Medical Imaging of the Pediatric Trauma Pa5ent

Transcription

1 Medical Imaging of the Pediatric Trauma Pa5ent November 13, 2014 Thaddeus W. Herliczek, MD, MS

2 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.

3 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.

4 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.

5 Imaging Menu Radiography Ultrasound Fluoroscopy Computed Tomography Magne5c Resonance Imaging

6 Radiography Advantages; Highest spa5al resolu5on. Excellent evalua5on of osseous structures. Fast. Portable. Inexpensive.

7 Radiography Disadvantages; Limited soft tissue contrast. Ionizing radiation.

8 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.

9 Ultrasonography Advantages Portable No ionizing radiation Less expensive than CT or MRI

10 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

11 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.

12 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.

13 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.

14 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.

15 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)

16 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.

17 MRI Disadvantages 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

18 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

19 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

20 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

21 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

22 Important Principles ALARA Risk vs. Benefit The Bobom Line ALARA= As Low As Reasonably Achievable

23 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.

24 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

25 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.

26 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

27 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

28 Resources Radiation Risks and Pediatric Computed Tomography (CT): A Guide for Health Care Providers. National Cancer Institute at U.S. National Institutes of Health. Frush et al. Computed tomography and radiation risks: What pediatric health care providers should know. Pediatrics 112; 4: Brenner, D. and Hall, E. Computed Tomography-An Increasing Source of Radiation Exposure. NEJM 357;22: ImageGently.com

29 Cervical Spine Imaging Controversial Topic. No accepted consensus.

30 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.

31 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.

32 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.

33 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.

34 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.

35 References American College of Radiology Appropriateness Criteria Benya et al. Abdominal sonography in examination of children with blunt abdominal trauma. AJR 2000; 174: Brenner et al. Estimated risks of radiation induced fatal cancer from pediatric CT. AJR 2001; 176: Brenner, D. and Hall, E. Computed Tomography-An Increasing Source of Radiation Exposure. NEJM 357;22: Bushberg, J. The Essential Physics of Medical Imaging 2 nd edition., Radiation Biology. Lippincott Williams and Wilkins. New York Pps 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: Kleinerman, Ruth A. Cancer risks following diagnostic and therapeutic radiation exposure in children. Pediatric Radiology 2006; 36: Netter, Frank. Atlas of Human Anatomy 2 nd Ed. Hoechstetter Printing Co Parry et al. Typical Patient Radiation Doses in Diagnostic Radiology. from The AAPM/ RSNA Physics Tutorial for Residents. Radiographics Vol. 19 No. 5. Pps Richards et al. Blunt abdominal trauma in children: Evaluation with emergency ultrasound. Radiology 2002; 222: Slovis, Thomas L. The ALARA concept in pediatric CT: myth or reality? Radiology 2002; 223: 5-6.

36 Medical Imaging of the Pediatric Trauma Pa5ent November 13, 2014 Thaddeus W. Herliczek, MD, MS