Injury Specificity for NAT
| Injury Type | Specificity for NAT |
|---|---|
| Classic metaphyseal lesions (CML) — corner/bucket-handle fractures | High |
| Posterior rib fractures | High |
| Interhemispheric subdural hematoma | High (abusive head trauma) |
| Scapular body fractures | Moderate–High |
| Spinous process fractures | Moderate–High |
| Sternal fractures | Moderate |
| Fractures of multiple/different ages | High (context-dependent) |
| Bruising in non-mobile infant | Clinical — high specificity |
High-specificity fractures that must not be missed:
- Classic metaphyseal lesions (CMLs): Corner or bucket-handle appearance at the periphery of the metaphysis; result from shearing forces at the primary spongiosa — pathognomonic for violent acceleration/deceleration
- Posterior rib fractures: Result from squeezing of the chest; near the costovertebral junction; often only visible on oblique views; acute fractures may be subtle
- Interhemispheric subdural: Blood layering along the falx or in the posterior interhemispheric fissure; may be bilateral; indicates violent shaking (abusive head trauma)
Abusive Head Trauma (Shaken Baby / Inflicted TBI)
CT head findings:
- Subdural hematoma — bilateral, posterior interhemispheric, or mixed-density (acute on chronic)
- Subarachnoid hemorrhage
- Diffuse axonal injury (DAI) — best seen on MRI diffusion
- Cerebral edema — loss of gray-white differentiation, effacement of sulci
- Retinal hemorrhages — diagnosed by ophthalmology, not CT; always request ophthalmology exam
Mixed-density subdural hematoma (hyperacute/acute blood layering on chronic) implies repeated injuries at different times — not a single event. This is one of the most important findings to recognize and explicitly describe.
Skeletal Survey Protocol (ACR/SPR)
Standard skeletal survey images:
- Skull: AP and lateral
- Spine: AP and lateral (all segments)
- Chest: AP, bilateral obliques (for posterior rib fractures)
- Abdomen/pelvis: AP
- Upper extremities: AP humeri, AP forearms, PA hands (each as separate images — not single AP shot of both)
- Lower extremities: AP femora, AP tibiae/fibulae, AP feet
Follow-up skeletal survey at 2 weeks: Healing fractures become more apparent (periosteal reaction, callus) — the follow-up survey is required by ACR guidelines and frequently reveals fractures invisible on the initial study.
Reporting Checklist
- All fractures: location, type, and estimated age (acute / healing / chronic)
- High-specificity fractures: posterior rib fractures / classic metaphyseal lesions / interhemispheric subdural / scapular body
- Moderate-high specificity: spinous process fractures / sternal fractures
- Multiple fractures of differing ages: yes / no — specify
- Intracranial findings: subdural (bilateral, posterior interhemispheric) / SAH / cortical contusions / DAI / cerebral edema
- Retinal hemorrhage: ophthalmology exam recommended — not assessable on CT
- Visceral injuries without adequate trauma mechanism (liver, spleen, pancreatic laceration)
- Clinical history adequacy: mechanism adequate / inadequate / inconsistent with imaging findings
- Mandatory reporting obligation: state per institutional protocol
Mandatory reporting: In all U.S. states, radiologists are mandated reporters. If imaging findings are inconsistent with the provided history or reveal high-specificity NAT injuries, this must be communicated to the clinical team and reported per institutional child protective services protocol. Document this communication in the report.