Reading the ACR Appropriateness Criteria for Head Trauma in a Case File

The Structure: Variants, Not Rules

The Criteria are organized by clinical variant rather than by procedure. Separate variants address mild acute head trauma with imaging indicated by a clinical decision rule, short-term follow-up when the neurologic exam is unchanged and initial imaging was unremarkable, short-term follow-up with new or progressive neurologic deficits, suspected intracranial arterial injury, and suspected cerebrospinal fluid leak, among others.

That structure is the whole point. The right question is never 'was a head CT appropriate?' It is 'which variant did this patient present with, and what was rated appropriate for that variant?' Matching the presentation to the correct variant is where most disputes are actually won or lost.

What 'Usually Not Appropriate' Really Means

The Criteria assign consistently low ratings to several advanced modalities in the initial evaluation of acute head trauma. The panel notes there is no relevant literature supporting MR spectroscopy, FDG-PET/CT, or HMPAO SPECT in the initial imaging evaluation of acute head trauma, and the same conclusion is reached for short-term follow-up. Catheter cervicocerebral arteriography likewise lacks supporting literature for initial evaluation of subacute or chronic head trauma with unexplained cognitive or neurologic deficits.

This aligns closely with the RSNA position that advanced neuroimaging in TBI remains investigational. When a report builds a causation opinion primarily on one of these modalities, the Criteria are directly relevant to its weight.

Findings That Change Management

The evidence narrative in the Criteria also contains details that matter in specific fact patterns. One cited study of 472 patients with closed head trauma and a skull fracture crossing a dural venous sinus identified a high incidence of small epidural hemorrhages — roughly 81% — which can be compressive and can be misdiagnosed as venous sinus thrombosis.

For suspected CSF leak, the document describes when high-resolution CT is insufficient on its own — for example, when a meningoencephalocele is suspected or when preoperative HRCT cannot pinpoint a single osseous defect in the skull base. These are precisely the situations where a general review misses the issue and a subspecialty review does not.

The Guideline Caveat Attorneys Should Quote

The ACR's own disclaimer limits how far the Criteria can be pushed. They are intended to guide radiologists, radiation oncologists, and referring physicians in making imaging decisions. The complexity and severity of the patient's condition should dictate selection, availability of equipment and personnel may influence it, and the ultimate decision regarding appropriateness rests with the referring physician and radiologist in light of all circumstances presented in an individual examination.

In other words, the Criteria are educational guidance, not a liability checklist. The legal standard remains whether the physician acted as a reasonable practitioner under the circumstances known at the time — not whether every choice matched a ratings table in retrospect.

Also: Use the Current Version

ACR updates these documents regularly and instructs readers to verify they are accessing the most current content. Citing a superseded version is an avoidable credibility problem, and it is one of the first things a careful opposing expert will check.

How We Apply It

In our reviews we identify the applicable variant from the clinical record, compare the imaging actually performed against the ratings for that variant, and state plainly where a deviation exists and whether it plausibly changed the outcome. Where the record supports the imaging choices made, we say so — that answer is often just as valuable to the retaining party.