Endocrine Abstracts

Introduction: Surgery is the definitive treatment for primary hyperparathyroidism. Accurate preoperative localisation of parathyroid adenomas is paramount for minimally invasive parathyroidectomy. Common imaging modalities include 99mTc-SPECT-MIBI, co-registered CT, and ultrasound (US), though adding CT increases radiation dose, cost, and time. This retrospective study evaluated concordance among SPECT, CT, and US in lesion detection and surgical outcomes.

Methods: Patients with suspected primary hyperparathyroidism who underwent imaging and successful surgery between September 2023 and August 2025 were included. Out of 348 records screened, 47 met inclusion criteria, as most others were either waitlisted for surgery or managed medically.

Results: Out of 47 patients, 77% were female (n = 36), aged 28–85 years (median 52, IQR 20). Ten were <40 yrs, 10 aged 41–50 yrs, 21 aged 51–65yrs, and 6 were >65 yrs. FECa-based genetic testing (n = 8) showed two positives. Mean serum calcium was 2.92 mmol/l (median 2.82, IQR 0.23). Forty-six patients underwent all three imaging modalities; one had US only. US detected 31 lesions (4 inconclusive, 12 negative); 99mTc-SPECT-MIBI detected 30 (2 inconclusive, 15 negative); and co-registered SPECT/CT identified 29 (5 inconclusive, 13 negative). Twenty-two showed concordant SPECT/CT and US findings—20 of them (91%) matched surgical localisation, with 2 differing only by superior/inferior position. Seven lesions were diagnosed on CT-only, nine on US-only, and nine were undetected on imaging but underwent surgery due to severe hypercalcemia. Post-operative normocalcemia was achieved in all patients indicating excellent surgical outcomes.

Conclusion: This study demonstrated 91% accuracy for concordant preoperative parathyroid adenoma localisation, indicating that only two modalities are necessary—either 99mTc-SPECT-MIBI+ co-registered CT or 99mTc-SPECT-MIBI + US (when co-registered CT is unavailable). The choice depends on equipment and expertise. Simplifying from three to two modalities may reduce patient burden, streamline workflow, and lower costs without compromising diagnostic accuracy.