PET/CT in non-small-cell lung cancer: value of respiratory-gated PET.

The use of PET in the staging of patients with NSCLC is cost-effective, mainly due to a reduction in the number of futile operations. The addition of SUVmax to pathologic tumor size identifies a subgroup of patients at highest risk for death as a result of recurrent disease after resection. Tumor staging is more accurate with PET-CT than with CT alone or with PET alone. The greatest source of error in accurate localization and quantification on PET or PET-CT in lung cancer is respiratory motion. At MSKCC respiratory-gated PET (RGPET) is used in treatment planning. The lesion in the gated image is smaller in diameter than in the ungated image. Respiratory-correlated dynamic PET (RCDPET) can be considered an alternative method to RGPET. RCDPET shows very accurate local co-registration that can be used to make an attenuation correction and obtain an SUV. Gating gives a much clearer picture resulting in more than a one-third increase in the quantification. The SUV of lung lesions must be re-evaluated based on these techniques. This development will have important implications in areas such as the liver for controlling respiratory motion, which is a major problem in terms of lesion detection. We have successfully taken the first step in an attempt to correct for respiratory motion artifacts in PET imaging of lung lesions. (Chang