Introduction. The Obvious. The Subtle. The Controversial. Agenda. Vocabulary. Overview

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1 Radiological Imaging of Traumatic Brain Injury: The Obvious, the Subtle, and the Controversial Mark D. Herbst, M.D., Ph.D. St. Petersburg Independent Diagnostic Radiology, Inc. Introduction How radiology tests fit in with other attempts to obtain OBJECTIVE evidence of brain injury What can routine and new types of imaging do to show brain injury? Pitfalls in imaging The Obvious Displaced skull fractures Large areas of brain destruction Changes between pre-injury and postinjury images The Subtle Non-displaced fractures Small areas of blood or brain abnormalities that might be missed on first look Changes in the brain that are definitely present, but that might have come from causes other than trauma The Controversial Subtle findings from conventional imaging methods invite controversy when causation is debatable Unconventional or new imaging methods that are not widely used or accepted Agenda Choices of imaging tests This choice matters, since findings are often shown better on one test than another. Standards for choosing the right imaging tests The American College of Radiology has established standards for imaging choices. CT of TBI CT is the best first and follow-up test. MRI for aging blood and if CT is normal Blood breaks down in a predictable sequence that is visible and that can be dated on MRI. New imaging technologies and their potential While possibly controversial now, these new methods will probably become the standards for imaging in the future. Overview LOC Medical imaging is only one piece of the puzzle. Imaging tests are complementary with each other and with other tests. Followup Risk factors 2nd MRI First CT scan Coma Scale 2nd CT Amnesia 1st MRI scan Vocabulary X-ray=radiographs=RG=plain films CT=Computed Tomography=Computed Axial Tomography=CAT scan MR=Magnetic Resonance=Magnetic Resonance Imaging=MRI fmri=functional MRI DTI=Diffusion Tensor Imaging PET=Positron Emission Tomography SPECT=Single Photon Emission CT

2 Initial Imaging Tests How do you know if the appropriate imaging tests were done? Plain films of skull are nearly useless, since they do not show intracranial injury, and CT shows fractures and intracranial blood. ACR guidelines-- EFNS Task Force--European Federation of Neurological Societies American College of Radiology Appropriateness Criteria How to find the appropriateness criteria on the American College of Radiology Website: Quality and patient safety Appropriateness Criteria Access Appropriateness criteria Expert Panel on Neurologic Imaging Head Trauma PDF file

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4 European Federation of Neurologic Societies Task Force Review of MEDLINE literature Established in 1999, published recommendations in 2002 Similar US task force, Congressional Task Force on TBI, is still looking for funding EFNS Task Force EFNS Task Force EFNS Task Force--Risk Factors EFNS Task Force Unclear or ambiguous accident history Continued post-traumatic amnesia Retrograde amnesia longer than 30 min. Trauma above the clavicles including skull fracture Severe Headache Vomiting Focal neurological deficit Seizure Age < 2 years Age > 60 years Coagulation disorders High energy accident Intoxication with alcohol/drugs EFNS Task Force EFNS Task Force CT Normal CT Abnormal

5 EFNS Task Force Abnormal Head CT findings Skull fractures Epidural hematoma Subdural hematoma Contusions Intraparenchymal hemorrhage Brain edema (focal or diffuse) Subarachnoid hemorrhage Pneumocephalus Linear skull fracture Most common type of skull fracture Linear skull fracture Most common type of skull fracture Plain film may show a line or band of decreased or increased density Linear skull fracture Most common type of skull fracture This case also shows subcutaneous swelling and brain swelling Depressed Skull Fracture Skull Base Fractures, aka Basilar Skull Fractures Linear fractures that occur at the base of the skull Skull Base Fractures, aka Basilar Skull Fractures Linear fractures that occur at the base of the skull Transverse and longitudinal petrous bone fractures

6 Dura Mater Subdural=below dura Epidural=extradural= above dura (between skull and dura Subdural Hematoma Occurs between brain and dura Pushes on soft brain This illustration shows midline shift Acute blood is bright on CT, and it gets darker in time Subdural Hematoma Occurs between brain and dura or along the falx Pushes on soft brain This illustration shows midline shift Acute blood is bright on CT, and it gets darker in time Epidural Hematoma Occurs between skull and dura Subdural Hematoma Occurs between brain and dura Pushes on soft brain This illustration shows midline shift Subdural Hematoma Occurs between brain and dura or along the falx Pushes on soft brain This illustration shows no midline shift Acute blood is bright on CT, and it gets darker in time Epidural Hematoma Occurs between skull and dura Brain Contusion Commonly affected areas in red are in the anterior frontal and temporal lobes and posterior superior temporal gyrus Less commonly affected areas in blue are the lateral midbrain, posterior inferior cerebellum, and superior midline cortex

7 Brain Contusion Acute contusion, with right frontal hemorrhage and edema, right temporal tip hemorrhage, and left frontal subdural hematoma Coup-contrecoup injuries Pattern of contusions at the site of impact and on the opposite side of the brain Brain Contusion Coup-contrecoup injuries Pattern of contusions at the site of impact and on the opposite side of the brain Brain Contusion Brain Edema First sign is loss of the gray-white junction This case shows mass effect also Subrachnoid Hemorrhage Blood in the sulci of the brain (between the gyri) Air inside the head From open fracture through skin or sinus Pneumocephalus Air inside the head From open fracture through skin or sinus Pneumocephalus Air inside the head From open fracture through skin or sinus Pneumocephalus

8 Shear Injury Shearing between brain tissue of differing firmness, between gray matter and white matter Produces microhemorrhages at the gray-white junction Aka DAI=diffuse axonal injury Shear Injury Shearing between brain tissue of differing firmness, between gray matter and white matter Aka DAI=diffuse axonal injury If the lesions are not hemorrhagic, they are dark on CT MRI Appearances of TBI Shear Injury Diffusion-weighted MRI MRI of blood--gradient Echo Gradient echo images magy show blood not shown on regular MRI images Shear Injury Shearing between brain tissue of differing firmness, between gray matter and white matter Produces microhemorrhages at the gray-white junction Aka DAI=diffuse axonal injury MRI Appearances of TBI Shear injury T2-weighted images Bright spots on T2WI MRI Appearances of TBI Shear Injury Gradient Echo image, aka microhemorrhage technique This technique can show abnormalities not seen on CT or regular MRI Normal RBC breakdown Normally, red blood cells break down in the liver. Hemoglobin breaks to globin and heme Heme breaks to billirubin and iron Iron is stored as hemosiderin and ferritin

9 MR Appearance of Hematoma: Compared to normal brain, 1.5 T Stage Hyperacut e Acute Subacute Age 0-24 hrs 1-3 days 3-14 days Hb Type Oxy-Hb Deoxy-Hb Intracellular met-hb Extracelllular met-hb T1WI Isointense Isointense T2WI Isointense Hypointense Hypointense Pitfalls - 1.5T vs. 3.0T MRI T2WI, FLAIR, T1WI 1.5T and 3.0T Acute hematoma (2nd day), appears darker at 3.0T than at 1.5T on T2WI and FLAIR Chronic >2 weeks Extra-cellular Met-Hb Hemosiderin (around periphery) Hypointense Ancient Monthsyears Non-paramagnetic heme pigments Hemosiderin(around periphery Hypointense Sl. hypointense Hypointense Pitfalls - 1.5T vs. 3.0T MRI T2WI, FLAIR, T1WI 1.5T and 3.0T Subacute hematoma (6th day), appears darker at 3.0T than at 1.5T on T2WI and FLAIR Volume Averaging Poor Resolution Noisy Images Pitfalls Volume Averaging Volume Averaging In-Plane Resolution This is a photo that has been taken at 165x256 resolution In-Plane Resolution This is a photo that has been taken with 329x512 resolution

10 In-Plane Resolution Signal-to-Noise Original Resolution 720x1150 Signal-to-Noise Signal-to-Noise Signal-to-Noise CT and SPECT in acute TBI SPECT=single photon emission computed tomography Shows area of hypoperfusion PET in chronic TBI PET=positron emission tomography PET in chronic TBI PET=positron emission tomography

11 PET in chronic TBI PET=positron emission tomography Patients recovering from TBI show increased brain activity when performing memory tasks This may indicate reorganizing memory pathways or regions of less efficient brain activity DT-MRI in DAI DT-MRI=diffusion tensor MRI Shows where axons are malfunctioning This case show abnormal splenium in an injured patient, compared to twin brother Functional MRI fmri=functional MRI, shows oxygen use in the brain This image shows normal activity during various tasks The abnormal brain shows increased activity compared to normal fmri in TBI How to image TBI How to image TBI Start with CT, and do follow-up CT scans If CT is normal or minimally abnormal, consider MRI Remember to do special microhemorrhage technique on MRI, the stronger the magnet, the better. Consider other tests if CT and MR are nearly normal Other tests include fmri, DT-MRI, PET, SPECT SPECT can be positive in 53% of those with normal CT and MR, but it is hard to find a good SPECT imaging center. fmri and PET and DT-MRI may soon prove as good or better than SPECT, but these are considered experimental for now. Summary Various imaging tests are available Standards exist regarding proper imaging choices (ACR Appropriateness Criteria) CT shows most abnormalities Gradient Echo MRI ( microhemorrhage technique ) can show lesions that are not seen otherwise New methods are considered promising, but they are still experimental. Where to Get More Information Google TBI, MTBI, DAI, etc. Numerous attorney websites exist that review anatomy, physiology, imaging, and tips on questioning experts