Preoperative Imaging for Parathyroid Gland Localization

First-Line Imaging Modalities

The American College of Radiology recommends the combination of ultrasound (US) and sestamibi scan with SPECT/CT as the first-line imaging approach for preoperative localization of parathyroid adenomas, with reported sensitivities ranging from 67% to 86% for parathyroid adenoma detection 1, 2
Ultrasound (US) offers high sensitivity with the benefit of concomitant evaluation of the thyroid gland, and is particularly useful for identifying adenomas in the typical juxtathyroid location, but has limited sensitivity for detecting ectopic glands, especially in the mediastinum (reported sensitivity of only 7% for ectopic glands) 1, 2, 3
Sestamibi scan with SPECT/CT significantly improves localization accuracy compared to planar sestamibi imaging alone, with a meta-analysis showing pooled sensitivity of 86% for dual-phase sestamibi with SPECT/CT compared with 70% for sestamibi planar alone 1, 4

4D CT provides excellent anatomical detail but involves radiation exposure, and is particularly useful when first-line imaging is inconclusive, with reported sensitivity of 79.3% overall 1
MRI is an emerging technique with sensitivity between 64% and 98% when performed with IV contrast at 3.0T, and may be considered in patients with contraindications to radiation or iodinated contrast 4

Sestamibi scan sensitivity decreases in the setting of multigland disease, concomitant nodular thyroid disease, small adenomas (less than 500mg), and mild hypercalcemia 4

Using multiple complementary imaging modalities, such as US and sestamibi SPECT/CT, improves overall sensitivity and positive predictive value, with concordant results increasing confidence in localization 1, 3

Relying solely on planar sestamibi imaging without SPECT/CT may miss adenomas due to lower sensitivity, and ectopic parathyroid glands may be missed if only one imaging modality is used 1, 2
Imaging has no role in confirming or excluding the diagnosis of hyperparathyroidism - biochemical confirmation should precede imaging, as recommended by the American College of Radiology 5