MRI ORBIT – Overview , ANATOMY AND PATHOLOGY,

MRI ORBIT – Overview

MRI Orbit is a non-invasive imaging test used to evaluate the structures of the eyes (orbits) and the surrounding soft tissues. It provides detailed visualization of:

• 👁️ Eyeball (globe)

• 🔍 Optic nerve

• 💪 Extraocular muscles

• 🧠 Optic chiasm

• 🦴 Bony orbit

• 🩸 Blood vessels

• 😷 Orbital fat and soft tissue

Indications – Why MRI Orbit is Done?

1. Visual Disturbances:

   • Sudden or progressive vision loss

   • Optic neuritis

   • Papilledema

2. Orbital Masses or Tumors:

   • Optic nerve glioma

   • Meningioma

   • Lymphoma

   • Retinoblastoma (in children)

3. Inflammatory and Infectious Conditions:

   • Orbital cellulitis

   • Thyroid eye disease (Graves’ orbitopathy)

   • Sarcoidosis

4. Trauma:

   • Orbital fractures

   • Intraorbital foreign bodies

5. Congenital Abnormalities

6. Evaluation of Optic Pathway Gliomas or Multiple Sclerosis (MS)

Common Sequences Used in MRI Orbit

Sequence	Purpose
T1W	Anatomy, fat, and hemorrhage detection
T2W	Fluid-sensitive; edema, inflammation, cysts
STIR/FS T2	Suppress fat; better for optic nerve & muscles
FLAIR	Helps in brain & optic chiasm evaluation
T1+C (Post-Contrast)	Enhances tumors, inflammation, infections
DWI/ADC	For detecting abscesses or high cellular lesions

With or Without Contrast?

• Without contrast: Useful for basic evaluation.

• With contrast (Gadolinium): Helps identify tumors, inflammation, infection, and vascular lesions more clearly.

 MRI Orbit – Sample Findings:

Condition	MRI Finding
Optic Neuritis	T2 hyperintensity & contrast enhancement of optic nerve
Thyroid Orbitopathy	Enlargement of extraocular muscles sparing tendinous insertions
Orbital Cellulitis	Diffuse inflammation, fat stranding, post-septal spread
Optic Nerve Glioma	Fusiform enlargement of optic nerve, T2 hyperintense
Cavernous Hemangioma	Well-defined mass, isointense T1, hyperintense T2, enhances with contrast