In primary hyperparathyroidism caused by a single parathyroid adenoma, the 4D-CT scan is used for preoperative localization. The '4D' in 4D-CT refers to:
- A 4 phases: non-contrast, arterial, venous, delayed — with time as fourth dimension ✓
- B Four dimensions: sagittal, coronal, axial planes plus volumetry
- C Four detector rows enabling high-resolution imaging
- D Four gland imaging protocol with separate non-contrast enhanced phases
Explanation
4D-CT (four-dimensional CT) for parathyroid localization incorporates three spatial dimensions plus time (contrast enhancement dynamics) as the fourth dimension. It uses non-contrast, arterial phase (25-30 seconds), venous phase (65-70 seconds), and delayed phase imaging. Parathyroid adenomas show rapid arterial enhancement with early washout compared to thyroid and lymph nodes, exploiting their rich blood supply. This dynamic perfusion pattern differentiates adenomas from lymph nodes and thyroid nodules with high sensitivity (70-85%), particularly for ectopic or small adenomas missed by sestamibi.
Reference: Bailey & Love's Short Practice of Surgery, 27th ed.
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Written and medically reviewed by the StethoPrep medical team.