Table 1.
Differentiating features of parathyroid adenoma from lymph nodes and thyroid nodules on imaging
| Modality | Features | Parathyroid adenoma | Thyroid nodule | Lymph node |
| USG | Echogenicity | Homogenously markedly hypoechoic | Homo/Heterogenously hypo/isoechoic | Central echogenic hilum |
| Vascularity | Peripheral polar vessel sign present | Not seen | Central/hilar vascularity | |
| Calcification | Less common | Common | +/- | |
| Cystic changes | Less common | More common | +/- | |
| CT | Non contrast | Hypodense | Hyperdense | Hypodense |
| Arterial | Intense arterial enhancement | Enhancement in arterial phase but less than parathyroid adenomas | No enhancement in the arterial phase | |
| Venous | Washout | Persistent enhancement | Progressive enhancement in venous phase | |
| MRI | Morphology | Cleavage plane with thyroid gland | No cleavage plane | Cleavage plane present |
| Diffusion weighted Image | High SI | High SI | ||
| PET Choline | Uptake | Present | Variable | Uptake may be present, however is delayed and of lesser intensity |
USG: Ultrasound; CT: Computed tomography; MRI: Magnetic resonance imaging; SI: Signal intensity; PET: Positron emission tomography.