V. D. Krishnamurthy1, S. Sound1, A. K. Okoh1, P. Yazici1, H. Yigitbas1, D. Neumann2, K. Doshi3, E. Berber1 1Cleveland Clinic,Department Of Endocrine Surgery,Cleveland, OH, USA 2Cleveland Clinic,Department Of Nuclear Medicine,Cleveland, OH, USA 3Cleveland Clinic,Department Of Endocrinology,Cleveland, OH, USA
Introduction:
There are scant data in the literature about repeated sestamibi imaging in patients with primary hyperparathyroidism (PHPT). We aimed to determine the utility of repeat sestamibi scans in these patients.
Methods:
We performed a retrospective review of patients with PHPT who underwent repeat sestambi scans from 1996-2015 within our healthcare system. Patients underwent single-agent dual phase 99mTc-sestamibi ‘delayed’ scans (DS), iodine-subtraction 99mTc-sestamibi scans (ISS), or both. Patient demographics and disease characteristics were recorded. Findings between initial and subsequent sestamibi scans were compared, followed by univariate and multivariate regression analyses to identify predictors for conversion from an initial negative to a subsequent positive scan.
Results:
We identified 133 patients who underwent repeat sestamibi scans. Sixty-three scans were initially negative (44%), of which 23 were DS (37%) and 40 were ISS (63%). Of repeated scans, seven were DS (11%) and 56 were ISS (89%). Twenty-two patients had scans that converted to positive (35%), five with subsequent DS (8%) and 17 with subsequent ISS (27%). Initial negative DS were more likely to convert to positive with subsequent scan compared to initial negative ISS (p=0.03). Of patient groups, scans of patients with normocalcemic or normohormal PHPT were less likely to convert to positive than scans of patients with classic PHPT (p=0.003). Scans of asymptomatic patients demonstrated the highest rate of conversion to positive (73%, n =16), of which 80% were initial DS followed by subsequent ISS. In multivariate analysis, increase in serum calcium (p=0.009) predicted conversion from a negative to a subsequent positive scan.
Conclusion:
Repeating the sestamibi scan was helpful in 35% of patients, especially when the initial exam was a delayed scan and the subsequent exam was an iodine-subtraction scan. Repeat scans of patients with classic hyperparathyroidism were more likely convert than those of patients with variant biochemical profiles. Consideration should be given to obtaining an iodine-subtraction scan after an initial negative scan, especially in patients who are asymptomatic or have higher serum calcium levels. To our knowledge, this is the first study looking into the utility of repeat sestamibi scans in patients with primary hyperparathyroidism, which can be useful in planning surgical approach.