Intracranial Abnormalities with Diffusion Restriction.

Area of Science:

• Neurology
• Radiology
• Pathology

Background:

• Diffusion-weighted imaging (DWI) is a sensitive MRI technique for evaluating water diffusion in brain tissue.
• Changes in water movement, or diffusion, can indicate various pathologic processes.
• Restricted diffusion is a key finding, particularly in acute ischemic stroke.

Purpose of the Study:

• To review common and uncommon central nervous system disorders presenting with restricted diffusion on DWI.
• To illustrate examples of restricted diffusion secondary to cytotoxic and/or intramyelinic edema.
• To cover a broad spectrum of etiologies, including ischemia, infection, demyelinating diseases, metabolic disorders, neoplasms, and trauma.

Main Methods:

• Review of neuroimaging literature focusing on DWI findings.
• Compilation of representative case examples of diverse pathologies.
• Correlation of imaging findings with underlying pathophysiologic mechanisms (cytotoxic/intramyelinic edema).

Main Results:

• Restricted diffusion is not exclusive to acute infarction and is observed in a wide array of conditions.
• Examples provided encompass infectious, inflammatory, neoplastic, metabolic, toxic, traumatic, and iatrogenic causes.
• Pathologies discussed include ischemia, abscesses, demyelinating lesions, metabolic encephalopathies, tumors, and post-treatment changes.

Conclusions:

• DWI is a versatile tool for diagnosing a broad range of brain pathologies beyond stroke.
• Recognizing the diverse patterns of restricted diffusion is crucial for accurate diagnosis.
• Understanding the underlying edema type (cytotoxic vs. intramyelinic) aids in differential diagnosis.