Preoperative Parathyroid Imaging Correlated with Histopathology
Objective: Hyperparathyroidism is a diverse condition and is a biochemical diagnosis. It is classified into primary, secondary or tertiary. Imaging guided intervention (surgery and alcohol injection) is evolving in the management of these conditions. We compare the results of Sestamibi Parathyroid Scans and Ultrasound in primary and secondary hyperparathyroidism, with histopathology as the gold standard.
Method: A cohort of 32 patients who had nuclear imaging and parathyroidectomy at our institution were included. High resolution neck ultrasound with Dopppler was performed in most patients. The Tc-99m Sestamibi imaging protocol of early planar and delayed SPECT imaging was replaced by dual phase pinhole imaging during study period.
Results: Parathyroidectomy revealed parathyroid adenoma in 10 patients, parathyroid hyperplasia in 20 patients, and adenomatous hyperplasia in two patients. The parathyroid adenoma was correctly lateralised in 100% (7/7) of patients with ultrasound, and 90% (9/10) with Sestamibi. Both techniques correctly localised the lesion in around 70% of patients. The 20 patients with parathyroid hyperplasia had 70 abnormal parathyroid glands at histology. Ultrasound detected 19% (11/58) of abnormal glands in seven patients, with 10 normal studies. Sestamibi detected 29% (20/70) of abnormal glands in 15 patients, with five normal studies.
Conclusion: Both ultrasound and Sestamibi show excellent sensitivity in lateralising a parathyroid adenoma. Localisation of the adenoma was around 70% for both techniques. While Sestamibi was somewhat more sensitive in secondary hyperparathyroidism, hyperplastic parathyroid glands are still difficult to detect reliably. Image guided intervention in this cohort would be problematic with current diagnostic tools.