Traumatic Brain Injury Advanced Imaging. V. Michelle Silvera MD Division of Neuroradiology Boston Children s Hospital

Transcription

1 Traumatic Brain Injury Advanced Imaging V. Michelle Silvera MD Division of Neuroradiology Boston Children s Hospital

2 No disclosures

3 CT: Noncontrast head CT first-line imaging Imaging Approach to TBI 1 y.o. s/p fall, hit back of head, progressively lethargic over 24 hours MRI and MRA for more detailed detection and analysis of ICI Ultrasonography SDHs, edema, shift vasospasm Conventional Angiography diagnostic and therapeutic for vascular injury FLAIR MRI 24 hours later Trace DWI

4 Beyond Conventional Imaging SWI MRS Perfusion imaging DWI/DTI PET/SPECT (BOLD) fmri MEG NIRS

5 AJNR, November 2014 Advanced neuroimaging techniques have shown promising results in group comparison analyses Data currently available confines the use of advanced imaging techniques to the research arena for group comparisons There is insufficient evidence at the time of this writing, to conclude that these advanced imaging techniques can be used for routine clinical use for diagnosis and/or prognostication at the individual patient level

6 Beyond Conventional Imaging SWI MRS Perfusion imaging DWI/DTI PET/SPECT (BOLD) fmri MEG NIRS

7 Diffusion Weighted Imaging

8 17 y.o. girl s/p syncopal episode in the shower, fell, hit back of head, lethargic but arousable; GCS 13

9 T2WI ADC Map

10 DWI Measure of average diffusion speed of water Marker of cytotoxic (cellular) edema DWI images are also T2- weighted ( T2- shine through ) Apparent Diffusion Coefficient (ADC) and Exponential Maps are quantitative measures of diffusion rate provide a diffusion rate without the influence of T2 Fractional Anisotropy degree of directionality of diffusion Trace Map Fractional Anisotropy Exponential Map Apparent Diffusion

11 DWI 16 yo boy who collapsed at a baseball game Echo-planar spin echo T2- weighted sequence Measure of average diffusion speed of water in tissue Marker of cytotoxic (cellular) edema DWI images are also T2- weighted ( T2- shine through ) T2WI Trace Map Apparent Diffusion Coefficient (ADC) and Exponential Maps are quantitative measures of diffusion rate provide a diffusion rate without the influence of T2 Fractional Anisotropy Degree of directionality of diffusion Apparent 1 year Diffusion later Exponential Map

12 T2WI ADC Map

13 Susceptibility-Weighted Imaging

14 Susceptibility-Weighted Imaging (SWI) High spatial resolution, fully velocity compensated, long echo, 3D GRE MR technique Exploits differences in magnetic susceptibility between tissues Paramagnetic substances Blood (deoxyhgb, intracellular methgb, hemosiderin) cerebral venous architecture Diamagnetic substances calcifications minerals air Filtered Phase Image SWI Magnitude Image SWI MinuP

15 Susceptibility-Weighted Imaging (SWI) High spatial resolution, fully velocity compensated, long echo, 3D GRE MR technique Multiple cavernous malformations Exploits differences in magnetic susceptibility between tissues Paramagnetic substances small foci of deoxygenated blood cerebral venous architecture Diamagnetic substances calcifications minerals Filtered Phase Image SWI Magnitude Image SWI MinuP

16 16 yo s/p MVA with 45 mins LOC 2.5 months ago SWI is 3-6x more sensitive than conventional GRE in detecting number and size of lesions Number and volume of hemorrhagic lesions on MRI and may correlate with prognosis and outcome T2WI FLAIR Beauchamp et al Cortex 2013; Tong et al Radiology 2003, Arh Phys Med Rabil 2008; Babkian et al Pediatr Neurol 2005; Chastain et al. J Neurotrauma 2009 Conventional GRE SWI

17 17 year old pedestrian struck by car on his way to school? LOC, confused, GCS 14 FLAIR SWI

18 16 yo cyclist hit by truck, pupils fixed and dilated, posturing, GCS 5 Brainstem involvement is a important predictor of long-term outcome Mannion et al. J Neurotrauma 2007; Skandsen et al. J Neurotrauma 2011 Chew et al. J Neurosurg 2012; FLAIR SWI

19 2 year old girl s/p fall off couch, not well for 2 days Rt sided hemiparesis and neglect Cerebral venous architecture: Increased conspicuity Hypoxemia: O2 extraction CBF vasospasm arterial dissection, occlusion, thrombus ICP Decreased conspicuity O2 extraction CBF vasodilation Decreased conspicuity may predict risk for ICP and cerebral swelling Polan et al. SWI in PAIS, AJNR 4,2015 SWI

20 Cerebral venous architecture: Increased conspicuity Hypoxemia: O2 extraction CBF vasospasm arterial dissection, occlusion, thrombus ICP Decreased conspicuity O2 extraction CBF vasodilation Decreased conspicuity may predict risk for ICP and cerebral swelling Polan et al. SWI in PAIS, AJNR 4,2015 T2WI ASL SWI Trace DWI 2 ADC Days Map Later

21 3-month-old boy with concern for AHT Fundoscopic examination: bilateral extensive RHs out to ora serrata, multilayered SWI can detect retinal hemorrhages Zuccoli et al. Neuroradiology 2013 T2WI SWI SWI MRI on day of admission

22 Arterial Spin Labelling (ASL)

23 Perfusion Imaging Xenon-enhanced CT Single-photon emission CT (SPECT) PET Perfusion CT Perfusion-weighted MRI (Bolus tracking-dsc) Arterial Spin Labelling (ASL)

24 Arterial Spin Labeling (ASL) Emerging tool, non-invasive, no radiation, no gadolinium, no needles, repeatable Tracer: endogenous H2O magnetically tagged arterial water protons used as endogenous contrast agent Techniques: CASL, PCASL, PASL, VS-ASL Spatial resolution: 2 mm Qualitative and quantitative Characterizes hypo- and hyperperfusion states and changes in regional blood flow Children: CBF varies by age and gender challenges higher CBF contamination secondary to systemic tagging quantification: T1 relaxation time blood

25 Arterial Spin Labeling (ASL) Emerging tool, non-invasive, no radiation, no gadolinium, no needles, repeatable Tracer: endogenous H2O magnetically tagged arterial water protons used as endogenous contrast agent Techniques: CASL, PCASL, PASL, VS-ASL Spatial resolution : 2 mm Qualitative and quantitative Characterize hypo- and hyperperfusion states and changes in regional blood flow and cognitive deficits Children: CBF varies by age and gender challenges higher CBF contamination secondary to systemic tagging quantification: T1 relaxation time blood Udomphorn et al Pediatr Neurol 2008

26 15 year old girl with a left ICA dissection T2WI MRA SWI FLAIR Trace DWI PASL

27 3-month-old s/p fall from father s arms Regional heterogeneity in perfusion in mtbi correlates with psychological and neurocognitive impairment, posttraumatic amnesia Preserved vs impaired cerebral autoregulation with ICP, after decompression, vasospasm, brain death 3D model NCCT T2WI Perfusion of cerebral contusions and brain injury Wang et al. Dev Neuropsychol 2015; Amorim RA et al J Neuroradiol 2012; Wintermark Met al Radiology 2004, Liu W et al. NMR Biomed 2013 ADC Map PASL

28 16-month-old girl with abusive head trauma 7 hours after 1 st onset of symptoms T2WI SWI TE 270 msec Trace Image ADC Map PASL

29 Conclusion Clinical applications of DWI, SWI, ALS Provide greater diagnostic accuracy in the individual child May identify vulnerable brain for targeted interventions