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Apparent diffusion coefficient measurements within intracranial epidermoid cysts in six patients
1Department of Medical Imaging, Cliniques Universitaires Saint-Luc, Université Catholique de Louvain, Avenue Hippocrate 10, 1200 Brussels, Belgium.
Neuroradiology
|March 27, 2002
Summary
Epidermoid cysts (ECs) appear bright on diffusion-weighted (DW) images due to T2 shine-through, not solely reduced apparent diffusion coefficient (ADC). This finding impacts MRI interpretation of ECs.
Area of Science:
- Radiology
- Neuroimaging
- Medical Physics
Background:
- Epidermoid cysts (ECs) are common intracranial tumors.
- Diffusion-weighted imaging (DWI) is crucial for characterizing brain lesions.
- The bright signal of ECs on DWI is often attributed to restricted diffusion.
Purpose of the Study:
- To investigate if a low apparent diffusion coefficient (ADC) causes the bright signal intensity of epidermoid cysts (ECs) on diffusion-weighted (DW) images.
- To differentiate the contribution of true diffusion restriction versus T2 shine-through in ECs.
Main Methods:
- Six patients with surgically confirmed ECs were studied.
- Apparent diffusion coefficient (ADC) values were calculated within ECs, deep white matter, and cerebrospinal fluid (CSF).
- Data acquired using T2-weighted DW-EPI-SE sequences.
Main Results:
- All ECs showed high signal intensity on DW trace images.
- Mean ADC values were higher in ECs (1,070 x 10(-6) mm(2)/s) than in white matter (764 x 10(-6) mm(2)/s).
- EC ADC values were significantly lower than CSF values (3,185 x 10(-6) mm(2)/s), but not as low as expected for true diffusion restriction.
Conclusions:
- The bright signal intensity of ECs on DW images is not solely due to reduced ADC.
- T2 shine-through effect is a significant contributing factor to the bright DWI signal in ECs.
- Relying solely on ADC may lead to misinterpretation of ECs on DWI.