Value of PET/CT Imaging for Diagnosing Pulmonary Metastasis of Colorectal Cancer

Background/Aims: Several types of cancer can be clinically diagnosed by PET/CT, which can also perform whole-body imaging based on 18F-fluorodeoxy-glucose (FDG) uptake. The present study assesses the value of PET/CT for diagnosing of pulmonary metastasis of colorectal cancer. Methodology: We staged or re-staged 256 patients with colorectal cancer by PET/CT. Actual and suspected pulmonary metastases were detected in 37 (male, n=23; female, n=14) patients with primary or recurrent colorectal cancer. Among them, 35 (21 males, 14 females) patients had extant homochronous (n=7) and metachronous (n=28) pulmonary metastasis. Results: The sensitivity and specificity of FDG-PET/CT for pulmonary metastasis were 57.1% and 99.1%, respectively, and the positive and negative predictive values were 90.1% and 93.6%, respectively. The uptake of FDG was affected by the size of the metastatic nodules; uptake was positive and negative in pulmonary metastases with an average size of 14.9mm and 5.75mm, respectively. The limit of positive FDG uptake was reached in pulmonary metastases of about 9mm. Conclusions: Pulmonary metastasis of colorectal cancer can be accurately and conveniently diagnosed by PET/CT, especially when nodules are >9mm.