What is the recommended imaging protocol for parathyroid disease?

Parathyroid Imaging Protocol

For initial imaging of primary hyperparathyroidism, order either ultrasound of the parathyroid glands OR sestamibi dual-phase scan with SPECT/CT—these are equivalent first-line options, though using both together maximizes localization accuracy. 1

Clinical Context Before Imaging

• Imaging has no role in diagnosing hyperparathyroidism—the diagnosis is purely biochemical (elevated or inappropriately normal PTH with elevated serum calcium). 2
• Only order imaging after biochemical confirmation for preoperative localization purposes. 2, 3

Primary Hyperparathyroidism (PHPT) - Initial Imaging

First-Line Options (Choose One or Both)

Ultrasound Parathyroid:

• Sensitivity of 57-90% depending on operator experience and presence of thyroid disease. 4, 5
• Excellent for typical juxtathyroid adenomas but poor for ectopic glands (only 7% sensitivity for ectopic locations). 1, 3
• Provides simultaneous thyroid evaluation. 1, 3
• No radiation exposure—particularly valuable in pediatric patients. 1

Sestamibi Dual-Phase Scan with SPECT/CT:

• Sensitivity ranges 67-86% with SPECT/CT, significantly better than planar imaging alone (70%). 1, 3
• SPECT/CT improves localization from 42% (planar) to 67% (SPECT) to 86% (SPECT/CT). 1
• Superior to planar techniques for multigland disease detection. 1

Combined Approach (Recommended for Optimal Results):

• When both ultrasound and sestamibi SPECT/CT are concordant, sensitivity reaches 78-89%. 4, 5, 3
• Concordant imaging allows confident minimally invasive parathyroidectomy. 1

Alternative First-Line Options

CT Neck with and without IV contrast or sestamibi scan with I-123 or pertechnetate thyroid scan are also considered usually appropriate initial imaging. 1

Factors That Decrease Imaging Sensitivity

• Multigland disease (sensitivity drops to 24-66%). 1
• Concomitant nodular thyroid disease. 1, 5
• Small adenomas (<500mg). 1, 3
• Mild hypercalcemia. 1, 3

Recurrent or Persistent PHPT After Surgery

Use the same imaging options as initial PHPT, but consider more aggressive multimodal approach:

• Ultrasound, CT neck with contrast, sestamibi with SPECT/CT, or dual-tracer techniques are all usually appropriate. 1
• These modalities should be used complementarily to maximize confidence via concordant results. 1
• Consider selective venous sampling if noninvasive imaging is nonlocalizing, equivocal, or discordant. 1

Secondary and Tertiary Hyperparathyroidism

Initial imaging options:

• Ultrasound parathyroid, CT neck with contrast, sestamibi dual-phase scan, or sestamibi with SPECT/CT are usually appropriate. 1
• Goal is to identify all eutopic and ectopic/supernumerary glands since these are typically multigland diseases. 1
• Sestamibi sensitivity is lower in this population (29-59% per lesion for ectopic glands). 1
• Ultrasound sensitivity for ectopic glands is particularly poor (7-32%). 1

Controversial options:

• Sestamibi with I-123 or pertechnetate thyroid scans have insufficient evidence in secondary/tertiary hyperparathyroidism—the ACR panel did not reach consensus on these. 1

Pediatric Considerations

• Sestamibi is useful only in older children with single adenomas in sporadic PHPT. 1
• Sestamibi adds minimal information beyond ultrasound in neonates or familial PHPT. 1
• Prioritize ultrasound to minimize radiation exposure. 1

Common Pitfalls to Avoid

• Never use imaging to diagnose hyperparathyroidism—only for localization after biochemical confirmation. 2, 3
• Do not rely on planar sestamibi alone—always add SPECT or SPECT/CT for improved sensitivity (86% vs 70%). 1, 3
• Do not use only one imaging modality for ectopic glands—ultrasound misses 93% of ectopic locations. 1, 3
• Expect lower sensitivity with multigland disease, thyroid nodules, or small adenomas—consider complementary imaging upfront in these scenarios. 1, 3