It is unlikely that a spot that looks clear on an MRI scan is a lipoma. A lipoma, or a benign tumor, appears as a distinct fatty mass on both MRI and CT scans, says Radiopaedia.org.
An MRI machine uses a powerful magnetic field and radio frequency pulses to distinguish between different types of tissue, which allows for detailed images of the brain's physiology, reports RadiologyInfo.org. So-called fat saturated images are often used to identify fat, but even when such images are not available, lipomas can easily be distinguished from other types of tissue. One indication that fat is present is when a chemical shift artifact appears on the scan, says Radiopaedia.org. This type of misregistration occurs as a consequence of the slightly different resonance frequencies of water and fat.
Lipomas are typically asymptomatic and found by chance. Although both CT and MRI scans can locate these tumors, MRI scans are better than CT scans at identifying atypical characteristics that may indicate that the growth is cancerous. Therefore, MRI scanners are the preferred tool for imaging lipomas. However, liposarcoma, a malignant tumor, of the brain is extremely rare, as stated in an article published in Clinical Radiology.
Lipomas in the brain rarely require treatment. In fact, the risks of removing the tumor often outweigh the potential benefits, claims Radiopaedia.org.