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Clinical NeuroImaging aspects of mTBI: what a neurologist see in a brain scan Steven Chao M.D., Ph.D. War-Related Injuries and Illnesses Study Center (WRIISC)

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Presentation on theme: "Clinical NeuroImaging aspects of mTBI: what a neurologist see in a brain scan Steven Chao M.D., Ph.D. War-Related Injuries and Illnesses Study Center (WRIISC)"— Presentation transcript:

1 Clinical NeuroImaging aspects of mTBI: what a neurologist see in a brain scan
Steven Chao M.D., Ph.D. War-Related Injuries and Illnesses Study Center (WRIISC) Palo Alto VA Health Care System

2 Disclaimer Department of Veterans Affairs or
The views expressed in this presentation are those of the authors and DO NOT reflect the official policy of the Department of Veterans Affairs or the United States Government

3 Background-TBI Traumatic brain injury (TBI) Epidemiology
Injury to the intracranial structures following physical trauma to the head vs. Head Injury both intracranial and extra-cranial structures (scalp and skull) Epidemiology >1.5 million Americans suffer a TBI each year >57 million individuals worldwide hospitalized by 1 or more TBI It is referred as the “signature injury” of OEF/OIF/OND TBI is the major cause of disability in young adults

4 VA/DOD Definition of TBI
A traumatically induced structural injury AND/OR physiologic disruption of brain function as a result of an external force new onset or worsening of at least one of the following clinical signs immediately following the event Any period of loss of consciousness Any loss of memory for events immediately before or after injury Any alteration in mental state at the time of injury Neurologic deficits Intracranial lesion

5 Background-TBI classification
Mechanism: Primary injuries - direct result of trauma Secondary injuries - complications of 1O lesions Location penetrating/open blunt/closed

6 TBI Background - Classification
GCS PTA LOC Mild 13–15 <1 day 0–30 mins Moderate 9–12 >1 to <7 days >30 min to <24 hours Severe 3–8 >7 days >24 hours

7 Background-mild TBI For mTBI the number recorded is primarily a function of patient reporting and provider identification since the effects of mTBI are less evident by comparison with moderate and severe, are most often transient, and may be overshadowed by other diagnoses and mission requirements Increase in 07 may be due to improving processes for diagnosis and more locations of case ascertainment and reporting

8 Background-mild TBI Head Injury Interdisciplinary Special Interest Group of the American Congress of Rehabilitation Medicine -mTBI any period of loss of consciousness any loss of memory for events immediately before or after the accident Any alteration in mental state at the time of the accident focal neurologic deficits that may or may not be transient American Academy of Neurology - concussion Grade 1 transient confusion with no loss of consciousness and concussion symptoms that resolve in less than 15 minutes Grade 2 similar, except that symptom resolution occurs beyond 15 minutes Grade 3 any loss of consciousness

9 How do we diagnosis TBI Clinical history Residual symptoms Biomarkers
Witness/ medical records Self report Residual symptoms Cognitive impairment Physical limitation Mood/Anxiety Biomarkers Imaging Blood/CSF Pathology

10 Complicated Mild TBI When clinical neuroimaging findings are present following a mTBI, the classification changes to “complicated mTBI,” which has a 6-month outcome more similar to moderate TBI Williams et al., Neurosurgery 1990;27(3):422-8. Kashluba et al., Arch Phys Med Rehabil 2008; 89(5): From Heather Belanger’s presentation From Belanger, 2009

11 Imaging Classification of TBI Primary injury
Extra-axial injury Intra-axial injury Vascular injury Epidural hematoma Subdural hematoma Sub-arachnoid hemorrhage Axonal injury Cortical contusion Intra-cerebral hematoma Dissection Carotid cavernous fistula Arterio-venous dural fistula Pseudoaneurysm

12 Imaging Classification of TBI Secondary injury
Acute Chronic Diffuse cerebral swelling/dysautoregulation Brain herniation infarction Infection Lepiolmeningeal cyst Hydrocephalus Encephalomelacia Cerebrospinal fluid leak

13 Neuroimaging in TBI X-ray CT MRI functional study

14 Neuroimaging-Skull films
poor predictors of intracranial pathology mTBI - rarely demonstrate significant findings severe TBI - Negative findings may mislead medical management

15 Neuroimaging in TBI X-ray CT MRI functional study Indication
Limitation MRI functional study

16 Neuroimaging -CT Indication Moderate and severe TBI (GCS< 12)
Mild TBI age >60 years persistent neurological deficit headache or vomiting amnesia, loss of consciousness longer than 5 minutes depressed skull fracture penetrating injury bleeding diathesis or anticoagulation therapy Le and Gean. Mount Sinai J Med 2009

17 Neuroimaging -CT Modality of choice in acute setting
Fast, widely available Highly accurate for skull fractures and intracranial hemorrhage Life-support and monitoring easier than MR Better at radio-opaque foreign bodies Non-contrast CT first for hemorrhage CT angiography has better resolution Le and Gean. Mount Sinai J Med 2009

18 Neuroimaging -CT Limitation-Low sensitivity for mild TBI
abnormal findings on clinical computed tomography 5% GCS 15 20% GCS 14 30% GCS 13 Borg et al. J Rehabil Med 2004

19 Neuroimaging in TBI X-ray CT MRI Functional study Indication
Compare to CT FLAIR GRE (T2*) Functional study

20 Neuroimaging - MRI Indication Acute TBI Subacute Chronic TBI
neurological findings are unexplained by the CT findings Subacute Chronic TBI

21 Neuroimaging - MRI T2/Fluid Attenuated Inversion Recovery (FLAIR)
Focal cortical injuries (e.g. contusions) White matter shearing injuries SAH by suppressing the bright (CSF) signal Diffuse axonal injuiy (DAI) particularly can be seen in the corpus callosum and the fornix Sagittal and coronal FLAIR improves the detection

22 Neuroimaging - MRI

23 Neuroimaging - MRI Gradient-Recalled-Echo (GRE) T2*-Weighted /susceptibility weighted imaging (SWI) highly sensitive to ferritin & hemosiderin (breakdown products of blood) hemosiderin can persist indefinitely- good for remote TBI limited in the evaluation of cortical contusions of the inferior frontal and temporal lobes because of the inhomogeneity artifact induced by the sinuses and masioid air cells.

24 Neuroimaging - MRI

25 MRI vs. CT comparable acute epidural hematoma(EDH)
subdural hematoma (SDH) more sensitive subtle extra-axial smear collections (blood) nonhemorrhagic lesions Brainstem injuries subarachnoid hemorrhage (SAH) 93% of nonhemorrhagic lesions were detected by MRI but only 18% were appreciated on CT Among TBI patients with normal CT scans 30% had abnormal MRI (Bazarian 2007) Hofman et al, Am J Neuroradiol 2001 Hughes et al , Neuroradiology 2004 Gentry et al, AJR Am J Roentgenol1988

26 MRI still misses many lesions
post concussive syndrome headaches, dizziness, fatigue anxiety attention deficits and memory problems Mild encephalopathy (a few days to weeks) 30% continue to have persistent syndrome 43-68% mTBI has negative MRI scan vs. PTSD

27 Neuroimaging in TBI X-ray CT MRI Functional study PET SPECT

28 Neuroimaging – PET Positron Emission Tomography
measures regional brain metabolism with 2-Fuoro-deoxy- glucose(FDG) In animal studies acutely injured show increased glucose metabolism Followed by a prolonged period of regional hypometabotism lasting up to months Human studies has no consistent results both hypermetabolism and hypometabolism in the same regions across different TBI patients

29 Neuroimaging - PET 16 WRIISC pt with TBI histroy 4 abnormal MRI
5 abnormal PET

30 Neuroimaging- SPECT Single Photon Emission Tomography (SPECT)
nuclear medicine study that measures cerebral blood flow (CBF) potentially provide a better long-term prognostic predictor Worse prognosis multiple CBF abnormalities larger CBF defects involve the basal ganglia, temporal and parietal lobes, and brainstem less sensitive in detecting small lesions that are visible on MRI SPECT imaging is complementary to MRI

31 Neuroimaging- What else?
Diffusion Tensor Imaging (DTI) F-MRI Diffusion-Weighted Imaging Diffusion-Spectrum Imaging Magnetic Resonance Spectroscopy Magnetization Transfer Imaging Magnetic Source Imaging

32 Thank you for your attention!

33 DTI as a promising tool for a deeper understanding of white matter pathology
Ansgar Furst, Ph.D. Director of Neuroimaging Laboratory, WRIISC VA Palo Alto, CA Clinical Assistant Professor (Affiliated) of Psychiatry and Behavioral Sciences and of Neurology and Neurological Sciences Stanford University School of Medicine, CA

34 Neuroimaging- What else?
Diffusion Tensor Imaging (DTI) F-MRI Diffusion-Weighted Imaging Diffusion-Spectrum Imaging Magnetic Resonance Spectroscopy Magnetization Transfer Imaging Magnetic Source Imaging

35 Neuroimaging- What else?
Diffusion Tensor Imaging (DTI) F-MRI Diffusion-Weighted Imaging Diffusion-Spectrum Imaging Magnetic Resonance Spectroscopy Magnetization Transfer Imaging Magnetic Source Imaging

36 Too many imaging sequences ?

37 Broad classification scheme
Structure Function T1-weighted T2-weighted T2-FLAIR T2*-GRE SWI DTI fMRI PET

38 Broad classification scheme
Structure Function Mass effects Volume changes Midline shifts Altered synaptic/ metabolic activity, network connectivity

39 Broad classification scheme
Structure Mass effects Volume changes Midline shifts

40 Broad classification scheme
Function Altered synaptic/ metabolic activity, network connectivity Stay tuned …

41 Diffusion Tensor Imaging (DTI)
MR sequence (available since the 90s) relatively simple to implement and time efficient Measures microscopic motion of water molecules in brain tissue Gives an indirect account of integrity & connectivity of white matter fiber tracts

42 How does it work ?

43 How does it work ?

44

45 Soaker hose analogy

46 Soaker hose analogy

47 FA maps – no sense of direction

48 Tensors code direction of movement

49 (Directionally) colored FA maps
Anterior Superior Left Right Inferior Posterior

50 Patient 014 32-year old OIF veteran
Blow to the head with LOC ~ 2 min, additional LOC in bar fight and motor cycle accident < 1 min Was in vicinity of numerous mortar blasts – no LOC but confused about circumstances afterwards Patient complains about severe headache Was diagnosed with TBI during WRIISC visit

51 Patient 014

52 Patient 014

53 Patient 014

54 Patient 014

55 Patient 014

56 Patient 014

57 DTI – just pretty pictures ?
DTI imaging (particularly fiber tracking) can be a very powerful tool in identifying otherwise unnoticed white matter compromises However, customized fiber tracking is very time consuming and difficult to automatize as each patient’s fiber tract architecture is unique In order to be useful to clinicians more easily interpretable, reliable quantification of white matter damage is needed

58 DTI – towards a diagnostic tool
Please come and visit us at our poster!

59 Suggested reading If you want to learn more about DTI
Recent data showing superior sensitivity of DTI in detecting TBI

60 THANK YOU!


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