Accuracy of Sestamibi Scan in parathyroid surgery

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					Accuracy of Sestamibi Scan in
    parathyroid surgery

1. Denham D and Norman J.
J Am Coll Surg 186 (3): 293-305; 1998.
2. Delbridge LW et al
MJA 172(9): 418-422; May 2000.
3. Reeve TS, Delbridge LW, Madden GJ.
Aust NZ J Surg 70(4): 244-250; April
2000.
           Sestamibi Scan
• What is Sestamibi?
• Hexakis-2-methoxyisobutyl isonitrite

• Biokinetic & imaging basis of Sestamibi
• Increased metabolic activity  nonspecific
  localization in mitochondria & cytoplasm

• Dual phase VS Subtraction scan
             Sestamibi Scan

• Metaanalysis:

  –   6331 patients over 10 years
  –   87% single adenoma
  –   Sensitivity: 90% (80-100%)
  –   Specificity: 99% (93-100%)
Primary Hyperparathyroidism

• Aetiology:

  –   Single adenoma    87%
  –   Double adenomas   3%
  –   Hyperplasia       9%
  –   Carcinoma         1%
    Reliability of Sestamibi Scan

•   Sensitivity        90%
•   Single adenoma     87%
•   Suitable for       90% X 87% = 78%
•   Full exploration   22%

• Specificity          99%
• Failure rate         1%
          What does it imply?
• Selection of patients for minimally invasive
  parathyroidectomy

• Advantages:
  –   Cosmetic result
  –   Possible local anaesthesia
  –   Less pain/discomfort
  –   More cost-effective
            Cost-effectiveness
• Minimally invasive vs full exploration:
  –   L/A vs G/A
  –   Operating time
  –   Frozen section
  –   LOS
  –   ?Less morbidity
• Full exploration 22%  waste of preop
  scan
• Thus, needs 78% to offset 22%
                 Summary I
• Preoperative Sestamibi scan:
  –   sensitivity    90%
  –   specificity 99%
  –   suitable for 78% of 1o hyperparathyroidism
  –   success rate 99% for single adenoma
• Minimally invasive parathyroidectomy:
  – cost-effective
  – less morbidity
        LW Delbridge MJA
• Prospective, non-randomized, non-blinded
  trial

• Period: 05/98 to 10/99

• Patients:    50 MIP
               150 full exploration
                 Results I
• MIP:
  – 42(84%) successfully completed & cured
  – 7 (14%) converted to open & cured
  – 1 (2%) persistent hyperparathyroidism
• Overall cure rate:   98%
• Complications:
  – 3 had temporary RLN palsy
  – No wound haematoma
  – No wound infection
                Results II
• Full exploration:
  – 147 (98%)   successful
  – 3 (2%)      persistent hyperparathyroidism


• Complications:
  – 1 had temporary RLN palsy
  – 4 wound haematoma
  – No wound infection
              Summary II
• Full exploration
  – 98% success rate
  – Acceptable scar
  – minimal complication of <1%
• MIP
  – Preop Sestamibi scan accurate BUT if used
    alone, missed at least 1 enlarged gland in >10%
    of cases (Pattou et al Surgery 1999 ---- double
    adenomas or incorrect localisation)
  – Intraoperative gamma probe or QPTH
   Reeve, Delbridge, Madden
• Systematic R/V of literature
• Preop localisations:
  – sestamibi, Th-Tc, U/S, CT
• Results:
  – Overall complications favour MIP
  – Operating times, LOS favour MIP
• Deficiencies of studies:
  – selection bias
  – large CI
               Summary III
• Safety:
  – No clear benefit, possible rupture, S/C
    emphysema, difficult visualization
• Efficacy:
  – Original approach already cost-effective
  – New technique needs to be better
• Recommendations:
  – Strict selection criteria
  – Level 2.2 procedure
  – Needs further studies
              Conclusion
• Sestamibi scan is accurate
• Strict selection of patients for MIP
  important based on preop Sestamibi
• Preop Sestamibi + intraoperative nuclear
  mapping or QPTH improves success rate
• Currently MIP not proven to be better
• Needs established technique
• Needs further trials