Prediction of residual disease of spine infection using F-18 FDG PET/CT

Prospective study.

To determine whether F-18 fluoro-deoxy-glucose positron emission tomography/computed tomography (F-18 FDG PET/CT) follow-up imaging after treatment in patients with spinal infection (SI) could provide useful prognostic information and determine the residual SI.

There are seldom data on the capability of follow-up imaging methods to predict residual disease and treatment efficacy in patients with SI.

Thirty patients with SI underwent F-18 FDG PET/CT at initial and during follow-up. From F-18 FDG PET/CT, quantitative indexes were obtained. The residual SI was determined by the presence of preoperative symptoms, hematological infection marker, and radiologic findings.

The SUVmax were significantly declined after treatment in both of residual (2.85 +/- 1.17 vs. 2.06 +/- 1.03; P < 0.0001) and nonresidual SI (4.31 +/- 2.07 vs. 1.44 +/- 0.46; P < 0.0001). The SUVmean were also decreased after treatment in both of residual (1.45 +/- 0.45 vs. 1.04 +/- 0.29; P = 0.0014) and nonresidual SI (2.09 +/- 1.03 vs. 0.81 +/- 0.25; P < 0.0001). By lesion-based analysis, when < or =43.01% of %deltaSUVmax was used as threshold value, the area under curve (AUC) was 0.879 (P = 0.0001). The sensitivity and specificity were 85.7% and 82.6%, respectively. When < or =44.12% of %deltaSUVmean was used as threshold value, AUC was 0.828 (P = 0.0001). The sensitivity and specificity were 85.7% and 68%, respectively. In patient-based analysis, when < or =46.14% of %deltaSUVmax was used as threshold value, AUC was 0.904 (P = 0.0001). The sensitivity and specificity were 100% and 76.9%, respectively. When < or =41.78% of %deltaSUVmean was used as threshold value, AUC was 0.923 (P = 0.0001). The sensitivity and specificity were 100%, 76.9%, respectively.

F-18 FDG PET/CT is useful for discrimination of residual and nonresidual SI after treatment. Among the various quantitative indexes, %deltaSUVmax is a potent predictor of residual SI in the current study.