From the Guidelines
Ring-enhancing lesions on brain imaging are most commonly caused by brain metastases, primary CNS neoplasms, abscesses, and inflammatory processes.
Causes of Ring-Enhancing Lesions
- Brain Metastases: The presence of multiple, enhancing intracranial lesions in a patient with a preceding cancer diagnosis should raise concern for brain metastases 1.
- Primary CNS Neoplasms: Primary CNS neoplasms such as gliomas, primary CNS lymphomas, and meningiomas can also present as ring-enhancing lesions 1.
- Abscesses: Abscesses can present as ring-enhancing lesions, and the central, nonenhancing, necrotic portion of abscesses tends to restrict diffusion 1.
- Inflammatory Processes: Inflammatory processes such as multiple sclerosis, acute disseminated encephalomyelitis, or sarcoidosis can also cause ring-enhancing lesions 1.
Diagnostic Considerations
- Imaging Characteristics: The imaging characteristics of the lesion, such as its location, shape, and enhancement pattern, can help narrow down the differential diagnosis 1.
- Clinical History and Exam: A thorough clinical history and exam can also help distinguish between different etiologies of ring-enhancing lesions 1.
- Biopsy: In some cases, a biopsy may be necessary to confirm the diagnosis, especially if the lesion cannot be distinguished from other pathologies with certainty 1.
- MRI with DWI and ADC Sequences: MRI with diffusion-weighted imaging (DWI) and apparent diffusion coefficient (ADC) sequences can help diagnose brain abscesses, which typically show restricted diffusion 1.
From the Research
Causes of Ring-Enhancing Lesions
The causes of ring-enhancing lesions on brain imaging are diverse and can be attributed to various infectious, tumoral, demyelinating, and vascular diseases 2. Some of the specific causes include:
- Infectious diseases such as abscesses and tuberculosis 2, 3
- Tumoral diseases such as gliomas and metastases 4, 3
- Demyelinating diseases such as multiple sclerosis 4
- Vascular diseases such as hematoma 5
Characteristics of Ring-Enhancing Lesions
The characteristics of ring-enhancing lesions can vary depending on the underlying cause. For example:
- Abscesses tend to have hypointense rims on T2-weighted images and are often bright on diffusion-weighted images 4
- Metastases and gliomas tend to have arcs or rims on T2-weighted images, but are less likely to be homogeneous centrally 4
- Multiple sclerosis lesions can have either rims or arcs on T2-weighted images and are often multiple 4
Diagnosis and Management
Diagnosing ring-enhancing lesions can be challenging, and a combination of clinical evaluation, imaging studies, and laboratory tests is often necessary 6. In some cases, brain biopsy may be required to establish a definitive diagnosis 3, 6. Management of ring-enhancing lesions depends on the underlying cause and can include surgery, chemotherapy, and radiation therapy 3.