From the Guidelines
Imaging for primary hyperparathyroidism typically begins with a sestamibi scan (technetium-99m sestamibi scintigraphy), often combined with SPECT (single-photon emission computed tomography) as the first-line imaging modality, as recommended by the most recent guidelines 1. This nuclear medicine study helps localize abnormal parathyroid glands by detecting areas of increased radiotracer uptake.
- The sensitivity of sestamibi with SPECT is approximately 80-90% for single adenomas, which account for about 85% of primary hyperparathyroidism cases.
- Ultrasound of the neck is frequently performed alongside sestamibi, offering complementary information without radiation exposure and can identify adenomas as hypoechoic nodules posterior to the thyroid.
- For cases where these initial studies are inconclusive, 4D-CT (four-dimensional computed tomography) provides excellent anatomical detail and functional information through multiple phases of contrast enhancement.
- MRI may be used as an alternative when radiation exposure is a concern or in patients with renal impairment.
- In difficult cases, selective venous sampling for parathyroid hormone levels can help lateralize the source of excess hormone production, as supported by recent studies 1. Accurate preoperative localization is crucial as it enables minimally invasive parathyroidectomy rather than traditional bilateral neck exploration, reducing operative time, complications, and hospital stay, which is in line with the latest recommendations from the American College of Radiology 1.
From the Research
Imaging Modalities for Primary Hyperparathyroidism
The following imaging modalities are used for primary hyperparathyroidism:
- Technetium-99m-sestamibi scintigraphy 2, 3, 4, 5
- High-resolution ultrasonography 2, 6, 5
- Dual-tracer 99mTc-sestamibi/123I subtraction scanning 3, 5
- Single photon-emission computed tomography/computed tomography (SPECT/CT) 6, 4
- 18F-fluorocholine PET/CT 3
- 4-dimensional CT 3
- MRI 3
- Ultrasound-guided fine-needle aspiration 3
- Selective venous sampling for parathyroid hormone measurement 3
Comparison of Imaging Modalities
Studies have compared the accuracy of different imaging modalities for preoperative localization of parathyroid adenomas:
- Technetium-99m-sestamibi scintigraphy has been shown to be effective as a single agent for preoperative parathyroid scintigraphy 2
- Dual-tracer 99mTc-sestamibi/123I subtraction scanning plus neck ultrasound is the preferred first-line option 3
- Combined ultrasound and SPECT/CT has an overall sensitivity of 95% and accuracy of 91% for the preoperative localization of solitary parathyroid adenomas 6
- SPECT-based scans have been shown to be more accurate than planar scans 4
- Technetium-99m-sestamibi/I-123 radionuclide scan is more sensitive than high-resolution ultrasonography for the preoperative localization of abnormal parathyroid glands 5