Diffuse axonal injury and rim enhancing contusions

Case contributed by Alexandra Stanislavsky
Diagnosis almost certain


Unconscious patient following a high speed MVA

Patient Data

Age: 20
Gender: Male

There are multiple acute intracranial hemorrhages, includingthe right dorso-lateral midbrain, left thalamus and scattered subcortical petechial hemorrhages predominantly in the right frontal and temporal lobes.There is also moderate volume traumatic subarachnoid hemorrhage, maximal over the right frontal convexity, and a thin right cerebral convexity subdural hematoma There is no midline shift or herniation. Multiple small locules of intracranial gas associated with the left petrous temporal bone fracture (see bone windows). There is also gas within the left transverse sinus. The lateral portion of the transverse sinus is relatively hyperdense compared to the remainder of the dural sinuses.

Multiple skull fractures, including a complex left petrous temporal bone fracture with transverse and longitudinal components occipital fracture with associated widening of the left parieto-occipital suture, left parietal bone and extensive sphenoid sinus fractures. Fractures involve walls of both the left jugular foramen and the left carotid canal.

A number of days later


Followup study performed some time after admission.  Contrast was given due to clinical concern of possible ventriculitis.

The non contrast CT decreased volume and density of the multifocal hemorrhages, in keeping with expected temporal evolution.  There are several regions of parenchymal hypoattenuation in the right frontal lobe, deep to the site of a bur hole.  

Post contrast, these regions demonstrate thin rim enhancement with mild surrounding vasogenic edema.

There are multiple findings which may be correlated with the earlier CTs:

  • The ring enhancing right frontotemporal lesions seen on the second CT are present as areas of T2 and T1 hyperintensity with associated peripheral enhancement.  There is some increased DWI signal, although not conforming clearly to the areas surrounded by ring enhancement. The associated edema is quite mild.
  • The foci of T2 and T1 hyperintensity within the right dorsolateral midbrain and left thalamus correspond to the areas of hemorrhage seen on the initial CT. 
  • There is T2 hyperintensity and some associated enhancement within the lateral aspect of the left cerebellar hemisphere (as seen on the second CT).  
  • Thin subdural hematoma overlies the right cerebral hemisphere. There is linear low T2* signal compatible with hemosiderin. 
  • Increased DWI signal is present within the posterior body and splenium of the corpus callosum as well as the left cerebral peduncle and posterior left thalamus.  

In summary, 

  1. The MRI appearance of the right frontal and temporal "ring enhancing lesions" favors subacute hemorrhagic contusions. 
  2. As expected from the CTs, the MRI shows the appearance of severe diffuse axonal injury (grade 3). 

Case Discussion

This case demonstrates two important imaging appearances.  

The first is that of a typical severe diffuse axonal injury (Grade 3), as well complex base of skull fractures, seen in the acute setting after a high speed motor vehicle accident.

The subsequent CT and MRI demonstrate the presence of rim enhancement in a resolving contusion - an appearance that may cause diagnostic confusion, needing to be differentiated from other cerebral ring enhancing lesions.

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