Sestamibi as an alternative to mebrofenin for the diagnosis of acute cholecystitis: An alternative option during supply chain disruption

Abstract

PurposeTo determine the accuracy of Tc-99m sestamibi for the diagnosis of acute cholecystitis during a supply chain disruption of mebrofenin. Material and MethodsDuring a national shortage of Tc-99m mebrofenin in 2019, our institution initiated sestamibi imaging for suspected cases of acute cholecystitis using a standard hepatobiliary imaging protocol. Forty-one patients underwent hepatobiliary imaging with sestamibi, 39 to assess for acute cholecystitis. The examinations were initially interpreted by one nuclear medicine physician and subsequently overread by 5 blinded nuclear medicine physicians (8-30 years’ experience). SPECT/CT was obtained for 8 of these patients at the discretion of the primary interpreter. An additional 23 asymptomatic patients (6 with prior cholecystectomy) underwent abdominal scintigraphy as a negative control to determine the normal time to sestamibi accumulation in the gallbladder. A composite reference standard was used (chart review by 3 physicians). Sensitivity, specificity, and positive (PPV) and negative (NPV) predictive values were calculated with and without SPECT/CT (mean ± 95%CI). ResultsOf 39 symptomatic patients, 17/39 had acute cholecystitis and 22 did not. The sensitivity, specificity, PPV and NPV for acute cholecystitis at planar imaging were 97.6±4.6, 62.7±5.2, 67.0±3.6, and 97.3±5.2% (N=39). The values changed to 95.7±4.7, 77.9±4.7, 72.1±4.1, and 97.0±3.3% when control patients were included (N=62). With SPECT/CT, these mildly improved to 98.8±2.3%, 69.1±4.4%, 71.3±3.2%, and 98.7±2.6% (N=39), but not significantly different. On average, sestamibi activity was detected in the gallbladder in negative controls within one hour. ConclusionTc-99m sestamibi has excellent sensitivity and NPV for diagnosing acute cholecystitis and can serve as an alternative when mebrofenin is unavailable for evaluating cystic duct obstruction during shortages of standard agents.