Raccoon Eyes on MRI
Yes, raccoon eyes (periorbital ecchymosis) would be visible on MRI, as MRI provides excellent soft-tissue resolution for detecting blood products and soft tissue changes in periorbital tissues.
Why MRI Can Detect Periorbital Ecchymosis
MRI excels at visualizing periorbital soft tissue pathology, including hemorrhage and blood tracking. MRI provides excellent soft-tissue resolution of structures within the orbit, including the globe, muscles, tendons, nerves, and vascular structures 1. Blood products in various stages of evolution demonstrate characteristic signal changes on different MRI sequences, making hemorrhage readily detectable.
Periorbital ecchymosis is caused by blood tracking along tissue planes into periorbital tissues, causing discoloration in the upper and lower eyelids 2. This extravasation of blood into the periorbital skin and subcutaneous tissues around the eyes 3 would appear as signal abnormality on MRI sequences, particularly on T1-weighted and T2-weighted images depending on the age of the hemorrhage.
Clinical Context: When Imaging Is Indicated
The presence of raccoon eyes should prompt evaluation for underlying skull fractures, intracranial hemorrhage, and cranial nerve injury 2. While the clinical sign itself is visible on physical examination, imaging is indicated to assess for:
- Basal skull fractures - the most common association with periorbital ecchymosis 2
- Convexity fractures and facial fractures 2
- Intracranial hemorrhage 2
- Cranial nerve injury - observed in approximately 28% of patients with periorbital ecchymosis 2
Optimal Imaging Modality Selection
CT is typically the preferred initial imaging modality in the acute trauma setting, not because MRI cannot detect the ecchymosis itself, but because CT is superior for detecting fractures and is faster in emergency situations 1.
CT Advantages in Trauma:
- Superior for foreign body assessment, calcification detection, and osseous evaluation 1
- Can evaluate for bone erosion and fractures using thin-section protocols 1
- Faster acquisition time in emergency settings 1
MRI Advantages:
- Greater soft-tissue resolution than CT 1
- Better for evaluating intracranial complications and soft tissue injuries 1
- Preferred when detailed assessment of orbital soft tissues, optic nerve, or intracranial extension is needed 1
Important Clinical Pitfall
Periorbital ecchymosis can be associated with a variety of clinical features beyond basal skull fractures. In a trauma series, only 42% of patients with periorbital ecchymosis had basal skull fractures, while 25% had soft tissue injuries without fractures, 22% had convexity fractures, and 8% had facial fractures 2. Additionally, periorbital ecchymosis can occur in non-traumatic conditions including amyloidosis 4, multiple myeloma, neuroblastoma 5, 6, and even from vomiting 3.
The classic signs of basal skull fracture (Battle's sign, hemotympanum, CSF otorrhea/rhinorrhea) are rarely present together with periorbital ecchymosis, occurring in only 8%, 19%, 3%, and 8% of cases respectively 2.