What imaging techniques are used to diagnose hyperparathyroidism?

Imaging for Hyperparathyroidism Diagnosis

Primary Recommendation

For primary hyperparathyroidism requiring surgery, begin with either ultrasound combined with 99mTc-sestamibi scintigraphy (preferably with SPECT/CT), or proceed directly to 18F-choline PET/CT for preoperative localization. 1

Critical Distinction: Imaging Does Not Diagnose Hyperparathyroidism

• Imaging has no role in confirming or excluding the diagnosis of hyperparathyroidism—diagnosis is established biochemically through elevated serum calcium and parathyroid hormone (PTH) levels 1, 2
• The sole purpose of imaging is to localize abnormal parathyroid glands preoperatively to facilitate minimally invasive parathyroidectomy (MIP) 1

First-Line Imaging Modalities

Ultrasound Combined with Sestamibi Scintigraphy

• Combined ultrasound and scintigraphy demonstrates the highest sensitivity for localizing parathyroid adenomas, particularly in patients with concurrent thyroid disease 3
• Ultrasound provides a safe, radiation-free modality but is operator-dependent 4
• Sestamibi scan sensitivity is improved when performed with SPECT or SPECT/CT imaging 3, 4
• For primary hyperparathyroidism, sestamibi dual-phase scans with SPECT/CT show sensitivities of 85% on a per-patient basis 5

18F-Choline PET/CT

• Superior performance for identifying multigland disease, parathyroid hyperplasia, and multiple adenomas compared to traditional scintigraphy 1
• Particularly valuable when multigland disease is suspected (15-20% of primary hyperparathyroidism cases) 1

Second-Line and Problem-Solving Imaging

4D-CT (CT Neck Without and With IV Contrast)

• Reserved as a problem-solving technique in challenging cases and after failed neck exploration 4
• Utilizes multiphase technique (noncontrast, arterial, and venous phases) leveraging unique perfusion characteristics of parathyroid adenomas 5
• For single-gland disease, sensitivities range from 92% to 94% with positive predictive values of 88% to 92% 5
• For multigland disease, sensitivities drop to 43% to 67% 5
• Overall sensitivity ranges from 62% to 88% in retrospective studies 5

MRI Neck

• Limited data available for primary hyperparathyroidism 5
• No relevant literature exists for secondary or tertiary hyperparathyroidism 5
• Sensitivity of 81% reported in older comparative studies 6

Algorithmic Approach by Clinical Context

Single Adenoma (80% of Cases)

• Start with ultrasound plus sestamibi with SPECT/CT or 18F-choline PET/CT 1
• Confident preoperative localization enables MIP, which offers shorter operating times, faster recovery, and decreased costs compared to bilateral neck exploration 1

Suspected Multigland Disease (15-20% of Cases)

• 18F-choline PET/CT is preferred due to superior diagnostic performance for identifying multiple adenomas and hyperplasia 1
• Consider combining multiple imaging modalities—concordant results from two or more studies improve sensitivity and positive predictive value 5

Persistent or Recurrent Hyperparathyroidism

• Preoperative imaging is essential as reoperations have lower cure rates and higher complication rates 1
• If standard imaging (ultrasound, sestamibi, CT) yields nonlocalizing, equivocal, or discordant results, consider selective parathyroid venous sampling for PTH levels 5, 2
• Venous sampling sensitivities range from 40% to 93% but is invasive and typically reserved for reoperative cases 2

Secondary/Tertiary Hyperparathyroidism

• Imaging aims to identify all eutopic, ectopic, and supernumerary glands 5
• CT neck shows sensitivities of 60% to 85% for secondary hyperparathyroidism 5
• Sestamibi with SPECT/CT demonstrates 85% sensitivity on a per-patient basis 5
• For tertiary hyperparathyroidism, parathyroidectomy should be considered despite negative imaging 2

Negative Initial Imaging

• Bilateral neck exploration under general anesthesia is the standard approach when preoperative localization studies are negative 2
• Consider 4D-CT parathyroid scan (sensitivities 62% to 88%) 2
• Selective venous sampling may be considered for surgical candidates with non-localizing results 2

Combination Imaging Strategy

• Multiple imaging modalities used together maximize accuracy through concordant results 5, 1
• When two or more tests are positive at the same location, sensitivity reaches 79% with positive predictive value of 86% 6
• Three concordant techniques show 63% sensitivity but 92% positive predictive value 6

Critical Pitfalls to Avoid

• Never use imaging to diagnose hyperparathyroidism—diagnosis is biochemical only 1, 2
• Failing to consider multigland disease can lead to inadequate treatment, as it is more difficult to localize with standard imaging 1, 2
• In patients with concurrent thyroid disease, which occurs more frequently in hyperparathyroidism patients, combined ultrasound and scintigraphy is most sensitive 3
• For ectopic glands in multigland disease, sestamibi dual-phase scans with SPECT show only 29% sensitivity on a per-lesion basis 5