images are very crisp and can produce dramatic proof of damage to a specified area of the brain. This can prove to be a tremendous demonstrative aid for a plaintiff attorney attempting to prove up the existence of a mild traumatic brain injury.
Unfortunately for us brain injury attorneys for Clearwater, DTI has not been accepted as an admissible test in many jurisdictions. In Hillsborough County, DTI was ruled in the case of Hammer vs. Sentinel Insurance to be a commonly accepted medical test that has been peer reviewed and can be utilized by the appropriate physician to correlate the existence of a traumatic brain injury.
Susceptibility Weighted Imaging (SWI)
SWI is a diagnostic test utilizing high resolution imaging to detect injury to the brain manifested in the form of a microhemorrhage or shearing /tearing of the axons of the brain also known as a diffuse axonal injury. This new technology allows medical practitioners to see even the smallest lesions of the brain.
SWI is very sensitive to both iron and blood products and as a result, can locate microhemorrhages that would be missed by a conventional MRI. Many Radiologists and physicians treating victims of mild traumatic brain injury utilize both susceptibility weighted imaging and diffusion tensor imaging (DTI) in conjunction to best illustrate the existence and extent of diffuse axonal injury and brain lesions. SWI is a very new technology and much is still to be learned about the use of this study and its applicability in a Florida Courtroom. This was a great review of medicine and law and we want to thank Dolman Law firm for guest speaking today.