V. Sant1, A. Kundel1, J. Ogilvie1, K. Patel1 1New York University School Of Medicine,Endocrine Surgery,New York, NY, USA
Introduction: Tc-99m sestamibi imaging is commonly used for preoperative localization of parathyroid adenomas, allowing for a focused minimally invasive procedure. However, a significant false-negative (FN) rate often necessitates four-gland exploration. Prior efforts in assessing predictive factors for FN imaging have demonstrated mixed results regarding significance of histology. We hypothesize that parathyroid histology influences the sensitivity of preoperative sestamibi localization of parathyroid disease.
Methods: All parathyroid surgeries from 2007-2013 were analyzed. Cases with indeterminate pathology, absent preoperative sestamibi scan, prior neck surgery, and pathology consistent with hyperplasia were excluded. Failure of sestamibi localization but surgical finding of parathyroid adenoma was classified as false-negative (FN); concordance of sestamibi with surgical localization was deemed true-positive (TP), and discordance between sestamibi and surgical localization was deemed false-positive (FP). Results were stratified by TP, FN, and histology. Statistical significance was calculated using Pearson’s Chi-squared test. Parathyroid weight and preoperative calcium, PTH and vitamin D levels were compared using Student’s T-test.
Results:659 cases underwent analysis. 374 were TP, 31 FN and 254 FP. Of TP, 275 (73.5%) were chief cell predominant, 60 (16.0%) oxyphil, 27 (7.2%) mixed, and 12 (3.2%) clear. Of FN, 28 (90.3%) were chief cell predominant, 1 (3.2%) oxyphil, 0 mixed, and 2 (6.5%) clear. The difference in chief vs oxyphil predominance in TP vs FN was statistically significant (p=0.045). Overall sestamibi sensitivity was 92.3%, with 90.8% for chief predominance and 98.4% for oxyphil (p=0.045). Average parathyroid weight was 816 mg, TP 1012 mg and FN 405 mg (p=6.34×10-7). This difference persisted for chief cell predominance (TP 1068 mg, FN 350 mg, p=9.34×10-9), but differences for the remaining histological subtypes were not statistically significant. Preoperative levels of calcium, PTH and vitamin D were not significantly different (calcium: TP 11.3, FN 14.0; PTH: TP 122.0, FN 130.4; vitamin D: TP 26.4, FN 31.2).
Conclusion:Sestamibi imaging is significantly more sensitive in detecting parathyroid adenomas with oxyphil predominance, a cell type known to have high mitochondrial activity, which localizes sestamibi. As expected, sestamibi imaging detected TP adenomas, that were on average, over twice the mass of those in FN scans. This study represents the largest single-institution study to date on this topic. Further work to identify adenomas without oxyphil cell predominance may significantly improve preoperative localization and increase the success of a focused minimally invasive approach.