Accuracy of Parathyroid Scintigraphy in a community hospital: Implications for Treatment of Hyperpar

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Accuracy of Parathyroid Scintigraphy in a
community hospital Implications for Treatment of
Hyperparathyroidsim

• UND Research Colloquium
• June 27, 2008
• David B. Cox, MD

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Primary Hyperparathyroidism

• Clinical profile historically was of symptomatic
  hypercalcemia.
• Kidney stones, bone disease, neuromuscular
  dysfunction, gastro-intestinal complaints
• Routine automated screening in early 1970s
  changed the clinical pattern of hypercalcemia
• Modern clinical profile is of the asymptomatic
  patient with mild hypercalcemia and PTH excess
• Incidence
• Women 1 500
• Men 1 2000
• Risk factors Hx neck irradiation, familial
  history of PHPT

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Primary Hyperparathyroidism

• Single adenoma in 85-90 of cases
• Four gland hyperplasia 6-9 of cases
• Double adenoma in 3-4 of cases
• Rarely carcinoma

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Current Surgical Approaches

• Traditional bilateral cervical exploration
• Yields 95 success in experienced hands
• Complication rate 1-3 in experienced hands
• Imaging used as adjunct or in re-operation

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Current Surgical Approaches

• Minimally invasive approach
• Unilateral neck exploration
• Video assisted technique
• Fully endoscopic approach
• Accurate preoperative imaging particularly when
  combined with intraoperative PTH assay makes
  these approaches possible

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Current Surgical Approaches

• Advantages to minimally invasive procedures
• Similar long term hypercalemia cure rates.
  (Russell, BJS 2006)
• Similar hospital stay and costs. (Barczynski,
  World J Surg 2006)
• Lower incidence of transient postoperative,
  symptomatic hypocalcemia. (Bergenfelz, Ann
  Surgery 2002)

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Preoperative Localization Studies

• 99mTc-sestamibi scintigraphy
• High-resolution cervical ultrasound
• CT Scan
• MRI
• Hand-held gamma detection probes

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Tc99m sestamibi

• Sestamibi is a radiopharmaceutical used in
  nuclear medicine imaging. The radioisotope
  attached to the sestamibi molecule is technetium
  99m, forming 99mTc-sestamibi.
• The parathyroid gland takes up IV sestamibi and
  the patient's neck is imaged with a gamma camera.
  A second image is obtained after a washout time
  (approximately 2 hours), and mitochondria in the
  abnormal glands retain the Tc99m and are seen
  with the gamma camera.

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Tc99m sestimibi
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99mTc sestamibi Sensitivity Meta-analysis
Johnson N, AJR Am J Roentgenol. 2007
Jun188(6)1706-15.
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Study Objectives

• Determine the accuracy of 99mTc-sestamibi
  parathyroid scintigraphy at MeritCare.
• Examine outcome results of single surgeon using
  bilateral cervical exploration for treatment of
  PHPT at MeritCare.
• Determine if the accuracy of scintigraphy could
  facilitate potential transition to minimally
  invasive parathyroidectomy.

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Study Design

• Retrospective chart review of sequential patients
  undergoing bilateral cervical neck exploration
  for PHPT between Mar 2006 May 2008
• Data on demographics, scintigraphy results by
  radiologist, OR/pathology results, chemistry
• Correlated OR/pathology results with scintigraphy
  reading to determine accuracy

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ResultsDemographics

• N79
• Male 12 (15)
• Female 67 (85)
• Average age 62
• Average preop Ca 11.1 (8.5 10.2)
• Average preop PTH 111 (14 - 72)
• Average postop Ca 9.0 (8.5 - 10.2)

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ResultsPathology

• Single adenoma in 92 of patients
• Hyperplasia in 3 (3.5) of patients
• Two with inconclusive scintigraphy
• One with conclusive single sided reading
• Double adenoma in 3 (3.5) of patients
• One with inconclusive scintigraphy
• Two with conclusive single sided reading
• No carcinoma

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ResultsComplications

• Biochemical cure rate at 30 days was 96
• One patient with post-op hoarseness which
  resolved over time.

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ResultsOverall Scintigraphy Accuracy
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ResultsScintigraphy Results by MD
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ResultsOverall Scintigraphy Accuracy
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ResultsConclusive Scintigraphy
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Conclusions

• Overall scintigraphy at MeritCare is not
  sufficiently sensitive to allow transition to
  routine minimally invasive parathyroidectomy.
• Conclusive scintigraphy has sufficient
  sensitivity to allow transition to selective
  minimally invasive parathyroidectomy.