Clinical Utility of 99mTc-Labeled Ubiquicidin 29–41 Antimicrobial Peptide for the Scintigraphic Detection of Mediastinitis after Cardiac Surgery

BackgroundPrevious studies demonstrated that 99mTc-labeled-ubiquicidin 29–41 (99mTc-UBI 29–41) imaging is an accurate method for detection of bacterial infections. This study was conducted to evaluate the clinical use of 99mTc-UBI 29–41 for detection of mediastinitis after cardiac surgery.MethodsThirteen patients with suspected mediastinitis after cardiac surgery were included. Qualitative and semiquantitative analyses of 99mTc-UBI 29–41 images were performed. Mediastinitis was confirmed by bacterial culture.ResultsQualitative analysis correctly identified the infection in 5/6 patients with mediastinitis. For observer 1, there were five true-positive results, six true-negative results, one false-positive result and one false-negative result (sensitivity: 83%, specificity: 85%, positive predictive value: 83%, negative predictive value: 85%, and overall diagnostic accuracy: 84%). For observer 2, there were five true-positive results, five true-negative results, two false-positive results and one false-negative result (sensitivity: 83%, specificity: 71%, positive predictive value: 71%, negative predictive value: 83%, and overall diagnostic accuracy: 76%). Agreement between observers was 0.847 (SE = 0.145, p = 0.002). Semiquantitative analysis showed a higher mediastinum uptake of the 99mTc-UBI 29–41 in patients with mediastinitis than that derived from patients without mediastinitis. Mean uptake of 99mTc-UBI 29–41 was 60.4 ± 10.3 counts/pixel and 47.4 ± 5.5 counts/pixel, respectively (p = 0.01). At the threshold value of ≥57 counts/pixel using ROC analysis, the sensitivity, specificity, positive predictive value, negative predictive value and overall diagnostic accuracy for detecting patients with mediastinitis were 83, 100, 100, 87, and 92%, respectively (p = 0.02; 95% CI: 0.65–1.10%).Conclusions99mTc-UBI 29–41 imaging yielded fast and promising first results for patients with suspected mediastinitis after cardiac surgery and, as such, deserves further investigation.