Abstract
1557
Objectives To evaluate the diagnostic performance of dual time point FDG PET/ contrast enhanced CT (dtp FDG PET/ceCT) in the response assessment of colorectal cancer liver metastases.
Methods 28 patients, with colorectal liver metastases and treated with neoadjuvant chemotherapy, were prospectively evaluated with a dtp FDG PET/ceCT. Metabolic and morphologic studies were evaluated to assess the location, size and suspected diagnosis of lesions (benign or malignant). The final diagnosis was established by histopathology or clinical/radiological follow-up greater than 6 months. Statistical diagnostic parameters for early and delayed PET, ceCT and the combined assessment were obtained. Receiver operating characteristic (ROC) analysis was used to compare the area under the curve (AUC) of each modality.
Results A total of 130 liver lesions were identified, 123 malignant and 7 benign. From the malignant lesions, 110 were identified with the ceCT, 46 with the early PET and 54 with the delayed PET. The combined early PET/ceCT and delayed PET/ceCT revealed 115 and 116 lesions respectively. The sensitivity of early PET, delayed PET, ceCT, early PET/ceCT and delayed PET/ceCT were of 37%, 44%, 89% and 94% for both combined evaluations. The values of AUC in ROC analysis were 0.687 (p=0.09), 0.720 (p=0.05), 0.876 (p=0.001), 0.896 (p<0.001), 0.900 (p<0.001) for the early PET, delayed PET, ceCT, earlyPET/ceCT and delayed PET/ceCT respectively.
Conclusions Dual time point PET offers a limited sensitivity to detect liver metastases viability during chemotherapy treatment. An integrated evaluation with a contrast enhanced CT is mandatory to a reliable evaluation of treatment response.