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Intracranial Abnormalities with Diffusion Restriction
1Department of Radiology/Imaging Sciences, University of Rochester Medical Center, University Medical Imaging, 4901 Lac de Ville Boulevard, Building D - Suite 140, Rochester, NY 14618, USA.
Abstract:
Multiple pathologic conditions can cause changes in the random movement of water, which can be detected with diffusion-weighted imaging (DWI). DWI plays a powerful clinical role in detecting restricted diffusion associated with acute brain infarction. Other disorders can also result in restricted diffusion. This article focuses on showing examples of common and uncommon disorders that have restricted diffusion secondary to cytotoxic and/or intramyelinic edema. These disorders include ischemia, infection, noninfectious demyelinating diseases, genetic mutations affecting metabolism, acquired metabolic disorders, toxic or drug exposures, neoplasms and tumorlike lesions, radiation treatment, trauma, and denervation.
Insights
Diffusion-weighted imaging (DWI) detects water movement changes in the brain. This review highlights various conditions causing restricted diffusion, including ischemia, infections, and neoplasms, often due to cytotoxic edema.
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.
