Dear Phil Jones:

Your question is certainly comprehensive and wide. In hospitals imaging services have several imaging modalities, all depends on the stage of brain injury study.

If the trauma is recent one CT scanner (with and without contrast) with a simple Rx is recommended.

If the traumatic injury is older requires MRI studies including T1w, T2W, diffusion (ADC maps, DTI, etc).

So I would have a little more clarity on what you intend.

Best regards, Evelio

Dear Phil Jones,

Another imaging modality, mostly used in research, is magnetic resonance spectroscopy (please see reviews by Mechtler LL et al., 2014 in Nuerol Clin: Advanced neuroimaging of mild traumatic brain injury; Bartnik-Olson BL et al., 2013 in Front Neurogenetics: Insights into the metabolic response to traumatic brain injury as revealed by 13C NMR spectroscopy; Gradner A et al., 2013 in J Neurotrauma: A systematic review of proton magnetic resonance spectroscopy in sport-related concussion.)

Best regards,

Carmen

Phil, good question and it is always difficult to communicate brain imaging to the general public. MRI provides structural information about the brain for both white and grey matter. PET is not typically used for detecting TBI. CT is good for detecting infarcts related to stroke or bleeding. EEG is used for detecting network disruptions to the brain, or more simply its connectivity in task, or self regulation at baseline. MRI cannot provide network information and fMRI is not approved for clinical diagnostics. So we do the best with what we have. It is better to have more than one source of information, as well as corresponding neuropsychological testing data.

Hi Phil,

You've received some quality answers so far. I will add that there is a useful scan using MRI called FLAIR (FLuid Atteuated Inversion Recovery) to detect white matter degradation due to traumatic injury. The technique is sensitive to infiltration of cerebrospinal fluid into what would normally be high-density white matter. However, these scans are most sensitive to older injuries rather than acute cases.

We have had good results by staining with antibody to APP. App is a relatively very early marker for axonal injury (less than 15 minutes post trauma). Electron microscopy can also be a god tool especially for white matter injury.

The diagnosis of TBI is designed primarily to answer the three key points : 1. Detecting changes in the organic matter of the brain . 2. Detecting changes in the neurodynamics of the brain. 3. The Diagnostic of hydrodynamic conflict in the cranial cavity . So I think the best use of MRI of the brain to exclude gross brain injury ( contusion, hematoma ). The most sensitive for the diagnosis of early signs of brain's dysfunction is the methodology of clinical EEG and Clinical UZDG (technology Lushchyk UB - http://istyna.kiev.ua/ua/index.php?option=com_content&task=view&id=117&Itemid=68&lang=en), which can detect early changes in neurodynamics, hydrodynamics and hemodynamics as major channels of life support and management in the brain.

Hi Phil

One additional MRI modality that was not mentioned in the above suggestions is susceptibility weighted imaging (SWI) for the detection of extravascular blood. This technique certainly out performs CT in detection of blood (acute and chronic). However, typically in mild TBI there is little or no blood. There is an sub-group of patients however following TBI that may exhibit hemorrhagic progression, ~10-25% of patients can go on to bleed at later times after the initial TBI event. You can find a nice review by Kurland et al 2012 J Neurotrauma 29:19-31. We have also published a similar finding in a model of mild TBI (Donovan et al 2012 Neuroimage:Clinical 1:18-28). A good review of imaging for TBI, albeit pediatric TBI (Hunter et al 2012 J Neurotrauma 29:654-71).

As you can see, the two most common technologies are CT and MRI, and both offer the option of adding an additional substance to increase contrast among tissues of interest, most often to make abnormal tissue (e.g., tumor, hemorrhage, etc.) either darker or lighter than surrounding tissue. A couple additional points about these two technologies that may help build you background:

1) CT uses x-rays delivered at various angles and a computer to synthesize all the information together. MRI uses a strong static magnetic field and a variety of other weaker magnetic fields to measure properties of hydrogen protons (i.e., hydrogen protons in water, blood, fat, and large proteins all react differently to these magnetic fields).

2) Because of the different ways images are obtained, they carry different safety concerns. CT is generally safe for anyone as long as they don't have them too often. A CT can be run on someone who is unconscious, someone with medical complications, or someone with implanted medical devices. In contrast, MRI has no ionizing radiation (Hooray!), so someone can have an MRI every day and be just fine. However, they have to be thoroughly screened for a variety of medical devices and other metallic/electrical implants that would be VERY dangerous in a magnetic field.

3) Also because of the different ways the images are obtained, CT and MRI have different image "abilities". CT is quite inflexible. On all but the most advanced systems, you're limited to 2 images (with contrast or without contrast) and need to shift the patient to get different slice angles. In contrast, MRI is virtually limitless in its flexibility. There are 3 basic contrasts (T1, T2, PD), each of which can be done with or without contrast, along with the myriad others noted by prior respondents (DWI, SWI, T2*, MRA, FLAIR, etc.). Generally DWI (and DTI) is great for looking at white matter damage (e.g., diffuse axonal injury), and FLAIR is great for looking at vascular damage.

In the end, CT is best for the acute emergency room stage while MRI is preferred for the more chronic stage in which a neurologist is looking for damage associated with specific symptoms.

Dear Phil, there has been a useful description of the various MR ,CT and EEG modalities in use. They all need to be put into a clinical context for effective treatment and neuro-rehabilitation. Would recommend this review:

Levine B, Robertson IH, Clare L, Carter G, Hong J, Wilson BA, Duncan J, Stuss DT.

. (2000 ) Rehabilitation of executive functioning: an experimental-clinical validation of goal management training. J Int Neuropsychol Soc Mar;6(3):299-312.

These answers all seemed outstandingly helpful. Being able to explain how these obviously very complicated imaging tools in clear, simple language instead of throwing a bunch of technical terms around both helped me immensely, and demonstrates a comprehensive understanding of the lecture material on the part of the answering academics.

I am very grateful! I'm going to make some introductory-level powerpoint lessons on all three to both maximize my own comprehension, and to show this to my colleagues interested in the quantitative side of neuroethnography. Thanks so much, guys!

Was your interest only on diagnostic/clinical technologies or were you interested in research tools as well?

I'd love to hear about other equipment used in this field of research.

Some of the stuff here that we've been using would be developments like MEG (magnetoencephalography - like electroencephalography, but using magnetic fields) which allows you to get down to the resolution of small clusters of neurones.

Not sure if the extension of MRI, fMRI (functional) has been mentioned, couldn't find it in the thread, but probably is. Simply, it's an extension of MRI so you can look at changes over time in high resolution taking frames over time.

Another technique now being used is functional near-infrared neuroimaging which is almost certainly going to have huge implications for the future of research as it can be worn on the head in the same way as 24 hour EEG monitoring has been used. It is essentially a way of doing imaging as people move around doing 'things' in their life, and being able to correlate brain activities with those things (whatever they might be), rather than having people lying in a scanner. It gets ride of some of the problems associated with magnetism and radiation, but has limitations as to depth of scanning at the moment, since it is based on infrared emissions near the surface of the brain.

As an anthropologist (as I understand you are), I would suggest fNRNI is the birth of a new era for research in your field. Now I will wait for people to tell me I'm wrong!