J Nucl Med 2002 Jul;43(7):871-5
Dual time point 18F-FDG PET for the evaluation of pulmonary nodules.
Matthies A, Hickeson M, Cuchiara A, Alavi A.
18F-FDG PET has reached widespread application in the assessment of pulmonary
nodules. This study compares the diagnostic accuracy of standard 18F-FDG PET
scanning with those of dual time point 18F-FDG PET scanning. METHODS: Thirty-six
patients (21 women, 15 men; mean age, 67 y; range, 36-88 y) with 38 known or
suspected malignant pulmonary nodules underwent PET of the thorax at 2 time
points: scan 1 at 70 min (range, 56-110 min) and scan 2 at 123 min (range,
100-163 min) after the intravenous injection of 2.5 MBq 18F-FDG per kilogram of
body weight. All scanning was performed on a dedicated C-PET scanner. The mean
interval between the scans was 56 min (range, 49-64 min). Regions of interest
were overlaid onto each fully corrected image in the areas of the
radiographically known lung densities. The standardized uptake values (SUVs)
were calculated for both time points. RESULTS: Surgical pathology and follow-up
revealed 19 patients with 20 malignant tumors, whereas 16 patients had benign
lesions. The tumor SUVs (mean +/- SD) were 3.66 +/- 1.95 (scan 1) and 4.43 +/-
2.43 (scan 2) (20.5% +/- 8.1% increase; P < 0.01). Four of 20 malignant
tumors had SUVs of <2.5 on scan 1 (range, 1.12-1.69). Benign lesions had SUVs
of 1.14 +/- 0.64 (scan 1) and 1.11 +/- 0.70 (scan 2) (P = not significant).
Standard PET scanning (single time point) with a threshold SUV of 2.5 (at time
point 1) reached a sensitivity of 80% and a specificity of 94%; dual time point
scanning with a threshold value of 10% increase between scan 1 and scan 2
reached a sensitivity of 100% with a specificity of 89%. CONCLUSION: Dual time
point 18F-FDG PET results in a very high sensitivity and specificity for
detection of malignant lung tumors.
