Medical  Imaging  of  the  Pediatric  Trauma  Pa5ent  November  13,  2014  

Thaddeus  W.  Herliczek,  MD,  MS  

Objectives

•  Describe the imaging modalities available to image the pediatric trauma patient.

•  Describe the ALARA principle and the risks of CT in pediatric patients.

•  Identify appropriate imaging algorithm for imaging pediatric cervical spine trauma.

Take  Home  Points  •  Every imaging modality has advantages and

disadvantages. •  Plain radiography and CT are the modalities of

choice for the pediatric trauma patient. •  Potential benefits of appropriate imaging in

pediatric trauma patient exceed the risks of radiation.

•  Pedi C-spine: radiographs first, not CT. •  When in doubt, talk to your radiologist.

Trauma  

•  600,000  trauma-­‐related  pediatric  hospital  admissions  annually  in  the  U.S.  

•  Trauma5c  injuries  can  be  difficult  to  diagnose  by  physical  exam  alone.  

•  Prompt  and  appropriate  imaging  can  prevent  significant  morbidity  and  mortality  of  pediatric  trauma  pa5ents.  

Imaging  Menu  

•  Radiography  •  Ultrasound  •  Fluoroscopy  •  Computed  Tomography  •  Magne5c  Resonance  Imaging  

Radiography  

•  Advantages;  – Highest  spa5al  resolu5on.    – Excellent  evalua5on  of  osseous  structures.  – Fast.  – Portable.  –  Inexpensive.  

Radiography  •  Disadvantages; – Limited soft tissue contrast. –  Ionizing radiation.

Ultrasonography  

Two types in setting of trauma; 1. Diagnostic US 2. F.A.S.T.= Focused Abdominal Sonogram for

Trauma

-­‐Assessment  for  intraperitoneal  fluid.  -­‐Replaced  peritoneal  lavage.  

Ultrasonography  

•  Advantages – Portable – No ionizing radiation – Less expensive than CT or MRI

Ultrasonography  •  Problems –  Availability –  Time –  Low sensitivity and specificity for detecting visceral

injuries and hemoperitoneum. –  US does not adequately evaluate osseous structures,

retroperitoneum, gas containing structures (bowel and lung) and mediastinum.

–  Operator Dependent

Ultrasonography  –  Low sensitivity and specificity for detecting visceral

injuries and hemoperitoneum. –  Missed 12/32 splenic injuries. –  1/3 of visceral injuries do not have hemoperitoneum

–  Low sensitivity and low negative predictive value render a normal screening US insufficient to exclude abdominal injury.

–  Presently, US is not recommended to exclude traumatic injury.*

*  Minimal  controversy  and  there  is  ongoing  research  esp.  contrast  enhanced  US.  

Fluoroscopy  

•  Real  5me  “con5nuous”  evalua5on  with  x-­‐rays.  

•  Usually  following  inges5on  or  injec5on  of  contrast  medium  into  an  orifice  or  blood  vessel.  

•  Rarely  used  in  trauma  pa5ents.  •  Men5oned  only  for  completeness.  

Computed  Tomography  (CT)  •  Advantages; –  Excellent soft tissue contrast resolution. –  Readily available. –  Fast. –  High sensitivity and specificity. –  Multiplanar reformats. –  Excellent evaluation of all tissues except spinal cord

and ligament/tendon trauma.

Computed Tomography

•  Its advantages render it the imaging modality of choice to assess traumatic injury of the head, face, neck, abdomen and pelvis.****

•  *** Could be on the “test”.

CT  

•  One of the keys to a successful chest or abdomen/pelvis trauma CT is infusion rate of IV contrast.

•  This is dramatically influenced by the caliber of the IV in place. The ideal IV line for CT is an 18g in the right antecubital fossa.

•  Please place larger catheters whenever possible. (Bernoulli’s Principle)

Magne5c  Resonance  Imaging  (MRI)  

•  Uses  non-­‐ionizing  radia5on.  •  No  known  deleterious  effects.    •  Some  studies  suggest  it  is  equivalent  to  CT  for  evalua5on  of  trauma5c  injuries.    

•  Excellent  so]  5ssue  contrast.  •  Imaging  modality  of  choice  for  spinal  cord  injury.  

MRI  

–  Longer image acquisition time –  Sedation (< 7 years, developmental delay, agitation) –  High magnetic field limits supportive equipment and ability to monitor and resuscitate

patients –  Limited availability –  Expensive –  Limited evaluation of cortical bone/fractures

Disadvantages  

Ionizing  Radia5on  

•  X-rays from plain radiography, CT, and fluoroscopy are a form of ionizing radiation.

•  X-rays can have deleterious effects. – Burns - Cancer – Alopecia -Birth defects

ALARA=  As  Low  As  Reasonably  Achievable  

•  Children  are  more  sensi5ve  to  radia5on  exposure  than  adults.  –  Inherently  more  radiosensi5ve.  (esp.  thyroid,  breast  5ssue,  gonads)    

– Longer  life  expectancy  over  which  to  express  the  radia5on  induced  damage  to  genes.      

– Girls  are  slightly  more  sensi5ve  than  boys.  

ALARA=  As  Low  As  Reasonably  Achievable  

Radia5on  Scale  

•  US, MRI and the decision not to obtain imaging expose the child to the same amount of ionizing radiation: None.

•  Radiography exposes children to relatively low doses of ionizing radiation.

•  CT exposes children to the greatest amount of ionizing radiation in medical imaging.

•  The possibility of a deleterious effect from medical radiation is very small.

ALARA=  As  Low  As  Reasonably  Achievable  

Radia5on  Scale  

•  One year of natural background radiation exposure is similar dose as 30 chest radiographs.

•  Transcontinental flight on a commercial airliner exposes child to same dose of radiation as 2 chest radiographs.

•  On our Hasbro CT scanner (iterative reconstruction

algorithm), CT of the chest is the same radiation dose as 6 chest radiographs.

ALARA=  As  Low  As  Reasonably  Achievable  

Important  Principles  

•  ALARA  •  Risk  vs.  Benefit  •  The  Bobom  Line  

ALARA= As Low As Reasonably Achievable

A.L.A.R.A.  •  As Low As Reasonably Achievable

– American College of Radiology tenet on radiation dose/exposure.

– All medical professionals must strive toward this goal when caring for all patients, but especially

children. – Potential risks of unnecessary exposure to ionizing radiation warrant judicious patient

selection for CT scanning.

*** Could be on the “test”.

How  do  we  keep  radia5on  exposure  ALARA?  

•  Clinicians  –  Request  imaging  only  when  necessary.*  •  Area  of  ongoing  research  

–  Request  the  appropriate  exam.  

–  Communicate  with  your  pediatric  radiologist.  

•  Radiologists  –  Ensure  imaging  is  

necessary.  –  Ensure  that  the  appropriate  

exam  is  requested.    –  Suggest    appropriate  

alterna5ve  modali5es  (ex.  MRI  for  C-­‐spine).  

–  Communicate  with  the  reques5ng  clinician.  

–  Adjust  imaging  parameters  to  keep  radia5on  exposure  low,  but  maintain  diagnos5c  image  quality.    

ALARA=  As  Low  As  Reasonably  Achievable  

The  Transferred  Pa5ent  

•  Many  children  with  trauma5c  injuries  arrive  at  Hasbro  Children’s  Hospital  for  treatment  having  already  received  diagnos5c  imaging  at  an  outside  ins5tu5on.  

•  The  CD’s  or  films  that  accompany  them  are  crucially  important.  If  these  get  lost,  it  can  result  it  repeated  diagnos5c  imaging,  unnecessary  radia5on  exposure  and  delayed  diagnosis.  

•  Please  help  prevent  misplacement  of  these  exams.  

Risk  vs.  Benefit  

•  While  x-­‐rays  (plain  radiography  and  CT)  increase  the  risk  of  deleterious  effects  such  as  cancer,  the  poten>al  benefit  from  the  clinically  necessary  imaging  study  drama>cally  outweighs  this  risk.  

ALARA=  As  Low  As  Reasonably  Achievable  

The  Bobom  Line  is….  •  The possibility for traumatic injury must

dictate the need for radiation-based medical imaging as the risk from exposure to ionizing radiation associated with radiological examinations is low. Nevertheless, it is still advisable to avoid such exposure where possible.

ALARA=  As  Low  As  Reasonably  Achievable  

Resources  •  “Radiation Risks and Pediatric Computed

Tomography (CT): A Guide for Health Care Providers.” National Cancer Institute at U.S. National Institutes of Health. www.cancer.gov

•  Frush et al. “Computed tomography and radiation risks: What pediatric health care providers should know.” Pediatrics 112; 4: 951-957.

•  Brenner, D. and Hall, E. “Computed Tomography-An Increasing Source of Radiation Exposure.” NEJM 357;22: 2277-2284.

•  ImageGently.com

Cervical  Spine  Imaging  

•  Controversial Topic.

•  No accepted consensus.

Another  problem  

•  Cervical spine trauma can involve osseous, ligamentous, capsular, vascular and neural structures.

•  No one imaging modality can evaluate injury to all these tissues. –  Radiographs and/or CT for osseous structures. –  MRI for ligamentous, capsular and neural structures. –  CTA/MRA for vascular injury.

Cervical  Spine  Imaging  in  Pediatric  Trauma  Pa5ents  

•  Imaging algorithm varies by age, institution, superstition, etc.

•  Guidelines for imaging exist, but they vary by institution, association, etc.

•  Literature on pediatric cervical spine imaging remains sparse.

Pediatric  Cervical  Spine  Imaging  

•  Controversy in pediatric imaging is secondary to desire to exclude/identify cervical spine trauma versus maintaining radiation exposure (and cost) As Low As Reasonably Achievable (ALARA).

•  Most recommendations are based on adults. •  Given the controversy and variability, we’ll

review what the American College of Radiology recommends and what I think.

What  do  I  propose?    

Cervical  Spine  Injury  Suspected  

Plain  radiographs    first  

Tailored  cervical  spine  CT    and/  or  cervical  spine  MRI    as  needed  

                     

????: If abnormality present or questioned abnormality.

*** Could be on the “test”.

Take  Home  Points  •  Every imaging modality has advantages and

disadvantages. •  Plain radiography and CT are the modalities of

choice for the pediatric trauma patient. •  Potential benefits of appropriate imaging in

pediatric trauma patient exceed the risks of radiation.

•  Pedi C-spine: radiographs first, not CT. •  When in doubt, talk to your radiologist.

References  

•  American College of Radiology Appropriateness Criteria •  Benya et al. “Abdominal sonography in examination of children with blunt abdominal

trauma.” AJR 2000; 174: 1613-1616. •  Brenner et al. “Estimated risks of radiation induced fatal cancer from pediatric CT.”AJR 2001;

176: 289-296. •  Brenner, D. and Hall, E. “Computed Tomography-An Increasing Source of Radiation

Exposure.” NEJM 357;22: 2277-2284. •  Bushberg, J. The Essential Physics of Medical Imaging 2nd edition., “Radiation Biology”.

Lippincott Williams and Wilkins. New York. 2002. Pps. 853-60. •  Children’s Hospital Boston Clinical Practice Guidelines •  Keenan et al. “Using CT of the cervical spine for early evaluation of pediatric patients with

head trauma.” AJR 2001; 177: 1405-1409. •  Kleinerman, Ruth A. “Cancer risks following diagnostic and therapeutic radiation exposure in

children.” Pediatric Radiology 2006; 36: 121-125. •  Netter, Frank. Atlas of Human Anatomy 2nd Ed. Hoechstetter Printing Co. 1997. •  Parry et al. “Typical Patient Radiation Doses in Diagnostic Radiology.” from The AAPM/

RSNA Physics Tutorial for Residents. Radiographics Vol. 19 No. 5. Pps. 1289-1302 •  Richards et al. “Blunt abdominal trauma in children: Evaluation with emergency ultrasound.”

Radiology 2002; 222: 749-754. •  Slovis, Thomas L. “The ALARA concept in pediatric CT: myth or reality?” Radiology 2002;

223: 5-6.

Medical  Imaging  of  the  Pediatric  Trauma  Pa5ent  

November  13,  2014  Thaddeus  W.  Herliczek,  MD,  MS