Objective: To compare the diagnostic value of ⁹⁹Tc(m)-MIBI SPECT/localizable CT and ¹⁸FDG-PET/CT in patients with indeterminate solitary pulmonary nodules (SPNs) and assess the feasibility of using ⁹⁹Tc(m)-MIBI SPECT/localizable CT as an alternative when ¹⁸FDG-PET/CT is not available.
Methods: Thirty-nine patients with indeterminate SPNs were examined by ⁹⁹Tc(m)-MIBI SPECT/localizable CT, and another 46 patients by ¹⁸FDG-PET/CT. The findings of the two modalities were analyzed qualitatively and semiquantitatively to assess their efficacy for a definitive diagnosis of SNPs.
Results: Of the 39 patients examined by ⁹⁹Tc(m)-MIBI SPECT/localizable CT, 13 were identified to have malignant SPNs and 26 had benign SPNs; the diagnostic sensitivity, specificity, accuracy, positive predictive value (PPV) and negative predictive value (NPV) of the examination were 92.31% (12/13), 88.46% (23/26), 89.74% (35/39), 80% (12/15) and 95.83% (23/24), respectively. Of the 46 patients receiving ¹⁸FDG-PET/CT examination, 29 malignant cases and 17 benign cases were identified with a diagnostic sensitivity, specificity, accuracy, PPV and NPV of 96.55% (28/29), 76.47% (13/17), 89.13% (41/46), 87.50% (28/32) and 92.86% (13/14), respectively. The two modalities showed no significant differences in the diagnostic sensitivity (χ² =0.356, P=0.55), specificity (χ² =1.084, P=0.298), accuracy (χ² = 0.008, P=0.927), PPV (χ² = 0.453, P=0.501) or NPV (χ² =0.157, P=0.692). The ROC curve showed that with the early uptake ratio (EUR) of ⁹⁹Tc(m)-MIBI ≥ 1.474 and ≥ 1.38 as the cutoff values, the sensitivity of ⁹⁹Tc(m)-MIBI SPECT/localizable CT was both 100% and the specificity both 76.90%; with the maximum standard uptake value (SUVmax) of ¹⁸FDG ≥ 2.40 as the cutoff value, the sensitivity of ¹⁸FDG-PET/CT was 96.60% and the specificity was 76.50%, showing no significant differences between the two modalities in the diagnostic efficacy.
Conclusion: ⁹⁹Tc(m)-MIBI-SPECT/localizable CT may be a useful and practical modality for early diagnosis of SNPs for patients with a medium or low income in small and medium-sized cities.