Blunt Cerebrovascular Injury (BCVI): Spectrum of Imaging Findings Joao Inacio, Ferco Berger, Daniel Hou, David Tso, Adrian Reagan, Savvas Nicolaou Radiology Department, Emergency Trauma Section, University of British Columbia /Vancouver General Hospital Vancouver, BC, Canada www.ubcERradiology.com ASER, Seattle, 11-14th August 2010

Blunt Cerebrovascular Injuries (BCVI) [= Blunt Carotid/Vertebral Arterial Injury] Objectives: Scope of Blunt Cerebrovascular Arterial injury Rationale for Screening Screening Imaging Modalities CTA Technical Aspects BCVI: Spectrum of Imaging Findings Conclusion

Introduction: BCVI includes: Common and internal carotid arteries (71%)* Vertebral arteries (29%)* Both BCVI is uncommon in the general blunt trauma setting but is more common than previously believed. Incidence of 0.1-1.55% of all blunt trauma admissions** Stroke prevention is a feasible goal of early diagnosis and treatment of BCVI * Bub- Trauma: 2005 ** Miller- Annals of Surg: 2003

Scope of the problem: BCVI-related mortality rates of 23%, with 48%-80% of survivors suffering permanent severe neurological sequelae The Denver group confirmed that many injuries are clinically occult at admission The majority of injuries diagnosed after CNS ischemic symptoms, hours to days after the traumatic insult

Blunt Cerebrovascular Injuries (BCVI) Objectives: Scope of Blunt Cerebrovascular Arterial injury Rationale for Screening Screening Imaging Modalities CTA technical aspects BCVI: Spectrum of Imaging Findings

Rationale for Screening : Patients at risk for BCVI can be identified and diagnosed before the onset of symptoms with the application of an appropriate screening modality Institution of medical therapy or revascularization has significant impact on prognosis Screening BCVI : exceeds 1% of blunt trauma admissions Incidence up to 2.7% in patients with Injury Severity Score ≥16

BCVI and Stroke: Majority occur 10 – 72 hours post trauma Effective screening criteria remain elusive Blunt Carotid injury: Mortality - 28% Neurological Sequelae - 58% Blunt Vertebral Artery Injury: Mortality - 8% Neurological Sequelae - 24%

BCVI and Stroke: Screening for BCVI: Identification of asymptomatic patients with BCVI and prevent neurological complications.

Criteria for screening/ Risk Factors Denver Modified BCVI Screening Criteria Clinical Signs/Symptoms of BCVI Risk factors for BCVI (High-energy transfer mechanism) Blunt Cerebrovascular Injury Practice Management Guidelines, J Trauma. 2010

Criteria for screening/ Risk Factors Denver Modified BCVI Screening Criteria (I) Signs/symptoms of BCVI: Arterial hemorrhage Cervical bruit Expanding cervical hematoma Focal neurological deficit Neurologic examination unexplained by neuroimaging findings Ischemic stroke on secondary Head CT Blunt Cerebrovascular Injury Practice Management Guidelines, J Trauma. 2010

Criteria for screening/ Risk Factors Criteria for screening/ Risk Factors Denver Modified BCVI Screening Criteria (II) Risk factors for BCVI: Lefort II or III fractures Cervical spine fracture patterns: Subluxation Fractures extending into the transverse foramen Fractures of C1–C3 Basilar skull fracture with carotid canal involvement Diffuse axonal injury with Glasgow Coma Scale score <6 Seatbelt contusion on neck (not isolated) Near hanging with anoxic brain injury Blunt Cerebrovascular Injury Practice Management Guidelines, J Trauma. 2010

Denver Modified BCVI Screening Criteria: Limitations 20-27% patients with BCVI may not fulfill the commonly reported screening criteria Other liberal screening criteria: Thoracic Abbreviated Injury score of ≥3 Injury Severity Score ≥16 Skull/ C-spine Fracture line extending to vascular channel

Vancouver General Hospital Screening Criteria Any blunt trauma patient with GCS ≤ 13 Any trauma patient with GCS > 13 plus: Cervical spine injury Basal Skull fracture Diffuse Axonal injury LeForte II/III fracture Significant thoracic injury Abnormal neurological exam not explained by CT scan of the head Discretion of attending Trauma Surgeon

Objectives: Scope of Blunt Carotid/Vertebral Arterial injury Rational for Screening Screening Imaging Modalities CTA technical aspects BCVI: Spectrum of Imaging Findings

Screening Imaging Modalities What is the appropriate modality for the screening and diagnosis of BCVI? Diagnostic digital subtraction (DSA) four-vessel cerebral angiography: remains the gold standard modality. MDCT is the best non invasive screening modality in place of DSA. MRI Angiography is promising but with limited availability. Duplex ultrasound is not adequate for screening for BCVI. Blunt Cerebrovascular Injury Practice Management Guidelines, J Trauma. 2010

BCVI Screeninng: MDCT vs DSA Controversy and Consensus Strokes are prevented by early diagnosis and antithrombotic therapy. The harder you look for BCVI, the more injuries you will find Does CTA false-positive/ negative studies reflect the technology or the interpretation? ≥16-slice MDCT CTA is the most accurate noninvasive screening modality available More data needed to know if and when to submit patients to confirmatory DSA, with its attendant risks and expense. Biffl, Walter L., (editorial) J Trauma February 2010

Objectives: Scope of Blunt Carotid/Vertebral Arterial injury Rational for Screening Screening Imaging Modalities CTA technical aspects BCVI: Spectrum of Imaging Findings

CT Trauma Evaluation Technical Aspects STANDARD (Segmented) MDCT PROTOCOL: Scout head and C-spine Nc Head CT C-spine or CTA vertex to arch - Arms Reposition- CTA Chest + Abd (arterial) CT Abd + Pelvis (venous) - 5’ delay- CT Delayed excretory phase and Focused CT: Peripheral vascular injuries Complex limb fractures 1st bolus IV contrast 2nd bolus IV contrast 3rd bolus IV contrast

VGH Blunt Neck Trauma CTA Protocol: Part of Segmented Trauma Series CT Arterial phase Arch to COW mAs(Tube A) kV 120 500 Kernel B B46(Mediastinum) 2 x1mm MIP recon thru COW and Carotids B75(Bone) 2x 1mm for C Spine Collimation 128 mmx 0.6mm Pitch 1.1 Rotation Time 0.28-0.5s CTDIvol 25 Note: Bolus tracking at arch using 120 cc of 320 mgI/mL at 5.0mL/s for arterial phase acquisition.

CT Trauma Evaluation Technical Aspects WHOLE BODY (CONTINOUS) MDCT PROTOCOL: Scout head to toe or NO SCOUT Nc Head CT (1st scan) CTA vertex to pelvis (arterial) (2nd scan) CT Abd + Pelvis (venous) (3rd scan) Pros: Faster acquisition Less radiation Less iodine contrast 1st bolus IV contrast Cons: Artifacts from arms position Lower signal to noise ratio Demanding post processing

CTA Arch to vertex: Technical Aspects POST-PROCESSING: Multiplanar reformation is applied for precise quantitative analysis of lumen and vessel wall Routine reformatted series: Axial source images 2mm MPRs 2mm: Cervical Coronal Oblique sagital of carotid bifurcations MIPs 3mm: Head and neck: axial Cervical: carotid bifurcations Head: coronal, sagital                    Sagital Head to COW bone images 2mm

Objectives: Scope of Blunt Carotid/Vertebral Arterial injury Rational for Screening Screening Imaging Modalities CTA technical aspects BCVI: Spectrum of Imaging Findings

BCVI: Spectrum of Imaging Findings Denver Grading Scale: Grade I – Minimal Intimal injury / intimal irregularity with <25% narrowing Grade II - Dissection with raised intimal flap; intramural hematoma with >25% narrowing; Intraluminal thrombus Grade III - Pseudoaneurysm Grade IV - Occlusion/ Thrombosis. Grade V - Transection with free extravasation Arteriovenous fistula: ± Hemodynamic significance (Grade II or V) Blunt carotid arterial injuries: implications of a new grading scale, Biffl et al. J Trauma 1999

Grade Injury and Prognosis Denver Grading Scale: Stroke incidence in Blunt Carotid Injury: Grade I - 3% Grade II - 11% Grade III – 33% Grade IV - 44% Grade V – 100% Blunt carotid arterial injuries: implications of a new grading scale, Biffl et al. J Trauma 1999

Grade Injury and Prognosis Denver Grading Scale: Stroke incidence in Blunt Vertebral Artery Injury: Grade I – 19% Grade II - 40% Grade III – 33% Grade IV - 13% Grade V – 0 cases Biffl WL, et al, Blunt carotid and vertebral arterial injuries. World J Surg 2001

BCVI: Spectrum of Imaging Findings Major segments involved: Distal Cervical segments of ICA Petrous and Cavernous ICA Vertebral arteries C1-C2 and C6 18-36% Multiple Arteries Are Injured

Left Internal Carotid Minimal Intimal Injury (Grade I) Figure 1. Left Internal Carotid Minimal Intimal Injury. 39y Male, MVC. Sagital Cervical MPR. MRI axial T1 image. Left Internal Carotid Minimal Intimal Injury with high intensity Intramural hematoma, <25% luminal narrowing.

Right Vertebral Minimal Intimal Injury (Grade I) Figure 2. Right Vertebral Artery multofocal Minimal Intimal Injury.

Left Internal Carotid Dissection (GRADE II) Figure3. 40y Male, MVC. Sagital Cervical MPR and axial source image. Left Internal Carotid Artery dissection with raised intimal flap.

Vertebral Artery Dissection (GRADE II) Figure 4. 34 y female, MVC . Whole body CT trauma protocol with coronal cervical MPR and posterior fossa axial image. Left vertebral artery dissection with raised intimal flap, and left cerebellar ischemic infarct. DSA correlation with long vertebral artery dissection from C2 to C6.

Right Internal Carotid Dissection/Intramural Hematoma >25% Luminal Stenosis/Pseudoaneurysm (GRADE II AND III) Figure 5. Grade II Injury. Snowboarding injury with 15 minutes loss of consciousness at the scene. CTA with oblique sagittal and coronal MIP reformats with bilateral wall hematoma resulting in >25% stenosis, with extension to the petrous segment on the right. There is also a pseudoaneurysm in keeping with a grade III injury.

Right Internal Carotid Pseudoaneurysm (GRADE III) Figure 6. Grade III Injury. Distal Right Internal Carotid Pseudoaneurysm. CTA coronal, sagital , axial images with DSA correlation.

Bilateral Occlusion of Vertebral Arteries (Grade IV) Figure 7. Grade IV Injury. Bilateral Occlusion of the Vertebral Arteries. MVA with seat belt sign neck, > 50% subluxation of C5/C6 with locking facets: two associated risk factors for BCVI.

Unilateral Occlusion of Vertebral Artery (Grade IV) Figure 8. Grade IV Injury. 30 y male, MVC . RIPIT protocol with coronal neck MPR and posterior fossa axial image. Left vertebral artery traumatic thrombosis and left cerebellar infarct.

Left Vertebral Artery Transection with active contrast extravasation (Grade V) Figure 9. Grade V Injury. 35 y Male, MVC ; Whole body CT trauma protocol with cervical VR. Atlantoaxial dissociation, left vertebral artery transection with active contrast extravasation.

Left Vertebral Artery Transection with active contrast extravasation (Grade V) Figure 10. Grade V Injury. Left Vertebral Artery transection with active contrast extravasation.

Follow-up imaging: Both untreated and medically treated injuries can either heal or progress Standardized follow-up regimens are mandatory ≥7-10d post trauma

Western Trauma Association Critical Decisions in Trauma: Screening for and Treatment of Blunt Cerebrovascular Injuries. Biffl, Walter et all, J Trauma December 2009. 2

Conclusion Diagnostic Imaging plays a vital role in diagnosis of cerebrovascular injuries Prompt diagnosis and treatment impacts prognosis DSA is the gold standard for BCVI screening CTA as proved especially valuable CTA technical aspects and Interpretation must be considered in management decisions Screening and treatment of BCVI is effective

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