Scintigraphic pitfalls in giant parathyroid glands

Area of Science:

• Nuclear Medicine
• Endocrinology
• Radiology

Background:

• Hyperparathyroidism can present with enlarged parathyroid glands that may anatomically resemble thyroid tissue.
• Accurate preoperative localization of hyperplastic parathyroid glands is crucial for successful surgical management.

Observation:

• A case of hyperparathyroidism with bilaterally enlarged parathyroid glands presented a diagnostic challenge, mimicking a normal thyroid gland.
• Technetium-99m-pertechnetate-201Tl chloride subtraction scintigraphy was inconclusive due to suppressed thyroidal uptake.
• Technetium-99m-sestamibi double-phase scintigraphy initially showed homogeneous uptake, mimicking normal thyroid tissue without differential washout, leading to misinterpretation.

Findings:

• Visual interpretation of technetium-99m-sestamibi scintigraphy can be misleading when parathyroid uptake mimics thyroid tissue.
• Semiquantitative assessment of tracer washout in double-phase scintigraphy can differentiate normal thyroid tissue from symmetrical parathyroid uptake.
• This method enhances diagnostic sensitivity, particularly when anatomical details are obscured or visual assessment is ambiguous.

Implications:

• Semiquantitative analysis of technetium-99m-sestamibi washout improves the diagnostic accuracy of parathyroid scintigraphy.
• This technique is valuable when interpreters are unaware of the anatomy, thyroid uptake is blocked, or visual interpretation is inconclusive.
• Implementing semiquantitative assessment can prevent misdiagnosis and guide appropriate surgical intervention for hyperparathyroidism.