Congressional NFL Hearings – Dr. Ronald Benson Testifies about Neuroimaging Advances – Susceptibility Weighted Imaging

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Posted on 7th January 2010 by Gordon Johnson in Brain Injury

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As I have stated here and elsewhere, diagnosing accidental concussions involves reconstructed evidence and the reliance on history from someone who likely has memory problems as to what happened, because they were concussed. In contrast to football or boxing concussions, real world concussions are rarely witnessed in the critical 30 second time window when the evidence is the clearest. See today’s blog at http://www.subtlebraininjury.com/blog/2010/01/evolution-in-understanding-of_07.html

Thus, with such an imperfect diagnostic process I am always hoping that the newest neuroimaging technique can provide us with a bright light of “objective evidence” of injury. I have heard Dr. Ronald Benson speak and his state of the art imaging techniques are the most promising of any of those I have seen to date. Dr. Benson testified to Congress about the advances being made in those techniques, principally through new ways of using the familiar MRI scanner.

Dr. Benson testified principally to two state of the art methods of using MRI, Diffusion Tensor Imaging (“DTI”) and Susceptibility Weighted Imaging (“SWI”).

Dr. Benson said in his prepared remarks:

Most of our work has used victims of transportation related injuries and falls, however our principle research focus has always been closed head injury, under which concussion falls and is otherwise known as mild head injury. I will also include some examples of former players scans. The focus of my testimony will be susceptibility-weighted imaging (SWI) and diffusion tensor imaging (DTI).

I have been using DTI for years now in our forensic cases, with significant success, but SWI is something new to me. Dr. Benson explained SWI as follows:

Susceptibility-Weighted Imaging (SWI) Imaging research of TBI began at WSU in 2004 when an eleven year old boy (C.G.) survived after his family’s ATV skidded off a mountain road in Colorado plunging 200 ft. He was still in coma two months later when we scanned him at WSU. His CT and standard MRI revealed a skull fracture and atrophy but not much more. Figure 1 compares a standard, clinically available T1-weighted image with a susceptibility-weighted image (SWI) through the temporal lobes and brainstem for C.G. sixty days after injury. Note the many “black holes” present in the
SWI image which are small (“micro”) hemorrhages indicating severe diffuse axonal injury (DAI) from TBI.

Developed by Mark Haacke, SWI is extremely sensitive to iron and blood products and detects microhemorrhages where conventional MRI fails. SWI detects hemorrhage at all stages, since iron remains even after the fluid from blood is reabsorbed. Prior work by Dr. Haacke with Loma Linda University (Karen Tong, M.D.) had demonstrated the value of SWI for detecting DAI in children with “shaken baby syndrome” where it was five times more sensitive than gradient echo imaging. In a series of 20 TBI patients (transportation related and falls) varying in severity and elapsed time since injury, we found an excellent correlation (Ρ =0.54) between total hemorrhage volume and the number of days in post-traumatic amnesia which is known to be a good T1‐Weighted SWI predictor of one-year neurological outcome (JMRI, 2009). We have, since 2004, scanned over 100 TBI patients with SWI at WSU alone and a similar number at Loma Linda. In addition to TBI, it is being used in stroke, cerebral amyloid angiopathy (CAA) (Figure 2), Alzheimer’s disease and disorders of iron metabolism. SWI is now clinically available on GE and Siemens MRI scanners.
Every few years, I get newly excited about a neuroimaging technique that will give us a bright line of diagnosis for those with long term problems after a concussion. In 2000 what gave me great hope was learning about the development of techniques to see hemosiderin staining, principally the technique Gradient Echo Imaging. The theory of Gradient Echo Imaging is that when bleeding in the brain occurs, it leaves behind iron deposits, even after the there is no liquid blood visible on a CT or MRI. Those iron deposits are the hemosiderin. The hemosiderin is highly magnetic because it is principally iron. So if the magnet in the MRI is tuned precisely, this imaging technique can show evidence of a non-acute bleed, in theory years after the original injury. Here is a comparison between a conventional MRI image and the SWI image. The SWI is on the right and of import is the small black circles which don’t appear on the image to the left.

Figure 1. Comparison of T1 and SWI images for C.G. Note the many dark
“holes” in the SWI image that are not present on the T1 weighted image. These
“black holes” are caused by signal loss induced by paramagnetic hemoglobin or
other iron containing blood products.

It was exciting when I learned about Gradient Echo Imaging. It has not had any actual value in my cases. The exciting news about SWI is that it is five times more sensitive than Gradient Echo Imaging. The challenge in neuroimaging is whether five times better is enough when you are talking about multiplying zero. The math analogy isn’t totally valid, but if no hemosidrin deposits show up on even disabling mild traumatic brain injury cases, it may very well be that the kind of bleeds that leave hemosiderin behind are not the principal culprit in the Post Concussion Syndrome. Time will tell.

Diffusion Tensor Imaging (DTI) is more focused at the likely pathology, injury to the axons. We will discuss Dr. Benson’s testimony about DTI in our next blog.

Guidelines for Coma Management

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Posted on 4th March 2008 by Gordon Johnson in Brain Injury

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One of the most difficult challenges in being a brain injury attorney and an advocate, is struggling with what to tell people when they call up and their loved one is in a coma. The Brain Injury Law Group is here to a significant degree, because that was one of the challenges we faced when we first started doing web advocacy. We created http://waiting.com in 1997, with a sense of urgency to help those who were waiting for word as to whether their loved one would ever awake. The story of our frustration with the Brain Injury Association’s refusal to accept our offer of help to create such a page, and our decision to do it ourselves, is well explained on that page.

The Brain Trauma foundation is an organization which shares a similar advocacy to help those in a coma, and I received this email from them today, covering the guidelines to assist medical professionals dealing with coma patients. To get to those links, click here: http://www.guideline.gov/whatsnew/newthisweek.aspx#date

What these new guidelines don’t call for, which I believe they should, is the use of funtional imaging, such as PET scans or fMRI to tell the degree to which there is sufficient brain function going on in the comatose person, to predict any reasonable chance of recovery. Coma guidance from doctors is far too much “we will just have to wait and see” and most times, from a very pessimistic outlook. I believe that PET scans and fMRI should be routinely used to give guidance to the family, when they are trying to make that awful decision as to whether there is enough chance of a satisfactory recovery, to keep trying to save the life of the comatose person. We always counsel prayer and inner searching. But when there are tools out there that could be used to provide more meaningful information on what is going on inside of that skull, we believe they should be used. I have instructed the person who is my health care power of attorney to demand that I have a functional imaging test if I am ever in that situation, and there is no valid reason why doctors don’t do the same.

They Brain Trauma Association has guidelines on the following:

Anesthetics, analgesics, and sedatives.
Antiseizure prophylaxis.
Blood pressure and oxygenation.
Brain oxygen monitoring and thresholds.
Cerebral perfusion thresholds.
Deep vein thrombosis prophylaxis.
Hyperosmolar therapy.
Hyperventilation.

Indications for intracranial pressure monitoring.
Infection prophylaxis
Intracranial pressure thresholds.
Nutrition.
Prophylactic hypothermia.
Steroids.

Innovations in Functional Imaging

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Posted on 29th February 2008 by Gordon Johnson in Brain Injury

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A recent story from the Navy Times about a new concept in what is technically referred to as functional imaging. Functional imaging, such as a PET scan or fMRI, is an imaging technique which tells not whether there is a bleed or damage to a structure of the brain, but whether there has been a change in the way the brain is operating at a given moment. Most of the major discoveries about how the brain works has been done in the functional imaging area, particularly fMRI. While PET scans have been used for legal cases for more than a decade, fMRI is still only being used peripherally in forensic matters. We have continued to push for more utilization in our cases, but has yet to add anything significant. This new combat breakthrough might add something to the ER equation in civil cases, and could add a major new element to differentiating between the cases with good recoveries, and those where there is ongoing basis for concern.

From the Navy Times story:

“Dr. Richard Dutton heads up trauma anesthesiology at the R. Adams Cowley Shock Trauma Center at the University of Maryland and sees about 4,000 people a year who doctors believe have a brain injury.

Dutton and a team of engineers decided to see if they could use sonar to “listen” for differences in healthy brains and injured brains. They used a headband with sensors to pick up the sound transmitted through the brain with sonar and then analyzed the data fed back into a computer. The Air Force paid for the research.

“We’d ‘ping’ them with sonar and then listen,” Dutton said Feb. 20 at an American Institute for Medical and Biological Engineering conference.

They didn’t learn much from the pinging, but when they just started listening, they were able to detect significant differences, which turned about to predictive as to whether the severely injured person would awake or not. The portability of this technique is important, but that functional imaging could make such distinction is not new. PET scans for decades have been able to add significant prognostic value to differentiate between the levels of coma, because they show how much activity the brain actually has. I have complained for more than a decade that a PET scan (and now perhaps fMRI) should be used to help make decisions and inform family members about the probably that someone will awake from a coma.

But the most intriguing breakthrough in the military technique is not just that it seems to add portability to the equation (which of course is essential in combat) but also that such portability is sensitive enough to be able to detect abnormalities in even the concussed, as opposed to, comatose brain.

The Navy Times story goes on:

“When Dutton and the engineers tried out their equipment on people they believed to have mild TBIs, they found turbulent blood flow — or irregular bandwidths — on the Brain Acoustic Monitor.

“You hit your head, your BAM becomes abnormal,” Dutton said. “We think we may have an objective marker for brain injury. This is pretty exciting stuff.”

And it’s completely portable, which could be good news for troops in Iraq and Afghanistan. In Iraq, there’s one CT scan — in Balad — and no MRI machine. Medics don’t have access to the heavy, expensive equipment.”

If this BAM technology can be licensed and distributed to Emergency Room settings, it might not just help on the battlefield, it might also add significant diagnostic utility for civilian use. While the scope of the concussion/head injury issue in Iraq is important, it is a relatively small number compared to civilian use. If there have been even 5,000 concussions a year in Iraq, that is only 5% of the estimated 1,000,000 concussions in the United States alone, each year.

Of course, the challenge will remain to educate the ER personnel to even the possibility that someone who knows who they are, where they are, what day it is and how they got hurt, could still be suffering brain damage.

FOR MORE ON FUNCTIONAL IMAGING, GO TO http://subtlebraininjury.com/normalimaging.html and particularly http://subtlebraininjury.com/pet.ht