Double-phase 18F-FDG PET-CT for determination of pulmonary tuberculoma activity

The aim of this study is to evaluate the potential role of double phase acquisition of (18)F fluorodeoxyglucose (FDG) positron emission tomography (PET) for the differentiation of active pulmonary tuberculoma.

A total of 25 consecutive patients with pulmonary tuberculoma were enrolled. PET/CT imaging was performed 60 (range 53-71) and 120 min (range 109-131) after injection of (18)F-FDG. The intensity of (18)F-FDG uptake by pulmonary lesions was assessed visually, and the intensity was scored with a four-point scale (grade 1: absent, grade 2: faint, grade 3: moderate, grade 4: intense).

Active tuberculoma shows statistically significant higher values in maximal standardized uptake values SUV(maxE) (active = 2.3 +/- 0.75, inactive = 0.79 +/- 0.15), SUV(maxD) (active = 2.48 +/- 0.79, inactive = 0.75 +/- 0.13), and %DeltaSUV(max) (active = 8.07 +/- 7.77%, inactive = -3.83 +/- 6.59) than those of inactive tuberculoma. When greater than or equal to visual grade 2 was used as the cutoff value, the sensitivity and specificity were 100 and 81.8%. When SUV(maxE) 1.05 was used as the cutoff point, the sensitivity and specificity were 100 and 100%. When SUV(maxD) 0.97 was used as the cutoff value, the sensitivity and specificity were 92.8 and 100%. When %DeltaSUV(max) 6.59 was used as the cutoff value, the sensitivity and specificity were 71.4 and 100%. The %DeltaSUV(max) was the potent predictor by logistic regression analysis.

The DeltaSUV(max) is a potential predictor for activity of pulmonary tuberculoma. However, the diagnostic performances were similar between visual and quantitative analyses. The visual assessment may be sufficient for determination of pulmonary tuberculoma activity. Further studies are needed to confirm these results and improve statistical accuracy.