Determination of Seat Belt Use and Positioning with Three Dimensional CT Fat Volume Rendering in CIREN Frontal Crash Cases
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Determination of Seat Belt Use and Positioning
with Three‐Dimensional CT Fat Volume
Rendering in CIREN Frontal Crash Cases
T. Hartka, T. Ward, J. Crandall, C.G. Shaw, M. Sochor,
R. Freeth, C. Vo, A. Rizzo
University of Virginia ‐ INOVA Fairfax Hospital
CIREN Center
Challenges with analyzing crash injuries
• Belt use
• Improper restraint use
• Occupant kinematics
• Involved physical
components (IPCs)
2007 Saturn Ion Vs.
2004 Mitsubishi Outlander
Occupant Kinematics
Safety system interaction CIREN ID 160154029
Seatbelt sign
• Visible ecchymosis, purpura,
or abrasion due contact with
seat belt
• Indicator of internal injury
• A meta‐analysis from JAMA
2012 of clinical features of
patients requiring abdominal
surgery or embolization:
– Seatbelt sign – LR 5.6‐9.9
– Hypotension ‐ LR 5.2
– Abd pain – LR 1.6
Nishijima DK, Simel DL, Wisner DH, Holmes JF. Does this adult patient have a blunt intra‐abdominal
injury? JAMA. 2012 Apr 11;307(14):1517‐27. doi: 10.1001/jama.2012.422.
Seatbelt syndrome
– Seatbelt sign associated with
constellation of injuries:
• Hollow viscous injuries
• Splenic laceration/rupture
• Liver laceration
• Rib fractures*
– Pediatric study found seatbelt sign had
increased risk of injury but decreased
overall mortality
Sharma OP, Oswanski MF, Kaminski BP, et al. Clinical implications of the seat belt sign in
blunt trauma. Am Surg. 2009 Sep;75(9):822‐7.
Post‐tramatic changes to subcutaneous fat • Lipoatropy/liponecrosis may follow breast trauma from seatbelt • May be seen on mammography: – Thin‐walled fat cysts – Band of increased density – Parenchymal calcifications • Ultrasound also demonstrates lipid cysts DiPiro PJ, Meyer JE, Frenna TH, Denison CM. Seat belt injuries of the breast: findings on mammography and sonography. AJR Am J Roentgenol. 1995 Feb;164(2):317‐20.
Fat stranding: Atraumatic,
Pancreatitis/Appendicitis
Fat Stranding
Fat stranding – Traumatic, Axial Slice
Fat stranding – Traumatic, Sagittal Slice
Fat density change – etiology • Macroscopic – Ecchymosis – Hematoma – Surface abrasions • Microscopic – Inflammation – Edema – Microhemorrhage
Volume Rendering from CT
Tissue density displayed on CT
Average Hounsfield Units
3500
3000 60
2500
2000 40
1500
1000 20
500
0 0
‐500 Fat CSF Kidney Blood Muscle Grey White Liver
‐20 matter matter
‐1000
‐1500
‐40
‐60
‐80
‐100Fat appearance on CT Fat
Spectrum Mapping
Fat
Air Bone
‐100 ‐503D Rendering ‐ Volume ray casting Observer
Normal female – 3D rendering – fat filter
CIREN ID 352217171 – 47YF, 163cm, 70kg,
Front right passenger
WinSMASH delta V = 91 km/h (57 mph)CIREN ID 352217171– Crush and Intrusions
Max Crush: 84 cm @ C3 IP: 15 cm
Toepan: 38 cmCIREN ID 352217171– Restraints
CIREN ID 352217171– Patient photographs
CIREN ID 352217171– Injuries
CIREN ID 352217171– 3D Rendering (fat filter)
CIREN ID 352217171– Front passenger
Carotid Occlusion Vertebral fx
Rib fx’s
Sternal fx
Hip contusionsFat damage during trauma • Areas that sustain trauma tend to shift toward green spectrum, which represents higher density • Areas are more likely to contain blood, edema, and inflammation
Comparison of Filter
CT Fat CT ‐ Muscle CT – Cardiac CT – Contrast
EnhancedFat stranding in planar view
CIREN database – High delta V, frontal impact
3 Dimensional rendering – Difficulties encountered • FAST Positive direct to OR • CT chest/abd/pelvis not indicated • DICOMs not uploaded • Formatting errors in DICOMs • Artifacts/Confounding factors
High delta V – Frontal Impacts
Belted Occupants
Belted Occupants
Belted occupants – 15YF, 2nd row
driver’s side passenger
[No photos were taken]
CIREN ID ‐ 352217329Belted occupants – 15YF, 2nd row
driver’s side passenger
Lung contusion
PTX Contusions
Liver lac
Pneumomediastinum
CIREN ID ‐ 352217329Belted occupants – 37YF, Driver
CIREN Case ID ‐ 317077952Belted occupants – 37YF, Driver
Rib fx’s
Sternum fx
Liver lac Spleen Lac
Vertebral fx’s
Acetabular
Pelvic ring
CIREN Case ID ‐ 317077952Belted occupants – 41YF, Driver
CIREN ID ‐ 338052018Belted occupants – 41YF, Driver
Facial fx’s
Rib fx’s
Mesentery Abd
contusion contusion
Femur fx
CIREN ID ‐ 338052018Belted occupants – 83YM, Driver
CIREN ID ‐ 338081059Belted occupants – 83YM, Driver
C‐spine fx’s
Sternum fx’s
Rib fx’s
PTX
L‐spine fx’s
CIREN ID ‐ 338081059Belted occupants – 80YF, Front passenger
Umbilicus
CIREN ID ‐ 338081305Belted occupants – 80YF, Front passenger
Neck contusion Chest contusions
Sternum fx PTX
Hemomediastinum
Abd contusion
CIREN ID ‐ 338081305Unbelted occupants
Unbelted occupants???
CIREN – Unbelted driver
• 56YF, 175cm, 66kg
• Evidence:
– Crash investigation
– Physical examination
– Kinematics
• Scalp laceration –windshield
• Facial fractures – A‐pillar
CIREN ID ‐ 352169891CIREN – Unbelted driver
Left rib fractures 7‐9
“… portions of her left chest
contacted the forward upper
quadrant of the door panel...”
CIREN – ID 35216989CIREN – Unrestrained driver
• 26YF, 165cm, 70kg
• Evidence:
– Crash investigation
– Physical examination
– Kinematics
• Hair ‐ sunvisor
• Knees ‐ IP
CIREN – ID 352300365CIREN – Unrestrained driver
Head into visor/windshield
Knees into bolster
CIREN – ID 352300365CIREN – Unbelted driver
CIREN – ID 352300365Submarining Cases
CIREN ID: 360222743 Abdominal Injuries:
1. Bilateral lumbar hernias
2. Major mesentery laceration
3. Bilateral major skin avulsion
4. Bilateral rectus muscles ruptures
5. Left renal contusion
Umbilicus
ASIS
Occupied seat 23 BMI: 37.9CIREN ID: 360222743 contd.
Thoracic Injuries:
1. Left ribs 3, 4, 5, 6, 7 w/o flail
Umbilicus
ASIS
Occupied seat 23 BMI: 37.9CIREN ID: 360222743 contd.
Thoracic Injuries:
1. Left ribs 3, 4, 5, 6, 7
w/o flail Umbilicus
ASIS
Occupied seat 23 BMI: 37.9CIREN ID: 360222743 contd.
Umbilicus
ASIS
Occupied seat 23 BMI: 37.9CIREN ID: 360222743, contd. Head
Head
Foot
Foot
Patient’s right flank Patient’s left flank
Occupied seat 23 BMI: 37.9Abdominal Injuries:
CIREN ID: 317116652 1. Cecum laceration
2. Abdominal abrasion across front
3. L1 compression fracture
4. L3 compression fracture
5. L4 compression fracture
6. Small bowel laceration
ASIS
Occupied seat 11 BMI: 18.7Confounding factors ‐ artifacts • Overlying objects – Cords – Tubes – Extremities • Skins fold and pannus • Tissue outside of CT imaging area
Artifacts ‐ Cords and tubes
Artifacts – Folds and pannus
Artifacts – Overlying hand
CIREN ID 317086120Artifacts – CT imaging area
Artifacts – CT imaging area
Anticipated difficulties • Lack of subcutaneous fat – Children – Thin subjects • Low delta V • Side impacts
Future Research
• Sensitivity and specificity analysis
– Independent review of 3D images
by blinded observers [Fat rendering image]
• Find association with BMI, delta V
• Correlation with internal injuries
• Investigate as triage assessment
tool
• Belt injury mechanism: fat shear
or compression?Summary • Fat rendering is a potentially useful tool determining seat belt use and position • Minimal training required for proficiency • Injuries areas have increased density • Images need to be interpreted in context of collision mechanics • You should examine external views for potential confounders • Further research will determine sensitivity and utility in injury prediction
Demonstration – 3D Slicer CIREN Case 352217171
Questions?
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