What causes the “wet diaper” artifact? computed tomography and magnetic resonance observations

Disposable diapers contain super absorbent polymers that absorb liquid. A radio-dense artifact, seen when the diaper is wet, obscures radiographic information but is frequently misinterpreted. Our purpose was to examine this artifact on CT and MR to further clarify and explain its origin. Dry and wet diapers were imaged. Fluid within the wet diaper appeared as small nodules with characteristics of bound water. No free water was detected. Dry diapers produced no artifact. The artifact is most undesirable on radiographs, but does not obscure diagnostic information on cross-sectional imaging. It should not be misinterpreted as contrast.