Halo

Halo is a term used in medicine to describe a circular structure or appearance. It is often used in the context of medical imaging, where a halo may be seen around a lesion or abnormality. The term is derived from the Greek word 'halos', which means 'disk' or 'ring of light'.

Causes of Halo Appearance in Medical Imaging

A halo appearance in medical imaging can be caused by a variety of conditions, including:

• Inflammation: Inflammatory processes can cause a halo appearance in medical imaging. This is often seen in conditions such as rheumatoid arthritis and sarcoidosis.
• Tumors: Certain types of tumors, such as lymphomas, can cause a halo appearance in medical imaging.
• Infections: Infections, particularly those caused by fungi or bacteria, can cause a halo appearance in medical imaging.

Halo Sign

The halo sign is a specific type of halo appearance seen in medical imaging. It is characterized by a ring of ground-glass opacity surrounding a nodule or mass in the lung. The halo sign is often associated with invasive fungal infections, particularly aspergillosis.

Halo Phenomenon

The halo phenomenon is another specific type of halo appearance seen in medical imaging. It is characterized by a ring of increased uptake surrounding a lesion on a positron emission tomography (PET) scan. The halo phenomenon is often associated with malignant tumors, particularly lymphomas.

See Also

• Ground-glass opacity
• Nodule (medicine)
• Positron emission tomography

Halo Resources
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