Normocalcemic primary hyperparathyroidism: 99mTc SestaMibi SPECT/CT results compare with hypercalcemic...

Area of Science:

• Nuclear medicine
• Endocrinology
• Radiology

Background:

• Normocalcemic primary hyperparathyroidism (nPHPT) presents with elevated parathyroid hormone (PTH) and normal serum calcium.
• Diagnostic imaging information for nPHPT is limited, particularly regarding parathyroid SPECT/CT scans.

Purpose of the Study:

• To compare the diagnostic yield of 99mTc-Sestamibi SPECT/CT scans in nPHPT versus classical hypercalcemic PHPT (cPHPT).

Main Methods:

• A retrospective study of 125 patients who underwent 99mTc-Sestamibi SPECT/CT scans.
• Patients were categorized into cPHPT (n=93) and nPHPT (n=32) groups.

Main Results:

• The detection rate of 99mTc-Sestamibi SPECT/CT was significantly lower in nPHPT (59.37%) compared to cPHPT (86.02%).
• Glandular size was smaller in nPHPT (mean 6.8 mm) and correlated with PTH levels.
• SPECT/CT sensitivity was 98% (per-patient) and 91% (per-lesion), with PPVs of 96% and 88%, respectively.

Conclusions:

• The localization rate of hyperfunctioning parathyroid tissue using 99mTc-Sestamibi SPECT/CT is reduced in nPHPT, linked to smaller gland size.
• Despite lower detection rates, SPECT/CT offers non-negligible positivity and sensitivity in nPHPT.
• Higher-resolution techniques like 18F-Choline PET/CT may be advantageous for nPHPT when clinically indicated.