Important MRI Technique Used to Characterize Adrenal Lesions

Left adrenal adenoma. Axial T1-weighted in- (A) and out-of-phase (B) images demonstrating signal drop-off on the out-of-phase sequence consistent with an adrenal adenoma with voxels containing both lipid and water protons.
The most important MRI technique used to characterize adrenal lesions is CSI. In 1992, Mitchell and colleagues showed that CSI could detect intracellular lipid that is present in most adrenal adenomas and differentiate them from metastatic disease and pheochromocytoma, which do not typically contain lipid. CSI of the adrenal glands should be performed as a dual-echo gradient recalled echo sequence in which both echoes are obtained in the same breath-hold. This protocol ensures adequate coregistration of data on in-phase and opposed-phase images and enables the derivation of subtraction (in-phase minus opposed-phase) lipid-only images. The opposed-phase TE should be shorter than the corresponding in-phase TE to ensure that the loss of signal intensity on the opposed-phase image is from lipid-water cancellation and not from T2*-induced susceptibility effects. At 1.5 T, this is readily achieved using 2D or volume-interpolated 3D sequences with TEs of approximately 2.2 and 4.4 ms.

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