Incidentaloma MRI

Adrenal MRI may be helpful in the diagnosis of incidentaloma. Findings on MRI suggestive of incidentaloma include mild enhancement and a rapid washout of contrast, while malignant lesions show rapid and marked enhancement and a slower washout pattern. MRI has advantages in certain clinical situations. The advantages of MRI over CT are its lack of radiation exposure, lack of iodine-based contrast media and its superior tissue contrast resolution.

• Adrenal MRI may be helpful in the diagnosis of incidentaloma.^[1]
  • MRI rather than CT is suggested if adrenal imaging is required in children, adolescents, pregnant females, and adults younger than 40 years of age.

• Findings on MRI suggestive of incidentaloma include:^[2][3]
  • T1 and T2-weighted imaging can distinguish benign adenomas from malignancy and pheochromocytoma.
  • MRI has advantages in certain clinical situations. The advantages of MRI over CT are its lack of radiation exposure, lack of iodine-based contrast media and its superior tissue contrast resolution.
  • On gadolinium-diethylene triamine pentaacetic acid (DTPA)-enhanced MRI, adenomas demonstrate mild enhancement and a rapid washout of contrast, while malignant lesions show rapid and marked enhancement and a slower washout pattern.

• Chemical shift imaging relies on the fact that protons in water vibrate at a slightly different frequency than protons in lipid.^[4][5][6]
  • By selecting appropriate sequencing parameters, separate images can be generated with water and fat protons oscillating in phase or out of phase to each other.
  • Benign adrenal cortical adenomas lose signal on out-of-phase images but appear relatively bright on in-phase images.
  • Whereas malignant lesions, pheochromocytomas, and lipid-poor adrenal adenomas remain unchanged because all lack intracellular lipid.

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