What is the best imaging approach for suspected hyperparathyroidism?

Optimal Imaging Approach for Suspected Hyperparathyroidism

For suspected hyperparathyroidism, the best initial imaging approach is a combination of neck ultrasound and sestamibi scan with SPECT or SPECT/CT, as these complementary modalities maximize accuracy and confidence in parathyroid localization. 1

Initial Diagnostic Workup

Before pursuing imaging:

• Confirm biochemical diagnosis with:
  • Elevated or inappropriately normal PTH with hypercalcemia
  • Low or low-normal phosphorus levels
  • 25-OH vitamin D level
  • Renal function tests
  • 24-hour urinary calcium

Primary Imaging Modalities

Ultrasound

• Sensitivity: 76-80%
• Positive Predictive Value (PPV): 93% 1
• Advantages:
  • No radiation exposure
  • Cost-effective
  • Widely available
  • Provides concurrent thyroid evaluation
• Limitations:
  • Operator-dependent
  • Limited for ectopic glands
  • Reduced sensitivity for multigland disease

Sestamibi Scan with SPECT/CT

• Sensitivity: 88-93% 1
• Advantages:
  • Provides both functional and anatomical information
  • Superior for detecting ectopic glands
  • Complements ultrasound findings
• Limitations:
  • Radiation exposure
  • Lower sensitivity in multigland disease
  • False negatives with small adenomas

Algorithm for Imaging Selection

1. First-line imaging: Neck ultrasound AND sestamibi scan with SPECT/CT 2, 1

   • Concordant positive results (both tests localize to same area): Proceed to minimally invasive parathyroidectomy
   • Discordant results: Consider additional imaging

2. Second-line imaging (if first-line imaging is negative or discordant):

   • 4D-CT (sensitivity: 62-88%, PPV: 84-90%) 1
     • Excellent for anatomical detail
     • Can detect small adenomas
     • Particularly useful when ultrasound and sestamibi are negative

3. Third-line imaging (if previous modalities fail):

   • MRI (sensitivity: 63-93%, PPV: 85-100%) 1
     • Useful alternative when radiation exposure is a concern
     • Valuable in reoperative cases

4. Last resort (for persistent/recurrent disease after surgery):

   • Selective parathyroid venous sampling (sensitivity: 40-93%) 1
     • Reserved for reoperative surgical candidates

Special Considerations

Primary vs. Secondary/Tertiary Hyperparathyroidism

• Primary Hyperparathyroidism (typically single adenoma):

  • Combined ultrasound and sestamibi SPECT/CT is highly effective 1

• Secondary/Tertiary Hyperparathyroidism (typically multigland disease):

  • Multiple imaging modalities may be needed to identify all abnormal glands 2
  • Recent evidence suggests F-18 fluorocholine PET/CT has superior accuracy (87%) compared to sestamibi (59%) and ultrasound (65%) in secondary/tertiary hyperparathyroidism 3

Multigland Disease

• Accounts for 15-20% of primary hyperparathyroidism cases
• Risk factors: MEN syndromes, lithium therapy, previous radiotherapy
• Imaging sensitivity is lower; bilateral neck exploration may be necessary 1

Ectopic Adenomas

• May be missed on standard imaging
• SPECT/CT is particularly helpful for localizing ectopic parathyroid glands 4, 5

Pitfalls to Avoid

1. Relying on a single imaging modality

   • Combined approaches improve sensitivity and PPV 2, 1

2. Proceeding to surgery without localization

   • Preoperative localization enables minimally invasive approaches with shorter operating time, faster recovery, and decreased costs 1

3. Ignoring discordant results

   • When imaging studies disagree, additional imaging or bilateral neck exploration may be necessary

4. Overlooking multigland disease

   • 4D-CT has higher sensitivity than sestamibi SPECT/CT in multigland disease (58.2% vs 30.8%) 6

By following this evidence-based approach to parathyroid imaging, clinicians can optimize surgical planning, reduce operative time, and improve outcomes for patients with hyperparathyroidism.